mod4

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Module 4

H line Progressive Scan Video Circuit

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ContentsOverview ............................................................................................................................ 3Video Switching ................................................................................................................. 5S-video Signal Path ........................................................................................................... 5Composite Signal Path ..................................................................................................... 5Colorstream and DTV Inputs .......................................................................................... 8Signal Path for NTSC (480I) ........................................................................................... 9Signal Path for 1080I and 480P ...................................................................................... 9Q501 Pin Descriptions .................................................................................................... 11Auto Sync Detect ............................................................................................................ 16

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Overview

The block diagram in Figure 1 shows the basicvideo processing stages for Toshiba’s HDTVready, progressively scanned televisions. The typeof input signal determines the video stage to whichthe signal is applied. The input signal may bypassone or more video stages. For example, the RFsignal is processed by all the video stages, whereasthe Colorstream input (R-Y, B-Y, and Y) bypassesmost video stages.

Tuner and IF Stage

Referred to as the “front end,” the Tuner and IFblock comprise the first video stage. This stagereceives an RF signal and demodulates it into acomposite video signal.

Comb Filter Stage

The second stage is the comb filter. It separatesthe composite video signal into a chrominance anda luminance signal. The chrominance signal con-tains the picture’s color information. The lumi-nance signal contains the detail (or black and white)information.

Color Demodulator Stage

After the comb filter separation, the color demodu-lator dismantles the chrominance signal into R-Yand B-Y signals. The luminance signal passesthrough this stage unchanged.

WAC

The Wide Aspect Converter (WAC) is only on theTheaterwide (16:9) televisions. It converts a videosignal with a 4:3 aspect ratio to fit a 16:9 aspectratio television. When viewing a 480I signal inthe Standard picture size, the WAC adds mattes tothe picture. The mattes are gray side panels thatfill in the 16:9 screen to keep the picture’s integ-rity. If the customer selects either the Full orTheaterwide picture size, the video signal passesthrough the WAC stage unchanged.

PIP/POP Stage

The Picture in Picture (PIP for 4:3 televisions)and Picture Out of Picture (POP for 16:9 televi-sions) add a secondary picture onto the main pic-ture. These features allow the viewer to displaytwo picture sources at the same time. Refer to thespecific owner’s manual for feature explanationsand operation details.

Up-converter Stage

The Up-converter doubles the horizontal frequencyand converts a 480 interlaced (480I) format to a480 progressive format (480P). Toshiba’s HDTV-ready televisions display either a 480P or 1080Ivideo format. The Up-converter changes the NTSC(480I) signal to the 480P format for display. Anexternal source must convert all other formats toeither 1080I or 480P before they can be applied tothe television.

(480I and 480P are also referred to as 525I and525P. 480 is the number of active scanning lines,or lines containing video information. 525 is thetotal number scanning lines).

Video Processing and Color Matrix Stage

The next video processing stage is composed ofthe video processing block and color matrix. Thevideo processing block applies all the customerand service controls to the video signal; i.e. color,tint, R-cut, B-cut, etc. The color matrix combinesthe luminance, R-Y, and B-Y to develop RGB sig-nals that, with the luminance signal, are applied tothe CRTs for display. This stage also adds the OnScreen Display (OSD) and Closed Captioning (CC)information to the video signal.

Troubleshooting Tip:

With any video problem, check all inputs beforetroubleshooting. This test saves time by narrow-ing a symptom to a specific video stage.

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Figure 1. Video Processing Block Diagram

The following is a list of external inputs and the type of signals they accept:

Video 1: Composite and S-videoVideo 2: Composite and S-videoVideo 3: Composite and S-videoColorstream: R-Y, B-Y and Y, either 1080I or 480PDVD: R-Y, B-Y and Y, either 1080I or 480PAnt 1: RFAnt 2: RF

Tunerand IF

CombFilter

ColorDemodulator

Up-Converter

VideoProcessor

andColor Matrix

Com

posi

te V

ideo

C (

Chr

oma)

Y (

Lum

inan

ce)

R-Y

, B-Y

and

Y

Composite S Video

ColorStreamor DTV

(1080I or 480P)

1080

I or

480P

R-Y

, B-Y

and

Y

ColorStreamor DTV(480I)

R,G

,B

R,B,GCRTs

Type of Signals:

Direct Inputs:No Direct

Input

RF

POP/PIPWAC

OS

D/C

C

Sec

onda

ryP

ictu

re in

fo.

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Video Switching

To understand the video switching circuitry, thefollowing explanations divide the video switch-ing into two parts. The first explanation is for theComposite and S-video switching. The secondexplains the DTV and Colorstream inputs.

S-video Signal Path

Figures 2 and 3 show the basic operation of thevideo switch IC, QV01. Using the Video 1 inputas an example, these diagrams demonstrate QV01’soperation. All other inputs operate in the samemanner but are represented by a common input la-beled “Other.”

Figure 2 displays the signal flow for the S-video(Y and C) input. The Y and C signals enter QV01on pins 11 and 9. Internal switch SW1 selects theproper Y and C outputs. Pins 44 and 42 of QV01apply the signals to the video processing IC, Q501.An internal adder combines the Y and C signalsinto a composite signal. Switch SW2 selects thecomposite video signal and applies it to pin 46.The television uses this composite signal as themonitor out, located on the back panel, and as async source for the sync circuits.

Composite Video SignalY &C Video Signal

Video 1Compositeand S-Video

48 Yin

46

40 Cin

26SDA1

27SCL1

C out

Y out

UY01 Comb Filter

DG

DD

DC

Monitor Out& Sync Circuit

D/AConverter

V in

11C

9Y

44

42

Y

C

E1

QV01A/V Switch

SW1

SW2

Other V Inputs

Other Y&C Inputs

V out

To Q501Color Demodulator

7

S-Video Switch

VTo D/A

S-video 0VComposite 5V

Adder

Composite Signal Path

The final output of QV01 must be a luminance (Y)and a chrominance (C) signal. If the Video 1 inputis a composite signal, the comb filter must sepa-rate it into Y and C signals. As shown in Figure 3,the composite video signal from the Video 1 inputenters QV01 on pin 7. SW2 selects the input andapplies it to the comb filter through pin 46. Thissignal is also used for the monitor out and synccircuit. The comb filter located on the Dual PCseparates the composite signal into Y and C sig-nals and reapplies them to pins 40 and 48 of QV01.Then, SW1 selects these signals as the source andapplies them to pins 44 and 42.


The Comb Through (DH) pin of the Dual PC(UY01) is a 3.58 MHz clock synchronized by thecolor burst. If this signal is missing, the combfilter does not operate properly. When trouble-shooting the comb filter, check all inputs into UY01including the clock on pin DH. Refer to the ser-vice manual for pin layouts and the circuit dia-gram.

Figure 2.

Basic Composite Switch Block Diagram

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Composite Video SignalY &C Video Signal

Video 1Compositeand S-Video

48 Yin

46

40 Cin

26SDA1

27SCL1

C out

Y out

UY01 Comb Filter

DG

DD

DC

Monitor Out& Sync Circuit

D/AConverter

V in

11C

9Y

44

42

Y

C

E1

QV01A/V Switch

SW1

SW2

Other V Inputs

Other Y&C Inputs

V out

To Q501Color Demodulator

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S-Video Switch

VTo D/A

S-video 0VComposite 5V

Adder

A switch inside the S-video input jack detects thepresence of an S-video cable. The switch placesa logic HIGH or LOW on the composite input ofQV01. QV01’s internal D/A converter reads andtransmits the logic level to the microprocessorthrough the I2C bus. The switch default is openwhich indicates the use of a composite input. Whenthe S-video cable is connected, the switch closesand places a logic LOW on the composite input.Microprocessor QA01 controls QV01’s internalswitches through the I2C bus (on pins 27 and 26)and selects the proper signal path for the type ofsignal used.

Figure 4 is the internal schematic for the compos-ite and S-video switching IC, QV01.

The picture out of picture/picture in picture (P0P/PIP) source switching operates in the same man-ner as the main picture. However, the compositesignal separated into luminance and chrominanceby a comb filter is not reapplied to QV01. Rather,the POP/PIP module (not shown) separates thecomposite video signal and selects between theseparated composite signal and the S-video sig-nal.

Figure 3.

Basic S-video Switch Block Diagram

L = Left AudioR = Right AudioV = Composite VideoC = Chrominance SignalL = Luminance SignalE1 = Video 1 Input

E2 = Video 2 InputE3 = Video 3 InputDVD = Colorstream InputDTV = Digital TV InputSDA = Serial DataSCL = Serial Clock

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Figure 4.

Internal Diagram of QV01

POP/PIP Source Switch

SL1

SR1

SC2

SC1

SY2

SY1

SE2

SE1

ST2

ST1

6dB AMP

6dB AMP

6dB AMP

6dB AMP

D/A

SV1 6dB AMP

SOY1

SOC1

SOY2

SOC2

I 2 C D/A

Converter

Mute

SV2

6dB AMP

46 V out to comb filter

48 Y in from comb filter

40 C in from comb filter

42 Final C output

49 Final Y output

C outputfor PIP/POP

V or Y outputfor PIP/POP

47 ClampClamp

36 PIP V out

47 ClampClamp

39 SPK-OUT R

41 SPK-OUT L

43 MAIN-OUT R

45 MAIN-OUT L

V E1 7

V E2 13

V E3 19

Y E1 9

Y E2 15

Y E3 21

C E1 11

C E2 17

C E3 23

V TV1 5

Y DVD 50

V PIP 2

R TV1 6

R DVD 49

R DTV 3

R E1 10

R E2 16

R E3 22

L TV1 4

L DVD 51

L DTV 1

L E1 8

L E2 14

L E3 20

26 SDA

27 SCL

25 Mute

D/A

D/A

18 Vcc

12 GN

D 1

24 GN

D 2

34

32

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Colorstream and DTV Inputs

Figure 5 shows the Colorstream (DVD) and DTV input signal paths. Figure 6 shows the logic commands forthe switching ICs. The Colorstream and DTV inputs apply R-Y, B-Y, and Y signals to two switching ICs:QV30 and QV07. QV30 selects either DVD or DTV for the 1080I or 480P signal path. QV07 selects theinput for the 480I (Standard NTSC) signal path.

YCrCb

DVD

YPbPr

DTV

Converter

Q501

YCrCb

YCrCb

YPbPr

QV07Switch

YCrCb

QV30Switch

YQI

YQI

YCrCb

QW01Switch

YQI

YQI

YCrCb

Q2201Switch

YPbPr

YCrCb

9141

81611

635

2, 7, 12

1331

1225

14415

H

L

YQI

4

56

YC

1513

1225

1331

14154

9141

81611

63

5

YQI

YQI

WAC

654

PW01A PW02A

YQI

YQI

Dual

P505 P504YQI

YQI

UPConverter

PX01A PX02A

576

Y05Y04Y06

312

139

11

282426

2, 7, 12

9, 10, 11

9, 10, 11

From Pin 6QA03

From Pin 5QA03

From Pin 5QA03

H

L

H

L

H

L

From Pin 4QA03

To Q501 Video Processing

(Composite / S-video)

(480I)

(480P or 1080I)

(Up-converted 480I)

From QV01

Figure 5.

Video Signal Path

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Signal Path for NTSC (480I)

Refer to Figure 5. Q501 converts the luminanceand chrominance NTSC signal from the videoswitching IC (QV01) to Y, I, and Q signals andapplies them to switching IC QW01. QW01 se-lects between the Q, Y, and I signals from Q501 orthe Colorstream and DTV (480I) inputs selectedby QV07. Then, QW01 applies its selected outputto the Wide Aspect Converter (WAC).

The WAC module is only in Theaterwide (16:9)televisions. It affixes gray side panels (mattes) toa 4:3 aspect ratio picture to fit the television’s 16:9ratio.

The next module the 480I signal passes through isthe Dual PC. This module gets its name from thefact that it has two functions. One function is acomb filter. The other function is the Picture inPicture (PIP) or Picture on Picture (POP). Theparagraphs concerning the Composite and S-videoswitching explain the purpose of the comb filterportion of the Dual Module. The PIP/POP portionis for viewing a second video source with the origi-nal picture. Theaterwide (16:9) televisions usethe POP to add a second picture to the screen. Itreduces the width of the main picture and placesthe second picture alongside the first. The PIP,used in the 4:3 televisions, places a second, smallerpicture in a corner of the main picture. Both thePIP and POP have other features related to the sec-ond picture. Refer to the television’s owner’smanual for an explanation of all the PIP/POP func-tions.

After the Dual Module, the 480I video signal goesthrough the Up-converter (UX01). This moduleconverts the 480I signal into a 480P signal. TheUp-converter doubles the horizontal frequencyfrom 15.734 kHz to 31.5 kHz, and by using frameand line doubling, doubles the number of scanninglines. Although the Up-converter doubles the hori-zontal frequency, the vertical frequency remainsthe same.


The Up converter is not repairable to componentlevel. It is a replacement module only.

Next, the 480I (now converted to 480P) signal runsthrough switching IC Q2201, which selects eitherthe up-converted 480I or the input from switchingIC QV30. Q2201 applies its output to the videoprocessing IC Q501.

The last stage the unconverted 480I signal passesthrough is Q501. Refer to the Q501 Pin Descrip-tion section for more details a block diagram ofQ501. Q501 detects whether the signal isColorstream (R-Y, R-B, and Y) or I, Q, and Y (con-verted from 480I). The IC converts either signaltype into RGB, adds the on screen display (OSD),closed-caption information and applies the set-upand customer adjustments. Q501’s RGB output isapplied directly to each CRT.

Signal Path for 1080I and 480P

The 1080I and 480P input signals bypass severalswitches and modules. QV30 selects the DTV orDVD input and applies it directly to switching ICQ2201. After passing through this switch, the 1080Ior 480P signal follows the same circuit path as theup-converted 480I signal.

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QW01Switch

To Pin 6QA03

NTSC

DVD 480IDTV 480I

To Up Converter

QV07Switch

To QV114Collector

DTV 480I

DVD 480I

To QW01

QV30Switch

To Pin 5QA03

DVD 480P1080I

DTV 480P1080I

To Q2201

QA03

DIGDTV / DVD 5

+9V

QV106

RV11410K

L

H

H

L

9, 10,11

2, 7, 12

Q2201Switch

To Pin 4QA03

DVD 480INTSCDTV 480I

DTV 480PDTV1080IDVD 480P

To Q501

H

L

2, 7, 12

WACDual

Up-converter

L

H

Up Conv.Up-conv / Direct 4

DIGDVD / NTSC 6

9, 10,11

Q3200Sync Switch

H

L

9, 10, 11To Pin 4QA03

To Q420 Deflection

Up Converter

Q3100DVD/DTVDirect inputs

SCL 14

SDA 15

QA03 Pin NumbersVideo Source 6 4 5DTV 480P X L HDTV 480I H H HDTV1080I X L HDVD 480I H H LDVD 480P X L LNTSC L H X

Figure 6.

Logic Control

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Q501 Pin Descriptions

1 CW (output) 3V This output is a 3.58MHz, 7Vpp sine wave generated by X501 and

synchronized with the color burst. The comb filter uses this signal

as a clock.

2 SCP (output) 0.9V This output is a 3.4Vpp Sand Castle Pulse comprised of the hori-

zontal equalization and the blanking pulse. This signal is a refer-

ence for placement of WAC’s side panels, and the signal clamps the

black level pedestal in the POP/PIP circuit.

3 SECAM This pin is only used in a SECAM system. It is not used with an

NTSC system.

4,5,6 Y, Q, I (output) 1-2V These pins are the Y, Q, and I outputs for the converted Y and C

input signals from pins 13 and 14. Each output signal is around .7

to 1Vpp.

7,8,9 Not used.

10 x’tal 3V Pin 10 is a 3.58MHz, 82mVpp oscillator input for the color de-

modulator. A loss of this signal causes a loss in color on the Com-

posite and S-video inputs only. Because the color on the DTV and

Colorstream inputs is already demodulated, this signal has no affect

on them.

11 APC 2.2V This is a filter and phase detect for the Automatic Picture Control.

It controls the synchronization of the color oscillator.

12 Vcc 5V Pin 12 is the 5V Vcc for the video and color portion of Q501. It

does not supply the deflection side of the IC.

13,15 2-3V Y/C Pins 13 and 14 are the luminance (Y) and chrominance (C) inputs.

The Y and C signals are converted to Y, I, and Q and sent out of

pins 4, 5, and 6.

Pin # Pin Name DC Voltage Description

12

16 V.Sep 5V Capacitor C315, connected to Pin 16, is a filter capacitor that

eliminates the horizontal sync pulses from the vertical sync.

17 HD (output) 0V The HD output signal is a 15.75KHz, 5Vpp pulse. It is the Horizon-

tal sync output for the NTSC and 480I signals. This output is not

used for the 1080I or 480P. A loss of output causes a loss of hori-

zontal sync when using the NTSC or 480I signal only.

18 Sync (output) 4.3V This sync signal is a 5Vpp negative going pulse used for the Main

and Sub tuner AFT feedback. A loss of this signal results in im-

proper tuning.

20 AFC (input) 7V The AFC is a feedback from Q350 that synchronizes the horizontal

output signal.

21 32fH 8.8V Pin 21 is the horizontal oscillator for the horizontal sync circuit. It

also is used for the vertical sync through a countdown circuit. Do

not place any test equipment on this pin.

22 9V 9V 9V supply for the horizontal deflection circuit.

24 CLP 4.9V Pin 24 is a clamping input that clamps and synchronizes the blanking

input on pin 25. This signal reduces high frequency noise and

prevents picture jumping when changing picture sources. A loss of

this signal constantly engages the blanking circuit and completely

blanks the picture and OSD.

25 BLK 0.7V The Blanking pulse input blanks the picture during vertical and

horizontal retrace. The input pulses are 65Vpp.

26,27 SDA, SCL 4.1V These lines are the I2C bus, digital communication to the Micropro-

cessor. 4.5Vpp digital pulses are present on both lines whenever

the television is ON. Without communication to the microprocessor,

the deflection circuit still operates but the video portion does not.

29,30,55 R, G, &B S/H 5V The blue and green sample and hold are filters for the red and green


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output. They reduce video noise when using the DTV or

Colorstream inputs.

31 VP(output) 4.2V This pin is the vertical sync output for the NTSC and 480I signals.

This output is not used for the 1080I or 480P. A loss of output

causes a loss of vertical sync when using the NTSC or 480I signals

only. The vertical output signal is a 59.94Hz, 5Vpp pulse.

32 Ys 0.6V Luminance input for service convergence grid and closed caption.

33,34,35 RGB 3.3 RGB inputs for convergence grid and closed caption

36 OSD Ys 0.2V Luminance input for the On Screen Display (OSD).

37,38,39 OSD RGB 3.3V RGB inputs for OSD. Theses signals are only present when the ODS

is activated.

40 9V 8.4V 9V supply input.

41,42,43 RGB Approx. 2.5V RGB Output to CRT drives

44 ABL (input) Automatic Brightness Level. This input changes DC level with the

brightness of the picture.

46 9V 8.6V 9V supply input.

47 Ym 0V This input signal creates the gray background behind the OSD. Just

like the OSD input, this signal is only present when the ODS is

activated.

48 VSM 3.3V This pin supplies pulses for the Velocity Scan Modulator. The

pulses are generated from transitions between light and dark areas

in the picture. The Velocity Scan Modulator varies the horizontal

scan to reduce the transition time and sharpen the picture.


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49 APL 3.7V Pin 49 is the Average Picture Level detect. This circuit determines

the average picture level. This is a reference for Gamma Correc-

tion, DC Restoration, and Black Level Correction that are all

performed internal to Q501.

50 Black DET 4.7V The Black Detect determines the picture black level. It differenti-

ates between black and blacker then black.

51,52,53 Y2, Q, I 4.7-6V The final I, Q, and Y input. All video sources enter Q501 at these

pins. Q501 Adds the OSD, CC, and Convergence grids to the signal

and converts it to RGB. Pin 41, 42, and 43 send the end result to

the CRT drive PCs.

54 COL 6V Color limiter and Peak Hold. This pin is a clamp that sets the

maximum color level to prevent over saturation.

55 8.6 9V supply input


15

17

H. V.SYNC SEP

16

20

PHASE DET<APC-1>

21

32 FH VCO

25

H. BLK

24

V.COUNT DOWN

V.P. OUT 31

SYNCOUT 18

27

D/ACONVERTER

REGISTER

DELAY LINE S WDELAY LINE

I2C BUSDECODER

26

28

4

GAMMACORRECTION

BLACKLEVEL COR.

BLACKSTRETCH

Y. CLAMP 53

50

49

48

D.C.RESTORE

A.P.L. DET BLACKPEAK DET

WHITEPEAK DET

SHARPNESSDELAY LINE HPF VM AMP VM MUTE

SHARPNESSCONTROL NR AMP SUB CONT UNI COLOR

5WPS HALF TONE CLAMP

6

33

34

35

36

37

38

39

32

44

RGB BRIGHT

CLAMP CONTRAST

YS SW

CLAMP OSD AMP

YS SW

RGBMATRIX

S WPEAK

ACL DET ABL AMP

DRIVE CLAMP BLK

RGB OUTCUT OFF

41 42 4347

POWER OFF INYM SW

2

S.C.P.OUTCW OUT

1

54

52

51

HI BRIGHTCOLOR

COLORPEAK DET

CDE COLORGAMMA

IQ/UVCLAMP

FRESHCOLOR

IQ UVCONVERT

S W

UNI COLOR COLOR TINT DELAYLINE

AXISG-Y MATRIX CLAMP

HALFTONE

8

9

10

11

FILTERAUTO ADJ

L.P.F.FSC TRAP

CHROMAVCO

C WMATRIX

CHROMADEMOD.

CHROMABLK

P/N IDENTDETAPC DET

ACC DETSUB

COLOR

13

ACC AMP SW

SW

SW

BPF

Fsc TRAPDELAYLINE

SYNC CHIPCLAMP15

V.SYNC SEP

V. SEPH.

COUNT DOWN

Y

30HD OUT

RGB S/H

29 30 55

Figure 7

Internal Block Diagram of Q501

.

16

Auto Sync Detect

The television detects the type of signal applied tothe DTV and Colorstream input. The informationis relayed to the Microprocessor, QA01. In turn,the microprocessor automatically makes the propervideo switching to accommodate the signal throughQA03. Figure 6 shows the logic switching ofQA03.

When using a 1080I signal, the horizontal circuitmust be changed to accommodate the change inhorizontal frequency. To detect the type of signalbeing used, the luminance output of QV30 is ap-

Figure 8

Sync Detection

Q3100

Q2300F/V Converter

Q2301

Q2303

Q2302

8

7

31614

HD Out

SyncSeparator

Buffer/Inverter

Amp.

Amp.

Frequency to

Voltage converter

To MicroprocessorPin 14 31/15

YCrCb

DVD

YPbPr

DTV YCrCb

QV30Switch

YPbPr

YCrCb

9141

81611

635

2, 7, 12To Pin 5QA03

H

L

4

480P = 2.3V480I = 0V

1080I = 4.4V

To Q220

9V

plied to sync separator Q3100. Q3100 passes thehorizontal sync (HD) to the frequency to voltageconverter Q2300. The output of Q2300 is appliedto buffer and amplifier circuit Q2300. Q2300 con-trols switching transistors Q2302 and Q2303.Using a voltage divider, the transistors determinethe voltage applied to the Microprocessor QA01.The value of the voltage applied to QA01 indi-cates the type of input signal. The Microproces-sor controls the input/output expander, QA02,which makes the proper changes to the horizontaland video switch circuits for displaying the inputsignal. If the DTV or Colorstream input is not inuse, the microprocessor defaults to 480I.

mod4

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