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Chapter 7Chapter 7

Basic Troubleshootingand

Repair Procedures

Basic Troubleshootingand

Repair Procedures

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OverviewOverview

• Tools Needed

• Circuit Troubleshooting

• Electrical Interference

• Tools Needed

• Circuit Troubleshooting

• Electrical Interference

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Tools NeededTools Needed

• Multimeters• Wiring Tools• Miscellaneous Tools• Do-It-Yourself Test Tools• Commercial Testers

• Multimeters• Wiring Tools• Miscellaneous Tools• Do-It-Yourself Test Tools• Commercial Testers

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MultimeterMultimeter

• Required features in a boat’s multimeter Measure up to 50 VDC

• DC voltages either 6, 12 and sometimes 24 Measure up to 250 VAC

• AC voltages either 120 or 240 Measure resistance or continuity

• Audible continuity checker is desirable

• Desirable features Measure AC and DC current up to 10 amps Entry level measure current to approx. 250

mA

• Required features in a boat’s multimeter Measure up to 50 VDC

• DC voltages either 6, 12 and sometimes 24 Measure up to 250 VAC

• AC voltages either 120 or 240 Measure resistance or continuity

• Audible continuity checker is desirable

• Desirable features Measure AC and DC current up to 10 amps Entry level measure current to approx. 250

mA

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Analog MultimeterAnalog Multimeter

• Advantage - Low cost• Disadvantages

Difficult to read measurement value Have to start at max value and work way

down

• Advantage - Low cost• Disadvantages

Difficult to read measurement value Have to start at max value and work way

down

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Digital MultimeterDigital Multimeter• Advantages

Easy to read measurement value More accurate readout

• Disadvantages Have to start at max value and work way

down Cost

• Advantages Easy to read measurement value More accurate readout

• Disadvantages Have to start at max value and work way

down Cost

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Auto-Ranging MultimeterAuto-Ranging Multimeter

• Advantage Only have to select function (not range)

• DC voltage, DC current, AC voltage or resistance

• Disadvantage - cost

• Advantage Only have to select function (not range)

• DC voltage, DC current, AC voltage or resistance

• Disadvantage - cost

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Wiring ToolsWiring Tools

• Wire Cutter – Diagonal Cutter 5 or 6” overall Plastic cushion grip

• Wire Stripper Don’t use knife Are dedicated tools Most used – Combination Cut/Strip/Crimp

Tool• Not to be used as crimp tool• Wire cutters at tip not effective

• Wire Cutter – Diagonal Cutter 5 or 6” overall Plastic cushion grip

• Wire Stripper Don’t use knife Are dedicated tools Most used – Combination Cut/Strip/Crimp

Tool• Not to be used as crimp tool• Wire cutters at tip not effective

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Wire Cutters / Wire Strippers

Wire Cutters / Wire Strippers

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Wiring Tools - 2Wiring Tools - 2

• Ratcheting crimp tool required by ABYC Covered in Chapter 2 Expensive compared to combination tool

• Soldering gun Normally boat wiring is NOT soldered

• Done with crimp on terminals and butt spices Required for some coax connectors Recommend dual 100/140 watt With appropriate tip will cut lines and

fuse ends

• Ratcheting crimp tool required by ABYC Covered in Chapter 2 Expensive compared to combination tool

• Soldering gun Normally boat wiring is NOT soldered

• Done with crimp on terminals and butt spices Required for some coax connectors Recommend dual 100/140 watt With appropriate tip will cut lines and

fuse ends

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Crimp Tool / Soldering Gun

Crimp Tool / Soldering Gun

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Miscellaneous ToolsMiscellaneous Tools

• Pliers To hold objects

•Not a substitute for a wrench Types

•Slip joint•Needle nose•5” or 6” overall with plastic cushioned

grips

• Wrench (for electrical work) Adjustable 6”

• Pliers To hold objects

•Not a substitute for a wrench Types

•Slip joint•Needle nose•5” or 6” overall with plastic cushioned

grips

• Wrench (for electrical work) Adjustable 6”

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Pliers / Adjustable WrenchPliers / Adjustable Wrench

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ScrewdriversScrewdrivers

• Blade 3/16” blade with 4” shaft 1/4” blade with 4” shaft

• Phillips #1 with 4” shaft #2 with 4” shaft

• Small 1/8” blade with approx. 2” shaft #0 Phillips with approx. 2” shaft

• Blade 3/16” blade with 4” shaft 1/4” blade with 4” shaft

• Phillips #1 with 4” shaft #2 with 4” shaft

• Small 1/8” blade with approx. 2” shaft #0 Phillips with approx. 2” shaft

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ScrewdriversScrewdrivers

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Circuit Trouble-ShootingCircuit Trouble-Shooting

• Batteries• Alternators• Battery Chargers• Boat Lighting System• Boat DC Electronic Systems• Boat AC Circuits

• Batteries• Alternators• Battery Chargers• Boat Lighting System• Boat DC Electronic Systems• Boat AC Circuits

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Battery TestingBattery Testing

• Hydrometer• Open-Circuit Voltage• Load Test• Three-Minute Charge

• Hydrometer• Open-Circuit Voltage• Load Test• Three-Minute Charge

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HydrometerHydrometer

• Hydrometer – best tester of flooded-cell Measures Specific Gravity Chapter 3, Table 5

• Hydrometer – best tester of flooded-cell Measures Specific Gravity Chapter 3, Table 5

Specific Gravity

100 % charge 1.265

75 % charge 1.225

50 % charge 1.190

25 % charge 1.155

Discharged 1.120

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Open-Circuit VoltageOpen-Circuit Voltage• For Maintenance Free, Gel & AGM

batteries When you can’t use a hydrometer

• Battery should rest for 24 hours, or discharge with a large light bulb for a few minutes

• Chapter 3, Table 5

• For Maintenance Free, Gel & AGM batteries When you can’t use a hydrometer

• Battery should rest for 24 hours, or discharge with a large light bulb for a few minutes

• Chapter 3, Table 5Voltage Flooded Gel AGM100 %

charge 12.65 12.90 12.85

75 % charge 12.4 12.65 12.6 50 %

charge 12.2 12.35 12.3

25 % charge 12.0 12.0 12.0

Discharged 11.8 11.8 11.8

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Specific Gravity & Voltages

Specific Gravity & Voltages

100 % charge 1.265 12.6 to 12.7 12.85 to 12.95 12.8 to 12.9 75 % charge 1.225 12.4 12.65 12.6 50 % charge 1.190 12.2 12.35 12.3 25 % charge 1.155 12.0 12.0 12.0Discharged 1.120 11.8 11.8 11.8

Charging voltage @ 80º F Bulk - 14.2 to 14.4 13.8 to 14.1 14.4 to 14.6 Acceptance - 14.2 to 14.4 13.5 to 13.8 14.1 to 14.4 Float - 13.2 to 13.6 13.2 to 13.5 13.2 to 13.5 Equilization - 15.0 to 16.0 Do NOT Equalize Do NOT Equalize

Chapter 3 Table 3-5

Specific Gravity (Flooded Cell @ 80 F)

Flooded Cell Voltage

Gelled Cell Voltage

AGM Voltage

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Load TestLoad Test

• Hydrometer and open-circuit voltage do not indicate ability to provide current under load

• Prevent engine from starting Operate starter motor for approx 15 sec Monitor battery voltage after 5 sec

• If voltage is over 10.5 VDC – Good Battery

• If voltage is under 10.5 VDC – Bad Battery Replace battery

• Hydrometer and open-circuit voltage do not indicate ability to provide current under load

• Prevent engine from starting Operate starter motor for approx 15 sec Monitor battery voltage after 5 sec

• If voltage is over 10.5 VDC – Good Battery

• If voltage is under 10.5 VDC – Bad Battery Replace battery

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Three-Minute Charge TestThree-Minute Charge Test• Actually takes six (6) minutes

• Charge battery at 40A for six minutes

• Measure voltage (at battery) with charger on

• If voltage under 15.5 VDC – Battery is good

• If voltage is over 15.5 VDC – Battery is bad Not accepting charge Is sulfated Replace battery

• Actually takes six (6) minutes

• Charge battery at 40A for six minutes

• Measure voltage (at battery) with charger on

• If voltage under 15.5 VDC – Battery is good

• If voltage is over 15.5 VDC – Battery is bad Not accepting charge Is sulfated Replace battery

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Alternator TestingAlternator Testing

• Drive Belt• Quick Test• Alternator Electrical Connections

• Drive Belt• Quick Test• Alternator Electrical Connections

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Drive Belt & Quick TestDrive Belt & Quick Test

• Drive belt Loose belt if “squealing” when engine

started Belt depression when pressed at midpoint

• Normal (correct tightness) is only 3/8” to ½”• Over ½” is too loose, tighten belt

• Quick test with engine & battery charger off Measure (battery) voltage at alternator Start engine and measure voltage at

alternator• Alternator working if voltage increases• Alternator not working if voltage constant

• Drive belt Loose belt if “squealing” when engine

started Belt depression when pressed at midpoint

• Normal (correct tightness) is only 3/8” to ½”• Over ½” is too loose, tighten belt

• Quick test with engine & battery charger off Measure (battery) voltage at alternator Start engine and measure voltage at

alternator• Alternator working if voltage increases• Alternator not working if voltage constant

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Alternator Electrical Connections

Alternator Electrical Connections

To check wiring between alternator & battery

• First discharge battery for five minutes

• Then start engine & check for high resistance connection between alternator & battery

• Voltage drop over 0.5 VDC needs to be fixed; or over 1.0 VDC if there are charging diodes Check both positive and negative circuit Clean and tighten the bad connection If you find a bad wire, replace it

To check wiring between alternator & battery

• First discharge battery for five minutes

• Then start engine & check for high resistance connection between alternator & battery

• Voltage drop over 0.5 VDC needs to be fixed; or over 1.0 VDC if there are charging diodes Check both positive and negative circuit Clean and tighten the bad connection If you find a bad wire, replace it

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Battery Charger TestingBattery Charger Testing

• Alternator vs Battery Charger• Quick Test• Troubleshooting

• Alternator vs Battery Charger• Quick Test• Troubleshooting

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Alternator vs Charger & Quick Test

Alternator vs Charger & Quick Test

• Alternator vs Battery Charger Batteries charged by alternator Batteries not charged by battery charger

• Defective battery charger; see Troubleshooting

• Quick test with engine & charger off Measure (battery) voltage at battery

charger Turn on battery charger and measure

voltage• Battery charger working if voltage increases• Battery charger not working if voltage constant

• Alternator vs Battery Charger Batteries charged by alternator Batteries not charged by battery charger

• Defective battery charger; see Troubleshooting

• Quick test with engine & charger off Measure (battery) voltage at battery

charger Turn on battery charger and measure

voltage• Battery charger working if voltage increases• Battery charger not working if voltage constant

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TroubleshootingTroubleshooting

• If Charger not working, check the AC input Troubleshoot like AC Circuit, covered later

• If there is AC input, check for a blown fuse Replace blown fuse ONCE If fuse blows a 2nd time

• Disconnect wire going to battery and install another fuse, then turn charger on

•If fuse blows again, have defective charger•If fuse does NOT blow, measure DC voltage

– Should be between 13 and 16 VDC

• If Charger not working, check the AC input Troubleshoot like AC Circuit, covered later

• If there is AC input, check for a blown fuse Replace blown fuse ONCE If fuse blows a 2nd time

• Disconnect wire going to battery and install another fuse, then turn charger on

•If fuse blows again, have defective charger•If fuse does NOT blow, measure DC voltage

– Should be between 13 and 16 VDC

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Troubleshooting - 2Troubleshooting - 2

• Turn Charger “Off”

• Disconnect charger positive wire at battery Tape it to prevent wire shorting to ground

• Reconnect positive wire at charger

• Turn “On”, if fuse blows have short in wire

• If fuse does not blow, may have high resistance connection between charger and battery Troubleshoot wiring like you would for alternator

• Turn Charger “Off”

• Disconnect charger positive wire at battery Tape it to prevent wire shorting to ground

• Reconnect positive wire at charger

• Turn “On”, if fuse blows have short in wire

• If fuse does not blow, may have high resistance connection between charger and battery Troubleshoot wiring like you would for alternator

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Boat Lighting SystemBoat Lighting System

• Boat light inoperative First replace bulb with known good bulb Alternate test of suspect bulb

•Check continuity of filament–Good bulb will have continuity

or low resistance–Bad bulb will indicate no continuity

or infinite resistance

If good bulb does not work•Need to troubleshoot lighting circuit

• Boat light inoperative First replace bulb with known good bulb Alternate test of suspect bulb

•Check continuity of filament–Good bulb will have continuity

or low resistance–Bad bulb will indicate no continuity

or infinite resistance

If good bulb does not work•Need to troubleshoot lighting circuit

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Lighting TroubleshootingLighting Troubleshooting

• Need a logical sequence

• First check circuit breakers and switches

• Then isolate to battery to power panel

or• Power panel to light

• Need a logical sequence

• First check circuit breakers and switches

• Then isolate to battery to power panel

or• Power panel to light

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Replace / CheckBulb

Boat Light Inoperative

LightWorking

?StopYes

NO

Powerto Panel

?

NO

Yes

BatterySwitch On

?

A

Turn Battery

Switch OnNOA

DCMain On

?

Turn DC Main OnNO

A

Yes

Yes

TroubleshootBattery to Panel

TroubleshootPanel to Light

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Battery to Power PanelBattery to Power Panel

No DC at battery side of DC main breaker

• Check/replace large fuse at battery Use multimeter

• Check/clean/tighten wiring Battery to battery fuse Batter fuse to power panel

No DC at battery side of DC main breaker

• Check/replace large fuse at battery Use multimeter

• Check/clean/tighten wiring Battery to battery fuse Batter fuse to power panel

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Power Panel to LightPower Panel to Light

Have DC at load side of branch circuit breaker

• Check/clean/tighten wiring at branch breaker

• Check/clean corrosion at light socket Use CRC QD Electronic Cleaner or

equivalent

• Check/replace in-line fuse near light• Check/replace switch in light• Check wiring with temporary wires from

branch circuit breaker to light fixture

Have DC at load side of branch circuit breaker

• Check/clean/tighten wiring at branch breaker

• Check/clean corrosion at light socket Use CRC QD Electronic Cleaner or

equivalent

• Check/replace in-line fuse near light• Check/replace switch in light• Check wiring with temporary wires from

branch circuit breaker to light fixture

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Boat DC Electronic Systems

Boat DC Electronic Systems

• 90% of equipment problems is lack of DC or bad corroded cable connections

• First check for power to equipment If there is power

• Check for blown fuse• If fuse is good, there is an equipment problem

• Then check/clean cable connections Use CRC QD Electronic Cleaner or equivalent

• Lastly troubleshoot like a lighting system Previously covered

• 90% of equipment problems is lack of DC or bad corroded cable connections

• First check for power to equipment If there is power

• Check for blown fuse• If fuse is good, there is an equipment problem

• Then check/clean cable connections Use CRC QD Electronic Cleaner or equivalent

• Lastly troubleshoot like a lighting system Previously covered

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Boat AC CircuitsBoat AC Circuits

• Testing• Troubleshooting

• Testing• Troubleshooting

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Testing AC CircuitsTesting AC Circuits

• Shore power polarity Verify correct with Reverse Polarity

Indicator

• Outlets When first installed and once a year Verify with AC Outlet Tester

• GFCI outlets When first installed and once a year Insert AC Outlet Tester

•Press “Test” – tester lights should go “Off”

•Press “Reset” – tester lights should go “On”

• Shore power polarity Verify correct with Reverse Polarity

Indicator

• Outlets When first installed and once a year Verify with AC Outlet Tester

• GFCI outlets When first installed and once a year Insert AC Outlet Tester

•Press “Test” – tester lights should go “Off”

•Press “Reset” – tester lights should go “On”

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Testing Hard Wired Appliances

Testing Hard Wired Appliances

• Turn on appropriate branch circuit breaker

and • Appliance “On” switch• Appliance should work or• Expose the AC terminal strip

Use multimeter Check for AC voltage and polarity

• If have AC input and won’t work = Defective

• Turn on appropriate branch circuit breaker

and • Appliance “On” switch• Appliance should work or• Expose the AC terminal strip

Use multimeter Check for AC voltage and polarity

• If have AC input and won’t work = Defective

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Troubleshooting AC Circuits

Troubleshooting AC Circuits

• Need logical sequence

• First check circuit breakers and switches

• Then isolate to dock to power panel or• Power panel to outlet or appliance

• Need logical sequence

• First check circuit breakers and switches

• Then isolate to dock to power panel or• Power panel to outlet or appliance

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AC Troubleshooting

NO

Powerto Panel

?

Yes

ServiceBreaker Tripped

?

Reset Service Breaker

NO

A

ACMain On

?

Turn AC Main OnNO

A

Yes

Yes

TroubleshootDock to Panel

TroubleshootPanel to

Outlet / Appliance

A

Start

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Dock to Power PanelDock to Power Panel

No AC at line side of AC main circuit breaker

• Check/reset dockside circuit breaker• Check service cord

Use adapters and AC Outlet Tester Power at dockside outlet? Power at boat end of cable?

• Check/clean/tighten connectors and wiring Disconnect AC power before working on AC Use CRC QD Electronic Cleaner on contacts

No AC at line side of AC main circuit breaker

• Check/reset dockside circuit breaker• Check service cord

Use adapters and AC Outlet Tester Power at dockside outlet? Power at boat end of cable?

• Check/clean/tighten connectors and wiring Disconnect AC power before working on AC Use CRC QD Electronic Cleaner on contacts

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Power Panel to Outlet/AppliancePower Panel to

Outlet/Appliance

Have AC at load side of branch circuit breaker

• Reset GFCI outlet• Disconnect AC power before working • Check/clean/tighten wiring at breaker• Check/clean/tighten wiring at outlet/appliance• Check wiring with temporary wires from

branch circuit breaker to outlet/appliance

Have AC at load side of branch circuit breaker

• Reset GFCI outlet• Disconnect AC power before working • Check/clean/tighten wiring at breaker• Check/clean/tighten wiring at outlet/appliance• Check wiring with temporary wires from

branch circuit breaker to outlet/appliance

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Summary – Circuit Troubleshooting

Summary – Circuit Troubleshooting

DC• Battery tests: Voltage, Load and 3-minute charge• Alternator tests: Drive belt, quick test and wiring• Battery Charger: Quick test, AC power and wiring• Inoperative lights: Bulb, bulb contacts and wiring• DC electronics: Verify DC power & clean contacts• DC wiring: Start at power panel and isolate

AC• Test outlets yearly• AC appliances: Verify AC power and check wiring• AC wiring: Start at power panel and isolate

DC• Battery tests: Voltage, Load and 3-minute charge• Alternator tests: Drive belt, quick test and wiring• Battery Charger: Quick test, AC power and wiring• Inoperative lights: Bulb, bulb contacts and wiring• DC electronics: Verify DC power & clean contacts• DC wiring: Start at power panel and isolate

AC• Test outlets yearly• AC appliances: Verify AC power and check wiring• AC wiring: Start at power panel and isolate

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Electrical InterferenceElectrical Interference

• Introduction• Sources of Interference• Locating Interference Sources• Interference Suppression• Mitigation Techniques

• Introduction• Sources of Interference• Locating Interference Sources• Interference Suppression• Mitigation Techniques

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IntroductionIntroduction

• Causes and Effects Caused by rapid on/off current switching Radiated through air Conducted though wiring Degrades high sensitivity electronic

equipment

• Noise Layers Usually have interference from several

sources Remove/reduce till acceptable Difficult to identify stronger interference

• Causes and Effects Caused by rapid on/off current switching Radiated through air Conducted though wiring Degrades high sensitivity electronic

equipment

• Noise Layers Usually have interference from several

sources Remove/reduce till acceptable Difficult to identify stronger interference

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Sources of InterferenceSources of Interference

• Ignition Systems• Charging Systems• Voltage Regulators• Electric Motors• Gauges and Instruments• Propeller Shaft(s)• Video Displays• Electronic Equipment• Fluorescent Lights

• Ignition Systems• Charging Systems• Voltage Regulators• Electric Motors• Gauges and Instruments• Propeller Shaft(s)• Video Displays• Electronic Equipment• Fluorescent Lights

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Identification by SoundIdentification by Sound

• Ignition Popping Sound related to engine

speed

• Alternator High-pitched musical whine

related to engine speed

• Voltage Regulator Intermittent rasping sound

• Electric Motor Hissing sound or whine

• Ignition Popping Sound related to engine

speed

• Alternator High-pitched musical whine

related to engine speed

• Voltage Regulator Intermittent rasping sound

• Electric Motor Hissing sound or whine

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Locating SourcesLocating Sources

• What is Different?• What is On?• How is interference getting into

equipment Radiated? Conductive?

• Pigtail Check (with bypass capacitor)• Radio Noise “Sniffer”

• What is Different?• What is On?• How is interference getting into

equipment Radiated? Conductive?

• Pigtail Check (with bypass capacitor)• Radio Noise “Sniffer”

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Interference SuppressionInterference Suppression

At source of interference

• Approaches

Repair or replace faulty equipment

Shielding to confine interference

Special-purpose components to reduce interference

At source of interference

• Approaches

Repair or replace faulty equipment

Shielding to confine interference

Special-purpose components to reduce interference

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General SuppressionGeneral Suppression

• Replace/repair faulty equipment• Correct defective wiring

Bonding straps still connected? Check wiring for loose connections

• Re-run wiring Separate power and signal wires/cables Dress regulator field wire close to the

alternator

• Shielding Wires Compartments with grounded copper screen

• Replace/repair faulty equipment• Correct defective wiring

Bonding straps still connected? Check wiring for loose connections

• Re-run wiring Separate power and signal wires/cables Dress regulator field wire close to the

alternator

• Shielding Wires Compartments with grounded copper screen

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Ignition SystemIgnition System• Primary

Shield ignition switch wiring• Ground shield at engine (only)

Ground case of ignition coil Install 0.1 µf coaxial capacitor

• in positive wire at coil Install 0.005 µf disc ceramic capacitor

• at negative terminal of coil• rated at 1,000 volts

Replace and adjust breaker points Select and replace capacitor

• Primary Shield ignition switch wiring

• Ground shield at engine (only) Ground case of ignition coil Install 0.1 µf coaxial capacitor

• in positive wire at coil Install 0.005 µf disc ceramic capacitor

• at negative terminal of coil• rated at 1,000 volts

Replace and adjust breaker points Select and replace capacitor

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Ignition System – cont’dIgnition System – cont’d

• Secondary

Install resistor spark plugs

• Secondary

Install resistor spark plugs

– Install resistor cable (between distributor and spark plugs)

– Can be used together if needed

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AlternatorAlternator• If output less than 50 Amps, add a

0.5 µf coaxial capacitor at output terminal

• If over 50 Amps add a low-pass filter or in-line choke at the output terminal

• Never bypass the alternator field

• If output less than 50 Amps, add a 0.5 µf coaxial capacitor at output terminal

• If over 50 Amps add a low-pass filter or in-line choke at the output terminal

• Never bypass the alternator field

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Charger / Voltage Regulator

Charger / Voltage Regulator

Battery charger• Install near battery and away from

electronics• Suppression built in by manufacturer• Home-made copper wire shield

Voltage regulator• May be built in to alternator• If external

Mount close to alternator Consider shielding field wire (ground both ends)

Battery charger• Install near battery and away from

electronics• Suppression built in by manufacturer• Home-made copper wire shield

Voltage regulator• May be built in to alternator• If external

Mount close to alternator Consider shielding field wire (ground both ends)

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Electric MotorsElectric Motors

• Well seated brushes• By-pass with 0.25 to 0.5 µf capacitor• Ground housing

• Well seated brushes• By-pass with 0.25 to 0.5 µf capacitor• Ground housing

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Gauges and InstrumentsGauges and Instruments

Gauges and instruments• Bypass with 0.25 to 0.5 µf 200 volt

capacitor• Some may stop working when bypassed

Electric tachometers• Don’t bypass (it will stop working)

• Shield wire and ground both ends

Gauges and instruments• Bypass with 0.25 to 0.5 µf 200 volt

capacitor• Some may stop working when bypassed

Electric tachometers• Don’t bypass (it will stop working)

• Shield wire and ground both ends

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Propeller HashPropeller Hash

Shaft Hash– Indicates stray current or galvanic current

problem• If possible fix problem

– Best to ground the shaft with carbon brushes– Fixes the symptom, not the problem

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Electronic EquipmentElectronic Equipment

• All electronics and appliances should be FCC Type Approved Part 15 B of the FCC Rules Look for decal/label

• Europe has a tougher RFI standard “CE” Look for decal/label

• All electronics and appliances should be FCC Type Approved Part 15 B of the FCC Rules Look for decal/label

• Europe has a tougher RFI standard “CE” Look for decal/label

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Mitigation TechniquesMitigation Techniques

At equipment being interfered with

• Approaches Shielding against radiated interference Filtering against conductive interference

• Capacitors (or condensers)• Chokes (or inductors)

At equipment being interfered with

• Approaches Shielding against radiated interference Filtering against conductive interference

• Capacitors (or condensers)• Chokes (or inductors)

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Shielding and CapacitorsShielding and Capacitors

• Shielding for radiative interference

• Capacitor (or condenser) For conductive interference Provide low reactance to AC Placed across (parallel) input power

terminals Bypass undesirable AC noise to ground

• Shielding for radiative interference

• Capacitor (or condenser) For conductive interference Provide low reactance to AC Placed across (parallel) input power

terminals Bypass undesirable AC noise to ground

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Chokes (Inductors)Chokes (Inductors)

• Choke (or inductor) For conductive interference Provides high reactance to AC Placed in series with power

wires

• Types of RF chokes In-Line Snap-On Ferrite Data-Line

• Choke (or inductor) For conductive interference Provides high reactance to AC Placed in series with power

wires

• Types of RF chokes In-Line Snap-On Ferrite Data-Line

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StepsSteps

• Ground metal case

• Shield (and ground shield)

• Bypass DC leads

• Bypass and shunt DC leads• Add choke (in series with DC leads)

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TV Conductive Interference

TV Conductive Interference

• Turn AC outlet “Off”

• Install 0.01 µF (micro farad) disc ceramic capacitor across hot and neutral terminals Keep leads as short as possible

• Install snap-on choke in power cord 5 turns, left to right, on one side or core Followed by 5 turns, left to right, on other

side

• Turn AC outlet “Off”

• Install 0.01 µF (micro farad) disc ceramic capacitor across hot and neutral terminals Keep leads as short as possible

• Install snap-on choke in power cord 5 turns, left to right, on one side or core Followed by 5 turns, left to right, on other

side

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Summary - InterferenceSummary - Interference

• Locating source By its sound What is different? What is on? By use of “sniffer”

• Interference suppression (at source of interference) Equipment repair Specific at equipment Shielding of equipment

• Locating source By its sound What is different? What is on? By use of “sniffer”

• Interference suppression (at source of interference) Equipment repair Specific at equipment Shielding of equipment

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• New electronics and appliances should be FCC and/or CE Type Approved

• Mitigation Techniques (at interfered-with equipment) Shielding Filtering

• New electronics and appliances should be FCC and/or CE Type Approved

• Mitigation Techniques (at interfered-with equipment) Shielding Filtering

Summary – Interference - 2

Summary – Interference - 2