electronics repair guide

8/4/2019 Electronics Repair Guide

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This guide is made up of selections from a : larger source.The, table on contents is accurate. but you will findsome pages that appear to be missing. This was

done. intentionally to remove some materialthat was not needed.



_ T , . ' .? '::. - . '. :.



CONTENTS

EMERGENCY GUIDE 8

ENTERTAINMENT SYSTEMS 12

RECEIVERS 18

AUDIOCASSETTE RECORDERS 28

TURNTABLES 42

COMPACT DISC PLAYERS 52

SPEAKERS AND HEADPHONES 60

TOOLS & TECHNIQUES 126



EMERGENCY GUIDEPreventing home electronics problems. The electronic unitsin your home are expertly designed for years of safe, worry-free use. With proper care and maintenance, most of them canlast a lifetime - outdated only by newer, more sophisticated

units. Yet, even with the latest in engineering technology,emergency situations can occur; it's usually only then that wepay belated respect to the electrical current coursing throughthe intricate circuits housed in these machines.

Although rare, electrical emergencies are the most likelyand serious threat to the user of an electronic unit. You caneasily prevent most electrical emergencies by proper installa-tion, use and maintenance of the machine. Familiarize your-self with the owner's manual that came with the unit; if youhave misplaced it, order a new one from the manufacturer.

The repair of electronic units need not be any more danger-ous than their routine use. Indeed, a repair procedure that isproperly performed can prevent hazardous conditions. The listof safety tips at right covers basic guidelines for the mainte-nance and repair of any electronic unit; consult the chapters onindividual units for more specific advice.

Electrical shock and fire are life-threatening emergenciesthat can happen in even the most safety-conscious of homes.Deprive fire of its sneak attack by installing smoke alarms ju-diciouslythroughout the house, Have the correct fire extin-guisher on hand to snuff out a blaze before it gets the upperhand, and learn how to.use it before you need it (page 1J J . Ifyou must rescue someone stuck to an electronic unit by livecurrent, do not touch him; use a wooden broom handle orwooden chair to push him free (page 10). Keep medical emer-gency numbers posted by the telephone, and do not hesitate touse them; in most areas, dial 911 in case of a life-threatening

emergency.Prepare yourself to handle emergencies before they occur.Read the Troubleshooting Guide on page 9, which placesemergency procedures at your fingertips. It lists quick-actionsteps to take and refers you to the steps on pages 10 and 11 fordetailed instructions. Also review Tools & Techniques (page

126); it provides invaluable information on repairing elec-tronic unit components and on the safe use of tools.

Get technical help when you need it. If you are in doubtabout the safety of an electronic unit or about the nature of arepair, have the unit checked out by a professional servicetechnician. And even in non-emergency situations, an inspec-tor from your utility company or fire department can answerquestions concerning the condition and proper use of your

home's electrical system.

8

SAFETY TIPS

1. Bafore attempt ing any repair in this book, read the enti re pro-

cedure. Famlliariza yourself with the specific safety information

presented in each chapter.

2. Read Entertainment Systems (page 12) to understand the

interre lationship of e lectronic units that are hooked up together,

Refer lo Tools & Techniques (page 126) for instruct ions on the

proper use of tools and on getting help when you need it.

3 . Never use or work. on electronic units under wet condit ions.

Make sure grounding wires are properly connected.

4. Turn off and unplug the electronic unit before a repai r. Dlscon-

nect the cables and any ground wire hooked up to il (page 12).

Set it on a clean work. table thaI is well lit; do not touch any inter'

nal component you cannot see.

5. Removewalches and jewelry before starting a repai r. Cover

the electronic unit if you take a break while working. Store tools

safely; do not set them down insloe the uni t.

6. Cover the power- supply components (page 138) with a non-

conductive shieJo as a precaution during voltage tests. Avoid

tciuchinganylhing but the-contact points being tested.

7. Never took directly at the laser ina compact disc player that is

plugged in and turned on; it can cause eye damage.

8. Wear eye protect ion when making repairs inside a television.

Prevent injury from picture-tube implosion by asking a quali fied

service technician to dispose safely of an old set.

9. When making outdoor repairs to antenna and cable systems.

work oil a dry, calm day. Work with a helper. or at least within

earshot of someone else. Do not service any system near over-

head utility lines. .

10. Use only replacement components of the same specificatiQns

as the originals. Consult the manufacturer of the electronic unit or

a reputable electroniCS parts supplier.

11. Perform a cold check for leaking voltage (page 141) after re-

assembl ing an electronic uni t but before plugging it back in . .If in

doubl about the safely of a . repair. have a qualifiet;f'professional

service technic ian check it.

12.•Avoid running power cords under carpets or through heavily

trafficked areas. Do not use ex.tension cords. Never spiice power

cords or remove the grounding prong from a three-prong plug.

Do not al ter the larger prong on a polarized plug.

13. Keep food and beverages away from elect ronic units. and

make sure ai r vents remain unobstructed and oust-free,

14. Unplug electronic units and disconnect external antennaconnections from the televis ion before going on vacation.

15. Instal l surge .suppressors to protect computers and other

sensitive electronic units from voltage spikes.

16, locate and label your home's electrical service panel.

17. Instal l smoke detectors and fire extinguishers in your home.

18. Post emergency. ut il ity company and repair service numbers

near your telephone.



EMER GE NC Y G UID E

TROUBLESHOOTING GUIDE

PROBLEM PROCEDURE

Fire In unit, powereordor wall outlet Call f ire department .

Use fire extinguisher rated for electrical fires (p. 11)

Shut off power at service panel; then, unplug unit power cord from wall outlet (p. 10)

I f f lames or smolgering continue,leave house and wait for f ire department

Unit power cord or plug sparking or hot Shut off power at service panel; then, unplug unit power cord from waUoutlet (p. 10)

Unit gives oft sparks or shocks. user Unplug uni t power cord f rom wal l out let or shut off power at service panel (p. 10)

Locate and repair cause of sparks or shock, or take unit for professional service

Smoke coming from unit , Uhplug unit power cord from w < ! - I I outlet or shot off power at service panel (p . 10)

Take unit for protsssionat service

Burning or other peculiar odor coming from unit Turn off unit and unplug unit power cord from wall outlet (p. 10) ; iNait until odor dissi-pates before servicing unit

Locate and repair cause of odor or take unit for professional serv ice

Unit is excessively hot Turn off unit and unplug unit power cord from wall outlet (p. 10 )

Check uni t ai r vents and clean air vents (p. 11) if necessary

Reposition unit with air venls unobstructed

Do nol touch unit or any plumbing i ixture; dry yourself if you are wetnit Is flooded

Shut off power at service panel; then. unplug, unit power cord from wall out le l (p. 10)

Dry unit with absorbent c loth and ~air dryer (p . 11 )

Beverage or other foreign material spilled Inlo unit Unplug unit pow.er cord from wall outlet (p. 10)

Dry unit With absorbent c loth and hair dryer if wet; or clean the components (p . 11)

If person is immobilized by l ive current, push him away from source with woodenbroom handle or wooden chair (p. 10)

Electrical shock

Check whether victim is. breathing and has pulse. If not, begln artiiicial resuscitationor cardiopulmonary resuscitation (CPR) i f you are qualif ied. Otherwise, place vict im inrecovery position (p. to), and call for help

Electrical burn Soak if1juryIn cold water ar id cover with ster ile gauze if severe

Seelunedical attention immedlately, since electrical burns can cause internal injury

Power failure Turn off a ll units that have molars, to prevent overloading electrical system whimpower is restored

Keep emergency supplies on hand, including a flashlight or candles

Leave a light on so that you wil l know when power is restored

Lightning storl)' l Unplug all e lectronic units or use a surge suppressor to protect them

Slay away from windows, doors, fireplaces, radiators, stoves, sinks and pipes

Util ity line down Call utili ly company, police or fire department

Treat every fal len line as if it were live with electricity. Stay faraway from the l ine andanything it touches, including fences, trees and antennas .

Antenna fa{len against util ity l ine Do not touch units hooked up to antenna

Do not attempt to dislodge antenna

Call utility company, police or fire department

Operation warning.A triangle with an

sxctarnatlon mark.

warns the user to

consult the owner's

manua l before oper-

atjng the unit.

Voltage warning. A triangle with a l!ghtning

bolt warns of a potential electrical snack hazard.Usually, this symbol can be found on th e back

or bottomottha un it . I f the symbol isposted on

an internal component, 'do not touch the compo-

nent: electrical current may be sterad in i teven

!hough the unit is turned off and unplugged.

laser warning. A triangle or square

"Yith a sunburst symbol warns of possible

danger f rom a laser. This symbol may be

found on the back or bottom of a compact

disc player. Never look directly at anop-

eraling laser: its intense light can cause

permanent eye damage.

SAFETY SYMBOLS ON ELECTRONIC UNITS

9



EMERGENCY GUIDE

CUTTING OFF ELECTRICAL POWER

Shutting down power at the. service panel. If th e flo or . a ro u ndtha service pa nel is w et, s ta nd on a dry boa rd o r a rubber ma t, O rw ea r ruboer boots . W ea r hea vy, dry rubber gloves a nd us e only

one h and: keep the other ha nd in your poc ket or beh ind your ba ck.A t a c irc uit b re Clk er p an el, flip o ff th e m a in b re ak er (ab9ve). A s ana dde d prec au tio n, u se y ou r knu ckle; th at w a y, a ny s ho ck w ilt jerk;your ha nd a wa y from the pa nel. A ta fuse pa nel, grip the ma in fus eblo ck b y its h an dle a nd p ull ito ut (inset). If the fuse pa nel ha s as h uto ff le va r , . sh ift it to th e OFF posit ion.

Pulling the power cord plug from the wall outlet. If th e flo ora ro und th e w a ll o utlet is w et,o r if th e w a ll o utlet its elf is s pa rkin go r bu rn ing, do n ot to uc h th e po wer c ord o r th e e lec tro nic u nit. In-

s tea d, s hu t o ff P ow er a t th e s ervic e pa ne l (left). Othel 'N i se, d iscc ir 1 -n sc t th e p ow e r ·c .o rd p lu g. P ro te ct y .o ur h a nd w ith a th ic k, d ry to w elo r a h ea vy w o rk gio ve. W ith ou tto uc hingfh e w a ll Q utle.! or th e a la e-tro nic u nit, gra sp th e po wer c ord s evera l. inc hes fro m ih e p lu g a ndpu ll th e p lu g o ut o f th e w a ll o utlet (above). Lo ca te a nd re pa ir th ep ro ble m b efo re u sin g th e e le ctro nic u nit o rth a o utle t a ga in .

RESCUING A VICTIM OF ELECTRICAl.. SHOCK

Freeing someone from a live current. U sua lly a pers on w hoc onta cts liv e c urrent w ill b e th ro w n b ac k fro m th e s ou rc e. B uts om etim es m us cle s c on tr ac t in vo lu nta rily a ro un d ill w ire o r c om -po nent. D o n ot to uc h th e. v ic tim o r th e u nit. P \lll th e po we r cordplu glro m th e w a ll o utlet (step above, rigbt) or shut off pow er a tth e m ain s ervic e pa nel ( st ep a bo ve , le ft) . IIthe po wer ca nnot becut im media tely, us e a w oo den bro om ha ndle or w ooden ch airto kno ck th e pe rs on free (above).

Handling a victim of electrical shock. C a ll to r h elp lm rn e-d ia te ly .C h ec k th e v ic tim 's b re a th in g a n d h ea rt be a t. If there is noI:lr ea th in g o r h ea rtb ea t, g iv e m outh -to -m o ut h r as u sc lt atlo n o r e a r-d iopu lm( )nary resusct ta t ion (CPA~o nly il Y ou a re qu alified . If th evic tim is brea th in g a nd h as n ot s us ta ined ba ck o r nec k in ju (Ies ,p la ce 'h im in th e re co ve ry p os itio n (above). T iltth e h ea d ba ck w iththe fa ce to one s ide a nd the to ngue forw a rd to m ainta in a n opena irW a y. K ee p tM v ic tim c alm a nd c om fo rta ble U ntil h elp a rriv es .

10



EM ER GE NC Y G UID E

. .

CONTROLLING AN ELECTRICAL F IRE

Using a fire extinguisher. Call the

f ire department inimediately. I f there are

flames or smoke coming from the wallsor ceiling, leave the house to.call lor help.

To snuff a small, accessible lire in an

electronic unit or at th e wall oullat, use a dry-

chemical fire extinguisher rated ABC or

BC. Stand near an exit, 6 to. 1Oleet from

th e f ire. Pul th e l o c k pin o ut of the extinguish-

er handle and, holding the extinguisher

upright, aim the nozzle at the base 01 the

flames. Squeeze the two levers. of the

handletogelher, spraying in a quick side-

to-side motion. Keep spraying unti l the fire

is completely extinguished. Watch care-

fully for ·f lashback," or rekindling, and be

prepared to spray again. You may also

have to shut off power at the service panel

(page 10) to remove the source of heal or

sparking causing the fire. Find the cause

of the fire and remedy it before using the

electronic unit or the out let again. Have

the l ire department examine the area

even if the fire is out.

CLEANING UP SPILLS AND DIRT

Drying and cleaning internal components. Turn off the elect ronic uni t and unplug it from the wal l outlet. Qisconnect its

cables and any ground wire hooked up to it (page 12). Set the unit on a clean work table. Refer to the chapter on the electronic

uni t for instructions on reaching the internal components. Using a clean, l int -free, absorbent cloth, carefully soak up pools of

liqUid. Dr y the internal components thoroughiy using a hair dryer set on the no-heat or low-heat position (above, left); aim with

slow, sweeping motions to avoid heating up a component. To remove sticky dust or dirt particles from components, spray them

with short bursts of compressed air (above, right). Use foam swabs to clean components; apply denatured alcohol to metal or

p lastic, rubber-cleaning compound to rubber, and electronic contact c leaner to circuit boards and switches. Final ly , lubr icate

moving parts by applying light machine oil to metal and white grease to plastic. Perform a cold check' for leaking voltage

(page 141) af ter reassembling the electronic uni t but before plugging i t back into the wal l outlet.

11



ENTERTAINMENT SYSTEMSIt may boast a top-of-the-line compact disc player and video-cassette recorder, or just a modest receiver,' turntable andspeakers, but a typical entertainment system (below) is aninvestment in leisure that can cost thousands of dollars. While

each additional unit adds new entertainment options, it alsocomplicates system hookups and problems diagnosis.

Thanks to solid-state circuitry, electronic. problem are rareand can be logically deduced from their symptoms. Refer tothe appropriate chapter to troubleshoot your telephone system(page 100) or your computer and printer (page 110). Butconsult the Troubleshooting Guide in this chapter (page 14)

first before referring to the chapter covering a specific audiovideo entertainment unit.

To answer questions about the set-up or cable hookups fyour entertainment system, check the owner's manual th

came with each unit or consult the manufacturer, As a generrule, most units perform best if the cables between them akept as short as possible, reducing electrical resistance aninterference that weaken the audio or video signal; if the cabis coaxial, this is less of a worry. An exception is the turntablwhich is highly sensitive to vibration and signal interferencposition it at least 3 feet away from the speakers.

Compa c t d is c p ll!y erLeft- and r ight·channela u dio o ut pu t c a ble s t ot ha r ecei ve r a r e con-n ec te d b y p ho ne p lu gs .

I I . . . I ~ l l I~I. t _ p : = = = = = ~ ~ . = = r = ; = ; = = r = = r = r ~ 10 IE5 c:s

AudiocaBSette

_rderle ft - a n d r ig ht ·c h anne l au diOi nput and out pu tc a ble s t o a n df rom t he r a ce iv erco nnec t w i th

phono p lu gs .

. . - • .> To ou tlet

Receive,Speaker cab les (shown) provide left · an d r igh t- charme l aud io ou tpu t to speaker s. Tw i re ends co nnec t t o sp ri ng -l oaded t erm ina ls , c eps o r sC reWS .l ef t· and right-channeou tpu t cab les (sbown) f rom t ur nt abl e o r compact d is c p la yer • .a nd left· and right-c h anne l i nput and out pu t c abl es (shown) t o and f rom audi oca s se tt e r eco rder , c o nnewith phono p lu g s, A ground wi r .1 i Ishowrr ) f rom tu rn table con l' 18C1so the ground ings cr ew . A n in do or FM antenna (Shown)connacts with spada lugs 10s c rews . S ignalc a ble fr om a n o ut do or a nt en na ma y b e c oa xia l, o r s h ie ld ed t w ill· le ad w it h c ap s o rs cr ew s c on ne ct in g it s w ir e e nd s: s ig na l c a ble fr om t he c a ble , s y st am is c oa x ia l. A u dinput .(shown) a n d o ut pu t c a ble s t o a n d from v ideocasse tte reco rder , o r aud iO ou tpucabl e f rom tel ev is io n, co nnec t w i th phono p lu gs o r co ax ia l c o nnect or s ,

,..,......." "" "! '-

:{!//ll//I/l///!////t

~ ~ : ; } O O . · . 1 , 0 .,/1 . 1111

,~ . ._ ..~ • c 4

~o

,"-~ '-~ ~' ..'--- '-' ..- .. ."---.'-~.---.~.--'~ '"-'.'-" ' G round " ..•. ,-; ,.-~ .~ .. To FM dipola antenna . ..~__ v_. To. , • 0n

IIl

e DO

o

i-.......'....- -~.I

I I

TelevisionS ig na l c a bla ir On ) a no uld oo r a n te nn a ma y be c oa x ia l, w it h a -s cr ew - on o r p os h -o n c on ne cto r. o r s h ie ld ed tw in -le a d. w ith s pa de lu gs c on ne ct in g t o a ma tc hin gt ra n sf orme r; s ig na l c a bl e f rom th e c a ble s ys tem is c oa x ia l. V id eo a n d a ud iO in pu tcable (snown) fr om th a v id eo ca s se tte r ec or de r, a n d a u d io o utp ut c a ble 1 0 th e r e-ce iv er , may be connec ted by .p I1ono p lugs o rcoax ia l connec to rs,

l I e I I.-t> D

VldeocliSll8tte recorder. S ignal c abl e (shown) fro m a n o utd oo r a nte nn a m ay b e c oa xia l, w ilh as c rew -o n connect or . o r s h ie lded tw in ·l ead w i th a ma tch ing- tr a ns f ormer ;,signal cable fr om t he c a ble s ys tem is c oa x ia l. V id eo o ut pu t ~ e (shown)

t o t he t el ev iS io n , and audi o o u tpu t c abl e (shown) t o t he t el ev is io n o r r ece iv er ,h a ve phono p lu gs o r co ax ia l c onnec to rs .

12



Many entertainment system problems can be resolved byadjusting cable hookups. Always turn off the units before tam-pering with their cables. If you 'must disconnect a cable, tag itfirst, noting at each end the specific terminal to which it con-nects; if there is more than one wire or connector' at the end ofthe cable, tag each one, Cable connections at a splitter box,which routes a signal to more than one unit,should be labeledas carefully as those at the entertainment system units.

To tame the profusion of power cords in an entertainmentsystem, install a grounded multiple-outlet plug in the walloutlet. Some are available with a voltage spike protector,

Headphones

.C on nec t 1 0 a ia ck o n th e

receiver (shown), audio-

casset te recorder, oompatid is c p la y er , v id e oc a s se tt e

r ec or de r o r t ele vls io n, w it ha 1/8- o r1 1 4· in ch h ea d ·

p ho ne p lu g.

'o_-·. __ . . · . , . _.,..- .. " " " _ 1

!

lumtllble.

Left· a n d r ig ht ·

c ha nn el a u dio

o u tp u t c a bl es 10

receiver (shawn)

a re co nnec ted '

b y _p h on e p lu g s.

A ground wire(shawn) con-n ec ts t o r ec eiv er

g ro un din g s cr ew , _

.® s ·

aspeakerF > o / l i t i v e a nd n eg at iv e le tt -c ha nn el o r r ig ht cc ha n ne l a u d i O

output fro m th e fe(;8 jveris se nt th ro ugh s pea ker c able

(shown). The w ire ends o r sp ade lu gs c onnec t to s pring·

l o aded . te rm i na l s , caps o r S crew s, E ns ure th at th e w ire

c on ne ctt, K1 to th e. p os itiv e te rm in al, in dic ate d b y th e c olo r

red o r a plus s ign ( ...), is the sa me w ire connected to the

p os it iv e t er min ai a t t he r ec eiv er .

ENT ER TA lNMENT S YS TEMS

which can shield sensitive electronic equipment from powersurges. First check your fuse box or circuit breaker panel tomake sure the circuit cart handle the load. especially if otherhousehold appliances will be running at the same time. Do notuse extension cords; reposition the units instead, if necessary.

Once you eliminate cable hookups as the source of a prob-lem, service the unit itself-First refer carefully to the Emer-gency Guide (page 8) and Tools and Techniques (page 126).

Then consult the unit's chapter; pay special attention to theintroduction and familiarize yourself with the exploded dia-gram before beginning work.

TELEPHONE SYSTEMMa y be c onne cie d to th e c om pu ter s ys tem

through a m od em , a tw o .w a y in te rfa cin g

d~ ce th ai C ha ngils c om pu ter s igna ls iilto

te le ph on e S ig na ls a nd v ic e v ers a.

Answering

mllChlne

P lu g o n lin e c ord

from wal l ja ck , a ndplug o n lin e c or d

f r om te lephoneba se, c onne ct to

ja c ks in m a ch in e.

, WaU lack

! 0C on ne cts lin e c ord fromi_-__.. : te le ph on e b a se , a ns w er in g

mach ine o r modem to .

~ telephone sys lem.

1

!_ _ ~ " "'- '" '_00 T o o u td o or

L:J cableas e

O ne ja ck a coepts the h andset co rd

p lu g. A no th er ja ck accepts t he p lu g

o n the line co rd from th e w alt ja ck o r

a n s wer in g ma c ll in e.

T erm in al b lo ck

In te rla ce b etw ee n o utd oo r a nd

indoo r ca ble ; m ay ha ve a ja ck:

Handset

A ja ck a cc epts th e

plu g o n the handset

cord from t he t ele ·

phone base.

COMPUTER SYSTEMMa y ti e CQnnectad to r,=======::::;-'th e t ele ph on e s ys te m

through a modem, at w o -w a y I nt er la c in g

d ev ic e lh a l changes

te le ph on e s ig na ls in to

compu ter s igna ls .

a nd v ic e v ers a.

Keyboard

Ca ble fro m key bo ard c onn ec ts to

m ain u nit w ith 0825 connector.

Moni tor

C ab le fr9 m m on ito r

c on nec ts to m ain

unit with 0825

connector.

M ain u nit

C a bl es l. ro m mo n it or ,

k ey bo ard a nd p rin te r

co nnec t w ith D B2 5 c on-

n so to rs . C ab le Ir om

printer has para lle l-portor serlal-port connector.

-..

13



ENTERTAINMENT SYSTEMS

TROUBLESHOOTING GU IDE

SYMPTOM POSSIBLE CAUSE PROCEDURE

AUDIO ENTERTAINMENT SYSTEMS

No display lights, no sound Receiver and/orotherunit unpluggedor turned off

Plug in and turn on receiver andlor audiocassette recorder, turntable.or compact disc player

Remote control dirty or faultyReset breaker or replace fuse (p.IO) DO; have out let servicedo power to outlet or outlet faultyService remote cornrol (p . 136) DO

Receiver, audiocassette recorder. turntableor compact disc player faul ty

Service receiver (p. 18) or audiocassette recorder (p. 28) or turntable(p. 42) O r compact disc player (p. 52)

Display lights, but. no sound Receiver and/or audiocassette recorder.turntable or compact disc pl.wer controlsset incorrectly

Adjust receiver andlor audiocassette recorder, turntable or compactdisc player controls; in particular, .check receiver volume and tape-monitor controls

Receiver, audiocassette' recorder. turntableor compact disc player faulty

Adjust receiver selector control to other modes, I f there is sound. sevice audiocassette recorder (p . 28), turntable (p . 42) or compact discplayer (p. 52); i f no sound, service receiver (p . 18)

Sound from only one speakerchannel

Receiver controls set incorrectly Adjust receiver controls; in particular, check i;lalance control

Cable hookup faulty between speaker andreceiver or between receiver and audio-cassette recorder, turntable or compactdisc player

Adjust receiver selector control to other modes, I f there is sound froboth speaker channels. check. cable hookups between receiver andaudiocassette recorder, turntable or compact disc player (p. 16) DO;i f there is sti ll sound from only one speaker channel, check cablehookups between speakers and receiver (p. 16) DO

Audiocassl;ltte recorder, turntable orcompact disc player faulty

Adjust receiver selector control to other modes. I f there is sound iromboth speaker channels. service audiocassette recorder (p. 28), turn-table (p. 42) or compact disc player (p. 52)

Speaker or receiver faulty Reverse receiver left- and righi-channel cable connections. If nosound from same speaker, service speaker (p. 60); if no sound fromother speaker, service receiver (p . 18)

Sound Intermit tent or distorted . .Receiver turier control set incorrectlyfrom the radio

Antenna posltloned incorrectly

Adjust !receiver tuner control

Adju'st antenna

Cable hookup faul ty between speaker andreceiver or between receiver and antennaor cable system

Adjust receiver selector control to other modes. If sound is OK, checcable hookups between receiver and antenna or cable system (p . 1DO; if sound not OK, check cable hookups between speakers andreceiver (p . 16) DO

Antenna or cable system faulty Adjust receiver selector control to other modes. If sound is OK.service antenna or cable system (p. 76)

Speaker or receiver faulty Reverse receiver left-and right-channel cable connscnons. If sound

not OK from same speaker, service speaker (p. 60); if sound not OKfrom other speaker, service receiver (p. 18)

Sound intermit tent or distortedfrom the audiocassette re-corder, turntable or compactdisc player

Cable hookup faul ty between speaker andreceiver or between receiver and audio-cassette recorder, turntable, or compactdisc player

Adjust receiver selector control to other modeS. If sound is OK, checable hookups between receiver and audiocassette recorder, turntabor compact disc player (p . 16) DO; if sound not OK, check cablehookups between speakers and receiver (p. 16) DO

Audiocassette recorder, turntable orcompact disc player faulty

Adjust receiver selector control to other modes. If sound is OK, ser-vice audiocassette recorder (p. 28). turntable(p. 42) or compact displayer (p. 52)

Speaker or receiver faulty Reverse receiver left- and right-channel cable connections. If soundnot OK from same speaker. service speaker (p. 50); if sound not OKfrom other speaker, service receiver (p : 18)

Humming, buzzingor rumbling noise

Speaker vibrating or too close to turntable Reposition speakers

Cable hookup faulty between speaker andreceiver, or between receiver and antennaor cable system, or between receiver and

audiocassette recorder, turntable or compactdisc player

Adjust receiver selector control to other modes. I f sound is OK, checable hookups between receiver and antenna or cable system (p. 1DOor between receiver and audiocassette recorder. turntable or.

compact disc player (p. 16) DO; if sound not OK, check cable hooups between speakers and receiver (p. 16) DO

Ground wire hookup faulty Check ground wire hookups (p. 17) DO

Antenna or cable system (radial, or audio-cassette recorder, turntable or compact discplayer faulty

Adjust receiver selector control to other modes. If sound is OK.service antenna or cable system (p. 76) or audiocassette recorder(p . 28). turntable (p. 42) or compact disc player (p . 52)

Speaker or receiver faulty Reverse receiver lell- and right-channel cable connections. II soundnot OK from same speaker, service speaker (p. 60); if sound not Ofrom other speaker, service receiver(p. 18)

DEGREE OF DIFFICULTY:

ESTIMATED TIME:

DEasy ~ Moderlilte • Complex

o Less than 1 hour' ~1 to 3 hours • Over 3 hours

14




ENTERTA INMENT SYS TEMS

V I D E O ENTERTAINMENT SYSTEMS


No display lights, no pictureand no sound.

Television orvldeocassene recorderunplugged or turned off

Plug in and turn on television and videocassette recorder

Cable converter unplugged

Reset breaker or replace 'fuse (p . 10) 00; have outlet serviced

Plug in converter

No power to outlet or outlet faulty

Television or videocassette recorder laulty Service television (p. 68)ar videocassette recorder (p_ 88)

Display lights, but no pictureand no sound

Adjust television and videocassette recorder controls; in particular,check channel selector controls,

Television or videocassette recorder controlsset incorrectly

Turn off v ideocassette recorder and tune in television. I I s ti ll nopicture and no sound, service television (p. 68); i f there are pictureand sound, service videocassette recorder (p _ 88)

Television or videocassette recorder laulty

Picture,but. no sound Adjust television and receiver controls; in particular, check teleVisionand receiver volume' controls and receiver tape-monitor control

TeleVision or receiver controls set incorrectly

Check audio cable hookups between television and videocassette re-corder, and between receiver and television or videocassette recorder(p . 16) 00

Audio cable hookup laulty between tetevl-slon and videocassette recorder. or betweenone of these units and receiver

Receiver faulty Adjust receiver selector control to other modes. II. no sound, servicereceiver (p. 18)

Television or videocassette recorder faulty Turn off videocassette recorder and tune in televis ion. I f st il l nosound, service television (p. 88): i f there is sound. service video-cassette recorder (p . 88)

Sound, but no picture Adjust television and videocassette recorder controls; in particular,check television brightness and contrast controls

Television or videocassette recordercontrols set incorrectly

Video cable hookup faulty betweentelevision and videocassette recorder

Check video .cable hookups between television and vldaocassetterecorder (p.16) 00

Television or videocassette recorder faulty Turn off v ideocassette recorder and tune in televis ion. I I s ti ll nopicture, service television (p _ 68); i l there is picture, service video-Cassette recorder (p . 88)

Sound from only one speakerchannel

Adjust television and receiver controls; in particular, balance controlselevision or receivercontrols set incorrectly

Audio cable hookup faulty between televi-sion and videocassette recorder. or betweenreceiver and television or videocassetterecorder, or cable hookup faulty betwe.enreceiver and speaker

Adjust ' receiver selector control to other modes. II there is sound fromboth speaker channels, check audio cable hookups Qetween televisionand videocassette recorder and between receiver and television orvideocassette recorder (p . 16) 00; if there is sti ll sound from onlyone speaker channel, check cable hookups between receiver andspeakers (p. 16) DO

Television or videocassette recorder tau Ity Tum off videocassette recorder and tune in television. If there is soundfrom both speaker channels, service videocassette recorder (p. 88);i l stlll sound from one speaker channel, service television (p _ 68)

Speaker or receiverlaulty

Adjust antenna

See audio entertainment systems {p . 14)

Picture and sound Intermittentor distorted

Antenna positioned incorrectly

Cable hookup faulty between antenna or ca-ble system and television or videocassetterecorder

Check cable hookups between antenna or cable system and tslsv l-sian or videocassette recorder (p . 16) 00

Antenna or .cable system, televisionor videocassette recorder faulty

Service videocassette recorder (p . 88), television (p . 68) or antennaor cable system (p . 76)

Picture intermit tent ordistorted .

Check video cable hookups between television and videocassetterecorder (p.16) 00

Video cable hookup faulty between televi-sion and videocassette. recorder

Turnoff videocassette recorder and tune in television. I f s ti ll nopicture, service television (p. 68); i l there is picture, service video,

cassetie recorder (p : 88)

Television or videocassette recorder faulty

Sound intermit tent or distorted Audio cable hookup laul ty between televi-sion and videocassette recorder, or betweenreceiver and television or videocassetterecorder, or cable hookup laulty betWeenreceiver and speaker

Adjust receiver selector contro l to other modes. II sound is OK·,checkaudio cable hookups belWeen television and videocassette recorder,and between receiver and television or videocassette recorder (p. 16)00; it sound not OK, chet;;k cable hookups between receiver andspeakers (p . 16) 00

Television or videocassette recorder faulty Turn off v ideocassette recorder and tune in television. I f s ti ll nosound, service television (p. 68); i f there is sound, service video-cassette recorder (p _ 88)

Speaker or receiver faulty See audio entertainment systems (p. 14)

DEGREE OF DIFFICULTV:

ESTIMATED TIME:

~Easy I O ; t MOderate .Complex

o Less than 1 hour ~ 1 to 3 hours • Over 3 hours

15



ENT ER TA INMEN T S YS TEMS

CLEANING CONNECTIONS

Cleaning cableconnectors and unit terminals. To clean a plug connector, use the eraserend of a pencil. Rub thoroughly around the outer shield and along the center pin (above,

left); apply only moderate pressure to avoid bending the pin. Clear away particles byspraying electrohic.contact cleaneror compressed air into the connector, or use a loamswab moistened with denatured alcohol. Use the pencil eraser as well to clean any acces-sible contact points on the terminal. To clean inside the terminal, spray short bursts ofelectronic contact cleaner or compressed air through the opening (above, right).~

SERVICING GROUND WIRE CONNECTIONS

Checkingindl)()r and outdoor ground connections. Carefully inspect ground wir.econnec-tions, both to troubleshoot problems and as a preventive measure, A loose or damagedground wire can be an annoying source of humming noise. It can also be a hazard in theevent a circuit is shorted or a cable is struck by lightning. Tighten a loose turntable groundwire at its terminal on the receiver (;lbove, left)..Tighten the outdoor ground wire from theantenna systemdiscl iarger or grounding block at the discharger or the grounding block,as well as at the grounding rod (above, right). Repair any damaged wire end or spade lug(page 132). To test a ground wire, set a mult ilester to test continuity (page 128), discon-nect one end of the wire and touch a probe to each end 01 the wire. If the ground wiredoes not have continuity. replace it (page 132). Be sure to run an outdoor ground wirein the shortest and straightest possible path.

17



.- .

The. cortex of most sophisticated audio systems is a' receiver

(below), an integrated unit consisting of an analog or digital

tuner, a preamplifier and a power amplifier. From the tuner, or

from a n auxiliary unit such as the turntable through cables

hooked up to the receiver, the preamplifier accepts the incom-ing signal, amplifies it ana routes it to the power amplifier.

There; the signal is further strengthened and sent out through

cables, usually to the speakers, Despite a jungle of cords and

cables, receiver problems can be logically deduced from their

symptoms. Consult the Troubleshooting Guide in Entertain-

ment .Systems (page 14) first, arid then the one in this chapter(page 19). .

Often, problems can be remedied by adjusting cable hookups

or by cleaning switches and potentiometers. Sometimes a wire

may be loose or broken, or a component may test defective.

Cleaning materials, and most replacement components, ar

readily available from an electronics parts supplier. Specia

parts may have to be ordered from the manufacturer.

A set of small screwdrivers, a multitester and a soldering iro

make up the basic toolkit for receiverrepairs (page 126). Refeto Toots &Techniques for tips on disassembly and reassembly(page 141), instructions for testing continuity, resistance an

voltage tpages 128.129). and directions for desoldering an

soldering (pages J30~J31).

'Before attemptingany repair to the receiver, tum it off an

unplug it . Disconnect the cablesand wires hooked up to it an

set it on a dean work table. Store fasteners and other small part

in labeled containers and write down the sequence of disassern

bly steps. Perform a cold cheek for leaking voltage (page 141

after reassembling the receiver but before plugging it back in

T un er c on tr ol

Wai gh il Jd s ha ti r Ota te s .10 wind a nd. ~ . nw i nd t un e r cord.

T un er c ord

T urn s th 9ca pa dtor oru ma~slicles t he lunerpo inter .

FM antenriaLis ua llya dipole w ire, a s

shoWn: may be SiJbstituted

for by a n O Ii Id OQr a n te nn a

O r a ta ble ho oku p.

AManteri i i .

O nio fl s w itc hSta r lSand s t o p ; f l a wo f . 12 0 -v o ~ '! hema ti ngt :U l l' s nt ( AC ) to pOWer,

.supPly Components;

18

Po~cor~S u pp lie s 1 2 0- vo li a R er na tin g

current (AC] to the J:!OWBrblOck which routes .ittopower ·s upp IY componen ts . Out.let

Supplies 12(} 'vol t aaei'nating currantlAC] t hr ou g h t he r ec e lv e r to power

e ith er u nits in th e s ys te m: r ed uc esJ u mb le o f cOrds at w e J I outlet .

Ba l ar ic e po ten tl ome t s rc on tro lR eg ula te s s ou nd le ve l .b elw ee n la ft a nd

right cftaI1~!S.

T re ble . p ole nllo ilie te r c or itr ol

Miustshigl l · frequsney ~!gnaJ.



RECEIVERS

TROUBLESHOOTI NG GUIDE

SYMPTOM PROCEDUREOSSIBLE CAUSE

No display lights, no sound Receiver unplugged or turned off Plug in and turn on receiver

Remote control dirty or faulty Service remote control (p . 136) DO

No power to outret or othlet faulty Reset breaker or replace fuse (p.10) DO; have outlet servicedPower cord faulty Test and replace power cord (p . 137) DO

Power fuse blown Test and replace power luse (p . 23) 00

On/off switch faulty Test and replace on/off switch (p. 25) DO

Power supply faulty Service power supply (p. 26) .Q

Circuit board faulty Take receiver for professional service

Display l ights; no sound

Auxiliary unit faulty Troubleshoot entertainment system (p. 14)DO

Receiver controls incorrectly set Adjust receiver controls

Selector switch or ci rcuit board f,!ulty Take receiver for professional service

Sound, no display l ights

Receiver controls incorrectly set Adjust receiliercontrols

. Display lights faulty Replace display lights (p. 134) 00

Sound fro,m only one channel

Speaker or auxiliary unit faulty Troubleshoot entertainment system (p. 14)DO

Volume or balance control potentiometerdirty or faulty Clean potentiometer (p. 24)00; test and replace potentiometer(p . 24)!;;IQ

Circuit board taulty Take receiver for professional service

Intermittent sound froman auxiliary unit .

Speaker or auxil iary unit faulty Troubleshoot errtertainrnem system (p o 14)DO

Volume or balance control potentiometerdirty or faulty

Clean potentiometer (p. 24)DO; test and replace potentiometer(p . 24)!;;IQ


Intermittent sound fromthe radio

Adjust antenna

Tuner control set incorrectly Adjust tuner control

Antenna positioned incorrec1ly

Speaker or cable system faulty Troubleshoot entertainment system (p . 14)DO

Variable capacitor dirty Clean variable capacitor (p . 22) DO

Antenna loose or faulty CheckFM antenna wire connections: test and replace AM antenna·(p.22) DO


Humrni,ng noise

Electrolytic fil ter power capacitor taulty Test and replace electrolyt ic filter power capacitor (p . 27) !;;IO

Auxil iary unit faulty Troubleshoot entertainment system (p. 14)DO

Analog, tuner control erraticor doesn't work

Tuner pulleys sticking or tuner cord slipping Service tuner (p . 20) 00

Tuner cord loose or a-oken Restring tuner (p o 21) I i i i i i I Q

Take receiver for professional service

Scratching noise when analogtuner control is adjusted

..Variable capaCitor dirty Clean variable capacitor (p. 22) 00

Variable capacitor or circuit board faulty

Scratching noise when selectorcontro l Is adjusted; backg roundnoise f rom another unit Selector switch or circuit board faulty Take receiver for professional service

Selactor switch dirty Clean selector switch (p. 23) 00

Volume, 'balance or tonecontrol abrupt, scratchy ordoesn't work

Control potentiometer dirty or faulty Clean potentiometer (p . 24) 00; 19S1 and replace potentiometer(p . 24)!;;IQ

Speakerfau Ity Troubleshoot entertainment system (p . 14)DO

Circuit board faulty Take receiver lor professional service

Burning odor

Clean heat sink

Air vents blocked or dirty Reposition receiver orclean air vents

Heat sink dirty

Power fuse blown Test and replace power fuse (p. 2.3) 00

Power supply faulty Service power supply (p . 26) .Q

Electrolytic fil ter power capaci tor faulty Tesi and replace electrolytic fil ter power capaci tor (p. 27) ~O


DEGREE.oF DIFFICULTY:

ESTIMATED TIME:

o Easy ~ Moderate • Complex

oLess than 1hour Q1to 3 hours • Over 3 hours

19



RECEIVERS

ACCESS TO THE COMPONENTS

Removing and reinstalling top, front and bottom panels. Tumoff the receiver, unplug it from the wall outlet and disconnect the cables

and ground wire hooked up to it (page 12). Top panel screws are usual ly

located on the sides, and sometimes on the back or bottom. Unscrew

the top panel, slide it out f(om under any lip on the front panel and lift it

off the receiver f rame ( above, l ef t) . Pull off or unscrew any controls too

large to fit through the front panel. Front panel screws may be at the

top, sides or bottom. Unscrew the front panel and gently p r y i t away

from the frame (above,center). TUrn over the receiVer. The bottom pan

.screws are on the edges and sometimes in the feet, Unscrew the botto

panel and 1 1 f t it pff the frame ( a l;ove , n 'gh t ). After working on the receiv

reverse this sequence to reinstall the panels, then cold check for leakin

voltage (page 141). Reconnect the cables (page 16) and ground wire

(page 17), plug in the receiver and turn it on, . .

SERVICING THE DIAL TUNER

1ubricating the pulleys and rail. Remove the top panel

(step above). Rotate the tuner control, checking the motion 01 the

tuner cord and the tuner pointer inside the receiver. If the tuner

cord is loose or broken, restring the tuner (page 21). If the tuner cord

does not travel easily, spray a tiny amount 01 silicone-based lubricant on

the axles of the tuner puHeys, avoiding contact with the tuner cord. Work

in the lubricant by rotating the tuner control (above). Use a dean cloth to

rub a little of the same lubricant on the pointer rail. If the tuner cord trav-

els easily but Ihe tuner pointer does not slide smoothly, reset the pointer

(step 2). When the tuner cord travels easily and the tuner pointer slides

smoothly, reinstall the lop panel (step above).

20

2Resetting the pointer. Unhook the tuner cord from the notche

or clipson the pointer plate. Rotate the tuner control fully in one

direction. then slide the pointer by hand fully in the same direc-

lion. Rethread the luner cord snugly through the notches or clips on th

pointer plate. Secure the tuner cord to the pointer plate by applying

a small dab of nail polish to each notch (above) or by pressing down

the clips with a smal l screwdriver. Reinstall the top panel (step above).



RESTRI NGI NG THE DIAL TUNER

RECEIVERS

1ying on cord at the capacitor drum. Remove the top·

panel (page 20) and check inside the receiVer for a sketch of the

luner cord route. If there is no sketch, draw one as complete as

possible, noting the sequence and the direction .and numberof urns the

tuner cord makes around each component .. I f the tuner cord. route cannot

be determined, consult the receiver manufacturer, or attempt to retrace

the route using a replacement tuner cord of about the same length.

Undo the knots securing the damaged tuner cord to the capacitor spring

and remove the cord. Purchase the requi red length of tuner cord at an

electronics parts supplier. Knot one end 01 the tuner cord 10 the capa-citor spring (above); then loop lt.aroune the capacitor drum. To keep

the capacitor drum stationary, turn it fully in the di rection of the loop.

3Threading cord through the tuner pointer. Puli the tuner

cord across the back of the front panel, feeding il under the

. poinier plate. Sti ll following' the di rection and number of turns

noted in the sketch, wrap the tuner cord tautly around the tuner pulley

at the end of the dial farthest from the tuner control shaft. Slide the

pointer by hand as claseas possible to the tuner control shaft . Pull the

luner cord to the pointer and thread it through the notches or dips on

the pointer plate (above). Finally, wrap the tuner cord around the tuner

pulley at the end of the diaf.c;losestto the luner Gontrof shaft and pull the

cord back to the capacitor drum, wrapping it around any other pulleys

indicated in the sketch.

2Wrapping cord around the tuner control shaft, Following

the direction and number ol turns noted in the sketch, wrap the

tuner cord tautly around the tuner pulleys on the route to the tuner

control shaft; i f you are proceeding without a sketch, start by assumingonce around each pul ley in the same direction as the ini tial loop around

the capacitor drum ..Wrap the tuner cord around the tuner CQntro lshaft

the direction and number of turns noted (above). In most instances, at

least two or three turns are required in the. same direction as the init ial

loop around the capacitor drum, to al low the pointer to tral iel the full

length of the tuner dial .

(

\

4Tying off cord at the capacitor drum, Wrap the tuner cord

. once around the capacitor drum in the direction opposite to the

initial. loop. If the new tuner cord ends up much shorter or longer

than the old tuner cord, retrace the routs taken and look for errors. If the

new tuner cord ends up about the same length as the old tuner cord,

tie the cord to the capacitor spring, cut off any excess and apply a small

dab 01 nail poush (aboYfi). Rotate the tuner cont rol to ensure that the

capacitor blades can open and close fully and that the pointer can travel

the full length of the tuner dial; i f required, reset the pointer (page 20).

Reinstal l the top panel (page 20).

21



RECEIVERS

SERVICING THE VARIABLE CAPACITOR

Cleaning a variable capacitor.R em ove th e to p p an el (p ag e 2 0).

R ola le lh e tu ne r c on tro l a s s ho wn;a n d in s pe ct th e v a ria b le c a pa c ito r

b la de s fo r d irt. o r d us t. T o clean th eb la d es . s p ra y th E lm q a re lu lly w ith s h or tbursts at c omp re s se d a ir (left), o r a pp ly

a . s rna ta mo unt o f tu ne r c le an er o re le ctr on ic c on ta c t c le a ne r. U s e tu ne r

cleaner a n d e le ctro nic c on ta c t c le a ne rs pa rin gly , h ow e ve r; th ey le nd to le .a vea s lig ht s tic ky re sid ue th a t tra ps d irt a nd

dust. If n ec es s ar y, . ge ntly u s e a to oth -pick or a folded s heet o f pa per tod i s lodge pa r ti cl es f rom ,be ly . teen theblades (inset). To q is lo dge pa ri ic le s

th a t a re d iffic ult to re ac h, try u sin ga vacuurndeaner. Re in sta ll th e to ppanel (p ag e 2 0).

SERVICING THE AM ANTENNA

1esting the a nte nn a. R em ovf;l th e to p p an el (page ~O ) and

lo ca te th e a nte nn a W ire . te rm in ~ls o n tb e c ,irc uit b Qa rd ,li a w ireIS l oo s e o r b ro ken , r epa ir t hew lr ec o nnect on (page 1 32 ). S et a

mu lti te s te r t o t es t c o nt in u it y (page 1 2 8). T ou ch o ne p ro be t o one a n-

ten na w ire te rm in al on th e c irc uit b Qa rd a nd to uc h th e o th er pro be intum to e ac h o f th e o th er a nte nn a w ire te rm in als (above). The mu lt it es te rs ho uld re gis te r c on tin uity a t le as t on ce . R epe al th is s ts pto te st e ac hte rm in al a ga in st e ac h o th er te rm in al. If th e m ultite ste rc be s n ot re gis te rth e c or re ct r as ults , re pla c e th e a n te nn a (step 2 ). If th e mu ltite s te r s h ow s

th at th e a nte nna is O K, re in sta ll th e to P panel (page2Q).

22

2Repl ac i n . .g the antenna. Ift he c i rcu it board is n ot C O de .dto tha nte nn a w ire C olo rs , n o te \tie w ire c on ta ct p oin ts .. D a so ld er th e

. w ire s fro m th e c irc uit b oa rd (pagfl 130) a nd pu ll Ih ea ntenna ofth e g ro mm et (above). P r y t he g romme fo ff 't he b a c k · p an el. o pe n it a ns lip o ut th e w ire s (inset). O rd er a n e xa ct rep la ce m€ nt a nten na {ro m thre ce ive r m a nu te cto re r, S lid e th e o pe n g ro mm et o nto th e w ire s; p re ss iit a ga in st th e ln su la te ds le eve , C lo se th e. g ro mrn eta nd th re ad th e w irth ro ug h th e o pe nin g in th e b ac k pa ne l. F it the g ro mm et in to th e. b ac kpa nel a nd push th e a ntenna onto th e grom met. S older th e w ires toth e c ir cu it b oa rd (page 1 31 ). R ein sta ll th e to p p an el " (p ag e 2 0) .



REPLACING THE POWER FUSE

RECEIVERS

/~

Removing and testing the fuse. T urn o ff th ere ce iv er a nd u np lu g it fro m th e w a ll o utle t. If th efu se is e xte rn ally m ou nte d in th e b ac k p an el, tu rnth e fu se c ap c ou nte rc lo ck w is e a nd p ull th e fu seo ut o f its ca sin g. If th e fu se is lo ca ted ins ide th er ec eiv er, r emo ve t he t op p a ne l (page 20). Grasp

th e fu se W ith a fu se pu ller a nd gen tly pry it ou t ofi ts r et a in in g d ip s (left). To tes t eith er fus e, s et amu tt it es t er t o t es t c ont in u it y (page 128 ) . Touchone probe to the cap a t one end o f the fuse andtouch the other probe to the ca p a t th e oth er end(inset). I f t he mu lt ite s te r d oe s n ot r eg is te r c on tin u-ity , p ur ch a se a n .e xa e t r ep la cemen t fu s e atane le ct ro nic s p ar is s u pp lie r. If t he mu llit es te r re gis -te rs c on tin uity , re in sta ll th e fu se : If th e fu se is

m ou nte d in th e back pane l, i nse r t it in to th e ca s-ing, s crew th e ca p in to the ba ck pa nel, plug inth e rec eiver a nd tu rn it o n. If th e fu se Is lo ca ted

in sic te t he r ec eiv er , g en tly p us h I t in to th e re ta in -in g c lip s a nd re in sta ll th e to p p an el (page 20).

If th e fu se b lo w s re pe ate dly , s erv ic e th e p ow e r-supply (page 26).

SERVICING THE SELECTOR SWITCH

Cleaning the switch. R em ove th e to p pa nel(page 20) a nd lo ca te th e s ele cto r s w itch o n th ec irc uit b oa rd b eh in d t he s e le ct or c om ro l, U s in ge le ctro nic c on ta ct c le an er. d ire ct th e n oz zle -th ro ug h th e o pe nin g in th e s w itc h c as in g. S pra ya sh or! bu rs t of dea ner in to th e switch a nd ro ta te

ih e s ele cto r c on tr ol f ully d oc kw i se a nd c ou nt er -do ckw is e a num ber o f tim es to work in th ecleaner (left). A ein sta ll th e to p p an el (page 20).

If th e p ro ble m p ers is ts . s us pe ct a fa ulty s ele cto rs w itc h o r c irc uit b oa l'd a nd ta ke th e re ce iv er fo rp r ofe ss iona l se r vi ce .

23



RECEIVERS

··. · ··

SERVICING POTENTIOMETERS

1leaning a potentiometer. Rem ov e th e lO P p a ne l (page 20)

a nd lo ca te th e p ote ntio me te r o n th e c irc uit b oa rd , b eh in d its c on -tr ol. S p ra y e le .c tr on ic c on ta c t c le a ne r th ro ug h th e o pe nin gS in t he

potentiom eter ca sing a nd rota te the contro l b~ a ndlorth to w ork inthecteaner (above). Rein sta ll th e to p p a ne l (page 20 ). 1 1 t he p rob lemper s is ts , t es t t he po te n ti ome te r (step 2).

3Removing a potentiometer. T o ta ke o ut th e c irc uit bo ard onwh ic h. th e. p o te ntiom ete r is lo ca te d, r em o ve th e f ro nt p a ne l (page20) a nd u ns cre w th e s ha ft lo ck nu t fo r e ac h p ote ntio me te r o n th e

c i rcu it board (above). Lift o ut th e c irc uit b oa rd ,p ullin g th e s ha fts th ro ug hth e o penings in th e fra me; if nec es sa ry , u ns crew o ne end o f th e fra mea nd p un it o ut s lig htly (inset). Oes o id er th e p in s o f th e fa u lty p ote ntiom e-te r (page 130). tu m o ver th e c irc uit bo ard a nd gently pry a ll th e po ten ti-o me te r. T es t its re sis ta nc e a ga in to c on firm th e p ote ntio me te r is fa ulty(step 2 ). If th e p ote ntiom ete r te sts fa u lty , r ep la c e it (step 4 ); if it te stsOK. s us pe ct a ta ulty c irc uit b oa rd a nd ta ke th e re ce iv er fo r s erv ic e;

24

2Testing a potentiometer. R em ove th e to p a nd bo tto m pa nels

(page 20). S et th e c oo tro t fu lly le ft, a nd s et a m ultite sle r to te stresistance (page 1 29). If th ere is one row of pins , hook one pro

to the m iddle pin in the row , a nd tou ch the other probe to one of theo ute r pins in th e ro w. R ota te th e c ontro l fro m left to righ t (above). Th em ultita s te r s ho uld re gis te r a v aria tio n in o hm s a s th e c on tro l is ro ta te dR es et th e c on tro l to ils left a nd tes t the s am e w ay betw een the m iddlepin a nd the other outer pin in the row . A ga in; you s hould s ee a va ria tin ohms ,lfthere a re tw o row s of pins , tes t ea ch row the sa me w ay. Iy ou d o n ot g et a v aria tio n in o hm s e ac h tim e, re pla ce th e p ote ntio me tIf th e p ote ntio me te r is O K, re in sta ll th e b otto m a nd to p p an els (page

4Replacing a potentiometer. Purchase a n e xa c t r ep la c emen tp ote ntiom ete r a t a n e le ctr on ic s p a rts s lJ p plie r. G e ntly p us h th ep ote ntio me te r p in s in to th e c irc uit b oa rd o pe nin gs , tu m o ve r th e

circuit board a nd s older th e pins in pla ce (page 131 )_S l id e t he po te ntio me te r s ha fts th ro ug h th e o pe nin gs in th e fram e a nd re po sitio n th ec uit b oa rd; il requ ired, pu ll o ut o ne end o f th e fra me, th en s crew it bai n p la ce . Sc[ew o n th e s h aft lo ck nu ts fo r e a ch p ote ntiom ete r. R ein stath e, b ottom , fr on t a n d to p p a ne ls (page 20).



TESTING AND REPLACING THE ON/OFF SWITCH

RECEWERS

1esting the switch. AE !m o ve th e to p p a ne l (page 20) and locate

th eon /o ff s witch te rm in als . It a w ire is lo os e or b roke n; re pa ir th ew i re connec ti on (page 1 .3 2 ). S et a m u ff ite ste r to te st c on tin uity

(page 1 2 8 ). C lip o ne p ro be t o o ne s w itc h ts rrn in al a nd to uc h th e o th erprobe to th e o th er s w itch te rm in al. S et th e s w itch in th e O N p os itio n a ndth en in th e O FF po sitio n (above) . T he s w itc h s ho uld h av e c on tin uity o nlyin th e O N po sitio n. If th e s witc h is fa ulty . rem ove it (step 2 ). If th e s witc htests OK, s erv ic e th e p ow e r s up ply (p ag e 2 6).

2·emoving the switch. R em ov e th e fro nt p an el (page 20)

a nd p ull th e c on tro l o ff th e O l1 l0 ff s w itc h s ha ft. U n sc re w th e o n/ off. s witC h, p ull th e s ha ft th rou gh th e o pen in g in th e fra me a nd lift th e

s w itc h o ut o f tt1 e r ec eiv er (above) . Oes old er th e w ire s fro m th e s w itC hterminals (page 130). T o c on firm th a t th e o n/ Off s w itc h is fa ulty . te stf or c o nti nu ity a ga in (step 1 ). II th e s w itc h s till te sts d ef ec tiv e, r ep la c e it

(step 3 ). If o il n ow tes ts O K, rs so ld er th e w ire s (page 131 ), r ei ns ta ll t heo n/ off s w itc h o n th e fra m e. p ut bed< th e o n/ off c on tro l a nd s erv ic e th epowe r s u pp ly (page 26).

3Replacing the switch. Purchase an e xa c t r ep la c ement o n/ of f s w itc h a t. a n e le ctr on ic sparts SU o p plie r. S old er Ih e w ire s to th e s w itc h te rm in als (page 1 3 1- ), us in g a s o ld er in g s ta n d

. if n ec es s ar y to k ee p th e s w itc h s ta tio na ry ( above , l ef t) . R ele as e th e s w itc h fro m th e s old erin g

s ta nd, s Up th e s witch s ha ft th ro ug h th e o pe ning in th e fra me a nd s cre w th e s w itc h in p la ce (above,

right). P ut ~ th e on/o ff contro l a nd reins ta ll th e front a nd top pa nels (pa ge 20 ).

25



RECEIVERS

SERVlel NG THE POWER SUPPLY

2Testing between the fuse and the power block. Locate the

contact paints for the two wires connecting the fuse terminaislo

the power blOck ter ininals .. I f a wire· is loose or broken, repair the

wire connection (page 132), Set a mulntester to test continuity (page

128). Clip one probe to one contact point tora wire and touch the ather

probe to the COntact point at the other end of the wire (abOve). The

mult itastsr should register continuity. Repeat this step 19rthe other wire.

If the multitester do\:Isnot register cont inuity for a wire. , replace the wire

(page 132). I f the mult itester re:gisters cont inui ty for each wire, test the

wires to the transformer (step 3 ) .

26

1esting between the on/off switch

and the power block. Remove the top

panel (page 20) and identify the power

supply corneonents (page 138). Locate the con

tact points for the two wires that connect theorv'offswitch. terminals to tbe powerblocktermi-

nals. If a wire is loose or broken, repair the wire

connectiori(page 132}. Set a mult ltester to test

continuity (page 12/3) .Clip one probe to one

contact point for a wire and touch the other

probe to the. contact paintal the ~otherend of

the wire (Jeff). The multitaster should re:gistet

cont inuity. Repeat this step for the other wire.

If the multi tester does not register continuity for

a wire, replace the wire (page 132). I f the multi

tester registers continuity for each wire, test the

wires between the power block and the fuse

( sf 8P 2 ).

3Testing between the transformer and the fuse. Locate the

contaCt points for the two wires connectIng the transformer 16 th

fuse terminals. If a wire is loose or broken, repair the wire conne

lion (page 132). Sel a multilester to test cont inuity (page 128), Clip on

probe to the fuse clip and touch the other probe to the transformer Wi

terminal (abOve). The mull itester should register continui ty. Repeat this

sfep for the other wire. II the rnultitester does not register continuity, s

pect a faulty Circuit board and take the receiver for protesstonal service

lf the mulli tester registers. continuity, test the transformer (step 4).



';"-:"~··i=8...".,~...·

RECEIVERS

4Testing the transformer. Locate the transformer-wire contact

points on the circuit board. If· the circuit board is not coded to . thewire colors, note the wire positions. Desolder the wires (page 130)

and isolate them. Set a rnul titester to test voltage (page 129). Clip one

probe to the odd-colored wire and hook the other probe to a matching-

colored wire (above); if there is no odd wire, dip the probes to a match-

ing wire pair. Plug in the receiver and turn it on; the multi tesler should

register voltage. Turn off the receiver and unplug it. Repeat this proce-

dure wi th the odd wire and each other matching wire, or with each

matching wire pair. 1 1 the. multitester does not register voltage, replace

the transformer ($tep 5). I f the multi tester registers voltage, suspect a

faulty circuit board and take the receiver for professional service.

5Rep1acing the transformer. Tag and desolder (page 130) the

. two transformer wires connecting ·to fuse terminals, on/off switch

terminals or power block terminals (step 3). Unscrew the trans-

former and remove it from the receiver. Purchase an exact replacement

transformer from the rnanutacturer, or buy a substitute at an electronics

parts supplier. Screw in the transformer and solder the wires (page 131)

·to their terminals at the fuse, or the onloff switch, or the power block,

and to the circuit board (above) . Then reinstal l the top panel (page 20) .

SERVICING THE ELECTRO LYTIC FILTER POWER CAPACITOR

1emoving the capacitor. Remove the top and bottom panels

(page 20). Wait 30 minutes for the capacitor to discharge com-

pletsly any stored voltage. Find the capacitor near the power-

supply components. locate the capacitor contact pins on the circuit

board, ar id careful ly note their posnions for reassembly. Desolder the

pins (page 130) f rom the circuit board (above), turn over the receiver

and gently pul l the capacitor of! the circuit board,

2Testing and replacing the capaci tor. Set a mul titeste'r to test

resistance (page 129). Clip the negative probe to the negat ive pin

and touch the positive probe to each positive pin in turn (above) ;

i f there are negative·and-positive pin pairs, test each pair . For each pair ,

the mulliteste( should register lo w ohms and then a rise in ohms. If the

capacitor tests OK, suspect a faulty circuil board and take the receiver

for prolessional service. I f the capacitor is faulty, purchase an exact re-

placement capacitor at an electronics parts. supplier and solder it to the

circuit board (page 131). Reinstal l the bottom and top panels (page 20) .

27



AUDIOCASSETTE RECORDERSCleaning supplies and tnost replacement components are

available at an electronics parts supplier; a specific motor,

however, may have to be ordered from the manufacturer.

Refer to Tools & Techniques for the basic tool kit (page

126 J , as well as instructions for disassembly and reassembly(page 140), testing continuity and voltage (pages 128-129)

and desoldering and soldering (pages 130-131).

Tum off and unplug the audiocassette recorder before any

repair. Disconnect the cables hooked up to it and set it on

clean work table. Store fasteners and other small parts in

labeled containers and write down the sequence of disassem-

bly steps. Perform a cold check for leaking voltage (page 14 J

after reassembling the audiocassette recorder but before you

plug it back in.

The audiocassette .recorder routes sound in two directions-

out of the unit in the play mode and into the unit in the record

mode. During the play mode, invisible magnetic tracks on the

audiocassette tape are interpreted by the head as electrical

current The current is sent out of therecorder through cables,usually to the receiver and from there to the speakers. During

the record mode, electrical current received from another au-

dio unit is "written" by the head as magnetic tracks on the

audiocassette tape for later play. when the head will route it

back through the receiver and the speakers.

Many recorder problems can be remedied by adjusting cable

hookups or by cleaning and demagnetizing the tape 'travel

'components. Consult the Troubleshooting Guide in Entertain-

ment Systems (page 14) as well as in this chapter (page 29).

:Capatan motor

Turns the capstan by dr iv ing a bel lwrapped around capstan flywheel.

Power transformerCon~erts 120·volt altemallng cur-

ren t to the low voltage required

by clrcult board components. A

rectifier the ACto DC .

Record-level

potentiometer

,Adjusts the sound leyel

ofthe recording.

EJKt mechanlsm.contml

Secures and releases l.h9

loading door.

Era_head

Electronically removes

magnetic tracks from

the tape.

Pinch roller

Hard rubber wheel pressesthe tape againsllhe rotat-ing capstan,. which pulls itfrom the reel.

Play/record headIn tha play mode, interprets

magnetic patterns on'the tapeas e leCtrica l cur rent; in the re o

cord mode. stores electrical

current as m;!ognetlc 'pat tems

on the tape. Some audio-

c a ss et te r ec o rd er s n ave s ee a-rate play and record heads.

L.oad lng doo rHolds the audiocassette in

place inthe taps.travel path.

Mode-switch control assembly

Controls that se t the audio mode.

speed and direction at the tape

tl:!rough the tape travel path.

Tap8cOuntet'

Indexes Ihstape posit ion for

locating and liming recordings.

28




AUD IO CAS SE TT E R EC ORDERS

SYMPTOM possr9LE CAUSE PROCEDURE

No display l ights, no sound

No power to outlet or outlet faulty Reset breaker or replace fuse (p. 10) [JO; have outle! serviced

Audiocassette recorder unplugged or off Plug in and turn on audiocassette recorder

Power fuse blown Test and replace power luse (p. 1$7) DO

Power cord faulty Test and replace power cord (p. 137) 00

On/off swi1ch faulty Test and replace on/off switch (p. 40) 00

Power supply faulty Service power supply (p. 40).0

Circuit board faulty Take audiocassehe recorder for professional service

Display lights, no sound

Audiocassette tape torn o r jammed Splice tape ( p. :1 0) 00; r emove jammed tape (p . 32) 00

Controls set incorrectly Adjust audiocassette recorder controls

Receiver faulty Troubleshootentertainment system (p . 14) 00

Drive belt loose or broken Service drive bells (p. 33) DO

PlaV/record head faulty Test and replace head (p. 35) DO

Play/record switch dirty or faulty Clean play/record switch (p.S8) DO; replace switch (p. 38) .Q

Capstan motor faulty Test and replace capstan motor (p o 41) 1iiiI0

Circuit board faulty Take audiocassette recorder for professional service

Sound, no display lights

Adjust audiocassette recorder controls

Display lights faulty Replace display lights (p . 134) DO

Sound from only one channel Controls set incorrectly

Receiver or speaker faulty Troubleshoot entertainment system (p. 14) 00

Play/record head faulty Test and replace play/record head (p.35) 00

Record level potentiometer dirty or faulty Olean potentiometer (p . 39) PO; test and replace (p . 39) 1iiiI0

Circuit board faulty Take audiocassette recorder for profess.ional service

Sound intermit tent ordistorted

Audiocassette tape damaged Splice audiocassette tape (p. 30) DO; replace audiocassette

Receiver or speaker faulty Troubleshoot entertainment system (p. 14) 00

Tape travel patti dirty Crean and demagnetize tape travel path (p. 30) DOA

Play/record head misaligned Adjust play/record head (p. 33) DO

Drive belt dirty or loose Service drive belts (p. 33) DO

Capstan molar runs too fast or too 510",", Adiust capstan motor speed (p . 34) DO

Pinch roller faulty Replace pinch roller (p . 34) DO

Play/record head faulty Test and replace play/record head (p. 35) DO

Tape transport assembly dirty Service,tape transport assembly (p. 36) 1iiiI0

Record level potentiometer dirty or faulty Clean potentiometer (p. 39) 00; test and replace (p. 39) 1iiiI0

Tape selector or noise reduction switch dirtyor faulty

Clean switch (p. 39) DO; test and replace switch (p. 39) .~

Capstan molar faulty Test and replace capstan motor (p . 41).1iiiI0

Circuit board faulty Take audiocassette recorder tor professional service

Record level contro l abrupt,scratchy, or doesn't work

Circuit board fi3.ulty Take audiocassette recorder for professional service

Record leval poterniornerer dirty or faulty Clean potentiometer (p . 39) DO; test and replace (p . 39) 1iiiI0

Mode control can't be setor releases prematurely

Take audiocassette recorder tor professional service

Play/record switch dirty or faulty Clean play/record switch (p. 38) 00; replace swi tch (p. 38) ._.,

Circuit board faulty

Noise In fast forward, rewind,pause or stop mode

Circuit board faulty Take audiocassette recorder for professional service

Mute switch faulty ServiCe mute switch (p. 37) 00

Audiocassette 'ape can't beerased or recorded over

Audiocassette safety ta b removed .'Service audiocassette safely tab {p o 30) 00

Play/record head misaligned Adjust play/record head (p . 33) DO

Erase head faulty Test and replace erase head ( p o 35) 00

Play/record switch dirty or faulty Clean play/record switch (p. 38) 00; replace switch (p. 38).'"

Loading door doesn't open

Audiocassette tape lammed Remove jammed audiocassette (p . 32) 00

Eject mechanism faulty Service eject mechanism {p o 32) DO

DEGREE OF DIFFICULTY:

ESTIMATED TIME: ASpecial tool required

DEasy I i i i I Moderate • Complex

o Less than 1 hour ~ 1to 3 hours • Over 3 hours

29



AUDI00\SSETIE RECORDERS

SE RV IC lh lG AU D IOCASSETTES

Splicing audiocassette tape. Touching the undamaged audiocasset

tape as little as possible, snip off a length of rumpled tape withscis-

sors. .Slip the tape ends, shiny side up, into a splicing block,overiap-ping them slightly atthe cutting groove; Push down the levers, cutting

through ~he tape ends with the splicing blade,and blow away the tape

scraps. Use the blade to slice 0111/2 inch of splicing tape, taking care

001 to touch the sticky side. Pick up the splicing lapewith Ihe blade a

center it ,$ticky side down,acro!?S the cut ends of the audiocassette

tape (abovej; Run a foam swab over the splicing tape to press it firml

onto the audiocassette tape. Lift up the levers and remove the auclo-

cassette tape from thesplidngblock Turn the:alidiocassettel<lkeup

reel with a pencil to rewind the tape,

Removing and restorii1g the recording .safety tabs. Locate the

audiocassette safety tabs on.the top edge of Ihe housing. usually indi-

cated by arrows on the side edges. To prevent the audiocassette tape

from being erased orrseordsd over, break off each safety tab using

a small, f lat screwdriver (above); . if the safety tab falls into the audio-

cassette, remove it using long-nose pliers. To erase or record over

the auoiocassette tape, cover each safety tab opening with a.small

piece of plast ic tape.

SERVIC ING THE TAPE TRAVEL PATH

Cleaning and demagnetizing the tapetravel path. Unloa:panyaudiocassette, turn

the audlocassene recorder and ,unplug i .t from

the outlet, Using a foam swab dipped in dena-

tured alcohol, wipe the audio heads, the.cap-

stan and the guides;, for easier access to the

heads, press the play or pause control. U,se a

foarnswab dipPed in rubber-cleaninq c'ornpou

to wipe the pinch roller (Isft, top), turning itwit

a finger as you clean.

Purchase a demaqnetizerat an electronics

parts supplier. Plug the. demagnet izer into a w

outletand turn it on at least 2 feef away from

the audiocasseite recorder , Slowly br ing the

demagnetizer within 1/ 2 inch of an audio head

( le f t, bo tt om) , draw it about 2 feet away and tu

it all. Hepeatthls procedure for the other audihead as Well as for the capstan, the guides

and any other metal component that contacts

an -auotocassene. Plug in the audiocassette

recorder.

30



AUDIOCASSETIE RECORDERS

ACCESS TO THE INTERNAL COMPONENTS

Removing and reinstalling the top panel.Unload an y audiocassette, turn off l ind unplug

the a.udiocassette recorder, and disconnect

the cables hooked up 10 i t (page 12). Top

panel screws m ay be located on the sides;

back or bottom. Unscrew the top panel, slide

it out from under any lip on the front panel

and lilt it off the frame (above). To reinstall

the top panel, slide it under the front panel

lip and screw it to the 'frame. Cold check the

audiocassette recorder for leakirig voltage

(page 141). Reconnect the cables and plug

in the audiocassette recorder.

Removing and reinstalling the frontplate or panel. Remove the top panel (Iliff).

If there is a front plate, check for tabs and

screws securing i t to the. frame. Unscrew the

front plate. press in the, tabs and pull off the

front plate (above). If there is no front plate,

unscrew the f ront panel. Pull off or unscrew

an y cont rols t09 large to fit through their

openings, and pull the front panel off the

frame. To reinstall the front plate, snap itonto the frame and put back an y screws.

To reinstall the front panel, screw it onto the

frame and put back any controls removed.

Reinstal l the top panel (Jeff).

8ackpanet

Removing and reinstalling the backpanel, Remove the top panel (far left). Un-

screw the back panel, careful ly pull it out from

the frame (above) and turn il face down, ex-

posing an y inter ior wire corinect ions, such as

those leading to the power cord. To reinstal l

the back. panel. set it against the frame and

put back the screws. Reinstall the top panel

{far leN}.

ACCESS TO THE TAPE TRAVEL PATH COMPONENTS

Removing and reinstalling the mode-switch control assembly.Remove the top panel and the front plate or panel (steps above). Press

the tabs at each end of the mode-switch control assembly toward each

other and pul l the assembly off the. frame; for easier access, upend the

audiocassette recorder (above). Tape the ends of the mode-swltch con-

trol assembly to prevent losing the washers and springs. Reverse the

sequence to reinstal l the mode-switch contro l assembly.

Removing and reinstalling the loading door. Push the eject mech-

anism control to open the loading door. Check for tabs securing a front

plate on the loading door; press In the labs andslide off tbe front plate.

I f there is nQ front plate, remove the mode-switch .oontrol assembly

(ieff). Press the tabs on each side of the loading door toward each

other arid pull off the loading door (above). Reverse the sequence

to relnstau the loading door.

31



AUDIO€ASSETIE RECORDERS

SERVICING THE EJECT MECHANISM

1·hecking the mechanism. Remove the top panel (page 31)

arid locate the. eject mechanism components, If the lever is bro-. ken, replaceit (step 2). If the lever slides poqrly, use a foam

swab to apply a little white grease to it, if the lever has worked loose,

tighten its mounting screw. Reconnect an unhooked spring using long-

nose pliers (aqavetor tweezers; if a spring is damaged, replace it

(page 135J Reinstall the top panel (p?ge 31).

' 2 ' . Replacing the mechanism. Unhook any spr ings connected to

the lever4sing long-no$e pliers or twee~ers. Remove the lever. mounting screw (abeve) and pull the lever free. of any retaining

clips. Order an exact replacement eject mechanism lever from the

man.ufactureror purchase a substi tute at an electronics parts supplier.

Press the lever into the retainihg clips, put back the mounting $Crew

;md rehooK the springs. R.einSlal i the to p panel (page 31).

REMOVING A JAMMED AUDIOCASSETTE

1eleasing the audiocassette. Tum off and unplug the audio-

cassette i 'ecord~r. Press the eject control to.open the loading

door. If the loading door opens and the audiocassette can be

Iiftedout easily, retrieve the jammed tape (st~p 2); If the loading door

does-not open enough to reach the auclocassette, or if the audio'

cassette cannot be removed easily, take oHlhe: top panel (page 31)

and the capstan plate (page 36). Pull out the capstan flywheel to re-

lease the audiocassette from the capstan, then press the eject control

(~bove). Carefully lift out theaudlocassette. push in the capstan fly"

Wheel and reinstall the capstan. plate, reversing the sequence used

to remove it (page 36).

32

2Retrieving jammed tape. Reslingthe audiocassette on lop o

the aUdi.o.assette recotde.r,ge.ntIY eidr~ct the. tape from. theta. p. travel path components (above);,avolp touching undamaged se

lions of tape with your lingers. If the tape is difficult to retrieve, C U I it

with' scissors, making sure not to leave behind any stray pieces. Reln

stall the top panel (page 31) if you. rernovadlt. J f the tape. has been c

or badly damaged, splice it ( pa ge 3 0), II the tape is OK, turn the audi

casset te take!1P reel wi th a pencil to rE;!windmetape. being careful no

to twist it.



ADJUSTING THE PLAY/RECORD HEAD


Resetting t he a zimu th a dj us tm ent Screw.Without disconnecting the cables hooked up

10 the audiocassette recorder, unplug it and re·

move the mode-switch contro l assembly (page

31). locate the green or red azimuth adjustment

screw an the play/recard head and twist it

slightiy with a screwdriver to break any bond.

Plug in and turn on the audiocassette recorder.

Load a prerecorded audiocassette, preferably

ane with considerable high frequency or treble

sound. fasVfarward or rewind the audiocassette

tape to midposit ian. Turn downlhe bass cantrol,

turn up the treble conirol and play the tape.

While l istening closely, s lawly turn the azimuth

adjustment screw clackwise and counterClock·

wise until the saund qual ity is optimum (left).

Lack the screw in position by applying a small

dab af nai l pol ish. Remove the audiocasset1e

and turn off and unplug the audiacassette

recorder. Reinstall the mods-switch control

assembly (page 31).

SERVICING THE DRIVE BELTS

1leaning a belt, Remave the top panei (page 31) and locate

the drive belts On the tape transport assembly. If a belt is worn or

broken, replace it (step 2). If a beit is sticky or aily, clean it mor-

oughly on both sides using a foam swab dipped in rubber·cleaning

compound (above); never apply anything oi ly and avaid touching the

belt wi th your fingers. Turn the bel t pulleys or the capstan flywheel with

a clean foam swab to reach the entire length of the belt. Reinstall the

tap panel (page 31).

2Replacing a belt. Use lonq-nosa pliers or tweezers to slip off

the belt and any other belt in its way (above). Note the belt posi-

tions on the pulleys or the capstan flywheel; be careful not to

pinch a belt, To. reach the capstan drive belt, remove the capstan plate

(page 36). Purchase an exact replacement belt at an electronics parts

supplier. Ho. lding the belt loosely, wrap i t around its pulleys or the

capstan flywheel. ReinstaJiany other belts you removed. Put back the

capstan plate by reversing the sequence used to remave it (page 36).

.Reinstall the top panel (page 31).

33



. .- ..•.-.~. • . . - - _ .. " .

AUD IO CAS SE TT E R EC O RD ER S

ADJUSTING THE CAPSTAN MOTOR SPEED

Resetting the motor speed. Without discon-

necting the cables hooked up to the audio-

cassette recorder, unplug it and remove the top

panel (page 31). Locate the motor-speed adius

men! screw in the opening on the back of themotor. I f there is no motor-speed adjustment

screw, reinstal l the top panel (page 31); to

ha;"e the motor speed adjusted, take the audio"

cassette recorder for .professional service. 'If

there is a motor-speed adjustment screw, plug

in the audiocassette recorder .fum it on and

load a praraeordedaudtccassatts, preferaIJly

one with conSiderable mid-range frequency or

VOicepassages. Play the audlocassette. tape fo

about fiVe minutes to warm up the motor, then

fast/ forward or rewind it to midposit ic in, While

listening clOSely to. thetaps, slowly turn thE!

motor-speed adjustment screw clockwise and

counterclockwise .unti l the sound quality lsoptl-mum (/e't). Remove· the audiocassette, turn cif

the audiocassette recorder, unplug i. 'and rein-

stall the top panel :(page 31).

REPLACING THE PINCH ROLLER

1emoving the pinch roller assembly. Remove the mode"

switch control assembly and the loading door (page 31)..Locatethe pinch roller assembly and note th e pinch-roller spring POsi-

tion. Fil the tip of a small screwdriver under the locking washer and

gently pry lt.ott (above); if required, use one hand to hold the pinch

roller assembly stationary. Slide the pinch roller assembly off its shaft;

noting its position.

34

2Installing a new pinch roller assembly. I f the pinch roller

,~ssemblysp~in~ is damaged. replace it (page 135); if the ~pring

. ISOK, leave I! In place. Purchase an exact replacement pinch

rol ler I; lssemely at an electrqnics pails supplier arid sl ip it onto thE!

shaft (above). Pressing the pinch rol ler assembly against the spring,

push the locking washer onto the shall. Reinstall the loading door

and the mode-switch Control assembly (page 31).



TE STIN G A ND R EP LA CIN G A N AUD IO H EA D

AUDIOCASSEITE RECORDERS

Soldering stand

1emoving a head. Remove the mode-switch control assembly and the loading door

(page 31) and locate the play/record and erase heads; note the position of the green or

red azimuth adjustment screw on the play/record head. Demagnetize a smal l screwdriver

(page 140), unscrew the head being serviced (above, left) and gently lift it out of the audio-

cassette recorder. If a wire connection is loose or broken, repair it (page 132). Put back the

head; forthe play/record head, tesetthe azimuth adjustmant screw (page 33). Reinstal l the load-ing door and the rnoda-switch-corurol assembly (page 31). I f the problem persists, test the head

(step 2). Access the head as above. Secure the head in a soldering stand and desolder

(page 130) the wires (above, right), noting their terminal posit ions.

2Testing the head. Set a mul titesterto test continuity (page 128).

If the head has three wires, touch one probe .to th~ ground termi-

nal and the second probe to each other termmal, In turn. The

mul titester should register continuity. If the head has four wires, tnere

are two ground wires; touch the probes to eachground/non-ground pair

of terminals. Themul titestershould register continuity for each pair. If

the head tests faulty, replace It (step 3). If the head tests OK, solder

(page 131) the wires tothe terminals and reinstall the head (step 3).

3Replacing the head. Order an exact replacement head from

the manufacturer or purchase a.substituta at an electronics parts

supplier. Securelhe head in the soldering stand, solder (page

131) the wires 10 the head terminals (above) and screw in the head. If

you serviced the play/record head, reset the azimuth adjustment screW

(page 33). Reinstall the loading door and the mode-switch control

assembly (page 31).

35



AUmOCASSETTE REO;)RDERS

" " " f

SERVIC ING THE TAPE TRANSPORT ASSEMBLY

1emoving the capstan plate. R em ove th e top p an el (Mge 31)

a nd u ns cre w th e c ap sta n p la te (abqve), S l ip t he d ri vj ;l b e .l tS o ffth e m oto r· p ulle y a nd th e. c ap sta n flyWh ee l u sin g lo ng -n os e p lie rs

or tw eez erS . A vo id to uc hin g o r p in ch ing a ny u nd am ag ed b elt. Lift ou tth e capstan pla te a nd th e m otor a long w ith th e ca ps ta n drive belt,ta king ca re not to oa ma ge th e m otor w ires .

3·Removing the tape. transport assembly. U ns cre w th e ta pe

tra ns po rt a Ss em bly from th e fra me. U sin g lo ng-n os e p lie rs or

tw ee ze rs . re move fro m it th e p la y/re co rd s witc h le ve r, a ny eje ctm ec ha nis m s prin gs a nd th e ta pe -c ou nte r d rive b elt, n otin g th eir p os i-

tio ns . fo r re as semb ly .. U nc lip th e ta pe tra ns po rt a s semb ly fro m ta bs s e-curing itto th e fro nt p an el (inset) a nd c are fully lilt it ou t of th e a ud io -c a s s et te r ec o rde r (above).

36

2'Cleaning and lubriCating the capstan. P ull th e c ap sta n fly -.w h ee l o ut o f th e ta pe tra ns po rt a s semb ly (above), e xp os in g th e

c ap sta n. C le an th e c ap sta n fly Wh ee l a nd th e. c aps ta n w ith a fo as w a b d ip pe d in t;lE in '!tu te d a lc oh o l (inset). U s e a .to olh pic kto d is lo dg e

d irt fro m th e c ap sta n ge ar tee th . t.u orlc ate th e ca ps ta n b as e u sin g afo am s w ab m ois te ne d w ith ligh t m ac hin e .oil, a vo id in g c on ta ct w ith th e

tip, w hich touch es th e a udioca ss ette ta pe. U se a toothpick to a pply alittle w h lle g rea se to th e capstanqear le eth . W ip e o ff excess lubr icantw ith a c lean loam sw ab. .

4Cleaning and lubricating the gears. C le a n th e ta p e tr an s po

a ss em bly g e~ rs u .S in .g a fo am s w ~b d ip pe d in d en atu r.e d a lc o~ o. U se a tooth pick to dis lO dge a ny dirt from th e gea r teeth. Lubri-

ca te th e g ea r tee th by a pp ly in g a tittle w hile g ri;ta se w ith a cleanstick(above); usea c lea n foa m sw ab to w ipe off exces s lubrica nt. If a geais d a rn a qe d, r ep la c e it (page 1 35 ). T o re in sta ltth e .ta pe tra ns po rt a s -sem bly, C lip it under th e ta bs on the front pa ns l, screw it to tha fra me.a nd in se rt th e c ap st;;m fly w he el. P ut b ac k th e p la y/ re co rd s w itc h le vea ny e je ct m ec ha nis m s pring s a nd th e ta pe -c ou nter drive b elt R ein stath e c ap sta n p la te , re ve rs in g th e s eq ue nc e in.step 1, th e n r ein s ta ll th e

.Iop panel (page 31) .



SERVICING THE MODE SWITCHES

AUDIOCASSETTE RECORDERS

Cleaning and lubricating the switches.Remove the mode-switch control assembly and

the loading door (page 31). Use a foam swab

dipped in denatured alcohol to clean the entire

surtacs of each switch (left); for easier access;

prass in and release the switch lever so that it

protrudes as far as possible. To lubricate the

sWitch, use a toothpick to apply a litt le white

grease iNhere the switch lever enters the switch;

press in and release the lever a number of

times to work in the lubricant. Avoid applying

lubricant to the control contact points. Wipe

off excess lubricant with a clean foam swab.

Reinstall the loading door and the mode-

sWitch control assembly (page 31).

SERVICING THE MUTE SWITCHES

fast forward/rewindmu te sw i tc h

1leaning and testing the switch. Remove the top panel (page31); to reach the pause/stop mute sWitch, also remove the cap-

stan plate. the capstan flywheel and the tape transport assembly

(page 36). If a switch leaf is damaged. replace theswilch (step 2). tf a

switch wire is loose or broken, repair il (page 132). Sat a mul titester to

test continuity (page 128). Touch one probe to a wire terminal on the

switch and touch the other probe in turn to each wire terminal on the

circuit board. The rnulntsster should register continui ty once-and only

once. Repeat this procedure for each swi tch wire. If a wire tests faulty,

replace it (page 132)c If each wire tests OK, gently run an emery board

over each leaf (above). Put back the tape transport assembly, jf you

removed 11.reversing the sequence used (page 36). Reinstall the top

panel (page 31). I f the problem persists, suspect a faulty circui t board

and take tM audiocassette recorder for protesslonal service.

< 2Removing and replacingtbe switch, Undip or unscrew theswitch from the tape transport assembly. Tag the switch wires.

noting thei r terminals. and desolder them from the swi tch (page

130). Order an exact replacement switch from the manufacturer or pur-

chase a SUbstitute at an electronics parts supplier. Set the switch in a

soldering stand and solder (page 131) the wires to the switch terminals

(above). Clip or screw the switch to the tape transport assembly. Put

back the tape transport assembly. if you removed i t, reversing th'e se-

quence used (page 36). Reinstall the top panel (page 31). If the prob-

tern persists. suspect a faulty circuit board and take the audiocassette

recorder for professional service.

37




SERVICING THE PLAY/RECORD SWITCH

2Turning over th.e circuit board. Carefully dis.engage the play/

record switch lever connected to the tape transport assembly

from the play/record switch; use long-hose pliers or tweezers, if

required. Push th~ control levers off the tape selector and noise reduc-

tion switches (above). To reach the switch pins, unscrew the circuit

board, remove any components in the way and turn over the circuit

board, avoidinq damage to any wire connect ions.

38

1leaning the switch. Remove the top

panel (page 31). Locate the playJrecord

switch on the circuit board. To clean the

switch, spray short bursts of electronic contact

cleaner through the opening in the switch cas-ing. Press in and release the switch several

times to work in the cleaner (left). taking care

not to damagetha hook-like switch lever con-

nected to the tape transport assembly. Reinstal l

the lop panel (page 31). If the problem persists,

remove the top and back panels (page 31) and.turn over the circuit board (step2) to reach the

play/record switch pins.

3Removing and replacing the switch. Desolder the switch pins

(page 130). Turn over the circuit board and pull off Ih!;! switch;

wiggle it to help release the pins. Order an exact replacement

play/record switch from the manufacturer or purchase a.substitute at an

electronics parts supplier. Rt the switch pins into the circuit board, turn

over the circuit board and solder (page 131) the pins (above). Put back

the circuit board. reversing the sequence used to remove it (step 2).

Carefully reconnect the switch lever to the play/record switch (inset).

Reinstall the back andtoppanels (page 31).



SERVICING THE RECORD LEVEL POTENTIOMETER

AUDIOO\SSETIE RECORDERS

1leaning and testing the potentiometer. Remove the top

.panel (page 31) and locate the potentiometer on the ci rcuit board

behind i ts control . Spray electronic contact cleaner into the po-

tentiometer casing (inset) and rotate the control back and forth to workit in. I f the problem persists, test ' the potenliomeier. Set a multi tester to

test resistance (page 129). Clip one probe to the center pin in one row

on the circuit board and touch the other probe in turn to the other pins

in the row (above), turning the control back and forth. The mult ltester

should register an ohms variation 'for each pin. Test the other row of

pins the same way. If the potentiometer tests faulty, remove it (step 2).I f the potentiometer tests OK, suspect a faulty circui t board and take

the audiocassette recorder for professional service.

2Removing and replacing the potentiometer. Pullthe control

off the potentiometer and unscrew the sha' ft locknut. lift out the

poteriiiometer and circuit board, pul ling the shaft through the

opening in the f ront panel. Desolder the potent iometer pins (page 130),

and pull 011the potentiometer; wiggle i t to help release the pins. Testresistance again to confirm the potentiometer is faulty (step f). Pur-

chase an exact replacement potentiometer at an elect ronics parts sup-

plier. Fi t the potentiometer pins into the circui t board, turn it over andsolder (page 131) the pins (above). Slide the shaf t through the opening

in the front panel. screw on the shaft locknut and put back the control.

If the potentiometer now tests OK, but the problem persists. suspect a

faulty circu it board and take the audiocassette recorder for professional

service. Reinstal l the top panel (page 31).

SERVICING THE FEATURE SWITCHES

1leaning the switch. Remove the top panel (page 31) and

locate the switch on the ci rcuit board behind the control. Spray

short bursts of electronic contact c leaner through the opening

In the switch casing (above); press in and release the control several

times to work in the cleaner. Reinstall the top panel (page 31). I f theproblem persists, remove Ihe top panel (page 31) and turn over the

circuit board (page 38) to reach the swi tch pins.

2Testing and replacing the switch. Set a mul titester to test

continuity (page 128). Test as tora mul ti-pole switch (page 138):

Touch one probe to the center pin in one roW and touch the

other probe in turn to the other pins in the row (above, top). For each

switch setting, the rnumtester should register continuity with only one

pair of pins. Test the other row of pins. lIthe switch tests faulty, de-

solder the pins (page 130} and pull off the switch. Purchase an exact

replacement switch at an electronics parts supplier. Solder (page 131)

the pins into the circuit board (above, bottom). If the switch tests OK.

suspect a faulty circuit board and take the. audiocassette recorder for

professional service. Put back the circuit board, reversing the sequence

used to.remove i t (page 38), and reinstal l the paneis (page.31J.

39



AUD IQCA SS EIT E R ECORP BR S,

TE'STING AND REPLACING THE ON/OFF SWITCH

1

esting the switch. 'Remove the top panel (pay? 31). Disengage the control leyer from

the onlof f switch (abOve. left), unscrew tMe switcb and the clrcultboard, and turn over the

. circuit board, Set a multitl;lster to test continuity (P<lge 128). Hook one probe to one switch

pili and touch the other probe to the other switch pin (above, right). Set the switch to the ON po -sition, then to the OFF position. The multitester should register continuity only in the ON position.

If the switch tests faulty, replace it (step ? J . If the switch tests OK, screw in tM circuit board and

the switch, reconnecttha control lever, and service the power &upply lbelowr

2Replacing the switch. Desolder the

. . pins (p ag e 1 30 ), turnover the circuit

board and pull oft the switch. Purchase

an exact replacement switch at an elsctronics

parts supplier. Fit the pins into, thecirtuitboard and solder (page 131) the pins (above).

Screw in the circuit board and the swiich, put

back the control lever, and reinstall the top

panel (page. 31).

SERVICING THE POWER SUPPLY

1·esting between .the transformer and the power block or

the on/otT switch or the fuse. Remove the top panel (page 31) .

andidehUfy the power ~upply components (page 13B). Locate.

the contact points ior the two transformer wires connecting to power

block, on/off .switch or fuse terminals. If a wire connection is loose or

broken, repair it (page 132). Set a mult itester to test continuity (page

128), Touch one probe to the terminal for cnetranstorrnerwlra and

touchfhe other probe to sach power blockterminal, in turn (abQve) .

The multi i.ester should register continuity once-e-andonly once. Test

the other transformer wire. If the multitester registers continuity for each

test, test the' transformer (step 2). If not, suspect a faulty circuit board

and taKe the audiocasset te recorder for professional service,

40

2Testing the transformer, Locate. the contact points for the.

transfo,rmer wires oth~r than t~ose tested in step 1: If the ,~ircuit

board IS not coded With the wire colors, nota the wirs.posjnons

anddesolder them (p ag e 1 30 ). Set a.multltesterto testvoJfage (page

129). If there are only matching-colored wire pairs. clip the probes to

one.rnatchtnqpalr (above); i l there is one odd-colored wire,clip.one

probe to it and clip the.other probe to.one of the rnatchinq wires. Plug

in the .audiocassette recorder and turn it on, The multitester should reg

ister voltage, Turn off the audioqassette recorder and unplug it. Repeat

this procedure with each matching wire pair or with the odd wire and

each matching wire. II the multitsster does not register voltage, replace

the transformer (step 3). I f the mult itester registers voltage, suspect a .faulty circuit board and take the' recorder lor protesslonal service ..



SERVICING THE POWER SUPPLY (continued)

AUDIOU \_ SS ETTE RECORDERS

3Removing and replacing the trans-former. Desolder (page 130) ths two

transformer wires connected to power

block, onloff switch or fuse terminals, noting the

wire positions. Unscrew the transformer ( fa r l e ft )

and remove it from the audiocassette recorder.

Order an exact replacement transformer from

the manufacturer or purchase a substitute at

an electronics parts supplier. Instal l the trans-

former and solder (page 131) aUthe wires in

their proper positions (near left). Reinstall the

top panel (page 31). I f the problem persists,

suspect a faul ty circuit board and take the

audiocassette recorder for professional

service.

SERVICING THE CAPSTAN MOTOR

1esting the motor.

Remove the top panel(page

31) and locate

the two wires CCinnecthig the motor to the circuit board. If a wire

is loose or broken, repair it (page 132); Set a multi tester to test

voltage (page 129). Plug in and turn on the audiocassette recorder.

Press the play/mode control . Touch a probe to each wire contact point

on the motor (above), avoiding any contact with other components.

The mulutester should register voltage. Release the play/mode contro l,

and turn off and unplug t_heaudiocassette recorder. I f the multi tester

registers VOltage, replace the motor (step 2). If the multitesterdoes not

re-gistsr voltag.e, suspect a faulty circuit board; reinstal l the top panel

(page 31) and take the audiocassette recorder for professional service.

2Replacing the motor. Remove the capstan plate (page 36)

an d unscrew the molar from it (jnset). Tag the motor wires, noting

their posit ions, and desolder the wires (page 130) from the mo-

tor.Order an exact replacement motor trom the rnanutacturer or pur-

chase a subst itute at an electronics parts supplier. Solder the wires

(page 131) to the motor (above). Screw the motor onto the capstan

plate and put back the capstan plate, reversing the sequence used to

remove it (page 36). Reinstal l the top panel (page 31). I I the problem

psrsists, suspect a faulty c ircu it board and take the audiocassette

recorder lor professional service.

41



TURNTABLESThe turntable (he/ow), whether belt drive or direct drive, auto-

matic or manual, I S the most. mechanical unit of the. audio sys-

tem. The stylus tracks in the grooves.of'.a record turning on the

platter; The cartridge transforms this motion into an electrical

signal, sending itthrough wires in the, tone arm to cables lead-ing to the receiver. There, the signalis amplified and sent

through cables t o the speakers.

To diagnose the turntable as the source of audio problems,

consult the Troubleshooting Guide in Entertainment Systems

(page U) and in this chapter (right). Most problems can be

remedied by securing cable hookups, rebalancing the tone arm,

realigning the cartridge or servicing the power supply. Replace-

ment components are usually available at an electronics part

suppliensome, however. may have to be ordered from the turn

table manufacturer.

A set-of small screwdrivers, a multitester and a soldering iro

make up the basic tool kitfortumtablerepairs (page 126).Refeto Tools &Techniques for tips on disassembly and reassembly

(page 140), testing continuity-and voltage (pages 128-129),and

desoldering and soldering (pages 130-13/).

Tum off and unplug the turntable before attempting anyre-

pair. Disconnect ' its cables and set it on a clean work table. Col

check for leaking voltage (page 141) after reassembling th

turntable but before plugging it in.

Moto r

Turns the pla tter, eith er w ~h a be~ ord ire ctly ; m ay o pe ra te o n d jre ct c urre nt

(D C) o rillte ma tin g c urre nt (A C).

P oWer t ra n sf ormer

Converts t;~O·voltattemating current (ACjtelo w v olt ag e r eq uir ed by

.electroriic cornoonents,

Dflve bell

D~lien p y moto rto tu m the p la ttE il '.

Ptatter

R oo nd p la te o rr w h ic h

the record S i t S ; fumeddirectly by the moto r o r

by a belt from tile motor,

I

Speed selector contro l

·S ets th e pla ne r s oe ed

usual ty by controllim theflo w o f c ur re nt 10 t he m o to r.

cartr idge

Translates t h e i nte rac t io n 01

the stylus and the recordg ro ll'( es in to e le ct ric a l s ig na l.

StylusTracks in . reCord

g ro ove s; u su ally a fln e

d ia i no nd ,i t· r equ ir e s

fraquen! replacement.

42

ReCord mat

Pads the record andkeepsil from slipping,

POWer· co rd

ProV ides 120·vo lta l te rnati ng. (AC] through th e

receiYjOtr or f r o m a wo i ll ou tl e l.

Cou,nl4lrwelghtAdjusts th e vertical

t ra c ki h g f () rc e . or

WEl i9ht, of t hs s ty lu s .

Shut-off mecllanlsmR i i i s e s ' l h e tOr\e a rm a nd s to ps

th e platter when t he S lY lu $reaches the en d of t he r e co ro .

On/off

May be a n a cl ua to rs w it ch i ha icloses a nd o pe ns ; p; or din g tot he to ne -a rm p os it io n.

Houses the cartridgeand s ty lus, ..



TURNTABLES

T RO UB LE SHOO TI N G G UID E

SYMPTOM POSS IBLE CAUSE PROCEDURE

T urn ta ble u np lu gg ed O r t urn ed o ff P lug in a nd tum on tu rnta blela tter does not turn

No power to o utle t, o r o ut le t fa u lty R es et brea ke r or re pla ce fus e (p. 10 ) DO; h a ve o utle t s erv ic ed

P ow er c ord fa ulty

R e ce iv er f a ult y T ro u ble s ho ot e n te rt ainmen t s y st em ( p . 14)DO

T es t a nd repla ce pow er c ord (p. 137) Db

D rive b elt lo os e o r b ro ke n S erv ic e d riv e b elt tp. 45) DO

Shut-o ff mechanism jammed C lean and lubrica te shut-offmechan i sm (p. 49)DO

On/off sw itch fa u lty Tes t a nd repla ce on/o ff sw itch (p. 50) DO

P ow e r s up ply fa ulty S e rv ic e. p ow e r s up ply (p. 50) ~O

Mo tor f a ul ty Te st a nd repla ce m otor (p. 51)~O

Circu it boa rd fau lty Take turntable for profes s iona l service

Pla tter turns a t w rong s p e e dor a t only one speed

D riv e b elt d irty orloose S er vic e d riv e b elt (p. 45) DO

S h ut- oft m e ch a nis m d irty

M otor running too fa st or too s lo w A dju st m oto r s pe ed (p . 46) DO

C le an a nd lu br ic a te s h ut- off m e ch a nis m (p. 49) DO

Speed selec tor sw itch fa u lty Tes t and repla ce speed selector sw itch (p. 49)DO

P ow er s up ply fa ulty S erv ic e p ow er s up ply (p. 50) ~OMo to r f au lt y T es t a nd rep la ce m oto r (p. 51) ~O

Circu it boa rd fau lty Ta ke tu rnta ble for profess iona l s ervice

P la tter does no t s top. turningor s tops before end 01 record

S hu t-o ff m ec ha nis m d irty o r ja mm ed Cleanand lu br ic a te s h ut -o ff m e ch a nism ( p . 49)DO

S h ut·o ff m ec ha nis m fa ulty T a ke tu rn ta b le fo r p ro fe ss io na l s er vic e

No . sound R e ce iv er f au lt y T ro ub le sh oo t e nte rta in m en t s ys te m (p ; 14) DO

Tone a rm w ires loos e or broken

Ca rtridge fa u lty Tes t and r epl a ce ca r tr id ge Ip . 47) DO

S ervic e to ne a rm (p.48) DO

C irc uit b oa rd fa u lty . T a ke t ur nt ab le f or p ro ie s s io na ls e rv ic e

Sound from only one channelor interm itte nt s ound

R ec ord o r s ty lu s d us ty C le an re co rd a nd s ty lu s (p o 44)00

R ec eiver or s pea ker fa ulty . T ro ub le sh oo t e nte rta in m en t s ys te m (p . 14 ) DO

T on e a rm u nb ala n ce d B ala nc e tone a rm (p. 44) 00

Ca r tr id ge m i s a li gned Ad j ti s t c a r tr id ge (p, 45) DO.

S tylus w orn o r b roken Repla ce s tylus a s sembly (p. 46) do

Ca r tr id ge f aul ty T es t a nd r ep la c e c a rtr id ge (p . 47) DO

T one a rm w ire loose or broken Service tone a rm (p.48) DO

S ouM dis torted; s cra tch ingor h is sing nois e

C ircu it boa rd fau lty Take tum tab le for profes s iona l serv ice

H ecordors !ylu s dus ty Clean record a n d s ty l! Js (p. 44) 00

R ec eiv er o r s pe ak er fa ulty T ro ub le sh oo t e nte rta in m en t s ys te m (p . 14) DO

T on e a rm u nb ala nc ed B ala nc e tone a rm (p. 44) 00

Ca rtridge m isa ligned A djus t ca rtridge (p o 45) DO.

S ty lu s w orn o r b ro ke n R ep la c e s ty lu s a s semb ly (p. 46) DO

Ca r tr id ge f au lt y T es t a nd r ep la ce c ar tr id ge (p. 47) DO

C ir cu it b oa rd fa ulty T a ke tu rn ta ble lo r p ro fe ss io na l s er vic e

Humming, buzz ing or

ru mb lin g n ois e

G ro uh d W ir e lo os e C h ec k g ro un d w ire c on ne ctio n (p. 17) DO

R ec eive r o r s pe ake r fa ulty T ro ub le sh oo t e nte rta in me nt s ys te m (p.14) DO

Ca rtridge fa u lty Tes t a nd repla ce ca rtridge (p . 47) 00

C ir cu it b oa r d f au lt y T a ke tu rn ta ble fo r p ro fe ss io na l s er vic e

Burning odo r Pow er supply f a u lty S erv ice p ow er s upply (p . 50} ~O

C ir cu it b oa rd fa u lty

Motor fa u lty Tes t and repla ce m otor (p. 51)~O

T a ke t ur nt ab le tor p ro fe s sio na l s e rv ic e

D EG RE E O F D IF AC ULT Y:

E ST IM A TE D T IM E:

oEasy ~ Modera te .Complex

o Les s than 1 h our 1O il1o 3 hours • Over 3 hou rs .S pec la l too l require d

43



TURNTABLES

CLEANING RECORDS AND THE STYLUS

1usting records, Turn off the turntable, leaving the record in

place on the spindle. Posi tion a nylon record brush across the re-

cord and light ly touch the brist les to the grooves. Applying steady,

gentle pressure on the brush wi th one hand, slowly rotate the platter

wi lhlhe other hand (above) . Wip~ of f the brush on a clean, lint-free

cloth. Turn over the record and repeat this step. Turn on the turntable.

To prevent record damage, perform this procedure before each p lay .If the record sound quali ty is still poor, clean the stylus (step 2).

Headshell

2Brushing the stylus. Turn off the turntable. With the tone arm

at rest on i ts stand., position a nylon StyIU. brush behind the stylu

just below the headshelL Pull the brush slowly forward from unde

the headshell , l ightly touching the brist les to the sty lus (above) ; avoid

any side-la-side or front-to-back motion. Wipe off the brush on a clean,

l int-free cloth. Turn on the turntable. To prevent damage to the stylus

or records, perform this procedure before each record-playing session.

BALANCI NG THE TONE ARM

Adjusting the counterweight and the anti-skating control. Tum off the turntable and

remove any record from the platter. Wi th the tone a rm at rest on its stand, flip :down the stylus

guard, if any. and set the anti-skating control to O. With the cueing lever loWered, liflthelone arm

and position it over the plat ter. Supporting the tone arm with one hand. rotate the counterweight

with the other hand until the tone a rm floats perpendicular above the plalter; then turn the calt-brated scale control unti l the 0 on the scale IS aligned with the mark on the tone arm (a bo ve , J e ff).

Place the tone arm back on i ts stand. Set the counterweight and cal ibrated scale to the midpoint

0 ' th e range specified by the cartridge manufacturer ( ab o vB , c e nt er ); adjust the anti-skating control

to the identica l setting (above, right). Flip up the stylus guard, if any.

44



ADJUSTING THE CARTRIDGE

TURNTABLES

Realigning a straight tone-arm cartridge. T urn o ff th e tu rn ta b lea nd re move a ny rec ord fro m th e pla tte r, If th e to ne a nn s ta rts a nd s top sth e p la tte r, u np lu g th e tu rn ta b le f rom th e re ce iv er (page 12) or w ail ou t-le t. U s e a s tr aig ht to ile -a n n a lig nmen t p ro tr ac to r s up plie d b y th e tu rn ta b le

man! J fac t ure r o r purchased a t a n e le ctro nic s p a rts s up plie r. P os itio n th eprotra ctor o n th e s pin dle a nd ge ntly low er th e ton e a rm to s ea t th e s tylu sin th e s ty lu s o pe nin g o n th e p ro tra cto r. C he ck th e c artrid ge a lig nm en tb y lo o ki ng s tr a ig h t down fro m a bove th e ton e a rm . If th e ca rtridg e is no te xa c tly p a ra lle l to th e g rid lin es , Ii.ft th e to ne a rm a nd lo os en th e c artrid gescrews (above). Lower the to ne a rm to re se at th e s ty lus a nd a dju st th ecartridge s o it is e xa ctly p ara lle l to th e g rid lin es . Lift th e tone a rm a nd

tig hte n th e h ea d sh eU s c rew s . Place th e ton e a rm back o n its s ta nda n d r emo ve th e p ro tr ac to r.

Realigning a J - or S-shaped tone-arm cartridge. Tu rn off th etu rn ta b le a n d r emov e th e h ea d sh ell (page 47). D epe nd ing on th e s ha peof th e lone a rm , us e a J- o r S -s h ap ed to ne -a rm a lig nmen t p ro tr ac to r

s up plie d b y th e tu rn ta ble m a nu fa ctu re r o r p urc ha se d a t an electronicsparts s up plie r. P os itio n th e h ea d sh ell in !h e p ro tr ac to r a n d c he ck th ec artriQ ge a lig nm en t b y lo okin g s tra ig ht d ow n a t th e c artrid ge fro m th efro nt o f th e haadshall, If th e s ty lu s is n ot e xa ctly c en te re d o ve r th e s ty lu smark o nth a p ro tra c to r, lo os en th e c a rtr id ge s cr ew s (above). A d ju st th ecartr idge 50 th e s ty lus is exa ctly c en tered o ve r th e s ty lus m ark a ndtig h te n th e h ea d sh ell SCf8WS. Re in s ta l l t he heads he ll ( pa ge 47) ,

SERVICING THE DRIVE BELT

Cleaning and replacing the drive belt.T urn o ff th e tu rn ta ble , remo ve a ny re co rd fro mth e pla tter a nd lock th e tone a rm . Lift off !h e re-c ord m at a nd lo ca te th e d rive be lt th rou gh th eo pe nin g in th e pla ne r. P ull th e b elt a w ay from

th e p uKey (left). lift o ff th e p la tte r and r em o ve th ebell. If th e belt is w orn or broken, order a n exa ct

r ep la c ement b elt f rom th e tu rn ta b le m a nu fa c tu re ror p urc ha se a substitute b elt a t a n e le ctro nic sp a rts s u pp lie r. If th e. b elt is s tic ky or g re a sy , w ip e

if th oro ug hly u sin g a d ea n, lin t-fre e d oth s prin -k le d w i th a little r ub be r c le a nin g c ompo un d; ne -v er a pp ly a ny th in g o ily . T o re pla ce th e b elt, tu m

th e p la tter fa ce do wn a nd w ra p th e b elt a rou ndth e tr ac kin g r im (inset), p ullin g it to th e o pe nin gin th e p la tte r; L ift th e p la tte r e no ug h to re a ch th e

b ali th ro ug h th e o pe nin g fro m th e o th er s ld ea ndturn th e p la tte r u prig ht w ith ou t tw is tin g th e b elt.S till h olding th e b elt, re se al th e pla ne r a nd p uBth e b elt a ro un d th e p ulley . P ut ba ck th e rec ordm at a nd unlock tM tone a rm . A djus t the m otorspeed (page 4 6) if n ec es s ar y.

45



TURNTABLES

ADJUSTI NG THE MOTOR SPEED

Fine-tuning the 'speed using a strobe disc. Tu m o ff th e tu IT lta ble a nd re mo ve a ny re co rdf rom t he p la t te r. If th e tu rn ta ble is n ot e qu ip pe d w ith a b uilt-in s tro bo sc op e, u se a s tro be d is c s up -p lie d b y th e tu rn ta ble m a nu fa ctu re r o r p urc ha s ed a t a n e le ctro nic s p arts s up plie r. L oc a te th e p itc h

a d ju s tm en t s c re w s , e ith er o n the to p p an el o r re ac he d th ro ug h a pe nin gs in th e p la tte r b en ea thth e rec ord m at, a s s ho wn. P os itio n th e s tro be dis c a n th e s pindle a nd tu rn o n th e tu rnta ble. S hinea flu ore sc en t lig ht o n th e tu rn ta ble a nd o bs erv e th e s tro be d is c m a rk in gs th at c orre sp on d to th es pe ed -s ele cto r s w itc h s ettin g. A dju st th e s cre w c or re sp on din g to th e s w itc h s ettin g to th e e xa ctpo in t a t w hic h Ih e: m a rkings a ppea r a sa s olid, m otio nles s b and. If th e s crew is u nder th e pla tter,y ou m us t tu rno ff th e tu rn ta ble, lift u p th e rec ord m at a nd a dju st th e s crew (above); th en , p ut b ac kth e r ec or d mat, tu rn o n th e tu rn ta ble a nd a ga in o bs erv e , H i e s tro be d is c m a rk in gs . R ep ea t th isp ro c ed ur e, if r eq uir ed , fo r e a ch s p ee d s ele cto r s w itc h s ettin g.

Fine-tuning the speed using a built-instroboscope. T urn o n th e tu rnta ble a nd o b-s erv e th e s tro bo sc op e m a rk in gs o n th e o ute r

edge o f th e pla tter th at c orres po nd to th es p ee d- se le cto r s w itc h s ettin g. A d ju s t th e p itc ha dju stm en t c on tro l d ia l o n th e fro nt, to p o r s ido f th e tu rnta ble to th e ex ac t po int a t w h ic h thm a rk in gs a pp ea r a s a s olid , m otio nle ss b an d(above). Rep ea t th is p ro ce du re , if r eq uir ed ,fo r ea ch s peed-s elector s witch s etting. '

REPLACI NG THE STYLUS ASSEMBLY

Installing a new stylus assembly. Turn off th e tu rnta ble a nd flip d ow n Ih e s ty lu s gu ard, if a ny .L ift u p th e to ne arm to c he ck h ow th e s ty lu s a s semb ly ' fits in to th e c artrid ge ; if y ou c an no t d ete rm in eh ow to la ke o ut th e s ty lu s a ss em bly , rem ove th e h ea ds hell (page 4 7) a nd ta ke it to a n el9 9lro nic sp arts s up plie r, In m a ny c as es , th e s ty lu s a s semb ly s lid es o ut fro m tra c ks u nd er th e c a rtrid ge . G ripth e h ea ds hell in o ne h and a nd gently pu ll th e s ty lu s a ss em bly s tra igh t o ut fro m u nder th e c artridgeu sin g a th um b a nd fo re fin ge r ( above , / e ft ). In o th er c a se s, th e s ty lu s a s semb ly is p ulle d s tra ig ht o ffthe c a rtrid ge . F or b ette r a cc es s to th is ty pe . re mo ve th e h ea ds he ll (page 4 7) a nd tu rn it o ve r. G r ipth e h ea ds hen in o ne h and a nd pu n s tra igh t u p o n th e s ty lu s a ss em bly w i t h the other (above. right).

Purchase an i de nt ic a l r ep la cemen t s ty lu s a s semb ly f rom an e le ctr on ic s p a rts s u pp lie r. S lid e th e s ty -lu s a s semb ly a lo ng th e tra ck s o f th e c artrid ge u ntil it' f its s nu gly . o r p re ss th e s ty lu s a s semb ly in toth e c a rtr id ge a n d r ein sta ll th e h ea d sh ell (page 4 7). F lip u p th e s ty lu s gu ard, if a ny . If nec es sa ry .ad ju s t t he ca rt ri dg e (page 4 5) a nd ba la nc e th e to ne a rm (page 44).

46



TESTING AND. REPLACING THE CARTRIDGE

TURNTABLES

1emoving the headshelJ. Tum off th e turnta ble a nd lock th e

to ne a rm . F lip dow n th e s tylus gua rd, if a ny, or rem ove th e s tylus

a ss em bly if it s lid es o ut e as ily fro m u nd er th e c artrid ge (page 46).S up po rtin g th e h ea ds he ll w ith o ne h an d, lo os en th e s cre w (above) or

t he c o lla r (inset) s ecuring it to th e ton e a rm a nd gen tly s lide it off. 1 1th eh ea d sh eU c an no t b e d eta ch ed , te st th e c a rtrid ge W ire s (step 3 ). T ur n

o ve r t he head! ;>hella nd check th e c a rtrid ge w ire c on ne ctio ns . . If th e w ir ec on ne ctio ns a re s ec ure , c he ck fo r s ig na l th ro ug h th e to ne a rm (step 2).

If a w ire is lo os e, c are fu liy re co nn ec t it to its te rrh in al u sin g tw ee ze rs .R ein sta ll th e h ea ds h ell a nd , if re qu ire d, p ut back th e s ty lu s a ss em bly o r

flip u p th e s ty lu s g ua rd . U nlo d< th e to ne a r m .

3Testing the cartridge. wires; Set a mullite ste r to te st c on tin uity(page 1 28). H ook one probe to th e crim p connector a t th e end ofone w ire a nd touch the other probe to the crim p connector a t the

oth er en d o f th e w ire; fo r ea sier a cces s, pu ll th e w ire off its term ina l(above). T es t e ac h w ire . If e ac h w ire re gis te rs e on tin uity , in sta ll a n ewcartridge (step 4 ). If e ac h w ire d oe s n ot re gis te r c on tin uity , p urc ha se a nid en tic a l re pla cement s et o f c a rtrid ge w ire s fr om a n e le ctr on ic s parts sop-p ila r. II t he c artrid ge w ire te rm in als a re n ot c od ed to th e c artrid ge w irec olo rs , n ote th e te rm in al p os itio ns fo r th e w ire s o r remo ve a nd re pla ceth e w ires one a t a tim e. R eins ta ll th e h ea ds hell (step 1) .

2Checking for signal through the tone arm. To c hec k th ew ire . c o nn ec tio ns b ey ?n d th e n ea ds ne ll, tu rn o n. t h e tu rn ta bl~ a ndre ce ive r, s et th e re ce iv er s ele cto r c on tro l to P HONO a nd a djU s t

th e re ce ive r v olu me c on tro l to s lig htly a bo ve its lo we st s ettin g. U sin g a

sm all m eta l s cr ew d riv er o r h old in g a la rg er s cre w driv er b y its b la d e, lig htlytou ch th e s cre wdrive r tip to ea ch term ina l. a t th e end o f th e ton e a rm(above). (f there is a n a udib le hum from the spea kers a t more or lessth an tw o to ns -a rm term in als , tes t th e ton e a rm w ires (page 4 8) , If th ereis a n a udible h um from th e s pea ke rs a t on ly tw o tone -a rm term ina ls ,tu rn o ff th e tu rn ta ble a nd te st th e c artrid ge w ire s (step 3).

4Installing a new cartridge. T o remo ve th e c a rtr id ge , d is co n-

n ec t th e c artrid ge w ire s fro m th e c artrid ge te rm in als a nd u ns cre wth e c artrid ge fro m th e h ea ds he ll. If re qu ire d, remo ve th e s ty lu s a s·

sembly (page 4 6) . P urc ha s e a r ep la c emen t c ar tr id ge a t a n e le ctr on ic sparts s up plie r. R ein sta ll th e s ty lu s a ss em bly , w ew th e c artrid ge to th eheadshel l (above) a nd c on ne ct th e c artrid ge w ire s to 'th e te rm in als u sin g

tw ee ze rs . If th e c artrid ge te rm in als a re n ot c od ed to th e w ire c olo rs ,c on ne ct th e w ir es if l th e id en tic al s eq ue nc e a s a t th e h ea ds he ll te r·m ina ls . Re in s ta ll th e heads hel l (step 1). If n ec es sa ry , a d ju st th e c a r-

tridge (page 45) a nd ba la nce th e tone a r m (page 44) .

47



TURNTABLES


1nscrewing the bottom panel. Tu m off th e tu rn ta ble a nd u n-

p lu g it fro m th e re ce ive r o r w a ll o utle t, R em ove a ny re co rd fro m

th e p la tte r a nd lo ck th e to ne a rm . D is co nn ec t th e tu rn ta ble c ab le sa nd g ro un d w ire h oo ke d u p to th e rec eive r (page 12) . S ec ure a ny tra ns its cre w s, remo ve th e re co rd m a t a nd lift o ff th e p la tte r; if re qu ire d. firs tre mo ve th e d riv e b elt (page 46). T um o ve r the tu rn ta ble a nd u ns cre w Ih eb otto m p an el, c he ck in g fo r h id de n s cre w s in th e tu rn ta ble fe et (above).

lift o ff th e bottom pa nel if th e tone armassernolv is m ounted on th e toppa nel. If th e tone a rm a ss em bly is m ounted th rough a oopening in th elo p p an el, re mo ve th e to p p an el (step 2).

2Lifting off the top panel, Ca re fu lly tu rn th e lu rn ta b le u pr ig h t,

p ull o ff th e d us t C ?v er. a nd remo ve th e h ea ds he ll (page 47). Screwo ff th e c ou nte rw e ig ht, re mo ve th e c ou nte rw e ig ht s ha ft a nd u nlo ck

th e tone a rm . lift up th e top pa nel, s lide th e tone a rm th rough th e openin g fo r th e to ne a rm a ss em bly (a/)ove) a nd re lo ck th e to ne a rm . G en tlytum th e to p p an el fa ce d ow n b es id e th e b otto m p an el. T o re in sta ll th ela p p an el, re ve rs e th is s te p a nd s te p 1 (left), a nd re co nn ec t th e c ab le s(page 1 6) a nd g ro un d w ire (page 1 7). R eb ala nc e th e to ne a rm (page 44

SERVICING THE TONE ARM

1esting the tone ann wires. R em ove th e to p o r b otto m p an el ( st ep a bo ve) . If !h e to ne

a rm a ss em bly is m ou nte d o n th e- bo tto m p an el, u ns cre w it a nd c are fy lly tu rn it o ve r, a s

s ho wn , to re ac h th e to ne -a rm w ire c on ta ct p oin ts o n th e c frc uit board. If a w ire is loose ori> r9k1 ;! n ,epa i r i t (page 1 3;). S et a m ultlte ste r to te st c on tin uity (page 1 28). Touch one probe to aw ire term ina l on th e tone a rm and touch th e oth er probe in tum to ea ch Wire c on ta ct p oin t o n th ec i rcu it boa rd (above). T he m ultite ste r s ho uld re gis te r c on tin uity o nc e--a nd o nly o nc e. T es t e ac hw ire ; il o ne is fa ulty , re pla ce th Ei t on e ru m (step 2 ). If ea ch w ire tes ts O K, s crew th e tone a rma s semb ly in p la ce ,i! re qu ire d, a nd re in sta ll th e to p o r b otto m p an el ( st ep a bove ). If th e p ro blemp ers is ts , s us pe ct a fa ulty c irc uli b oa rd a nd ta ke th e tu rn ta ble fo r p ro fe ss io na l s ervic e. -

48

2Replacing the tone arm. NQte t hE )

w ire p os itio ns a nd d es cld er th e w ire s( pa ge 1 30 ). Remo ve th e h e ad s he ll(page 47). u nlo ck th e to ne a rm a nd u ns cre wit from th e tone a rm a ss em bly . O rder a n exa cre pla ceme nt fro m th e m a nu fa ctu re r o r p ur-

c ha s e a s ub stitu te a t a n e le ctro nic s p arts s up -p lie r. T hre a d th e to ne arm w ire s th r.o ug h th eo pe nin g in th e to ne a rm a ss em bly , s cre w inth e tone a rm a nd lock it. S .o lder t he w ires toth e c ir cu it b oa rd (page 1 3 1 ), tu rn in g o ve r th etu rn ta b le , if r eq uir ed . R e in s ta ll th e to p o rb o ttom p a ne l ( st ep a bo ve) a nd th e h ea d-

shel l (page 47).



JQUMJi&€..JQ t. z

SERVICING THE SHUT~OFFMECHANISM

TURNTABLES

Cleaning and lubricating the gearsand levers. Remove the top or bottom panel

(page 48) and check the shut-off mechanism

components. II a spring or gear is damaged,

replace it (page 135). Using a foam swab

dipped in denatured alcohol, c lean dirt or dust

I rom the gears ahd levers (Jeft). To dislodge

stubborn particles, spray short bursts of com-

pressed air. II required, use a toothpick to re-

move part ic les from between the gear teeth.

Lubricate the levers and any other mechanical

metal parts using a li ttle light machine. oil . Re-

instal l the top or bottom panel. If the problem

persists. take the turntable lor professional

service.

SERVICING THE SPEED SELECTOR SWITCH

1esting the switch. Remove t~ top or bottom panel (page 48) and locate the. speed-

selectorswitchterminals.H a wire is I?ose or broken; repair i t (page 132). Set a mu!titesl~r

10test continuity (page 128). If the SWitch has two Wires, hook one probe 10 one SWitch wire

terminaland touch the other probe to. the other switch w~reterminal (above) . ~et the switch to one

posit ion, then the other. The mult ifester should register continuity in only one posit ion. If the switch

has three wires, hook one probe to. the center terminal and touch the other probe, in turn, to each

01the other twa terminals. In each switch position, the multi tester should register continuity. be-

tween only one pair of wires. If the switch tests faulty, replace it (step 2). If the switch tests OK,

locate the contact points for the switch wires on the.circui t board. Hook one probe to a wire termi-

nal at the switch and touch the other probe to the wire's contact point on the circuit board (inset).

Repeat this test for the o. ther switch wire . . Ifa wire does not have continuity, replace it (page 132) .

If each wire has continuity, test the motor (page 51).

2

·eplacing the switch. Tag each

. SWitCh.wire, not ing its terminal, and

desolder the wires (page 130). Unscrewthe switch from its mounting. Buy an exact

replacement switch at an electronics parts sup-

plier. Screw in the swi tch and solder (page

131) the wires to the terminals (abQve) . Rein"

stal l the lop or bottom panel (page 48). II Ihe

problem persists, test the motor (page 51).

49



TURNTABLES

SERVICING THE ON/OFF SWITCH

1estingtheswitch, Remove the top or bottom panel (page 48)

and locate the on/off Switch terminals. I ta wire is loose or broken;. repair it (page 132). Se~ a rnult itester to test continuitY (page 128).

Hook one probe toone liwitch terminal and touch lhe other probe to the

other switch terminal. Set the switch to the ON position and then to the

OFF position: for .anaetuator switch, use a small stick to press in and

release the side but ton (above). The switch shOuklhave continLiitYonly

in the. ON position. If the switch tests OK, test the switch wires (step 2).

lithe switch tests faultY, desolder ihe wires (page 1 3 0 j from the switch

terminals. Remove .the switch and purchase an exact replacement at

anetectronicS parts suppl ier. Install the switch and Solder the wires'

(page 131). Reinstal l the top or bottom panel (page 48).

2"es t ing the wires. Locate the contact points on the cl rcui t

. board tor the wires conneC!ed.tothe switch terminals; if the wiresare connected to cornactpms In a plug, remove jhe plug from the

drcuit board (inset). Touch one probe to a wire terminal on the. switCh

and touch the other probe to the, wire's contact polnr in the plug (above

or onme circuit board. Repeat this procedure for th.e other switch wire.

r f a wire.OOes not have continuitY, replace it (page 132). IIeach wireha$continuitY,1i8rvice the power supply (below).

SERVICI N G THE POWER SUPPLY

50

1e stin g b etw ee n the transformerand the power block. Remove the top

or bottom panel (ppge 4 8 ) and identi fy the

power supply components (page 138). Unscrew

the.drcuit board (inser) and turn over the Circuit

board to reach the t w O ' paths connecting trans-

former contact points. to power-block contact

points. Set a rnult itester to- test continuity (page

.128).Touch one probe to a transformer contact

point in one path and touch the other probe to

the power brock contact point in the. path (left).

The path. slJould have conlinl!i ty. Repeat this'

pmcedure for the other- path. If a path does not

have cont inuity, suspect a faulty ci rcuit board an

take' the turntable for professional service. 11eacpath rf3gisters contihuitY, test the transformer

(step 2),



SERVICING THE POWER SUPPLY (continued)

TURNTABLES

2Testing the transformer. Locate the two iransfOl'msr contact

points in paths other than to the power block. Set a multi tester

to test voltage (page 129). Careful ly hook the probes to the

transformer contact points, avoiding any contact with other components

(above). Plug the turntable into a wall outlet and turn it on; for an actua-

tor on/off switch, use a small stick, to press in and hoid the side button

(page 50). The mult ites ler should register voltage. Turn off the turntable

and unplug i t. Ii the transformer tests faulty, replace the transformer

(step. 3). I f the transformer tests OK, test t lle motor (below).

3Replacing the transformer. Desolder the transformer contact

points (page 130), noting the transformer pin posit ions and check-

ing for any orientation pins not in a circuit board path. Carefully

turn over the circuit board and puUoff the transformer; wiggling the pins

if required. Order an exact replacement transformer from the turntable

manufacturer or purchase a subStitute transformer at an electronics parts

supplier. Fit the Iransformerinto the circuit board, turn over the circuit

board and solder (page 131) the pins in place (above). Screw in the

circuit board. Reinstal l the top or bottom panel (page 48).

TESTING AND REPlACI NG THE MOTOR

1esting the motor. Remove the top or bottom panel (page 48).

If a wire connecting the motor circuit board to the power supply

is loose 0' broken, repair it (page 132). Set a mult itester to lest

voltage (page 129). Plug the turntable into a wal l outlet and. turn on the

turntable; lor an actuator on/off switCh, use a smal l stick to press in and

hold the side button (page SO), Carefully touch a probe to each motor

contact point, avoiding any contact with other components {above}.

Record the mult itester result , turn off the mrntahle and unplug it. I f the,

multitester registers voltage" replace the motor (step 2). l ithe multi tester

does not register voltage, suspect a faulty circu it board and take the

turntable for professional service.

2Replacing the motor. Dasoldar the wires (page 130) f rom the

.

motor 's c ircuit board that oonnect to the power supply, noUng their

positions. Unplug the speed-selector switch wires and unscrewlhe

motor. Order an exact replacement motor and ci rcuit board from the

turntable manufacturer or purchase a substi tu te motor and circuit board

at an electronics parts suppl ier. Screw in the motor, plug in the speed-

selector switch wires and solder the power supply wires (page 13t). Ae"

install the top or bottom panel (page 48). I f the problem persists, suspect

a faulty circu it board and take the turntable for professional service.

51



COMPACT DISC PLAYERSThe compact disc player is the most intricate unit ofthe audio

system, performing complex optical functions. The objective

lens focuses the laser onto digitally-encoded tracks stamped in

the rotating compact disc. The optical pickup assembly trans-

forms the patterns of reflected light into electrical signal. After

further electronic modification, this signal is sent out by cables

to the receiver, which amplifies it.

To diagnose problems, consult the Troubleshooting Guide

in Entertainment Systems (page 14) and in this chapter (page

53). Many problems can be remedied by adjusting cable hook-

ups, cleaning the compact disc or the objective lens, or servic-

ing a drive belt or a wire. Cleaning supplies and replacement

components are available at an electronics parts supplier; sp

cific parts may have to be ordered from the manufacturer

A set of small screwdrivers, a multitester and a solderin

iron compose the basic tool kit for compact-disc player repai

(page126); Refer to Tools & Techniques for instructions odisassembly and reassembly (page 140), testing continuit

and voltage (pages 128-129), and desoldering and solderin

(pages 130-131). While working. store fasteners and oth

small parts in labeled containers and write down the sequenc

of disassembly steps. Never look directly at the laser with th

power on. Cold check for leaking voltage (page 14/) after r

assembling the compact disc player.

Flapper

Holds the disc against

the platter; also called

the clamp or clampar.

Optical pickup motor

Slides the optical picllup assembly

along rai ls; on some models. the

motor operates a swing·arm plckup

assembly similar toaturntable tone

arm. Activated by a switch. Objective lens

Focuses the'laser

Spindle

Centers and rotates the

disc on the ple"er. Driven

by spindte motor that isactivated by a switcl1. Lo.dingplalform

H ou ses th e loading

assembly components.

PQwer translon'rMIr

Convel1s 120·volt '8Itemat·

in g current (AG) to the low

vol1age required by circuit

board components. A recti-

f ie r changeslhe AC to OC.

l.oadlng mOior

Orivss the loading-

assembly components;

activated by a switch.

OptlCl!I piCkUp assembly

HQuses the laser-a special type

of ligh(.emitting diode (LEO)--

the objective lens, aneotner opti·

cal par ts . The laser beam is to-

cused on the compact disc by

the Objective lens, reflected back

through tha lens, and trans-

formed into electrical current

~Ircull boardRoutes lo w -v oh a ge s ig na l

10electrical componenls.

Usually mtcroprocessor type.

soldered 10 a circuit board.

PlatterRound plata on

whlclr.lli a disc sits.

Loading drawer guard

Restricts movement of

the loading drawer,

52

Load ing drawer or t ray

S~des in and out along

rai ls ; posit ions Ihe disc in

th e loading assembly.



COMPACT DISC PLAYERS



No dlspllilY lights, no sound Compact disc player unpluggeclor oft Plug in and turn on compact. disc player

Remote control faulty Service remote control (p . 136)00

NO power to outlet or outlet faulty Reset breaker or replace fuse (p. 10) DO; have' outlet serviced

Power cord faulty Test and replace power cord (p. 137) DO

Power fuse faulty Test and replace power fuse (p. 137) DO

On/off switch faulty Test and replace on/off switch (p. 5 7) .~

Power supply faulty Service power supply (p ; 58) !IilO

Laser or circuit board faulty Take compact disc player for professional service

Disphiy lights, no sound Controls set incQrrectly Adjust compact disc player controls

Transit screws secured Loosen transit screws

Receiver faulty TroubJeshoot entertainment system (p. 14) DO

Objective lens dirty Clean objective lens (p. 54) 00

Drive belt loose or broken Service drive belts (p . 56) 00

Optical pickup/spindle molar switch faul ty Clean, test and replace motor switch (p . 56)00

Mode or feature switch dirty or faulty Clean switch (p . 57) DO; test and replace switch (p . 57) 1iiiI0

Optical pickup motor faufty Test and replace optical pickup motor (p. 59) .Q

Spindle motor faulty Test and replace spindle motor (p. 59) .~

Laser or circuit board laul1y Take compact disc player for professional service

Sound, no display lights Display lights faulty Replace display lights (p. 134)DO

Sound from only one channel Controls set incorrectly Adjust compact disc player controls

~ - - - - - - - - ~ ~ - - - - - - - - - - ~ - - ~ - - - - ~ ~ - - - - - - - - ~ - - - - - - - - -eceiver or speaker faulty Troubleshoot entertainment system (I' . 14 ) DO

Circuit board faulty Take compact disc player for professional service

Sound Intermittent Dr distorted Receiver or speaker faulty Troubleshoot entertainment system (p. 14) DO

~ - - - - - - ~ - - - - ~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ - - ~ ~ ~ - - - - - - - - - - - - - - -Compact disc dirty or faulty Clean compact disc (p. 54) 00; replace compact disc

Objective lens dirty Ciean objective lens (p. 55)00

Drive belt d irty or loose Service drive belts (p. 56) DO

Optical pickup/spindle motor switch faul ty Clean, test and replace motor swi tch (p . 56) 00

Mode or feature switch dirty or faulty Clean switch (p . S n DC); test and replace switch (p . 57) !IilO

Optical pickup motor faulty Test and replace optical pickup motor (p.59) .~

Spindle motor faulty Test and replace spindle motor (p. 59) .~ .

Circuit board faulty Take compact disc player for professional service

Mode or feature contro ldoesn't work

Mode or feature switch dirty or faulty Clean switch (p o 57)DO; test and replace switch (p . 57) ~O

Take compact disc player for professional service.

Compacl disc loads, plays,then stops prematurely

Laser or circuit board faulty

Transi! screws secured Loosen transit screws

Compact disc dirty or faulty Clean compact disc (p,54) DO; replace compact disc

Objective lens dirty Clean objective lens (p. 55) DO

Drive belt loose or broken Service drive. belts (p. 56) DO

OPtical pickup/spindle motor switch faulty Clean, test and replace motor switch (p . 56) DO

Test and replace optical pickup motor (p c 59) .~ptical pickup motor faulty

Test and replace spindle motor (p. 59) .~Spindle motor faultyLaser or circuit board laulty Take compact disc player for professional service

Loading drawer doesn't openor doesn't close

Drive belt loose or broken Service drive belts (p. 56) 00

Clean, test and replace loading motor switch (p. 56) DOoading motor switch faulty

Test and replace onloff switch (p. 57) .~n/oil switch faulty

Test and replace loading motor (p. 58) .~oading motor faulty

D.EGREE OF DIFFICULTY;

ESTIMATED TIME;

o Easy ~ Moderate • Complex

oLess than 1 hour ~ 1 to 3 hours • Over 3 hours

53




SERVICING COMPACT D.JSCS

Cleaning a disc. Unload the compact disc

from the compact disc player. Using a clean,

dry, lint-free cloth, wipe dust 9ft the disc. Hold-

ing the disc by its outside edge, gently wipe

from the. center toward the edge in smooth,

straight strokes (left); avoid any circular motion

and never wipe around the disc circumference.

To clean sticky lingerpr intsor dirt trorntha disc,

apply a commercial compact-dlsccreaner.

available at an electronics parts supplier . Or,

use a clean, lint·lree cloth moistened with d e -flatur.ed alcohol:' A disc may be washeq with

a solution-of !]"Ii !d detergent and warm water;

rinse well and dry with a lint-free cloth,


Removin'g and reinstalling the top and bottom panels. To reach components beneath the

loading assembly, fi rst. open the loading door (page 55). Unload any compact dlsc, torn off and

unplugthe compact disc player, 'and disconnect the cables hooked i.Jpto it (page 12), Secure

any transit screws. To remove the top panel,check tor screws on the top, sides, back or. bottom.

Unscrew the lop, panel (above, left), slide lt out from under any lip on the front panel, and lift it

off the frame. To remove the bottom panel, check fot hidden screws in the feli',t; unscrew the

panel and lift it off the frame (above, right). Reverse this sequence to reinStall the panels; Coldct'le<* the Compact disc play.er 'lor lei lking voltage (page 141). Reconnect the cables (page 16)and plug in the compact dISC player.

54

Removing and. reinstalling the frontpanel or plate. Remove the top panel (left).

Check. the tcip,.sides and bottom for tabs and

screws securinglhe front panel or plate tothe

frame. Unscrew the front panel or .plate, pres

in the labs (above) and pull it off. To reinstall

the front panel or plate, push it 'Onto the fram

to. lock the tabs and put back the screws,

Reins.lal l the top panel (Ie.ft).



, ,

ACCESS TO THE INTERNAL COMPONENTS (continued)

COMPACf DISC PLAYERS

Removlng the loading drawer. Press the open/close contro l fa open

the loading drawer, then remove the top panel (page 54). Unscrew the

loading drawer guard (inset) and set it aside. Gently slide out the load-

ing drawer through the front panel (above). To reach components .

beneath the loading assembly, remove the loading platform (right).

To, reinstall the loading drawer, slide it in through the front panel and

screw on the guard. Reinstal l the top panel (page 54) and press the

open/close control to close the loading drawer.

Removing the loading platform. Press the opervclose contralto

open the loading drawer. Remove the top panel (page 54) and the

loading drawer (left). Unscrew the loading platform and disconnect

any ground Wire connected tolt, Lift out the loading platform, sliding it

toward the back panel (above). Turn i t face down inside the compact

disc player, taking care not to. damage wire connections. Reverse this

sequence to reinstal l the loading platform. Reinstal l the loading drawer

(left) and the top panel (page 54).

SERVICING THE OBJECTIVE LENS

Cleaning the objective lens. Press the opent

close cont rol to open the loading drawer, and

then remove the top panel (page 54). Carefullylift up the flapper and blow dust 0 1 1 the lens with

short bursts of com pres sect 'air. To clean the

lens, use a foam swab moistened with pnoto-graphic lens cleaner, available at a photographic

supplier. Gently wipe the swab across the lens

(IaN); use a fresh, dry swab to wipe o ft excesscleaner. Reposition the flapper over the lens

and reinstal l the top panel (page 54).

5 5



COMPACT DISC PLAyERS

SERVICING THE DRIVE BELTS

1leaning a belt. Remove the top panel (page ~4)alld then

the loading drawer (page 55); to reach a belt on the bottom of

the loading platform, also remove the loading platform (page 55).

If a belt is loose or broken, replace il (step 2), .I f a belt is l;;licky or

greasy, clean it using a foam swab dipped in rubbeH::leaning com-pound (abovf1) ; never apply anything oily and avoid touching the belt

with your fingers; Turn the belt pulleys to reach the entire length of the

belt . Put back the loading platform (page 55) if you removed it. Rein-

st(j.1Ithe loadingdrawer (page 55) and the top panel (page 54').

2·eplacing.. a belt. ..S.IiPhe. dam.aged bslt off the pulleys (abOve

not ing its posit ion. First use. long-nose 'pliers or tweezers to

remove any oiher belt in the way; be careful no t to pinch a belt.Purchase an exact replacement belt at an ele.ct roni~. parts supplier.

Holding the belt loosely .with long-nose pliers pr tweezers, wrap itaround the pulleys; then reinstall any other belt removed. Pu t back thloading platform, if you removed it, and the loading drawer (page 55).

Reihstal l the top panel (page 54).

SERVICING THE MOTOR SWITCHES

1leaning and testing a switch, Remove the top panel'(page

54 ) and the loading plat form (page 55). The loadillg motor switch

.. is near .the loading gears and lever, as shown; the optical pickupl

spindle motor switch is next to the optical pickup assembly rail. If a

switch Illaf is damaqed, replace the switch (slep 2). ,If a switch wire isloose or broken, repair it (page 134). Set a rnulf itester to test continuity

(page 128). Touch OAe probe 10 a wire terminal on the switch and

touch the other probe in turn to aactr .swltch-wira terminal on the circuit

board. The niultitester should register COntinuity once - and only once.

Test each ~witch wire. If a wire tests faulty, replace it (page 1'32). If

each wirf;! tests QK, genily run an emery board oyer each l!lal 10 clean

the contacts (above). Reinstall the loading platform (page 55) and the

top panel (page 54).

56

2Removing and replacing a switch. Uncllp or unscrew theswitch from the loading platform, Tag the switch wires, noting

their terminals; anddesolder (page 130) the wires from the

swi.tchterminals, Order an exact replacement switch from the rnanutac

turer or purchase one ai an electronics parts supplier,.,S'et the switch

a Soldering stand and solder the wires (page 131)10. the switch terrnl-

nals (abOve) . Clip or screw the switch 10 the loading platform. Reinsta

the lo'ading 'platform (page 55) and the tap panel (page 54).



.:, ; : - - - - .. :: ..


SERVICING THE MODE AND FEATURE SWITCHES

1

leaning a switch. Remove the

top panel and the Iront panel or plate

(page 54). Locate the switch on the

ci rcuit board, behind i ts control. Clean theswitch with electronic contact c leaner, direct-

ing a short burst into the switch opening

(above). Press the switch several times to

work in the cleaner. Reinstall the front panel

or plate and the top panel (page 54). If the

problem persists, remove the panels again

to test the switch (step 2).

2Testing and replacing a switch. Set a multi tester to test continuity (page 128).

Set the switch to one position and touch a probe to each pin on one side of the switch

. (above, left); repeat this step with the switch sat in the other position. The switch shouldregister continuity in only one position. Repeat the procedure at the pins on the other side of

the swi tch. If the swi tch lests faulty, unscrew and .turn over the circui t board. Desolder the

switch pins (page 130) and wiggle all the switch. Test continuity again to confirm the switch is

faul ty. Order an exact replacement switch from the manufacturer or purchase one at an elec-

tronics parts supplier. Fit the switch pins onto the circuit board and solder (page 131) the pins

(above). If the switch tests OK, suspect a faulty circyit board and take the compact disc player

for professlonal service. Put back the cl rculr board and reinstall the panels (page 54).

SERVICING THE ON/OFF SWITCH

1esting and replacing the switch. Remove the top panel, the front panel or plate (page

54).and the loading platform (page 55). Push of f the swi tch control lever, uncl ip the switch

circuit board (inset) and lif t H O U I : Unplug or desolder (page 130) the wires from the switch

Circui t board. Set a multi tester to test continui ty (page 128) and test as for a multi-pole switch

(page 136). Hook one probe to a switch contact point and touch the other probe in turn to the

other switch contact points; prasslng in and releasing the swi tch for each test (ebove), Test each

contact polntwlth.each other contactpolnt, checking tor acontlnulty pattern, I f there is a pattern,

test the swi tch wires (slep2). If n61, desolder the swl tcn pins (page t 30) an d pull o ff the switch.

Order an exact replacement switch from the manufacturer or purchase one at an electronics

parts supplier. Solder the switch pins onto the circuit board (page 131). Put back the switch

circuit board, and reinstall the loading platform (page 55) and the panels (page 54).

2Testing and replacing the switchwires. If the wires are housed in a ca-

ble with connectors at the ends, unplug

it Set a muit itaster to test continui ty (page

128). Clip a needle to each probe. Touch one

needie to a COntact point at one end ota wireand touch the other needle to each contact

point at the other end of the cable (abC)ve).

The multitester should register continuity

once-and only once. Repeat the procedure

for each wire. If a wire tests faulty, replace it

(page 132) . If each wire tests OK, plug in the

cable or solder the wires (page 131) to the

switch ci rcuit board. Put back the circuit

board, reversing the sequence used to re-

move it (slep 1 ). Reinstal l the loading plat-

form (page 55) and the panels (page 54).

5 7




SERVICING THE POWER SUPPLY TRANSFORMER

1esting the transformer. R!; lmove the top panel (page 54)

and identify the power supply components (page 138). Locate

the transformer wires connected to the circui t board and unplug

ordesolder the wires (page 130). Sat a rnultltesterto test voltage

(p~ge 129). Clip one probe to the odd-colored wire and clip the other.probe to each matching wire, In turn (above); if there IS no odd wire,

clip the probes to each matching wire pair; in turn. Plug in and turn

on the compact disc player; do not look at the laser. The, rnulti tsster

should register vol tage for each test. If not, replace the t ransformer

(step 2). If the transformer tests OK. suspect a faulty circui t board

and take 1 h E ; ! compact d isc player for professional service. Reinsta ll

the top panel (page 54).

2Replacing the trariSfor.l1ler. Disconnect Ihe transformer wiresconnected to the power cord ..Unscrew and remove the trans-

former from the frame (above). Order an exact replacement

t ransformer from the manufacturer or purchase a substi tute at an elec-

tronics parts supplier. Instal l the I ransformer and reconnect the wires

to the power cord. Plug in or solder (page 131) the wires 10 the circuit

board. Reinstal ilhe top panel (page 54). .

TESTING AND REPLACING THE LOADING MOTOR

1esting the motor. Remove the top panel (page 54) and the

loading platform (page 55). Set a rnulti tester to test vol tage (page

129). Hook a probe 10 each motor wire, avoiding any contact with

olher components (above). Plug in and lurnon the compact disc play-

er; do not look attha laser. Press the loading draweropen/close con-

trol and note the mult itester reading. Turn off and unplug the compact

disc player. If the mul ti tester registers vol tage, replace the molar

(step 2). If not, suspect a faulty circuit board and take the compact

d isc player for professional serv ice. Reinsta ll the loading planorrn

(page 55) and the lap panel (page 54).

58

2Replacing the motor. Using long-nose pliers or tweezers, car

fully slip the bell off the motor pulley. Unclip the motor and l i f t it

from its housing. Desolder the wires f rom the motor terminals

(page 130). Order an exact replacement motor from Iha manufacturer.

Solder (page 131) the wires to the meter terminals (above) and clip th

motor into the housing. Reinslai l the drive belt· using long-nose pl iers

or tweelers. Reinstal l the loading plat form (page 55) and the top pane

(page 54). I f Ihe problemperslsts. suspect a faulty ci rcuit board and

take the compact disc player for professional service.




TESTING AND REPLACING THE OPTICAL PICKUP MOTOR

1

esting the motor. Remove the top panel (page 54) and the

loading platform (page 55). Set a mul titester to test voltage (page

129). Hook a probe to each opt ical· pickup motor wire (above).

Reinsta li lhe loading drawer in the platform (page 55). Plug in and turnon the compact disc player; do not look at the laser. Load a compact

disc and press the play mode control . Note the multi tester reading.

Unload the compact disc, and turn off and unplug the compact disc

player. I f the multi taster registers voltage. replace the motor (step 2).

I f not. suspect a faul ty circui t board and take the compact di~player

for professional service. Remove the loading drawer. put back the

loading platform (page 55) and reinstall the top panel (page 54).

2

Replacing the motor. Using long-nose pliers or tweezers, care-

ful ly s lip the drive belt .off the ophcal-plckup motor pulley. Uncl ip

the motor and lift it from its housing. Desolderthe wires (page

130) f rom the molor terminals. Order an exact replacement motor fromthe rnanutacturer. Solder the wires (page 131) to the motor terminals

(above) and Clip the motor into the housing. Slip the dr ive belt around

the motor pulley. Remove the loading drawer, put backthe loading

platform (page 55) and reinstal l the top panel (page 54). I f the problem

persists, suspect a faulty circui t board and take the compact disc player

for professional service.

TESTING AND REPLACING THE SPINDLE DRIVE MOTOR

1esting the motor. Remove tM'top panel (page 54) and theloading platform (page 55). Set a mult itsster to test voltage (page

129). Hook a probe to each spindle motor wire (above). Reinstall

the loading drawer in the platform (page 55). Plug in and turn on the

compact disc player; do not look at the laser. Load a oornpact disc and

press the play mode control . Note the multi tester reading. UnlO;ld the

compact disc, and turn off and unplug the compact disc player. If the

mull itester registers voltage. replace the motor (step 2). I I not, suspect

a faulty circuit board and take the compact disc player for professional

service. RemoVe the loading drawer, put back the loading platform

(page 55) and reinstall the top panel (page 54).

2Replacing the motor. Use long-nose pl iers or tweezers to

slip the bell off the motor pulley and remove the flapper spring.

Unclip the flapper (above). Unscrew the motor; turn the optica l-

pickup motor pulleY'!9 move the laser assembly out 91 the way. De-

solder the wires (page 130) from the motor terminals. Order an exact

replacement motor irom the manufacturer. Solder the 'wires (page 13 j)

to the terminals (inset) and screw in the motor. Slip the belt around the

pul ley, clip on the flapper and rehook the spring. Remove the loading

drawer, put back the loading platform (page $$) and reinstall the top

panel (page 54). If the problem persists. suspect a faulty circuit board

and take the compact disc player for professional service.

59



SPEAKERS AND HEADPHONESThe final step in sound transmission by an audio system is

performed by your speakers or headphones (he/ow). Inthe

speaker, incoming electrical signals are routed to the crossover

network, where they are divided into frequency ranges and di-

reeled to the drivers, which reproduce the signals as varioussound frequencies. In headphones, incoming signals are sent

directly to the drivers.

Many audio problems are experienced through the speakers

or headphones; often these units are not the cause, but can be a

valuable tool in troubleshooting other units in the audio system.

Consult the Troubleshooting Guide in Entertainment Systems

(page 14) and in this chapter (page 61).

Often, problems can be remedied by adjusting cable hook

ups. A wire may be loose or broken, or a component may te

faulty. Replacement components are usually available froman

electronics parts supplier. A special driver Of crossover networ

may have to be ordered from the manufacturer.A set of small screwdrivers, a multitester and a soldering iro

complete the basic tool kit required for speaker and headphon

repairs (page 126). Refer to Tools & Techniques for iristru

lions on testing continuity and resistance (pages 128-129) an

for directions on desoldering and soldering (pages 130-131)

When disconnecting a speaker cable, tag the positive wire

maintain the polarity of the electrical connection.

Driver

P ro vid es le ft o r r ig ht

c h an ne l s o un d.

PlugR ts in to jack o n r ec e iv e r

0( a u xU ia r y u n it ; d iv id e s

s ig na l in to tw o c ha nn els

ao d grounds~ble.

insulation

F o am • .lib er gla s s o r o th er

in su la tin g m a te ria l a g ain Sl

m o un tin g p la te o r s id e p an els .

C ro s SOV It f n e tw o r k

D iv id eS a n d d ir ec )s s o on df re qu en cie s t o '1ha drivers;

m a y c on ta in a ny c om bin atio no f c ap ajito rs , c ho ke c oils

a n d r es is to r s, an d may be

protected by a r us e.

Crol lsover networl! wlrell

C o nn ec t c ro s so ve r n elW o f1 < t os pe a ke r- ca b le t er min a l b lo c k;

u su ally m a rk ed p os itiv e a nd

negative.

M ou nting pla te

f ro nt o f e nc lo s ur e; contansmo un tin g h o le s f or d riv er s.

PegsS u pp or t s pe a ke r g rille ;

a dh es iv e pa ds a so

u s ed . F o am g rille s

m ay be g lu ed in p la ce .

S p ea k er e nc lo s ur e

Acous t i c box of wood .p la s tic o r m e ta l.

60

P ro te ctiv e s he ll

H ou se s d riv er an d encases

w ire c on ne cn on s: m a y

screw on o r snap on,

Ear eush l .onP ro vid es c om fo rt a nd blocks

o u t e x te rn a l noise: may ' b E I

foam o r plastic.

D r iv . er w i r es

Tw o wires c on ne ct d riv er t o

c ro s so ve r n et w or k: u su a llyma t i< . ed p o s il iv e a n d n e ga t iv e.

Tweeter

H ig h ·r a ng e d ri v9 / ' r ep ro d uc e s

h ig h fr eq ue nc ie s a s tre ble t on es ;srnallsstand l igh tes t d r i vl ! t' :

M Id -r an ge d riv erA ls o c a lle d s qu a w ke r;

-. O Dtiona l d river tha tr ep ro d u ce s m i d- ra n g e

frequencies.

Woo fer

lo w -r an ge d riv er r ep ro du c es

l ow f requenc i es a s ba ss to nes :largest a o o h e a vie s t d ri ve r.



SPEAKERS AND HEADPHONES


SYMPTOM PROCEDUREOSSIBLE CAUSE

Nos.ound

Troubleshoot entertainment system (p. 14)DO

Receiver or auxiliary unit faulty Troubleshoot entertainment system (p. 14)DO

No sound from speakers;sound from headphones

Receiver or auxdiary unit faulty

Speaker fuses blOwn Test and replace fuses (p o 137) DO

Test and replace fuses (p . 137) 00

Sound from only one speaker Receiver or auxiliary unit faulty Tfoubleshootenlertainment system (p. 14)DO

Speaker fuse blown

Crossover network faulty Service. crossover network (p . 54) DO

Intermittent sound fromspeaker

Test and replace drivers (p . 63) DO

Receiver or auxiliary unit faulty TroublashOolemtertainment system (p. 14 ) DO

Driver faulty

Crossover network. faulty Servtee crossover network. (p o 54) 00

Distorted sound from speaker

Cone loose O r punctured Repair speaker cone (p . 63)00

Receiver or auxiliary unit faulty Troubleshoot entertainment system (p o 14)DO

Driver faulty Test and replace drivers (p . 63) DO

Crossover network faulty Service crossover network (p. 54) 00

Humming, buzzing or rumblingnoise from speaker

Reposition speakers

Receiver or auxiliary unit faulty Troubleshoot entertainment system (p, 14)DO

Speaker vibrating or too close to turntable

Cone loose or punctured Repair speaker cone (p. 63) 00

Insulation loose Apply rubber cement to comers of insulation

Driver faulty Test an d replace drivers (p o 63) 00

Crossover network faulty· Service crossover network ( p . 54) DO

No low·range (bass) soundfrom speaker

Woofer faulty Test and replace drivers (p. 63) DO

Receiver or auxiliary unit faulty Troubleshoot entertainment system (p. 14)DO

Crossover nEitwork faulty Service crossover ryetwork (p . 54) 00

No high-range (treble) soundfrom speaker

Test and replace drivers (p.. 63) DO

Receiver or auxiliary unit faulty Troubleshoot entertainment system (p. 14) 00

Tweeter faulty

Crqssover network faulty Service crossover network (p . 54) DO

No mid-range (voice) soundfrom speaker

Test and replace drivers (p. 63) 00


Mid-range driver faulty

Crossover network faulty ~rvice crossover network (p . 64) 0,0

Speaker grille damaged

Plug in headphones

Wear and tear Replace speaker grille (p . 62) DO

N9 sound from headphones;sound 'rom speakers

Troubleshoot entertainment system (p. 14)DO

Headphones unplugged

Receiver or auxiliary unit faulty

Plugf'lulty Test and replace headphone plug (p . (j7) 00

Cable faulty Test and replace headphone cable (p. (7) 00

Jack faulty Take .unit .for professional service

Sound fr(lm only oneheadphone

Driver faulty Test and rBplace headphone drivers (p . 66) DO

Receiver or auxiliary unit faulty Troubleshoot entertainment system (p . 14) 00

Plug faulty Test and replace headphone plug (p. 67) DO

Cable faulty Test and replace headphone cable tp . 67) DO

Intermittent sound fromheadphones

Test and replace headphone plug (p . 67) DO

Receiver or auxiijary unil faulty Troubleshoot entertainment system (p . 14) 00

Plug faulty

Cable faulty Test and replace headphone cable (p . (7) 00

Jack faulty Take unit for professional service

Distorted sound fromheadphones

Driver faultY Test and replace headphone drivers (p. 66) DO


DEGREE OF DIFFICULTV:

ESTIMATED T1ME:

DEasy QModerate • Complex

o Less than 1 hour .~ 1to 3 hours • Over 3 hours

61




ACCESS TQ THE CQMPONENTS

2·emoving and reinstalling. the woofer. T urn o ff th e re ce iver a nd a ny oth er. in pu t un it

a nd d is co nn ec t th e c ab le fro m th e s pe ak er te rm in als .(page 1 2 ), ta g gin g th e p os itiv e te rm inw ire . U nS cre w th e w o ofe r fro m th e m ou ntin g p la te (above, left). H old th e w oo fer s ec ure ly

th e rim and g en tly p Ull iU re e o f th emO \.in tin g p la te . S up po rtin g th e w o ofe ro n its rimo r tu rn in gfa ce d ow n ,ta g th e p os itiv e w ire a nd d is co nn ec t o r d es old er (Page 130j th e w ire s fro m th e w oofeterminals (above. r ight) . C a re fu lly s et th e w o ofe r a sid e. If re qu ire d, re pe at th is p ro ce du re to remo

th e tw e e te r o r th e m iM a ng ed riv er . To r ein sta ll a d riv er , r ec on ne ct o r s O ld er (page 131) th e w i reto th e d riv erta rm in als , s creW th e d riv er to th e m ol,m lin g p la te , a nd p ut b ac k th e g rille (step 1).

.R ec on ne ct th e c ab le to th e s pe ake r te rm in als (page 16).' .

1emoving and reinstalling the

speaker grille. Remo ve . a n y S c rew ss ec ur in g th e f ro nt 'g rille a n d g en tly p ull

.it o ft th e pe gs o r a dh es ive ta bs (alxwe). If>the·g ri ll e .does no t CXJme"o ffeas il y , runa smal lp Utty knife u nd er e ac h c orne r to b rea k a nyg lu e b on d. T o re ac h in te rn al c om po ne nts ,remo ve th e w o ote r (step ' 2 ) . T o re in s ta ll th es pe aker grille , p re ss it o nto th e p eg s o r a dh e-s ive ta bs a nd put ba ck a n y s c rew s ; i f r equ ir sd ,a pply a s ma ll da b of cem ent to the C orners .

REPLACI NG THE GRILLE

Recovering the grille. Remo ve th e g rille(above). If th e g rille is : fo am , p urc ha s e a n id en

c a l r ep la c ement g rille . If th e . s p e a ke r g rille isd oth -c ov ere d, p ry o ff a ny s ta ple s q r ta ck s fio ldth e c lo th to th e fra m e u sin g a ' s m all ,s cre w driv

ru n a u tility K nife a ro un d th e e dg es , if re qu ire db re ak a ny ,g lue b on d. R em ove O ld g lu e fro m thfr am e w i th medium~g rit s a nd pa p er . M e a su re tho ld g rille c lo th a nd p urc ha se re pla ceme nt c lo than e lec t ron ic s parts s up plie r. lith e r ep la c emenclo th is to o la rg e, trim it a lm os t to s iz e us in g s

sors . S et the new clo th fa ce dow n on a dea nw ork ta ble a nd la y th e fra me on it. S ta ple th edoth s mooth ly a long one s ide of th e fra me. Pth e doth s nugly a cros s th e fra me a nd s ta ple ita lo ng th e o pp os ite fra m e e dg e (left). Repea t tprocedure on th eoth erlw a s ides o f th e fra meIf th e c lo th w rin kle s', p ull o ut th e n ea re st s ta ple

s tre tc h th e c io th a nd re sta ple it. C ut o ff a ny exc es s d oth , e sp ec la ily a t th e c orn ers , 10 avoidbu lk y p lea t s .

62



REPAIRING DRIVER CONES

SPEAKERS AND HEAPPHONE$

Reseating a loose cone. Remove the speaker grille (page 62). If the

woofer, tweeter or mid-range driver cone is damaged, remove the driver(page 62). If the driver cone is badly torn or separated from the spider,

or frame, replace the driver (page 64). If mere is a small hole in the

driver cone, seal the puncture (right). If a small section of the driver cone

is separated from the rim, gently· raise the cone away from the rim with a

small pU t t y knife and spread a small amount of rubber cement along the

edges olthe cone and rim (above). Allow the cement to dry, then l ightly

press the cone against the rim until the rubber cement adheres. Reinstall

the driver and the speaker gr il le (page 62).

Sealing it punctured cone. Remove the speaker grille (page 62).

II the woofer, tweeter or mid-range driver cone is damaged, remove the

driver (page 62). If the driver cone is badly tom or separated from thespider, or frame, replace the driver (page 64). If a small sectiori of the

driver cone is separated from the rim, resear the cone (left). II there is asmall hole in the driver cone, cut a patch slightly larger than the puncture

from paper about the same thickness as the cone. Wearing a rubber

glove, saturate the patch with rubber cement and use a small brush to

apply a light coat of rubber cement around the cone puncture (above).

Allow the cement to dry. then set the patch over the puncture and gently

press it unt il the cement adheres. Reinstal l the driver and the speaker

grille (page 62).

SERVICING THE DRIVERS

1esting between the driver and the crossover network.

Remove the speaker gr il le and the woofer (page 62). Totes! from

the woofer, the tweeter or the mid-range driver, remove the driver

(page 62) but leave the wires connected to the terminals. If a wire con-

necting to the crossover network is loose or broken. t ighten or replace

it (page 132). Set a multi tester to test continuity (page 128). Hook one

probe to a wire terminal on the crossover network and touch the other

probe to that wire's terminal on the driver (above). Repeat this step for

the other wire. lIa wire does not have continuity, replace it (page 132).

If each wire has continuity, test the driver (step 2).

o

2Testing the d.river. Tag the positive terminal wire and discon-

nect or desolder (page 130) the wires from the driver ierminals.

P1ace the driver face down on a work table and set a multi tester

to test resistance (page 129). Touch the positive probe to the positive

driver terminal and touch the negative probe to Ihenegative driver termi-

nal (above). The multi tester should register close to the ohms rating indi·

cated on the driver or speci fied by the speaker rnanutacfurer, If the driver

does not register what it 'should. replace it (step 3). I f the driver registers

what it should, service the crossover network (page 54).

63 .




SERVICING THE DRIVERS (continued)

3Replacing the driver. Purchasean

exact replacement driver at an electronics

parts SUpPliers. Connect or solder (page

131) the tagged posi tive wire to the posit ive

driver terminal ( fa r l e ft ) and connect or solder

the other wire to the negative driver terminal.

Supporting the driver by its rim, set it into the

opening in the mounting plate ( ne a r l ef t) and

screw it securely in place. Reinstal l the woofer,

i l required, and the speaker gril le (page 62).

SERVICING THE CROSSOVER NETWORK

1esting between the crossover and the terminal block.Remove the speaker gril le and the woofer (page 62). Locate the

two wires connecting the crossover network to the terminal block.

If a wire is loose or broken, tighten or replace it (page 132) ; if .required,

remove the terminal block (step 2). Set a mult itesler to test cont inui ty

(page 128). Clip one probe to a wire terminal on the crossover network

and touch the other probe to that wire's terminal on the terminal block.

Repeat this step for the other wire. II a wire does not h<fJe continuity,

replace it (step 2). If each wire has continuity, test the crossover

network (step 3).

64

2Repairing the wire connect ions, Disconnect or desolder

(page 130) the wire, from the crossover network terminal. To gai

access to the wire terminal on the terminal block, remove the

exterior terminal block screws and pull the terminal block off the back

panel. Secure the terminal block in a soldering stand and desolder the

wife. Purchase a length 01 replacement wire the identical gauge al an

electronics parts suppl ier; if required, also purchase a set of crimp con

nectors. Cut the wire to length and crimp on a connector at one end

(page 132) . Connect the end with the crimp connector to the terminal

on the crossover network and solder (page 131) the other wire end to

the terminal on the terminal block (above). Screw in the terminal block

and reinstal l the woofer and the speaker grille (pa(Je 62).



SERVICING THE CROSSOVER NETWORK (continued)


3Removing tbe crossover network. T ag th e w ires conn ecting

th e cros sover netw ork to the tw eeter, a ny m id-ra nge driver .a nd

. the term ina l block, noting the term ina l pos itions . D isconnec t or

deso lder (page 130) the w ires from the cros sover ne tw ork, lea ving the

w oofer w ires connected. U ns crew the cros sover ne tw ork from the back

pane l (above) a nd lift itout, T es t th e cros sover netw ork ca pa citors

(step 4) and choke coils (step 5); or, ta g and d isconnect ihe w ires 10 the

w oofer, noting th e term ina l pos itio ns , a nd ins ta ll a n exa ct repla cem ent

cros sover netw ork purch as ed a t a n e lec tro nic s pa rts s upplier (step B}.

5Testing and repla c ing the choke coils. D es older one ch okec oil w ire (page 130) a nd pull it o ff the c ircu it boa rd w ith long-nose

pliers. Set " a m ultite ste r to te st re sis ta nc e ( page 1 29 ). Touch one

probe to the mk:ld le choke coil w ire and touch the other p robe in turn to

ea ch oth er c hoke . c oil w ire (above) . T he m ultites ter s hould regis ter low ,

s teady ohm s for both tes ts . Repea t th is tes t for the. o ther choke coil. II

ea ch Choke co il regis ters w ha t it s hould, res olda r the choke coil w ires

(page 1 31 ) a nd reins ta ll th e cros sover netw ork (step 6). If a choke coll

does not regis ter w ha t it s hould, deso lder the other choke coil w ires

(p ag e 1 30 ), noting their pos itions , a nd rem ove the Choke coil. Purch ase

a n exa ct repla cem ent choke coil a t a n electronics pa rts supplier. Pos ition

it on the c ircu it boa rd, th read the w ires th rough the open ings and solder

them (page 1 31 ). R ein sta ll th e c ro ss ov er n etw ork (step 6).

4Testing and replacing the capacitors. Desolder one capac i -

to r w ire (page t30) a nd pull it o ff the circu it boa rd w ith long-nos ep lie rs . S eta m ultites ter to tes t res is ta nc e (page 129) and touch the

positive probe to the pos itive w ire and the nega tive probe to the nega tive

wire (above) . The multiles ter should regis ter a . s ha rp drop and then a

ris a In ohm s. Repea t th is procedure for ea ch ca pa citor. If ea ch ca pa citor

reg is ters w ha t it s hould, res older th ,e ca pa citor w ires ( page 131 ) and test

th e ch oke colis (step 5). II a ca pacitor does not regis ter w ha t it s hau ld,

deso lder its o th er w ir e (page 130) a nd rem ove th e c apa citor~ P urch as e

a n exa ct repla cem en t ca pa citor a t a n e lec tron ic s p arts s upplier; P os ition

the ca pa Citor on the circu it"boa rd, th rea d jhe w ires th rough the openings

a nd s old er t/:le m (page (3 1). R ein sta ll ttJ ec ro ss ov er n etw ork (ste p 6).

6·einstalling the crossover network. Po sit io n. th e c ro s so ve r

netw ork aga ins t the back pa nel and screw il securely in pla ce.

R ec on ne ct o r s old er (page 131 ) the w ires for the term ina l block

(sbove), any m id-ra nge driver a nd the tw eeter to Ihe cross over netw ork

terminals; if required, a lso reconnec t th e w ires for the w oofer. Reins ta ll

the w oofe r a nd the s pea ker grille (page 62 ). If th e proble m pers is ts ,

ta ke th e s pea ke r for profes siona l s ervice.

65




SERVICt NG THE HEADPHONE DRIVERS

2·.e.sting the driver. Lift th e d tive ro .u t o f th e s he ll a nd de so ld er

th ~ W ir e (pafje 130) fr om th .e fX Is itig e d riv er te rm in a l. P la c e th e

d river fa ce do wn o n a c lea n w ork ta ble . a nd s et a m lH tites t!;!r to

t es t r es is t ance (page 129). T ou ch th e p os itive p ro be to th e p (ls itive d rive rte rm in al a nd to uc h th e n eg ative p ro be to Ih e n eg ativ e d rive r te rm in al

(eeove) ..Th e m ultite sler s hoU ld reg is te r do se to th e o hm s ra ting ind i-c ated o n th e drive r o r s pe cifie d b y th e h ea dp ho ne ma ruJ fa ctu rer. If th e

dri- .:er registers 0 . o rin fin ile ohm s, r ep la c e: it (step J ). If th e d riv er re gis ~ters w ha t it s ho uld. s old er th e w ire to th e po sltive drive r te rm in al (page

1 31 ). fit th e d riv er in to lh e s he ll, re in sta ll th e s he ll (step 1) ahdserv iceth e h ea dp ho ne p lu g ( P ag e 67) .

66

1emoving the. shell. U np lu g th e h ea d-

p ho ne sf rom Ih e r ec eiv er o r-o th er a u xiliaunit j O O < . . T o re ac h th ed fiv er w ire te rm in a

o n la rg e h ea dp ho ne s,p ull th e e ar e os hlo n O ff

ShEiI land remove an y s cre ws from th e s he ll c a

ings (left). If th e caslngs do n ot s ep a ra te e a silyU$& a s ma ll pu tty klille to p ry th em ge ntly a pa rT o re ac h th e d riv er w ire te rm in als 'o n sm all h ea

ph on es , re move th e o uter foa m ca pa rd c are fupr y ouf th e q riv er u sin g a sm all s ct9 VOid riv er( inse t) . . I ( t he w i re c o onecnons iOOkSOO;I re ,t esth e d ri ve r (step 2 ). If a w ire is loose or broken;e ith er r ep a ir th e w ire c on ne ctiO n (page (32) orr ep la c e th ee nlire c a ble (page 67 ). T o r ei ns ta l l

th e s h ell. re ve rs e . t h e p ro ce du rB a bo vB ,. lf th ep ro blem per sis ts , rem ov e. th e s h ell a g ain an(!

. te s t t he d riv er (stflp 2 ) .

3··eplacing the driver. Desolder (page 130) th e o th er w ire fro

th e d riv er te rm in al (a oo ve ). O rd er a n e xa ct re pla ceme nt d rive r frIh e h ea dp ho ne m an ufa ctq re r o r p urc ha se a s ub stitu te d riv er a t

e le c tr on ic s pa rt s s u pp li er . S o lde r (page 1 3 1 ) Ih e i,ns ula t~ W ire to th ep os itiv e d riv er te rm in a l a n d .s o ld er th e u nin su la te d w ir e to . th e n eg a tiv ete rm in a l. P os itio n. th e. d riv er in th e' s h ell a n d r ei n sla ll th e s h ell (step 1)



SERVICING THE HEADPHONE PLUG


1esting the plug. Unplug the headphone cable and unscrew the

plug shell to expose the wire terrninals. If a wire is loose or bro-

ken, repair i t (page 132 ) or replace the cable (below). Sel a multi"

tester to test continuity .(page 128) . Touch one probe to one wire termi-nal and touch the other probe In turn 10 each of the three plug secnons

(above). The multitester should regislercontinuity onoo-a_rl(j only once.

Repeat this procedure at each Wire terminal. ff the plug tests faulty , re-

place it (step 2) or the cable (below). If the plug is molded to Ihe cable,

put on the headphon~ and sel a multitester to test resistance (page

129). Touch one probe to the plug tip and touch the other probe in turn

to the other two plug sections; then, touch both probes to the two sec-

tions farthest from the tip. There should be an audible cl ick for each test .

If the plug tests faulty, replace the cable. II the plug tests OK, have the

receiver or auxiliary unit jack serviced.

2Replacing the plug. Snip off the plug using wire cutters or a

uti lity kni fe and remove the shell and insulating sleeve from the

cable. Purchase an exact replacement plug at an electroniCs parts

supplier. Unscrew the shell and slide it and any insulating sleeve ontothe cable. Using a soldering stand to support the pl1.!g, repair the wire

connections (page 132), matching their posit ions in the old plug. Solder

(page 131 ) the uni.nsulated wire to the terminal farthest from the plug t ip

and the insulated wires to the other plug terminals (above). Squeeze the

plug dips together wi th pliers to secure the cable. Slide any insulat ing

sleeve and the shell over the plug wire terminals and screw on the shell.

SERVICING THE HEADPHONE CABLE

1esting the wires. Remove the shell (page 66) and liftou\ the

driver. Desolder the wire (p ag e 1 30 ) f rom the positive driver tar-

rnlnal, Set a mult itester to test continuity (page 1;?8). Touch one

probe to a driver wire terminal and touch the other probe in turn to each

wire terminal on the plug (above). The multi tester should register continu-

ity once-and only once. Repeat this step for the other driver terminal

wire. If a wire tests faulty, replace the cable (step 2). If each wire tests

OK, solder the wire (page 131 ) 10 theposil ive driver terminal, f it the

driver into the shell and [einslal l th e shell (page 66); have the receiver

or auxiliary unit jack serviced.

2Replacing the cable. Remove the other headphone shell and

desolder the wires (page 130) f rom the terminals ·of each driver

(above). Purchase a replacement headphone cable-and-plugset at

an electronics parts supplier. Connect one side of the cable 10 each driv-

er, soldering (page 131) the insulated wires to the posit ive driver termi-

nals and the uninsulated wires to Ihe negative driver terminals (above).

Posi tion the dr ivers in the shel ls and put back any screws in the casings;

i f required, apply a l it tle cement around the casing edges. Press in the

ear cushiOns or reinstall the foam caps. I f the problem persists, have the

receiver or auxiliary unit jack .serviced.

67



TOOLS & TECHNIQUESThis section introduces basic tests and procedures that arecommon to almost all home electronics repairs, from testingcontinuity, resistance and voltage to repairing loose or brokenwire connections and replacing damaged connectors, Check-

ing springs, servicing gear assemblies and replacing displaylights are typical repairs for units that, although possibly stillfunctioning, may not be performing at their best. Theelectri-cal heart of an electronic unit, the power supply is a likelysource of total unit failure, Principles of the power supply,along with several standard configurations of power-supplycomponents, are included. Information on reading circuitboards and schematic diagrams, the road maps Dian electronicunit. are presented on pages 138-139. Advice. on purchasingreplacement parts, and on how to deal with a professionalwhen your own efforts fail, appears on page 141.

You can handle most home electronicsrepairs with the baskit of tools and supplies shown below. For the best resulalways purchase the highest-quality tools you can afford ause the right tool for the job. A set of metric screwdrivers is

asset for repairs to many imported electronic units, althoughis usually possible to substitute conventional screwdriverTake the time to care for and store your tools properly, Clemetal tools - but never their handles - using a cloth moisened with light machine oil. To remove rust from a tool. rubwith fine steel wool. Protect tools in a sturdy plastic or metoolbox, with a secure lock if stored around children. A multester ( p a g e s 128·129) is virtually a must for testing compnents inside an electronic unit. Multitesters can often be rentefrom the same electronics parts supplier from whom you puchase replacement components.

CoaxIal cable str ipper

Parallel blades strip exactly

enough coaxial cable for a c on -nector to be installed. One blade

strips off only the outer insulation:

the other blade str jps' oN both

outer' and inner .insulation.

Phillips screwdrivers

(t Available in five sizes, numbered 0 to 4:

i==S!!1~~~§::J[D=)::::=~"izes 1 and 2 fit rnostPbillips-baadscrews. MetriC screwdrivers are useful

.for some imported electronic units.

~======:::;):15;:::=:==:=======:a?;)

~~======;~~-~Flat-lipped screwdrivEtrs ~ - : JTip widths of 1/8 , 3/16,114 and 5116

inch tit most standard screwnsads.

Coaxlal-cable crimping tool

Crimps connectors onto coaxial cable;

graduated. notches for different gauges of cable.

Wire euners

Hardened steel. diagonally·cut

blades can servea l ifetime· of wire

and cable cutting. The cuiling

edges ot pliers cir rnultipurpesa

tools are less reliable.

long-nO$$ pliersHave a wile cutter at the base at the

jaws; may be straight or bent-nosed.

Grip components in t ight places or form

wire to fit terminals; when soldering, dl-

vert heat from sensitive components.

Wire .slrlpper or mUlti -purpose tool

Removes insulation without d'amaging wires; graduated notches

f it s tandard wire s izes. A wire str ipper also has a wi re cut te r and

a hole in each jaw tobend wire endS; no tch at t ip crimps small

connectors. A multi-purposa 1001has graduated crimping notches.

126

DL]:

Compress.ed air

Aerosol carr of"air used to blowdust and dirt oNcomponents;

spray ma y be directed through an

e~tensiC;lIlnozzle into tight spaces.

Cleaning tiquide

Denatured alcohol cleans

metal and ptastlc components;

ruboer-cieaninq compound

cleans rubber components

such as drive belts.

Cleaning aerosols

Electronic contact cleaner that is anti-

static and leaves no residue i s r ecom-mended lor most electronic components

such as switches, potentiometers and

circuit boards. Tuner cleaner, a tluerocar-

bon solvent that may contain a lubricant,

is best resmcteo to tuners. An extension

nozzle localites the spray.



Review the owner's manual for the unit before undertaking

any repair; even a quick and simple job may void the warranty

provided by the manufacturer. Prevent accidents while work-

ing on a unit by unplugging it and disconnecting the cables

and any wires hooked up to it. Set up for a job on a clean work

surface·that is well lit and free of clutter. Work patiently and

methodically; never take short cuts. Keep in mind that even

seemingly complicated tasks are seldom more-than a sequence,

of easy steps. Check for hidden screws and tabs, for example,

ratherthan trying to force panels or casings apart. Magnetize

screwdrivers to avoid time-consuming hunts for a screw

dropped inside the unit. Always substitute a faulty component

with an identical replacement. Perform a cold check for leak-

ing voltage (page 141) before plugging a unit back in, to

ensure that no wires are crossed or disconnected.

Soldering standBall-jointed arms with clips hold

wor!<steady; jawSatB niCkel-pjated

to prevent solder from adhering.

Wlr_solder

Use number 22 gauge with a rosin core

flux; comes wrapped in a coil. 011 a. spool or in flat~ribbon-like lengths.

:::; ]2-----

UtHttyknife

General-purpose cutting tool; often fitted

with a relractable blade. Replacement

blades ate stored in the hol low handle.

FUSE! pul ler and car tr idge fuse

A fuse·puller grips cartridge luses saJely.

Check the ru se c ap for luse specit ications.

TOOLS & TECHNIQUES

Throughout this book, the use of a multitester, also known

as a volt-ohmmeter, is called-for to test continuity, resistance

and voltage. Be aware that although you may be performing

the same test using the same procedure, the purpose of the test

may vary from one instance to another. In one situation, conti-

nuity may mean a component is OK; in another situation,

continuity may mean a component is faulty. Or, for example,

when testing the resistance of a potentiometer in circuit, the

purpose is to confirm that the potentiometer is not the prob-

lem; when testing the resistance of the potentiometer out of

circuit, the purpose is to confirm that the potentiometer is the

problem. Likewise, when testing voltage, the purpose for the

test may differ: with a transformer, the results of the test show

the voltage coming out of the transformer: with amotor, the

results of the test show the voltage going to the motor ,

Soldering Iron stand

The coil dissipates heat; the weightedbase stores a moistenedspooge

used to wipe the l ip.

Magnetlzer/demagnotl.i:!!r

Magnetizes. and demagni;l-tizes lools. A magrietized

screwdriver holds. a screw

to its tip. freeing one hand.

Soldering loonA suitable power range is 1 5 1 0 4 5 watts; higher-

wattage irons ar e faster and hotter. bVt ris~ over-heating sensitive components. A fine. pencil·tip size

is beSt for.electronic components.

Desolderlng vacuum

SuCks up heated liquid solder wh·endesoldering.

The spl ing· lo ilded plunger is pushed down the

tube a n d released by pressing thatrigger.

rE D I I I I I .:»:- ~ _ _ ' - ' ; : _ ~ ~ ' - - .. _ ~ - . _ I t - . . . . . ·Demagnetizer

- - [ = = = = = = = = = = = = = = = = = = = = J = = = = = = = = = = = = = = J ! , J ) Electromagnetic tool discharges buildup;11ag~tism lrom metal components to

prevenl static. interference.

€?+%~T . . . .eezersHandy lor gripping delicate

components in tight places.

Applicators

Foam swabS are liilHree and recom-mended for cleaning. Pick ou t dusl or dir t

using a toothpick. Small sticks or toolhpicks

8(e handy for applying lubricant

~=;;:W(~

127



TOOLS & TECHNIQUES

TROUBLESHOOTING WITH A MULTITESTER

Us ing a multitester, To test continuity, rsslstance.or voltaqe; adigital (above, le't) or an analog (above, right) rnuttltester is re-

quired.ThEiir operating principles are the same, but the digitalmultltesler ,.more expensive than the analcq, is'easier to use.and read. For an accurate reading, theanaloq multltester must..be "zero.ed" after the selectorcontrol is sst to.the specifiedscale: Clip the probes together and turn the aejusrrnent.ctal toalign the needle as closely as possible with the zero on thescale, then unclip the probes, When testing continuity or rests-

lance, tha multitester sends a lo.w-voltage"electrfcal currentfrom its batteries through the component being tested. The

muitltester then registers theeprecise amount of resistance tothe elsctrlcal current Zero ohms, tota] lack o f resistance, indiocates a completed circuit or continulty, Infinite ohms indicate-,stoial resistance, no completed circuit, oran absence of.continuoity. A component may have resistance betwe.en these two ex-tremes. When testing voltage, the mulntesfer registers the pre-

cise amount of electrical clIfr:ent flowing in a completed clrcutt,

TESTINQ CONTINUITY

Us ing a tJ,Jgitalm ultltester, Plug theprobe cables into the jacks; if required,conned hooks-or clips to the probes.Set the on-conUnuitylolfcantrol to.CONTINUITY. Turn the range controlto. its lawest setting and turn the tunc-tion control to . i tsohms selling. Toucheach probe to the terminals indicated(above, center). If you hear a beep,there is continuity. If there is no.beep,there is no contlnulty.

128

Tes ti ng c o nt in ui ty . In this example, aswitch on a circuit board is being tested(above). Wh.en each prabe contacts aswitch terminal, the multitester trie-stosend low-voltaqa electrical current from itsbatteries through one probe. If the currentpasses throu.gh the switch to the otherprobe, ihere isa complete. clrctJiI and conn-nuity. If the current does not pass throughto the other probe, there is no.completecircuit and no.cantinuity.

Us ing ail analog multitester, Plug theprobe-cables into the jacks: if required;connect books or clips to the-probe-soSet the selectorcontrol to the AX1

ahms setting; zero. the multitester (step

ab9ve). Touch each probe to.the terml-nals indicated (above,aenter). If theneedle swings to zero ohms, there iscontinuity. If !heneedle does nat swingfrom infinite ohms, there is total resis-tance and no continuity.



TOOLS & TECHNIQUES

TESTING RESISTANCE

Using a digital multitester. Plug theprobe cables into the jacks; if required,

connect hooks or clips. Set the on-continuity/off control to ON. Turn therange control to its lowest setting and'turn the function control to its .ohrnsselting. Touch each probe to a termi-nal (above, center). Read the displayfor the resistance in the circuit.

Testing resistance. When each probe can.tacts a driverterminal (above), the multi-

tester tries to send low-voltage electricalcurrent from its batteries through oneprobe. The amount of electrical currentthat passes through the driver to the otherprobe is limited by the driver circuitry; thisis displayed, in ohms, as a measurementof resistance to the electrical current.

Using an analog multitester. Plugthe probe cables inlo the jacks; il re-

quired, connect hooks or dips. Setthe selector control to the RX1 ohmssetting; zero the mulfltester (page128), Touch each probe toa terminal(above, center). Check the needleposition on the scale forthe amount01 resistance the circuit has.

TESTING VOLTAGE

Using a digital multitester, Plu!;l in thecables and connect hooks or Clips. Set-theon-continuity/off control to ON andthe range control to 30. Turn the selec-tor control to ACV for a transformer,or a mo to r not connected to a circuitbcarc: use DeV tor a motor conne.ctedto a circuit board. Clip or hOok eachprobe to a terminal (above. center).Read the display for the amount ofvollage flowing in the circuit.

Testing voltage. In this example, the powerto a DC motor from a circuil board is beingtested (above). With each probe contactinga motor terminal, a low-voltage electricalcurrent is sent through the multitesler by

plugging the electronic unit inlo a wall out-let and turning it on, The amount 01 electri-cal current flowing through the multitesteris registered on the display.

Using.an analog multitester. Plugin.the cables and connect hooks orclips. Set the selector control to 50ACV for a transformer, Ora motor notconnected to a circuit board; useDCVlor a motor connected to a cir-cuit board. Zero the muUitester (page128). Hook each probe to a terminal(above, center). Check 'the needleposition on the scale lor the amount01 voltage flowing in the circuit:

129



TOOLS & TECHNIQUES

PREPARING A SOLDERING IRON

) (

,SoIdfl(ingirQn tip

II the soldering iron has been used before, plug it into a walloutlet and wait several minutes. Alter the solde.ring iron heatsup, wipe the tip across the sponge to remove any old solder

and dirt . Keep the soldering iron in its stand until you are readyto use it; wipe the tip on the sponge frequently .as you use it .Unplug the soldering iron when you take a break.If you have never used a soldering iron before, practice sol-

dering (page 13f) and dssotderinq (steps below) on lengths ofscrap wire or discarded components before undertaking repairsto an electronic unit. After using the soldering iron, wipe the tipon the sponge, unplug the soldering iron and untie the powercord Irom the table leg.

Setting up for soldering. Dampen a sponge and place it in thetray on the base of the soldering iron stand. Tie the soldering-iron power cord around a leg 01the work table: leave enough.

slack for the soldering iron to be used comfortably, but notenough for it 10 travel very far if it is knocked off its stand.I f the soldering iron is new, tin the tip by tight ly wrapping

a short length of solder In a spiral around it (above, left); usejust enough to coat the entire tip evenly. Plug the solderingiron into a wall outlet and allow the solder to melt; turn thehandle to help spread it . Lightly wipe the t ip across thesponge to dlstrtbuta the solder smoothly and remove anyexcess (above, right).

DESOLDERING

1emoving old solder. Prepare a soldering iron (SU~p

above). Light ly touch its tip against the old solder for alew seconds. until it begins to melt; if the iron is held any

longer, the heat generated may damage nearby components.Push down the plun.ger in the desoldering vacuum, position itover the solder and press the trigger (above), sucking up thesolder as it melts. Rep.eat the procedure unti l the solder iscompletely removed from the terminals. II the old solder doesnot come off easily, solder (page 131) and then desolder.Clean up stubborn traces of solder (step 2).

130

2Cleaning up solder and flux residue. To lift off remainingsolder, use desoldering braid. Place the braid over theold solder, gently touch the soldering iron tip against the

braid for a few seconds (above) and pull up the braid. Repeatthe procedure as required. To clean off flux residue left by theold solder, rub gently using a loam swab moistened with -dena-tured alcohol orwith flux-cleaning solvent (inset). Perform thesame procedure to clean up accidental solder drops thai Occurwhile soldering.



TOOLS & TECHNIQUES

SOLDERING

Connecting parts with solder. Prepare asOldering Iron (page 130); betore solderingwire ends, strip back the insulation (page132). If required, first clean up old soldertraces and flux residue from the terminals(page 130). Always usa rosin-core solder;never apply an acid-core solder.To solder a wire, hold it against the tar-

minai or twist itclockwise around it. Lightlylauch the soldering iron tip to the wire for alaw seconds (tett) and Hien touch the solderto the wire; avoid touching solder directlyto the soldering iron. Apply just enoughsolder. to coat the connection evenly.Perform the same procedure for each wirein a'cable or for each pin on a switch orpotentiometer. Avoid holding the solderingIron against a wire or pin tor more than afew seconds; the heat can damage

electronic components.

REPLACING WIRES AND CABLES

Choosing the right wire and cable. Most electronics parts sup-pliers stock a wide assortment of wires,and cables. Purchasethe correct gauge, which is a grading of diameter or thicknessusually marked on the insulation. When buying coaxial cable,refer to its ohms rating. Wires for an electronic unit generally

Low-voltage wlr.Solid or stranded inner conductorcovered with plastic insUlation.

Low-voltagemulti -conductor cableThree to fi\ l9 insulated wires; mayhave outer insulation. Use the color,coda or mark to cOnnOCI"he wires'wittlout reversing polarity.

Speaker cableTwo-conductor cable cova/ed withplastic insulation. Use· the color-code or mark toconnect lhe wireswithout rflversing polarity.

Shielded one-conductor cableSpiral 01 . bra ided shie ld acts as aground and protects the insulatedwire fram interference; commonlyreferred to as patch cord.

Shielded two-conductor cableSpi ra l or braided shie ld acts as aQround and protects the twoinsulated wires from interference.

fall between 16 and 24 gauge, with the thicker wire having asmaller number. Wires narrower than 18 are usually unmarked,When in doubt, snip off a length of the old wire and take it withyou. Never install replacement wire or'cable of a smallergauge; if necessary; use a larger gauge.

CoalCial cableStranded or solidce nter conductorprotected by foam insulatiOn, Spiralo r b ra ided outer conductor acts as aground. Outer insulation protectsthe cable from weather.

Shielded twln· lead cableTwo inner conductors protected byfoam insulation; may contain aninner foi l sheathing to protect thaInnar conductors from imetierenC9.Outer Insulation protects thecabls'from weather.

Ribbon cableMulli conductor; low'vottaga wireswithin plastic insulation. Ribboncable connectors pierce the

inSIJlation to contact the wires'.

Telephone cableFour insulated wires; usa the 'colorcodeto connect the \Vires withoutreversing polarity.

Groond wireSolijj t O-gsuga wira; oftllnuninsulated.

131



TOOLS & TECHNIQUES

REPAIRING DAMAGED WIRE CONNECTIONS

1tripping back wire ends. If a.wire connection rs looseor broken and the wire is long enough to be reconnected,. desolder (page t 30) and cut off the end. Ita wire or ca-

ble tested faulty or is too short to be reconnected, desolder(page 130) and replace it (page 131). To prepare a wire forsoldering or for a connector, use a wire stripper to remove 1/4

lnchol insulation. Fit the wire inlo the notch for its gauge,squeez.e the handles and pull off the insulatlcn. If the wire issolid, solder it (page 131) or install a connector (steps below).

If the wire is stranded, first t in the leads (step 2) .

To prepare a cable, cut all the outer insulation with a uti li tyknife, then strip back the insulation froni each wire as above;the amount stripped depends on the connector (page 133).

2Tinning wire leads. Prepare a soldering iron (page 130) .

Support the wire in a soldering stand and twist thestrands together clockwise between your thumb and tore-

finger. Hold the soldering iron t ip against the wire for a fewseconds, then lauch the solder to the wire (above), Apply justenough solder to coat the wire strands evenly; snip off anyprotruding untinned wire strands using wire cutters. After tin-ning the wir~ leads, solder the wire (page 131)or install a wireconnector (steps be/ow). If you are preparing' a cable, repeatthe procedure for each wire, then solder them (pagfl 131) orinStall a cable connector (PfJge 133).

INSTALLING WIRE CONNECTORS

Soldering and crimping a spade lug. Pur-chase spade lugs to f it the terminals andthe wire at an electronics parts supplier.To install a spade lug, strip back the wire(step above) and prepare a soldering iron(page 13PJ. Fit tha wire into the spade lugslee..... Hold the soldering iron tip to thesleeve lor a few seconds, touch the solderto the wire inside the sleeve, then crimp itwith a Wire stripper (above).

Crimping a connector. Purchasecrimp, or solderless, connectors at anelectronics parts supplier; be sure theyare appropriate to tile terminals andthe VJiregauge. To install a crimpconnector, strip back the wire (step

above), l it i t into the connector sleeveand crimp it using the outer notch on awire stripper (above). Gently tug thewire to ensure it is held securely.

Crimping for a plug. Purchase a plug,and crimp connectors to fit i ts termi·nals and the wires, at an electronicsparts supplier. Strip back each wire(step above) and install a crimp con-nector (far lett). Snap each crimp con-nector into the plug (above). GenUy lugeach wire to ensure it is held securely.If you install a plug at the other end ofthe wires, take care not to Cr05Sthem.

132



TOOLS .& TECHNIQUES

INSTALLING AUDIO AND VIDEO CABLE CONNECTORS

Replacing a phono plug. Snip all the old plug using wire cuttersor a uti li ty knite. Purchase an exact replacement plug at anelectronics parts supplier. Unscrew the shell and slide it onto' the cable. If the plug pin is solid, cut off 1/2 inch of outer insula-tion,strip back li4 inch of wira'insalatlon (page 132) and solder(page 131) the insulated wire to the terminal closestto the plugtip_If the plug pin has a hole, cut off 1 1/ 2 inches of outer insu-lation arid strip back 3/ 4 inch of wire insulation. Insert Ihe insu-lated wire into the pin and solder the wire to the pin t ip. Solderthe uninsulated wire to the remaining terminal (above) or 10 aplug clip. Using pliers, squeeze the plug clips together to se-cure the cable. Screw the shell onto the plug.

( .

Replacing a 118-or 1/4·jnch plug. Snip off Ihe old plug usingwire cutters or a utility knife. Purchase an exact replacementplug at an electronics parts supplier. Unscrew the .shell andslide it and any insulating sleeve onto the cable. Cut 1 1/ 2

inches of outer insulation off the cable and strip back 1/2 inchoi insulation from the wires (page 132)_ Solder (page 131) Iheuninsulated wire to the.terminal farthest ftom the plug tip, andSolder the insulated wires to the other plug terminals (above).Using pliers, Squeeze the plug clips together to secure thecable. Slide any insulating sleevaand the shell over the plugand screw on the shell.

Replacing a coaxial connector. Cut off the old connector usingwire cutters or a utl li ty knife. Purchase an exact replacementcermactor at an etectronlcs parts supplier, Slide th~ collar ontothe cable, then fit the cable into a coaxial cable stripper, withthe longer blade l{Z inch from the end. Squeeze the handlesand turn the stripper around the cable (above, laft) , CUlling It

in two places. Pull the outer insulat ion off the second cut, ex-posing the braided shield, and pull the braided shield off the firstcut. axposinq the pin. Unravel the braided shield and fold it backover the outer insulation. Push the connector onto the cable(inset) and slide the cellar over the connector. Crimp the collarsecurely using a coaxial-cable crimping tool (above, rjght)_

133



TOOLS & TECHNIQUES

SERVICING COMPUTER CABLE HOOKUPS

Senicing ribbon cable connections. Remove the connectorfrom the terminal at each .endof the cable. To dean the pinsand terminals, use a foam swab moistened with denatured al-cohol. T o lest the cable, set a multitester to test continuity(page 128). Hook one probe to a pin on one connector andtouch the other probe in turn to each pin on the other connec-tor; there should be continuity once-and only once. Repeatthe test with each pin on the connector. If the cable tests faultyor if a pin is damaged, cut off the connector with a utility knife.purchase an exact replacement cable or connector at a com-puter parts supplier. Use a screwdriver to unclip the connec-tor'souter and inner plates. Fillhe cable over the terminals,leaving 1/2 inch of overlap, and snap on the inner plate (inset).Fold the cable over the inner plate and snap 0 " the outerplate (above).

Servicing DB25 cable eonneetlons, Remove the connector fromthe terminal at each end of the cable. Unscrew and pry apartthe connector shells. If a wire is loose or broken, repair it(page 132); relnstalltheconnector shells. To test the cable,seta multitester to test continuity (page 128). Hook one probeto a pin on one connector and touch the other probe in turnto each pin on the other connector; there should be continuityoncB-andonly once. Repeat the test with each pin on theconnector. If the cable tests faulty, replace it; if a pin is dam-aged, cut off the connector with a uti li ty knife. Purchase an ex-act replacement cable or connector at a computer parts sup-plier. C ut off 11/2 inchasof outer insulation, and strip i2 inchof insulationofi the wires (page 132}..Solder (page 131) thewires to the terminals (above), snap the shells together (inset)and Install the screws.

REPLACING DISPLAY LIGHTS

134

R.eplacing a liquid-crystal display (LCD), a light-emit~ingdiode (LED) or a bufb, Consult the chapter on the unu to re-move any panels. Locate an LCD or LED on its circuit board;unscrew and take out the circuit board to reach its pins. De-solder (page 130) the pins and pull off the LCD or LEO; WIggleit to help release the pins. Order an exact replacement fromthe manufacturer or purchase a substitute at an electronicsparts supplier. Fit the pins into the circuit board and solder

(page 131)the pins. Reinstall any components removed andcold check for leaking voltage (page 141).To replace a bulb, locate the bulb and unscrew or wiggle it

out 'of its socket. If there are wires held by connectors to theback at the bulb, pull off th.ewires. Order an exact replacementbulb from the manufacturer or purchase a substitute at anelectronics parts supplier. Screw or press the bulb into itssocket, push on the connectors and crimp them using the outernotch of a wire stripper (inset). Reinstall any components re-moved and cold check lor leaking voltage (page 141):



TOOLS & TECHNIQUES

SERVICING SPRINGS

Removing and histalling springs. Consult the chapter on theunit to access the spring. If a spring is unhooked at one end,

reconnect it using long-nose pliers or tweezers_ To checkspring lension, usea small stick to tug on it gently (above,left). If Ihe spring does not snap back taully into a straightposition when released, note lts connection points and uselong-nose pliers or IV"eezers to unhook it. Snip off a fewspring windings with wire cutters. Send the cut end of the

spring into a hook using long-nose pliers and reconnect thespring. If a damaged spring cannot be shortened and reconnect-

ed, order an exact replacement from the manufacturer or buy asubstitute at an electronics parts supplier. Use lang.-nose pliersor tweezers to install the spring, being careful not to stretch it(above, right). Heinstall any components removed andcoldcheck for leaking voltage (page 141).

SERVICING GEAR ASSEMBLIES

Servicing gear assemblies. Consult the chapter on the unit t oaccess the gears. To clean a gear assembly, wipe off eachgear using a team swab moistened with alcohol. Use a tooth-pick to dislodge dirt from between the gear teeth (above, left).

To reach the entire gear assembly, try gently turning a gear byhand; too much force can break or strip the gear teeth. II gearsare difficult to reach and cannot be turned, spray ihem withshort bursts of compressed air or electronic contact cleaner.

To lubricate a gear assembly, applya little white grease to eachgear with a .srnall stick (above, right); use a clean loam swab 10

wipe off excess lubricant. If a gear is damaged, note its positionand remove it , saving any cl ip, washer or screw holdirig it inplace. Order an exact replacement from the manufacturer orpurchase a substitute at an electronics paris supplier. Fit thegear in pJace and install its fastener. Reinstall any components. removed and cold check.for leaking voltage (page 141).

135



TOOLS & TECHNIQUES

SERVICING SWITCHES AND POTENTIOMETERS

Testing multi-pole switches and potenti-ometers, Switches and potentiometersplaya key role in routing, reducing orstoppingeJectrical current thrQugh c ir -cuits. A switch doses a circuit, lettingcurrent flow, or opens a circuit, keepingcurrent from passtnq.. A potentiometer .varies the amount of resistance to cur-rent. Some typical switches and poten-tiometers are shown at right.Testing a multi-pole .switch or a double

potentiometer is sometimes a challenge,since they function in more than cne cir-cuit. However, by re<;tdinga circuil board(page 138), you can locate pairs or multi-ples of pins in the same path and test be-tween or among them. Determining theoperating pattern of the switch or potenti-ometer then becomes much easier. Tests

performed between pins in the same pathand another pin should register the sameresult in each switch ocsuicn,

~~- ~Closes or opens ~mota than one circuit; Switchtypica1ly'an onloll or Pushesn and off to close anda feature control. open a circuit; typically an onloll

or a feature contrOl.

Combined switCh/potentiometer'Switch closes and opens a circuit;potentiometer varies ·theesistancE!In the circuit; tr.Pical1yn on/of f andvolume contra.

Multi-poleganged switchPushesn and0 1 1 to cJ0$9 oropen a numberof circuits.

PotentiometerVaries th& resi! ltance in a circuit fromzero to infin ity; typicaJly a yolume ortone control.

DoublepotentiometerVaries resistance in two cir-cuits Irom zero to infinity;typicallya balance control.

SERVICING A REMOTE CONTROL

Cleaning a remote control. To clean the outside of the lenscover, wipe with a damp, lint-free cloth. Cneck the batteryterminals each time you change the batteries; i l the terminalsare dir ty, rub them gently using a pencileraser or spray themwith short bursts of electronic contact cleaner, To clean insidethe remote control, remove the screws holding the top and bot-tom casings together; ' check for hidden screws inside the bat"tery compartment or under the manufacturer's label. If thecasings do not separate easily, gently pry them apart using

a small putty knife. Unscrew and lilt out the circuit board. Usea foam swab moistened With denatured alcohol to clean theinside of the lens cover (ebove, /eft). To reach the key assembly,remove the key pad from Ihe circuit board. Clean the key-assembly contact points by gently rubbing them with a pencileraser and then Wiping them USinga clean foam swab moisten-ed with denatured atcohol (above, right). Reinstall the circuitboard and the pad, snap the casings back together and rein-stall the screws.

136



TOO lS & TECHNIQUES

REPLACING A FUSE

Rem ovin g an d r ep lac ing a fuse. Consullthe chapter on the unit to remove any

panels. If the fuse is externally mountedin the back panel, turn the fuse cap coun-terclockwise and pull the fuse out of itscasing, If the fuse ts internally mountedand its caps are held in retaining clips,grip the fuse with a fuse puller and gentlypry it out (Ie(t), If the fuse is internallymounted and its .caps are soldered toposts, leave it in place. Set a multitesterto test continuity (page 128). Touch aprobe to each fuse cap (inset). If a sol-dered fuse does riot register continuity,desolder it (page 131) and test again, Ifa luse doe-snot register continuity out ofcircuit, purchase an exact replacement-atan electronics parts supplier and install it., If you removed any panels, reinstall them,then cold check for leaking voltage (page'

141). If a fuse blows repeatedly, take theunit for professional service.

TESTING AND REPLACING A POWER CORD

1es ting the pow er co rd. Consult the chapter on the unit to

remove any panels, arid locate the power cord terminals,If the power cord wires are soldered, note their posit ions

and desoJder one wire (page 130);. if they are connected toother wir_esunder a cap msulatcr, cut one wire with wire cut-ters. Set a multitester to test continuity (page 128). Touch oneprobe to a plug prong and touch the other probe in turn to theerid of each power corp wire (ebove). The multitester shouldregister continuity once-and only once, Repeat the test withthe other plug prong and each wire. If the power cord tests OK,reinstall it (step 2); refer to the chapter on the uriit for servic ingthe power supply or take the unit for professional service.

2R eplac ing the pow er co rd . If the power cord tests faulty,desolder the other wire (page 130) or use wire cutters tocui the other wire, Pry out any strain reliel with pliers and

remove the power cord from the strain relief, Purchase an exactreplacement power cord and plug at an electronics parts suppli-er. ToinstaU the power cord, str ip back 3/4 inch of insulationfrom each wire (page 132). Solder tnewlras (page 131) to the.terminals ( abOVe ) or twist them together and crimp on a cap in-sulator (inset). Fit the power cord into the strain relief, if you re-moved it, and push the strain rel ief f irmly into place. Reinstallthe panels and cold check for leaking voltage (page 141).

137



TOOLS & TECHNIQUES

,, · · , .

SERVICING POWER SUPPLIES

Identifying and testing power-supply components. Powersupplies vary in their specific components, as well as in thesequence and wa y the components are connected. However,their operajing principles are fundamentally the same. FourtypiCal power supptlas found in electronic units are shown

above and on page 139.

The power supply provides electrical current to electroniccomponents in the unit. The power cord routes 120-volt alter-nating current (AC) to the power block from an outlet. The onloff switch starts the flow of AC by closing a circuit in the unit .The transtormersteps down the 120-volt AC 10 the low voltagerequired by circuit board components. A rectifier then changesthe AC to direct current (DC). Usually, a fuse protects the

parts from voltage spikes.

Simple tests can determine whether the power supply functionscorrectly. By testing the continuity (page 128) of the power cord,fuse; and onloff switch, as well as the wires and paths betweenthese components and between them and the transformer, you cadetermine whether current reaches the transformer: by testing thelow-voltage output {page 129) of the transformer, vo u can dstar-

mine whether current is being delivered to electronic components.The power-supply components are arranged in three typical se-

quences: fuse to on/ott .switch 10 translormer; on/off switch to fuseto transformer; and onloff switch to transformer. A variation, com-moniy found in a receiver, has a fuse, onloff switch and trans-former each connected to the power block.Wires and circuit board paths (step below) are often used in

Combination toconnect two components. IIcan be diff icult to

READING A CIRCUIT BOARD

B

Solder9d pins Circuit board A and B are in the same path; ""henl lachis leSt9d with any other pin, theresuns should be the same.

138

Tracing a path 00 a circuit board. Theelectrical current that flows through thecomponents inside an electronic unit isrouted, for the'most part, through paths onclrcuit boards. A path consists of a strip ofcopper foil, easily identified byits contrast

in color to the circuit board that sandwichesit. Any components' with pins or wires sol-dered in the same path are in the samecircuit (far lett}.When testinqa multi-pole switch (near

tett), differentiate between pins in the samepath and pins in other paths. Pins in thesame path should register the same resultin both switch positions when each is test-ed with any other pin.



TOOLS &TECHNIQUES

f igure out which wire or path goes where and to remember whetheror not it has been tested. But orienting yourself to one power-sup-ply component at a time assures you of testing each connectionbetween them. In the first example (page 138, lelt), the power-sup-ply components include an onloff switch, a fuse and a transformer.By following the two wires from the fuse, for instance, you woulddiscover that the power-supply component to which they connect isthe power block; you could then test the wires between thsm. Fol-lowing this procedure from the onloff switch would lead you to testthe wires between it and the power block. And, by following thetwo wires from the transformer, you would discover that the power-supply component to which its wires connect isalso the powerblock. Finally, you would locate the transformer wires leading awayfrom the power-suppiy components and test for low voltage.

The same procedure would lead to different, but equally thor-ough, testing of the connections between components in anyother power supply. In the second example (page 138, rig/H),you would test between the onloll switch and the power blockand between the transformer and the onloff switch; there is nofuse. The final test would be for low voltage from the transform-er, In the third example (above Jeff), by tracing the circuit boardpath you would test between the onloff switch and tha fuse, thetuse and the power block, and the transformer and the onloff

switch; then test for low voltage from the transformer. In thefourth example (above, right), you test belweenthe transformerand the power block, then for low voltage from the transformer;the on/off switch here is not directly connected to the powersupply components.

READtNG A SCHEMATIC DIAGRAM

COMPONENT SYMBOL COMPONENT SYMBOL

SWITCH ( ) ' " " ' " " ' Q OR ~LIGHT EMITTING

~IODE (LED)

POTENTIOMETER -vp-OR

~

LIQUID CRYSTAL

!1TIJiSPLAY (LCD)

FUSE -<f\.D- OR -E:3- BULB =E:::) OR =O

TRANSFORMER ~LOR~llc SPEAKER 0 ] OR w)))

MOTOR o-@r OR ::@r ANTENNA rO~ T oAlI

POWER P L U G~

:::()= GROUND ~ O.R~ ORJ..~. OR

Identifying schematic diagram symbols.A schematlc diagram uses symbols to showhow the components 01a unit are connect-ed. Some symbols are standard; othersvary depending on the manufacturer. Typi-cal basic symbols you are likely to find on

a schematic diagram are shown at leff.Component specifications are sometimes

listed right on the schematic diagram; Of,

there may be a part number for use as ref-erence in a schematic dia,grammanual, .When ordering a replacement part from themanufacturer or purchasing a substitute atan electronics parts supplier, be sure tostate.the component specifications andmanufacturer part number.

139



TOOLS & TECHNIQUES

TIPS ON DISASSEMaL V AND REASSEMBLY

Magnelizer/demagnetizer

140

Wo rk in g m eth od ic ally and $<lfe ly .Adheri'ng to a few simple disassembly and

reassembly guidelines ensures that your

exper iences in home electronics rapairarsrewwding and;;lccid~nt;free.Keep in mind

the warnings you a.re likely to find on the

back and bottom panels of a unit (page 9).

Before undertaking a major repair, review

the owner's manual and check whether

!h!;! u n i t . is stil l under warranty.

Set up for repairs on a Clean, welHil

work tabla; a wooden surface is ideal.

Protect the unit Irotn: scratches by cover-

ing the tabla with a clean'!llsulating pad;

an old blanket will do.

Magnetize screwdrivers before you start

to work by passing their heads throu.gh a

magnetizer/demagnetizer (top left). Keep

screws and other small partsin labeled

trays, jars or film containers ..Discharge. any static buildup from your-

self by touching a n exposed.iunpatntad

metal surface on the. unit. such as a screw;

hold the frame to ground yourself before

hafldling circuit boards and, especially,

a computer CPU chip.

Study the unit panels before beginning,

to determine the sequence in which they

were installed. Check for hidden screws

under labels (top fIght) and recessed ..

screws covered by a tab (center left).

To release a stubborn screw, press the

screwdriver fi rmly into the screwheadand

snap any glue seal with a sharp counter"

clockwise twist. Pull or slide off panels

gently; never force them. If a panel resists

being removed, check the edges for tabs

securing it to anoth.er panel or te the

trams (cenlerright).

Disassemble only what is rreaded to

reach parts being repaired. Refer to the

unit service manual, if it is available from

the manufacturer or an electronics parts

supplier. Write down YC:>,urequence of

dtsassernb ly steps fOTreference in reas-

sembly.

As you remove a panel, check behind

it for wires corinectinq it lo internal com-

ponents, Belore unplugging a connector

(bottom left), note lis te.rminal posit ions;

soldered connections rarely need to beremoved. .

Unscrew circuit boards us.ing. as littlepressure as possible: the'Y are very easily

damaged. Carefully pry any srnatlcllp off

a component (bOttom right); keep one

ha,nd ready to catch if.

I?efora reinstalling panels, check Ihat

no toots are left inside and that. all.cornpo-

nents are back in place. After reassembly,

but before plugging In-the unit, perform a

cold check for leaking voltage (page f 4 t).



TOOLS & TECHNIQUES

A COLD CHECK FOR LEAKING VOLTAGE

Testing for a potential electrical hazard,Before plugging in .a unit that has under-

gone an internal repai r, perform a simple

test to confirm thaI no internal electrical

circuits have been damaged or shorted ..

Clip a jumper cable to the prongs on the

power cord p.lug and set the on/oft control

to the ON position. Set a multitester to

lest continuity (page 128j.Clipone multi-

lester probe to a plug prong and touch the

other probe in turn to at least two or threeunpainted metal surfaces on the unit (left);

screws through the pane is into the frame,

and cable terminals. make ideal test

points. In each test. there should be nocontinuity. Unclip the jumper cable and a

touch a probe to each prong on the power

cord plug; in this test. there. should be

continuity. 1 1 the unit tests faulty in any

test, do not plug it into an outlet until youhave located the problem and remedied it;

il you cannot determine the cause of the

problem. take the unit for professional ser-

vice. If the unit tests OK in each test, set

the onloff control to the OFF position and

plug the unit into an outlet.

GETTING HELP WHE.N YOU NEED IT

Learning what you need to know for effective repairs, The key

to obtaining the correct replacement component. schematic di-

agram or owner's manual for your unit is the model and serial

nurribers, usually stamped on a plate or a sticker (above) on

Armed with this information, call your local electronics parts

supplier to check whether the part is in stock. Electrontcsparts

suppliers. of ten have comparison l ists of equivalent substi tute

components. If possible. take the faulty component with you.

When purchasing a replacement component, you have sev-

eral sources tram which to choose:

Electronics parts suppliers. If a store does not carry a part the

dealer may be able to order it or tell you where to tind it.

Audio/video stores and computer stores. Many do not sell more

than basic supplies such as cables, cleaners or software. Adealer may be able to help you locate. other sources.

Hardware stores. Many stock cable. toolsand basic audio and

video supplies, but their salespeople are not specialized.

electronics repair guide

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