dtv01_high definition tv

8/8/2019 Dtv01_High Definition TV

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S Training Manual

Circuit Description and Troubleshooting

Course: DTV-01

High DefinitionTelevision


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Introduction 1

HDTV Transmission Stream 3

Introduction to MPEG-2 Compression 9

Model KW-34HD1 - Normal Operation 19

Inputs 21

Overall Block 25

SIGNAL PROCESS

Video Block 1 29

Video Process A 31Video Process B 33

Video Block 2 35

Digital Realty Creation 37

MID - Multi Image Driver 41

Table of Contents

Video Process C 43

Video Block 3 45Video Process D 47

On Screen Display 49

Video Process E 51

Screen Voltage Control 53

POWER SUPPLY

Power Supply Block 55

Standby Power 53Converter 2 61

Overall Protection Block 67

D Board Protection Block 71

Protection Circuit 1 73

Protection Circuit 2 75

Protection Circuit 3 77Protection Circuit 4 81

DEFLECTION

Vertical Deflection 85

Horizontal Deflection Block 89

Horizontal Drive 91

Horizontal Driver 93

Horizontal Output PWM 1 97

Horizontal Output PWM 2 101

Pincushion Correction 105

Picture Tilt Circuit 109

Dynamic Focus Block 113


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Dynamic Focus 1 - B+ Mfg. 117

Dynamic Focus 2 - Location 121

Dynamic Quadrapole Focus 125

Appendix

Set-Back Box i

Picture Size Modes iii

Board Replacement iv

Service Mode Display vi


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1

Introduction

TV Transmission Formats

Standard Definition/High Definition

Picture resolution is commonly measured in pixels or lines. The numberof pixels is the number of black to white brightness changes possible onthe screen first in a horizontal, then in a vertical row (e.g. 960x480). CRTmanufacturing tolerances limits the number of pixels possible. This is acommon resolution specification in a computer monitor CRT.

In a TV broadcast, the studio camera is the limitation to higher resolution.The picture scanned by the camera is segmented by pixels similar to theviewers CRT. The greater the number of pixels in the horizontal and ver-tical row, the greater the resolution. This will be the current resolutionlimitation as the USA makes the transition toward high definition digital TV.

In a TV transmission, the ability of a signal voltage to quickly change fromlow to high and to produce a dark to white transition is comparable to apixel. This is not a limitation in the transmission format, but the number oflines transmitted is and is used as a resolution measurement in transmis-sions. The number of lines transmitted in the current USA NTSC format is525. This is considered a standard definition (SD) transmission.

A standard definition (SD) transmission of 525 lines can be transmitted inthe analog or digital mode. A higher definition (HD) transmission can betransmitted only in the digital (DTV) mode.

SDTV or SD Standard definition is the current 525 lines of resolution

transmitted, but only 480 of those lines are viewable. SD can be sentas an NTSC analog or digital (DTV) transmission.

HDTV or HD A high-definition transmission contains 720 or morehorizontal lines. HD is transmitted only in a digital format.

DTV A digital TV transmission refers only to the digital encoding ofthe picture signal that may contain either a high (HD) or low (SD) reso-lution picture. The digital picture is not viewable on an analog TV with-out a decoder box.

Digital Transmission Formats

There are 18 approved digital transmission formats. The first six offer HDsignals in a 16x9 aspect ratio. The remaining 12 formats are SD signalsin progressive (p) or interlaced (i) scan. Although not high resolution, theyoffer significant improvements over the NTSC analog signal.

18 Digital Transmission FormatsResolution Aspect

RatioFrames Resolution Aspect

RatioFrames

1. 1920x1080 16:9 30 i 10. 704x 480 16:9 24 p

2. 16:9 30 p 11. 4:3 60 p

3. 16:9 24 p 12. 4:3 30 i

4. 1280x 720 16:9 60 p 13. 4:3 30 p

5. 16:9 30 p 14. 4:3 24 p

6. 16:9 24 p 15. 640x 480 4:3 60 p

7. 704x 480 16:9 60 p 16. 4:3 30 i

8. 16:9 30 i 17. 4:3 30 p

9. 16:9 30 p 18. 4:3 24 p

A standard definition transmission permits space for another digital videostream to coexist on the same frequency (channel). Consequently a sta-tion can have more than one program stream on a digital channel. Themaximum number is not known at this time.


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2

How to use this book for servicing

When encountering this TV set for servicing there are several things youneed to know. Below is a list of the necessary servicing items and whereto locate them:

Servicing Needs

Information Location

1. Hookup / Operation / NormalOperation

First document in this trainingmanual (Normal Operation)

2. External HDTV set-back boxindicator lights

Appendix

3. Location of power handling partsand fuses

Service manual / visualinspection of heat sinks

4. Standby light indication message &board determination

Service manual andProtection Block document

5. Shutdown troubleshooting plan Protect Circuitry 3 & 46. Power Supply, Deflection, Video

Selection and Signal Flow CircuitryCircuitry in this training book.

See table of contents.

7. Focus Circuitry Circuitry in this training book

8. Dynamic Convergence adjustments Service manual page 27(same as in training manualsupplement)

9. Adjustments after tube replacement Notes on using the servicemode follow this chart.

A list of register names are inthe service manual.

Training manual supplement

Service Mode Adjustment Notes

Because of this TVs complexity, the following precautions should be notedwhile making service adjustments for convergence, video level, size, andwhite balance or positioning:

1. The numerous service mode registers are usually grouped by ICs for

easy access. Use the remotes #2 and #5 button to change IC groups.Then you can move from register to register with the #1 and #4 but-tons.

2. Each register that controls the pictures size, deflection and position(on pages 45-47 of the service manual) has seven sets of adjustmentdata, one for each of the seven picture size modes. These settings donot interact. Enter the service mode, adjust the TV during that picturesize, and store it.

Seven Picture Size Modes

NTSC or SD DTV HDTV

1. Normal 4:3aspect ratio

4. Wide Zoom 6. HDTV Full

2. Full 16:9 aspectratio

3. Zoom

5. Caption

(Top & bottom pixcompressed)

7. HDTV Twin View

1. Some registers are duplicated under different groups for ease of ad-justments. These duplicated registers have the same name. Chang-ing the register data at one location causes the data to change at theother location as well.

2. Save adjustments often. Changing registers will hold the new data,but changing picture sizes (zoom, full, caption, etc) will instantly loseany unsaved data that was just held.

3. There are separate contrast, color level, and hue adjustments for: The main picture The HDTV picture Each twin view pictureThey are adjusted for equal levels as you switch modes. This is sothe picture is not brighter in one mode than another.


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3

HDTV Transmission Data Stream

Transmission Block

The National Television Systems Committee (NTSC) was a group thatcreated the analog TV standard. The purpose of the Advanced Televi-

sion Systems Committee (ATSC) is to similarly set the digital TV stan-dard. The primary objective was to create a transport stream in a trans-mission scheme that would fit in the current 6 MHz bandwidth channel.For expansion and versatility, space in the transport stream was made foradditional service data. Using this transmission method, each station canbroadcast more than one digital program simultaneously on the same 6

MHz channel by compromising picture resolution.

In order to understand how a digital picture quality signal is sent within the6 MHz bandwidth, the block diagram of the transmission scheme is neededfirst, to explain the structure. The HDTV Transmission Block consists oftwo parts. The Transport Packet Generation part multiplexes the com-pressed video, audio, and additional digital data into a single stream. TheVSB Transmission part scrambles the data to reduce recovery errors,groups the data, adds sync data, and transmits the information.

The Transport Packet Generation

When both video and audio analog signals are converted to a digital for-mat, a huge bit stream is output. Without compression, this digital signalcould not be transmitted within the 6 MHz boundary. The video bit streamreduction is accomplished using four cohesive methods within the MotionPicture Experts Group (MPEG) encoder block. Audio bit reduction is per-

formed in the Dolby developed (AC-3) encoder block.The additional services data may contain information pertaining to the TVprogram or unrelated data such as Internet or computer data. TV pro-gram related information is in a structure called Program and SystemInformation Protocol (PSIP). It contains additional sync, real time, stationID, alternate channel number display and more.

The video and audio output from the encoders is multiplexed with addi-tional services data into a single bit stream by the Data Multiplexer. Thedata output is in groups called transport packets. They are applied to theVSB Transmission part of the block.

VSB Transmission

The Vestigial Sideband Transmission part of the block takes the transportpackets from the Data Multiplexer and performs the following:

Scrambles the data Groups the data

Adds syncData scrambling

The Data Randomizer block, the Reed Solomon Encoder block and theData Interleaver block all scramble the data but in different areas.

Scrambling the data is done for reliable recovery of lost, damaged, ormissing data. Scrambling scatters the data so it is no longer in the normal1, 2 3, 4, 5, 6 linear sequence. For example the scrambled data mayhave a packet sequence that looks like this: 3, 18, 33, 11, 4, 52, 89, 7 etc.

During the transmission if a large loss of data packets 11, 4, 52 occurred,the lost pieces are not as significant as if sequential data packets 4, 5, 6

were lost. This is because at the decoder where the packets are returnedto the linear order, data packets 11, 4, & 52 are in different places. Thelarge loss actually consists of smaller losses that can be interpolated fromthe remaining adjacent data.

Groups the Data

The Trellis Encoder works with the VSB modulator to reduce transmis-sion bandwidth. The encoder takes a stream of bits and groups them into3 bit words called symbols. The purpose is to ultimately reduce the band-width by reducing the frequency.

Sync is addedSegment sync and field sync added to the transport packets in the multi-plexer. The Segment sync marks each transport packet. The field syncidentifies a group of transport packets. The multiplexers data output iscalled a VSB data frame.


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4

VIDEO

AUDIO

MP E GC OMP R E S S ION

E N C OD E R

AC-3C OMP R E S S ION

E N C OD E R

ADDITIONAL

SERVICES

D A T A

D A T AMULTIPLEXER

D A T ARANDOMIZER

R E E D

S OL OMON

E N C OD E R

D A T A

INTERLEAVER

TRELLIS

E N C OD E R

MULTIPLEXER

(VSB DATAF R A ME

CREATED)

S E GME N TSYNC

FIELD

SYNC

VS B

MOD U L A T OR

RF

UPC ON V E R T E R

HDTV TRANSMISSION BLOCK

TRANSPORT PACKET

GENERATION VSB TRANSMISSION


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5

Data Process - Transport Packet Generation

After MPEG and AC-3 compression, the audio and video data is multi-plexed with additional services data into a 188-byte transport packet. Thetransport packet is output at a 19.4Mbits/sec data rate. The packet con-sists of a link header and a payload.

Link HeaderEach packet is preceded by a link header that contains:

Sync - Identifies the beginning of the packet and a sample of a 27Mhzclock.

Continuity Counter or Error Control Numbers each packet Transport Scrambling Control - Identifies if this packet is scrambled. Packet ID (PID) Links related and marks duplicated (important) pack-

ets. Marks the location of the unscrambling packet (if any).

Payload

The payload consists of 184 Bytes of multiplexed audio, video and addi-

tional services data.

TRANSPORT PACKET GENERATION

V I D E O

A U D I O

M P E GC O M P R E S S I O N

E N C O D E R

A C -3C O M P R E S S I O N

E N C O D E R

ADDITIONALS E R V I C E S

D A T A

D A T AM U L T I P L E X E R

L I N K H E A D E R(4 BYTES)

P A Y L O A D(184 BYTES)

188 BYTES

T R A N S P O R T P A C K E T

DATA RATE19.4Mbps

DATA RATE = 188 bytes* 8bits/byte *626segments/frame * 20.66 frames/sec


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6

Data Process VSB Transmission

Data Randomizer

The construction of the VSB data frame begins at the Data Randomizer.This block scrambles only the payload data in a set pattern so it can beunscrambled at the decoder.

Reed - Solomon Decoder

This decoder scrambles the entire transport packet except for the earlysync in the link header. It adds 20 parity bytes for error correction toinsure recovery. The transport packet has been increased to 208 Bytes.

Data Interleaver

This block scrambles about 1/6 of a field of data (more than a singletransport packet) in accordance to a preset pattern.

The Data Interleaver basically adds no additional bits. 208 Bytes is out-put.

Trellis Encoder

The details of the Trellis Encoder data processing scheme will be ex-plained later. To simplify the data structure understanding for now, theTrellis encoder adds additional bytes to the process and converts theincoming stream to 3 bit words, which represent 1 of 8 different levels.These 3 bit words are termed symbols. The details of the Trellis Encoderare beyond the scope of this manual but an overview is presented later.

Multiplexer

The Multiplexer combines the symbols with segment sync to from what is

defined as a segment. Each segment contains four symbols of segmentsync plus 828 symbols of payload data. Therefore each segment con-tains the equivalent of a scrambled transport packet + sync.

312 segments represent approximately a field of digital data. The multi-plexer adds an additional field sync to the beginning of the 312 segments,making a field equal to 313 segments. Two fields equals a frame so 626segments = a complete Vestigial Sideband (VSB) data frame. This frameis sent to the VSB modulator for transmission.

The Data Structure diagram shows the VSB Frame information sent insegments. Each segment contains sync, data and overhead

DATARANDOMIZER

REEDSOLOMONENCODER

(Adds 20 Bytes)

DATAINTERLEAVER

TRELLISENCODER

MULTIPLEXER(VSB DATA

FRAMECREATED)

SEGMENTSYNC

FIELDSYNC

VSBMODULATOR

RF

UPCONVERTER

SEG

MENT

SYN

C

FIELD SYNC #1

DATA + OVERHEAD

DATA + OVERHEAD

FIELD SYNC #2

832 SYMBOLS

313SEGMENT

S

313SEGMENT

S

VSB DATA FRAME

1 SEGMENT = 77.3us

NOTE :FRAME = (77.3us * 626SEGMENTS) = 48.38msTHEREFORE, THERE

ARE 20.66 FRAMES/S

INPUT DATA RATE19.4Mbps

INPUT DATA RATE = 188 bytes* 8bits/byte * 626segments/frame * 20.66

frames/sec

188Bytes

208Bytes

OUTPUT DATA RATE32.28Mbps

or

10.76Msymbols/sec

312

Bytes/segment

VSB TRANSMISSION

OUTPUT DATARATE

32.28Mbpsor

10.76Msymbols/sec

FIELD SYNC#1

FRAME = 626 SEGMENTS

FIELD SYNC#2

F IELD = 313 SEG MENTS F IELD = 313 SEGM ENTS

S

YNC

S

YNC

DATA

&O V E R H E A D

S

YNC

DATA

&O V E R H E A D

S

YNC

DATA

&O V E R H E A D

S

YNC

DATA

&O V E R H E A D

S

YNC

828 SYMBOLS

312 BYTES = 832 SYMBOLS = SEGMENT

SYNC4 SYMBOLS

(12 BITS)

LINK HEADER(4 BYTES)

P A Y L O A D(184 BYTES)

TRANSPORT PACKET

188 BYTES

INPUT DATA RATE19.4Mbps

OUTPUT DATA RATE = 3 bits/symbol * 832Symbols/segment * 626segments/frame *

20.66 frames/sec

DATA STRUCTURE


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7

Trellis Encoding Scheme

The Trellis Encoder works with the VSB modulator in a scheme to reducebandwidth by 1/3. The encoder converts the incoming stream into 3-bitword groups. The 3 bit words are assigned in a mapping table that isdesigned to reduce transitions (bandwidth). Each 3-bit word group iscalled a symbol.

The VSB modulator converts each 3-bit symbol to a corresponding DClevel for transmission. Three bit symbols can designate up to 23 = 8 ana-log levels. For example at the modulator input of the Trellis Schemediagram, the data is 110, 111, 101, 010, 111, 000. That corresponds to aDC level of +5, +7, +3, -3, and +7, as shown at the modulator output. Byreplacing the 3-bit word with a single DC voltage, the digital informationsent to the AM transmitter is reduced by 1/3.

TRELLISE N C O D E R

VSBM O D U L A T O R

DATA STREAM INTO TRELLIS ENCODER

01001101110100100111100100101010101

DATA STREAM OUT OF TRELLIS ENCODER

000 111 001 001 011 000 111 010 101 111 110

DATA STREAM INTO ENCODERU N D E R G O E S C O N V E R T I O NUSING A MAPPING SCHEME TO 3B I T W O R D G R O U P S C A L L E DSYMBOLS. T HESE SYMBOLS AREUSED BY THE VSB MODULATOR

DATA STREAM OUT OF TRELLIS ENCODER

000 111 001 001 011 000 111 010 101 111 110

SINCE THE SYMBOLS ARE 3 BIT,THEY CAN ONLY REPRESENTONE OF 8 POSSIBLE LEVELCOMBINATIONS. THE VSB MODCONVERTS THE SYMBOLS TOLEVELS.

+7

+5+3+1-1-3-5-7

111110101100011010001000

TRELLIS SCHEME


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8

Trellis Encoder B/W Reduction Scheme

To understand how the Trellis Encoder reduces bandwidth by 1/3, anexample using the worse case highest frequency digital signal is shown.The worse case signal is a waveform that is alternating between digital 0and 1. Twelve of these alternating bits are shown, occurring in one sec-ond (data rate = 12 bits/sec). By examining this waveform you can seethat two bits is the equivalent of one cycle. Therefore the data rate of 12bits/sec is equivalent to 6 cycles/sec (Hz).

The Trellis Encoder manufactures the 3 bit symbols and the VSB modula-tor translates each symbol into a single DC level for transmission. Theworst case transmission is also when the DC level is alternating betweenlow and high. However since 3 bits is represented by a single DC levelafter the modulator, the input data rate of 12 bits/sec results in a transmis-sion of only 2 cycles/sec instead of 6 cycles/sec.

This means that a data rate of 32.28Mbps is reduced by 1/3 to 10.76Mbps using the Trellis Encoder scheme. Since two bits are the equiva-lent of one cycle, the data rate is halved to arrive at the equivalent fre-quency. Therefore the audio, video and additional services data will havea maximum frequency of to 10.76 Mbps /2 = 5.38 MHz. This is within thecurrent 6 MHz TV channel bandwidth.

TRELLIS ENCODER BW REDUCTION SCHEME

12 BITS/SEC

ONEC Y C L E

DATA RATE = 12BITS/SEC

EQUATES TO 6 CYCLES/SEC FREQUENCY

TYPICAL DATA STREAM IN A WORST CASESCENARIO WHERE DATA IS TRANSITIONINGBETWEEN 1 AND 0 ALL THE TIME AS OPPOSEDT O R A N D O M .

TRELLIS ENCODED D ATA STREAM IN A WORSTCASE SCENARIO WHERE DATA ISTRANSITIONING BETWEEN ONLY TWO LEVELS111 AND 000 ALL THE TIME AS OPPOSED TOR A N D O M .

ON EC Y C L E

DATA RATE = 12BITS/SEC

EQUATES TO 2 CYCLES/SEC FREQUENCY

NET EFFECT OF THE TRELLIS ENCODER IS

REDUCTION OF TRANSMISSION FREQ BY AFACTOR OF 3, HENCE THE 32.28Mbps DATA

RATE IS REALLY TRANSMITTED AT10.76Mhz

SPECTRAL BANDWIDTH

6 M HZ

Nyquist it ~ 10.76Mhz / 2 = 5.38 Mhz

5.38 MHZ


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9

Introduction to MPEG-2 Compression

MPEG stands for Motion Picture Experts Group, named after the com-mittee that developed the standard.

Why Compress?MPEG defines a compression scheme for Video which evolved from theneed to transmit digital video on existing communication channels withlimited bandwidth. In addition to the bandwidth issue there is an obviousstorage one as well.

Fastest Communication Channels Typical Bandwidth

ISDN Line 144Kbps

T1 Line 1.5 Mbps

T3 Line 45 Mbps

With a whopping 4.7 gigabytes of data capacity, DVD-Video would seemto have more than enough room for motion pictures. Unfortunately, digitalvideo has an incredibly voracious appetite for storage.

Raw or uncompressed Digital Video requires an enormous 252 Mega-bits/sec of bandwidth and approx 31 Mbytes per second of storage.

720x480 (Res.) X 8bits/sample X 30frames/sec X 3 Components

To understand this figure, we need to understand video in its purest form.

Component Video

In its purest form, Video is made up of 4 components.- Luminance or Y which defines the brightness level and- Color which is made up of 3 components called R-Y, B-Y and G-Y.

As it works out, we can mathematically calculate the 4 th component (G-Y) from the others. Therefore, we only require 3 components for Video(Y, R-Y and B-Y).

Y = (R-Y) + (B-Y) + (G-Y)

Each sample we take of the video is represented by an 8 bit digital wordwhich translates to 28 or 256 different levels of each component. There-fore, each pixel is made up of 3 components which can represent up to28 (Y) X 28 (R-Y) X 28 (B-Y) = 224 (commonly known as 24 bit color)or 16million colors.

R-YB-YY

One PIXEL

The resolution or picture detail we require also plays an important role inour bandwidth and storage requirement. DVD uses a 720 Horizontal by480 Vertical resolution or 720 pixels across times 480 rows or lines.

720

480

In summary we need to:- sample 3 components (Y, R-Y and B-Y) each of which is composed

of 720 x 480 (350,000) pixels.- Represent each one by an 8 bit word (3 X 350,000 X 8 =

8,400,000bits). Therefore, each frame is made up of 8,400,000bits.

- Finally, we would need to display at 30 frames per second (30 X8,400,000 =252,000,000 bits/sec or 252 Mbits/sec Bandwidth.

To calculate the storage we simply divide the Bandwidth in bits by 8 bitsper byte and we get 31.5Mbytes/sec Storage requirement.

As illustrated, the requirement is enormous which paves the way for com-pression and MPEG.


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10

Compression Process

Compression of Video is accomplished via the following process.1. Selective Sampling2. Discrete Cosine Transform (DCT)3. Predictive & Motion Encoding4. Hoffman Encoding

Selective Sampling

The number of times per second that you sample a signal is called itssampling frequency. In Audio, the sampling frequency is 44,000 samples/sec which is approx 2 times the highest frequency in Audio (20,000 Hz).In contrast, Video is sampled at 4 times the highest frequency (13.5Mhz).Hence the term 4 in the sampling structure 4:4:4 representing the sam-pling ratio of Y, R-Y and B-Y respectively.

Therefore, the same number of samples are taken of Y as they are of R-

Y and B-Y.

Time

Signal

4:2:2

Since the eye is less perceptive to color changes than to Luminance,significant reduction of data can be accomplished in the Samplingprocess if we sample the color components (R-Y and B-Y) half asmuch as the Luminance component (Y). The result is a 1/3 reductionor a bandwidth of 166Mbits/sec.Video sampled using this technique is represented by a 4:2:2 samplingstructure. Y is sampled normally with R-Y and B-Y sampled half as much.

LINE 1

LINE 2.

.

.

.

LINE 480

ONE

PIXEL Samples taken in the Horizontal direction up to 720 per Line

Non Sampled components Illustrated as clear boxes

R-Y B-YY YR-Y B-YYY

R-Y B-YY YR-Y B-YYY

4:1:1

Consequently techniques such as the 4:1:1 further reduce color sam-pling to 1/4th of the Y component and compress by or reduce band-width to 125Mbits/sec.


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11

4:2:0

DVD takes it to another level by using a modified 4:2:2 sampling struc-ture called 4:2:0. 4:2:0 samples R-Y half as much as Y and skips B-Yon the 1st line. However, on the next horizontal line, B-Y is sampled halfas much as Y and R-Y is skipped. This routine is repeated effectivelyreducing the color components by another half achieving compres-sion or a 125Mbit/sec bandwidth.Through interpolation, the 4:2:0 is reconstructed into 4:2:2 without theextra bandwidth requirement.

YB-YY

R-YYYR-YY

Y B-Y Y

LINE 1

LINE 2

LINE 3

LINE 4

.

.

.

.

LINE 480

ONE

PIXEL Samples taken in the Horizontal direction up to 720 per Line

R-YY YR-YYY

B-YY Y

Non Sampled components Illustrated as clear boxes

Y

YB-YY

Discrete Cosine Transform

After the Selective Sampling process is complete, the next step in theMPEG process is to remove very fine picture detail imperceptible to thehuman eye. It is imperceptible because it is typically masked by otherpicture content.

In a Video Frame, the very fine picture details consist of high frequencyinformation which are basically fast changing Luminance and Colorcontent. In contrast, low frequency information are slow changingLuminance and Color content.

The high frequency information consumes the most data real estate andis where we focus to compress in this next stage.

The process of eliminating the imperceptible information is called Dis-crete Cosine Transform or DCT. The sampling process converts theinformation into digital data as described previously. Each digital picture

frame is then sectioned off into 5400 blocks each consisting of 8 pixelswide X 8 pixels high.

8 X 8

Pixel

Block

Picture

Frame

1 of 5400

Blocks

DCT transforms the 8X8 group of pixel values into frequency compo-nents.

Although pixel values vary randomly in the 8X8 block, DCT re-positionslow frequency components on the upper left corner and high frequencycomponents on the lower right of the block.Through an additional numerical conversion process called Quantiza-tion, frequency component values are assigned.

High freq components are identified by the zero values (lower right) andlow freq components by the larger values (upper left).


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12

Data compression is accomplished by elimination of the high frequencycomponents designated by the zeros.

10 5 1 0 0 0 0 0

5 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

8 X 8 Pixel Block

LFreq HFref

HFref

Spacial Redundancy

Within a Frame, there are many redundant pixels. An example wouldbe a blue sky. This type of redundancy within the Horizotal and Verticalplane of a frame is called Spacial Redundancy.

One pixel could be stored with information to repeat for the remainingpixels. This would eliminate the need to store every pixel in the frame.

Frames making use of this technique are called Intra-Frames.

Temporal Redundancy

Within Video scenes, there are many redundant frames. An examplewould be an anchor person reporting the news. With the exception oflip movement, the other portions of the frame remain unchanged overtime. This type of redundancy over time is called Temporal Redun-dancy.

The first frame could be stored as the reference or non changing por-tions while remaining frames carry the lip motion information. This wouldeliminate the need to store several full frames.

Frames using Temporal redundancy which predict information based onpreceding frames are called Inter-Frames or Motion predicted Images.

Predictive & Motion Encoding

The next step in the MPEG process is termed Predictive & Motion

Encoding and it takes advantage of both Spacial and Temporal redun-dancy to achieve compression.

I-Pictures

To begin the process of using Spacial and Temporal redundancy tech-niques in compression, we need a reference or a start frame which doesnot depend on previous or preceding frames.

This start frame would make use of Spacial redundancy within itself andis termed an I picture.

I pictures are Intra-Frames and have zero dependency on previous orpreceding frames. They do however provide information to precedingframes.

The other pictures types used by MPEG are called P-Pictures (Predic-tive) and B-Pictures (Bi-Directional).

I Pictures carry the most amount of data content. They are 3 times thesize of a P-Picture and 5 to 6 times the size of a B-Picture.


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13

P-Pictures

The P-Pictures are Predictive Encoded Images also known as Inter-Frames.

As the name indicates, a P-Picture is a predicted Image based onprevious I or P-Picture. The P-Picture is dependent on past Images toexist.

I or P

Picture

P-PicturePredicted

by looking

back at

previous

I or P PicInformation

passed togenerate

P Picture

B-Pictures

The B-Pictures have Bi-directional dependency and are called Bi-Directional Predicted Images.

The B-Picture is also a predicted Image but it is based on prior I or PPictures and preceding P-Pictures.

B-Pictures are typically made up of motion information and carry theleast amount of data.

I or P

PictureB-Pictures

Predicted

by looking

back atpreviousI or P Pic

And

FutureP Picture

P Picture


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14

I, P and B picture generation process

To clearly understand the relationship between the I, P and B pictureswe need to understand how they are generated.

1. The start of an entirely new scene would require an I-Picture or a

reference for other pictures to follow until the next I-Picture.- The information between the I-Picture and the next reference I-

Picture is called a GOP (Group of Pictures) which consist of one Iand many P and B Pictures.

- I-Pictures typically re-occur at 15 picture intervals.1. Next, the first P-Pictures in the GOP is generated based on the I-

Picture.2. In between the I and first P-picture, several B-Pictures are gener-

ated as necessary to convey motion information from the I to thefirst P-Picture. For this reason B-Pictures are dependent on past

and future pictures.3. Then the process repeats with the generation of second P-Picture

which is now based on the first P-picture. And so on

I

B

B

P

B

B

P

GOP

Time

I

Hoffman Encoding

The last step in the MPEG process uses a statistical approach to com-press the data further.The last process is called Hoffman Encoding. Basically, this processtakes a look at the string of MPEG data and replaces it with information

which allows regeneration.The best example is a string of eight 1s {11111111} replaced by {1x8}which represents; repeat the 1 eight times.


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MPEG II vs- MPEG I

The MPEG process described is common to both MPEG II and MPEG Ithus, explaining the backward compatibility between the two.

The main differences between MPEG II and I are:

- MPEG II used in DVD uses a 720 x 480 resolution while MPEG Iused in VIDEO CDs carries a resolution of 350 x 240. This differ-ence alone accounts for a 75% reduction in data using MPEG I overMPEG II.

- MPEG II compresses data to about 1/40 on average while MPEG Icompresses data to about 1/140 on average. Therefore 250Mbit/sare reduced to 6.25Mbits/s on average using MPEG II.

- MPEG II uses a variable rate compression while MPEG I uses afixed rate.

350 x 240 = 84,000 pixels720 x 480 = 350,000 pixelsMPEG I represents84,000/350,000 = 25% of MPEG II.

MPEG II additional information

MPEG II is a broad standard which encompasses many resolutionsincluding HDTV. These variations in MPEG II are defined by Levels andProfiles.

DVD is just one of the many profiles and levels defined by MPEG IIcalled Main Profile at Main Level ( MP@ML).


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The Bit Rate Fluctuates

For DVD, variable bit rate is a tremendous advantage. If the bit rate werefixed, it could not accommodate the changing needs of video scenes.Consider the fast-paced action of a football player, running for a touch-down as the camera pans past the crowd. Full of motion, this is an ex-tremely demanding scene, one that requires the bit rate to be very high.

Now picture the same football player after the game, sitting in a restau-rant, talking to his girlfriend. Almost nothing in the scene moves, so the bitrate can be quite low.

If DVD used a fixed bit rate, the system might fall short on the footballscene. And it would definitely be wasting bits on the restaurant scene.DVD-Video accommodates both scenes by varying the bit rate. In fact,the maximum bit rate is 9.8 megabits per second which is nearly threetimes as high as the average rate.

If DVD used a fixed rate, it would have to be at least 7 Mbps to maintainpicture quality! At that rate, total recording time would be cut in half. Sothe goal of capturing a full-length movie on a 3-3/4-inch disc could not berealized. Variable bit rate is one of the key technologies that makes DVDpossible.

By the way, Video CD uses MPEG-1 to yield a fixed bit rate of 1.15 Mbps.The fixed rate and low number translate into the vast quality differencebetween DVD-Video and Video CD.


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24 Frames-per-Second Storage

In video, what appears to be a continuously moving image is actually aseries of discrete still pictures, called frames. Every video frame consistsof two interlaced fields, each of which contains half the frames scanninglines. A U.S.-standard video picture runs at roughly 30 frames per sec-

ond. In contrast, movie file operates at 24 frames per second. So themovies you see on television, cable or videocassette have all had theirframe rates converted by a special machine called a telecine.

The telecine converts the 24 film frames into video fields. However, videorequires 30 frames or 60 fields and Film is 24. Telecine performs thisprocess by converting 12 film frames to 24 fields (2 Fields/Film Frame)and another 12 film frames to 36 fields (3 Fields/Film Frame). It is keptseamless by converting one Film Frame to 2 Fields and the next one to 3.This cycle is repeated 2, 3, 2, 3 until the 60 fields have been completed.This Telecine process is called 2-3 Pull Down.

To achieve maximum recording time, the DVD-Video disc is actually mas-tered in the original 24 film frame format. This reduces the video bit rateby 20%, even before MPEG-2 encoding. During playback, the DVD-Videoplayer performs the 2-3 pull down function to generate a standard 30 framesper second video output.


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NOTES


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Model KW-34HD1 - Normal Operation

These are normal operating conditions for Sonys first high Definition TV during power on/off and input selection conditions.

When this TV is ON there is no static electricity felt at the CRT screen.It is normal to have black left & right borders on both sides of the picture when viewing a 4:3 aspect ratio picture on a 16x9 aspect ratio TV picture tube.

Power ONOperation Initial Step Sounds Visual Conditions

Plug in AC connection Nothing Nothing Front panel Master power button off

Power ON

A

Master power ON

button pressed

1. 2 Relays click immediately2. Degaussing coil energized

(humming sound)

3. TV audio 1 sec after relays click

1. Front panel Standby light:2. Blinking after relay click3. Stops blinking in about 7 seconds when the picture

appears.

4. OSD: Yellow characters Please check DTVreceiver connections

AC connected.

Set formerly OFF (by remote).

1.3 Amps @120Vac

Power ON

B

Power ON in

remote pressed

1. 2 Relays click immediately2. Degaussing coil energized

(humming sound)

3. TV audio 1 sec after relays click

1. Front panel Standby light:2. Standby light starts blinking after relay click3. Stops blinking in 7 seconds when the picture

appears.

4. OSD reads in Yellow characters Please checkDTV receiver connections.

AC connected.

Master power button ON

Standby light ON

TV OFF

1.3 Amps @120Vac

TV OFF

A

Master Power

OFF pressed

2 relays clicks

TV sound mutes

Picture goes dark

All lights out

TV OFF

B

Remote power

OFF pressed

2 relays clicks

TV sound mutes

Picture goes dark

Standby light comes ON

TV Operation with NO Inputs connectedSelection Access Step Sounds Visual Conditions

Video input Press TV/Video button

until video 1, 2, or 3appear on the screen

No sound when there is

no video input.

Video 1, 2, or 3 appears in green letters at the upper left corner of the screen.

Screen is dark with no v ideo input.

Power ON

No inputs

DVD, HD, input or

High Definition TV input

from external box

Press TV/Video button

until DVD or HD input

is selected.

No sound when there isno input.

DVD or HD appears in green letters at the upper left corner of the screen.Screen is dark with no i nput.

Power ONNo inputs

VHF / UHF input Press the TV button on

the remote

Off the air white noise

from the unconnected

VHF/UHF input.

OSD station number appears in green at the upper right corner of the screen

with snow. TV channels can be entered by remote or the up/down buttons

will work if stations were programmed during set up.

Power ON

No inputs

Cable Input Press the TV button on

the remote

Off the air white noise

from the unconnected

cable input.

OSD C _ appears in green at the upper right corner of the screen with

snow. Cable channels can be entered by remote or the up/down buttons will

work if cable stations were programmed during set up.

Power ON

No inputs


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Input SelectionInput Connections Programming Steps Results

VHF / UHF VHF / UHF antenna to rear panel VHF /

UHF F type connector.

1. Power ON.2. Use the remote TV/Video button to select TV.3. The remote ANT button toggles between VHF / UHF

and cable. Select VHF / UHF (channel number

without a C prefix).

4. From the 4rd

Menu icon, select & enter AutoProgram: VHF / UHF.

5. Use Channel Up/Dwn to change stations for normaloperation.

1. See previous Power ON chart.2. Snow or a TV station with a channel

number will appear if you are correctly in

the TV mode.

3. Correct VHF / UHF channels will be

numbered 2-69. Cable channels arepreceded with a letter C like C78.

4. It takes almost 1 min. to scan through allthe VHF / UHF stations. At the end it will

select the lowest active VHF station.

Ca ble Connec t c able feed to rear pa nel Ca ble F typeconnector.

1. Power ON.2. Use the remote TV/Video button to select TV.3. The remote ANT button toggles between VHF / UHF

and cable. Cable station numbers are preceded with a

letter C. Select a C prefix station like C4.

4. From the 4rd

Menu icon, select & enter Auto

Program: Cable.5. Use Channel Up/Dwn to change stations for normal

operation.

1. See previous Power ON chart.2. Snow or a TV station with a channel

number will appear if you are correctly in

the TV mode.

3. Correct Cable channels will be displayedas C1 to C125.

4. It takes about 1 min. to scan through all thecable stations. At the end it will select the

lowest number active cable station.

High Definition

TV

Connect an UHF antenna to the DTV Receiver

(external set-back box) and the receiver to therear of the TV using the supplied multi-pin I/O

cable.

1. Power ON.

2. Use the remote TV/Video button to select TV.3. The remote ANT button toggles between VHF / UHF

and cable. Select VHF / UHF (without a C prefix).

4. From the 4rd

Menu icon, select & enter Auto

Program: VHF / UHF. This tells the set-back box

to auto program DTV stations too. (DTV Auto Add

is only used to add DTV stations after one was

found.).

5. Use Channel Up/Dwn to change stations for HDTVreception.

1. See previous Power ON chart.

2. Snow or a TV station with a channelnumber will appear if you are correctly in

the TV mode.

3. Correct VHF / UHF channels will benumbered 2-69. Cable channels are

preceded with a letter C like C78.

4. It takes about 1 min. to scan through all theVHF/UHF stations. At the end it will select

the lowest number active station.

DVD, Video 1-

3, or HD

Connect the video and audio cables of the

DVD, VCR, game, or camcorder to the rear

panel phono jacks. The video 2 input is located

on the front panel.

The HD box has component video (Y, R-Y, B-

Y) outputs. They plug into the HD input(phono jacks).

1. Power ON.2. Use the remote TV/Video button to select the desired

input.

1. See previous Power ON chart.2. The OSD will show the input selected as

you press the TV/Video button. The input

sequence is: Video 1-3, DVD, HD, TV and

it repeats.


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Inputs

RF Inputs

There are three independent RF inputs which allow the user to have cable,an outdoor antenna aimed for VHF and UHF stations and another an-

tenna oriented for digital TV stations. Each RF input has a channel num-bers assigned to it:

R F C h a n n e l N u m b e r A s s ig n m e n t

In p u t C h a n n e l N u m b e rs

C a b le 1 -1 2 5

V H F / U H F 2 -1 3 / 1 4 -6 9

D T V 1 -9 9

They are selected from the ANT remote control button.

Composite Video

This is a single video 1, 2, or 3 input cable that carries the combined Yand C signal. The TV/Video remote control button selects it. This com-posite signal requires the receiver to first separate the two components,usually using a comb filter. The chroma is demodulated into individualcolor components, such as RGB, before the color information can be used.These additional processing steps reduce resolution and could add noise,but composite video is a convenient method of transporting a video sig-nal.

PM3394, FLUKE & PHI LI PS

ch3

ch2

ch1

CH1! 5. 00 V~

CH2!1.00 V~ L=121

CH3! 500mV= CHP MTB10. 0us- 1. 08dv ch1p

1

2

3

This scope shot is taken of a video signal that produces a blue screen.The top waveform is composite video and contains a combined signal.The middle waveform is the chroma signal from the S video output. Itcontains the burst after the retrace blanking area. The bottom waveformis the luminance signal containing the H sync pulse below the base line.

S Video Input

The S input refers to Separate Video inputs consisting of independentluminance (Y) and chroma (C) signals and a shield wire for each. Theyare input using a 5 pin standard connector. The fifth pin serves to close aswitch in the jack that identifies the presence of the S video plug. The SVideo signal is selected instead of the composite video 1-3 when the Svideo plug is detected.

The S videos luminance signal is the pictures brightness level signal.This Y input signal also carries both of the horizontal and vertical syncpulses. The chroma signal contains the color information phase refer-enced to the burst frequency of 3.58MHz. This C input contains 8 cycles

of reference burst signal in the open retrace interval. The chroma signalrequires demodulation into individual color components such as RGBbefore the color information can be used.

Component Video

Conversion

Video can be made of four components:

Luminance or Y which defines the brightness level and Color, which is made of three components, called R-Y, B-Y and G-Y.

We can mathematically calculate the fourth component (G-Y) from theothers so only three components are required for video:

Assuming R+B+G = Y, and (R-Y)+Y = R, then (G-Y) = -R-B.

The manufacture of the G-Y signal can be performed in an electric matrixconsisting of summing op amps for adding (+) and subtractive op ampsfor the difference of the two signals (-). By adding the (inverted) signals,the last G-Y component can be derived.


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22

- VHF AND SETBACK BOX HDTV

- CABLERF (ANT)VIDEO 1

VIDEO 2VIDEO 3

DVDHD

TV/VIDEOANT

- VIDEO SETTINGS

- AUDIO SETTINGS

- VERTICAL SIZE AND CENTER- CLOSED CAPTION/VERTICAL SHIFT/TILT

MENU

TV

CABLE

VHF/UHF

ANALOG

TVINPUT

Y

PB

PR

LR

S VIDEO

VIDEO

HD

AUDIO OUTVAR/FIX

L(MONO)

R

CONTROL S IN OUT

DVD 1 3

FOR USE WITHHD (1080)

INPUT ONLY

HD

L(MONO)

AUDIO

R

DTV I/OFOR USE WITH

KW-34HD1(DTV RECEIVER)

ONLY

DTV I/OFOR USE WITH

KW-34HD1(DTV TV)

ONLY

DOLBY DIGITALOUTPUT

(OPTICAL)

VHF/UHF(DTV)DIGITAL

TV

ANTENNA

KW34HD1 REMOTE CONTROL

REAR PANEL

INPUTS

SET-BACK

BOX

HDTV44


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These simple matrixes are found in ICs frequently labeled as decoders orare part of a processor. A video processor IC can contain an additionalsimple electric matrix to convert the R-Y signals to their base Red signalvoltages by just adding the Y signal as (R-Y) + Y = R. The RGB signalsoutput can be used to drive the CRT.

R-Y resistor A R signal

Y resistor B

Identification

Component video is usually carried on three lines: Y, R-Y, & B-Y. Theycan also abbreviated differently, but are the same:

Y, U, V Y, Cr, Cb Y, Pr, Pb Y, R-Y, & B-Y.

The Y, Pr, Pb version designates the progressive instead of interlaced

picture scan format. This TV selects the DVD or HD component videoinput from the TV/Video remote button. However, the HD signal musthave a horizontal frequency of 31 to 34kHz or the screen will remain darkwith just an HD OSD.

Waveforms

The following is a scope shot of component video signals that makes up ablue screen picture. In the top waveform is the Y signal. It houses thehorizontal sync pulses (the vertical is not seen at this time base, but it ispresent in the Y signal). The line between the sync pulses represents thebrightness level. The higher the line, the brighter the picture. Therefore,

a voltage at the sync pulse level is black.The middle waveform is the B-Y signal. The area corresponding to thehorizontal sync pulse in the Y signal is at 0Vdc. The remainder of thevoltage minus the Y level is the Blue color level. Since this is a picture ofa blue screen, the voltage is high.

The bottom waveform is the R-Y signal. The area corresponding to thehorizontal sync pulse in the Y signal is also at 0Vdc. The red - Y levelduring a blue screen is below 0Vdc. It will be equal to 0Vdc if the Y signalis subtracted.


ch3

ch2

ch1

CH1! 5. 00 V~

CH2!5.00 V~ L=121

CH3! 5. 00 V= CHP MTB10. 0us- 1. 08dv ch1p

1

2

3

B l u e s c r e e n w a v e f o rm Y U V

N a m e L o c a t io n V o lta g e /d iv

C h a n n e l 1 Y D V D o u tp u t 7 .5 V p -p

C h a n n e l 2 B -Y D V D o u tp u t 5 V p -p

C h a n n e l 3 R -Y D V D o u tp u t 1 V p -p

T im e b a s e 1 0 u s e c /d iv

For comparison, the following component video waveforms are of a pic-ture on a blue screen. The Y signal contains voltages of various bright-ness levels centered on the screen between the H. sync pulses. The B-Yand R-Y signals contain changing color levels in the middle of the screen.Note that by looking at either color signal without the Y signal level, it isnot possible to know where the sync area is. It is therefore difficult foryour scope to sync on the R-Y or B-Y signal alone without a reference.


ch3

ch2

ch1

CH1! 10. 0 V~

CH2!5.00 V~ L=121

CH3! 5. 00 V= CHP MTB10. 0us- 1. 08dv ch1p

1

2

3

P i c t u r e c e n t e r e d o n B l u e s c r e e n w a v e f o r m Y s i g

N a m e L o c a t io n V o lta g e /d iv

C h a n n e l 1 Y D V D o u tp u t 7 .5 V p -p

C h a n n e l 2 B -Y D V D o u tp u t 5 V p -p

C h a n n e l 3 R -Y D V D o u tp u t 1 V p -p

T im e b a s e 1 0 u s e c /d iv


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- VHF AND SETBACK BOX HDTV

- CABLERF (ANT)VIDEO 1

VIDEO 2VIDEO 3

DVDHD

TV/VIDEOANT

- VIDEO SETTINGS

- AUDIO SETTINGS

- VERTICAL SIZE AND CENTER- CLOSED CAPTION/VERTICAL SHIFT/TILT

MENU

TV

CABLE

VHF/UHF

ANALOG

TVINPUT

Y

PB

PR

LR

S VIDEO

VIDEO

HD

AUDIO OUTVAR/FIX

L(MONO)

R

CONTROL S IN OUT

DVD 1 3

FOR USE WITHHD (1080)

INPUT ONLY

HD

L(MONO)

AUDIO

R

DTV I/OFOR USE WITH

KW-34HD1(DTV RECEIVER)

ONLY

DTV I/OFOR USE WITH

KW-34HD1(DTV TV)

ONLY

DOLBY DIGITALOUTPUT

(OPTICAL)

VHF/UHF(DTV)DIGITAL

TV

ANTENNA

KW34HD1 REMOTE CONTROL

REAR PANEL

INPUTS

SET-BACK

BOX

HDTV44


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Overall Block

There are three main sections in Sonys model KW34HD1 first generationHigh Definition Television (HDTV):

1. Video Processing

2. Deflection3. Power SupplyThe additional circuit blocks in each section and the external box neededto receive the off the air UHF, HDTV signals distinguish this High DefinitionTV from a conventional TV.

Video Processing

Because no one HDTV standard has been determined, this first genera-tion HDTV has the flexibility to accept any of the following inputs:

S o n y m o d e l K W 3 4 H D 1 in p u t s

In p u t B lo c k L o c a t io n S ig n a l fo rm a t

V H F / U H F a n t e nn aD i g i t a l c h a n n e l s 1 - 9 9

H D T V e x te r n a l b o x R F

V H F / U H F a n t e nn a

A n a l o g c h a n n e ls 2 - 6 9

M a i n & S u b T u n e r sv i a a n t e n n a s w it c h

R F

C a b l e

C h a n n e l s 1 - 1 2 5

M a i n & S u b T u n e r sv i a a n t e n n a s w it c h

R F

V i d e o 1 3

P h o n o j a c k s

V id eo S e le c to r S w C o m p os ite v id eo ;

L & R c h a n n e l a u d i o .

D V D

P h o n o j a c k s

D V D S w itc h Y , P b , P r

L & R c h a n n e l a u d i o

H D

P h o n o j a c k s

V id e o P ro c e s s o r Y , P b , P r

L & R c h a n n e l a u d i o

The signal path for these inputs is shown below:

Digital Input

VHF/UHF antenna

HDTV Box (accepts all 18 DTV formats)

Video Processor DTV Sw (twin view or SD picture)

MID (stores both twin pictures)RGB Driver Sel (selects twin pix path)

CRT cathode Video processor RGB Driver CRT

VHF/UHF /Cable Analog Reception

Air or cable selection by the Main Micro is performed at the input antennaswitch (SW). Thereafter the signal path is the same.

VHF/UHF antenna or cable

Input antenna switch (SW)

Main/sub tunersVideo selector

DVD switch

DTV switch

DRC

SEL

Video processor

RGB Driver

CRT cathodesVideo Inputs 1 3

Composite video from a VCR or satellite (DSB) receiver

Video selector

DVD switch

DTV switch

DRC

SEL

Video processorRGB Driver

CRT cathodes

DVD Input

DVD switch

DTV switch

DRC

SEL


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30/138

27

Video processor

RGB Driver

CRT cathodes

HD Input

This input is for an external HDTV (perhaps cable) box that receives and

decodes the HDTV to output component video: Y, R-Y, B-Y (also called Y,Pb, Pr or Y, Cb, Cr, or Y, U, V, depending upon where you are in the world).The component video path introduces the component video directly intothe video processor block. The scan width of this picture is a function ofthe horizontal frequency.

Video processor

RGB Driver

CRT cathodes

Deflection

The deflection control IC develops signals for:

= Vertical and horizontal deflection (VD & HD)= Horizontal pincushion (EW)= Picture tilt & horizontal trapezoid correction (VD)= Focus (V blk)Vertical and horizontal deflection

The vertical stage is conventional, but the horizontal stage is not. Both thehorizontal driver and output stages have individual PWM stages that sup-ply regulated B+ voltage to them. The H. output B+ comes from the PWMstage through the flyback.

Horizontal Pincushion

The horizontal pincushion correction stage compensates for a picture thatis bent inward at the middle of the screen. The E/W correction signal fromthe deflection controller is amplified and applied to the yoke at the horizon-tal output transistors collector to correct for insufficient scan.

Picture tilt and horizontal trapezoid correction

Vertical drive (VD) signals not only feed the vertical deflection stage, butalso the picture tilt stage that handles trapezoid correction. A controlledlevel of vertical sawtooth (VD) signal is used for trapezoid correction. Thiscorrection signal is mixed with a DC voltage for tilt correction and appliedto the N/S coil suspended about the bell of the picture tube by the yoke.

Focus

There are two focus circuits used in this TV. The dynamic focus circuituses horizontal pulses to correct the left and right side picture focus causedby the flat screen. The dynamic correction voltage is added into the static(DC) focus voltage that is applied to the picture tube.

The quad focus circuit uses both H & V signals to correct spot shape atthe four corners of the screen. The circuits correction voltage is output tofour QP coils mounted on a board surrounding the picture tubes elec-tron gun.

Power SupplyThe power supply consists of:

= A small 60Hz standby power supply that supplies standby +5V to theMain Micro.

= A Main Micro IC that controls the power relay as well as the deflection,video, and audio stages.

= A degaussing circuit.= Two almost identical converter stages. Converter 2 turns on converter

1. Different voltages are output from each converter to power the TV.= A protection circuit to detect excessive voltage and excessive current

in various parts of the TV. The protect circuit also monitors verticaldrive. A failure in the detected areas causes the power ON commandto be removed from AC relay.


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29

Video Block 1

Input Formats

This direct view 34 model KW34HD1 High Definition TV can accept vari-

ous formats and present them in a single or double Twin View picture.

To perform this, each input signal must be processed into a common for-mat, then selected for viewing. The inputs are:

S o n y M o d e l K W 3 4 H D 1 I n p u ts

In p u t F o rm a t P ro c e s s in g

N T S C a n a lo gV H F / U H Fc h a n n e l s 2 - 6 9

R F D e m o d u la t io n in to v id e o .

V i d e o i n t o Y & C .

Y & C in t o c o m p o n e n t v i d e o ( Y ,C b , C r .)

C o m p o n e n t v id e o i n to R G B

C a b l e (a n a l o g )c h a n n e l s 1 - 1 2 5

R F S a m e a s a b o v e e x c e p t d if fe re n tR F f r e q u e n c i e s a r e re c e i v e d .

V id e o 1 3 C o m po s ite v id e o

L & R a u d i o

V i d e o i n t o Y & C .

Y & C in t o c o m p o n e n t v i d e o ( Y ,C b , C r .)

C o m p o n e n t v id e o i n to R G B

D V D C o m p o n e n tv i d e o

L & R a u d i o

C o m p o n e n t v id e o i n to R G B .

H D S a m e a s a b o v e C o m p o n e n t v id e o in to R G B

Signal Flow

RF Input

The RF signals input to the main and sub tuners are channel selected andRF demodulated into composite video. The composite video from thetuner is applied to the video Switch IC2006 along with composite videos 1-3 from the rear and front panel for user selection.

Video Inputs

Video Switch IC2006 selects the video for the main and sub pictures. Italso sends the video through comb filters. The comb filters separate thecomposite video into their luminance (Y) and chroma (C) parts.

The main and sub (Y & C) outputs run parallel paths through similar ICsbefore leaving the A board. The main and sub signals are converted tocomponent video in Chroma Decoders IC2403 (sub path) and IC2404 (mainpath). The Y, R-y, B-Y signals are applied to switches IC2405 and IC2406to enable DVD input selection.

DVD Input

Switches IC2405 and IC2406 can now select between the processed com-posite video signal and the rear panel DVD input. The DVD signal mustalso be applied to the sub input line so that it can appear as the second orsub picture in the Twin View mode. Whatever is input on the main picturepath is duplicated in the sub path. Switch selection is performed usingserial data from the Main Micro IC3251 (not shown). The switched signalis applied to the next switch in both signal paths.

DTV Input

Switches IC2407 and IC2408 introduce the digital TV from the externalsetback box. This DTV signal path is used when:

Viewing the HD or SD Digital TV signal as a sub picture (Twin Viewmode); or

The DTV signal is of standard definition (525 lines/480 lines viewable)and line doubling is required.

When viewing just the single HDTV picture, the DTV signal is applied di-rectly into the video processor IC3005 (Video Block 3) and does not comethis way (except during Twin View).

A Board Output

The main and sub picture paths leave the A board and are passed through

the G board into the digital processing stages on the V board. This signalrouting through the G board is necessary because both the vertical A andV boards plug into the horizontal G board.

Sony, Trinitron, and Twin View are registered trademarks of Sony.


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Video Process A

The external video input from the rear panel and internal video from bothmain and sub tuners is applied to this stage for selection and conversionto (Y, R-y, B-y) component video. The major parts in this early video pro-cessing are listed below:

Major Video Processing Components Shown

Name Input Output Purpose

Video SwitchIC2006

2 tuners,

3 video inputs

Y & C from 2comb filters

Main Y & C

Sub Y & C(similarprocessing notshown)

Selectscompositevideo

Routes to combfilter

Buffers Q2016,Q2420, Q2422.

1Vp-p of Y fromIC2006/pin 35

1Vp-p of Y toIC2406/pin 28

Y buffers

YUV Switch IC2406

1Vp-p of Y atIC2406/pin 28

2Vp-p at pin 22 6db amp

Buffers Q2015,Q2421

1Vp-p of CfromIC2006/pin 31

1Vp-p of C toIC2404/pin 32

C buffers

ChromaDecoderIC2404

Main Y & C atpins 34 and 32

Y=2Vp-p,C=1Vp-p

Y = 1Vp-p;

Cr, Cb = 0.5Vp-p @ pins 18-20

Changes Y/Cto componentvideo

All signal levels were taken using a color bar input.

Video Switch

Five composite video inputs are applied to video switch IC2006. Serialdata from Main Micro IC3251 (not shown) chooses which input signalstake the main and sub picture signal paths. The chosen signals go to theirrespective comb filters. The 3D filter is always kept in the main picturepath and the glass filter (FL2001) is used in the sub picture path.

The Y & C outputs from both comb filters are returned to IC2006 andoutput again. The main picture path is from pins 31 and 35. The sub videopath is from switch IC2006/pins 25 and 30 and runs a parallel route to themain one (Video Block 1) for identical processing.

Component Video

Then the Y signal is input the Chroma Decoder. The chroma (C) signal isalso buffered and input to Chroma Decoder IC2404/pin 32. IC2404 usesboth the Y & C inputs for level conversion to Y, Cr, Cb (component video).


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Video Process B

Signal Flow

Input Selection

Main component video from the Chroma Decoder IC2406 is only one input

into switch IC2406. The second input to IC2406 is DVD component videofrom the rear panel phono jacks.

The Main Micro IC3251/pin 78 and 79 sends logic level voltages into IC2406/pins 25 and 4/27 for the input selection. The chart shows the switchingvoltages for selecting an input:

I C 2 4 0 6 S e l e c t i o n

In p u t s e le c te d IC 2 4 0 6 /p in 2 5 I C 2 4 0 6 /p in s 4 , 2 7

M a in (R F , v id e o ) L H

D V D H L

Closed Caption

The luminance passes through switch IC2406, which adds closed captionor XDS station information as an OSD. If the user requests this feature,this caption information enters IC2406 as an RGB signal from IC2409.The take off or input signal for the closed caption decoder IC2409 is at theoutput of this YUV switch at IC2406/pin 22.

Filtering

When high frequency analog signals are sent into a digital stage, the high

frequency component can create a secondary signal. This second signalis called an alias component. Alias signals are eliminated by low passfiltering (LPF) the analog input. That is the purpose of the filter networks atthe output of IC2406.

DTV Selection

Switch IC2407 chooses between the main and DTV signal for the mainpicture path. The DTV signal is chosen only when:

Viewing the HD or SD Digital TV signal as a sub picture (Twin Viewmode) or

The DTV signal is of standard definition (525 lines/480 lines viewable)

and line doubling is required.The DTV path is chosen when IC2407/pin 9-11 is low:

I C 2 4 0 7 S e l e c t io n

In p u t s e le c te d S w s ig n a l IC 2 4 0 7 /p in 9 , 1 0 , 1 1

M a in (R F , v id e o ) H

D T V L

The output of the DTV/Main switch IC2407 is buffered and sent throughthe G board to the V board for digital processing.


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Video Block 2

Overview

The V board is fully shielded and contains the digital signal processing.The V board is sandwiched in-between the analog A and B boards. All

three of these boards plug into the horizontal G board. The V board hasthe following inputs and outputs:

V B o a r d S i g n a l P r o c e s s i n g

In p u t (Y , C r, C b ) O u tp u t (Y , C r, C b ) P u rp o s e

M a i n S i g n a l

C N 5 0 3 / p i n s 7 , 9 , 1 1

S u b S i g n a l

C N 5 0 3 / p i n s 1 , 3 , 5

D R C p r o c e s s e dm a i n p i c tu r e o r M I DI C 5 0 6 p r o c e s s e dt w i n v i e w p i c t u r e .

S i m u l a t e s a 9 6 0 - l in ep i c t u r e f ro m a n a c t iv e4 8 0 l in e N T S C i n p u ts i g n a l .

S e l e c t s o n e ( m a i n ) o rt w o s i m u l t a n e o u s ( T w i nV i e w ) p i c t u r e s .

Signal Flow

The main picture signal is applied to both the DRC and MID digital circuitryfor processing:

Dig i ta l C i r cu i t r y

N a m e P u rp o s e

D R C D i g i ta l R e a l i t y C r e a t io n D o u b l e s s c a n n i n g l i n e s a n d p i x e l sa f t e r m a s s i v e p r e s e n t a n d p r e v i o u sl in e i n f o rm a t io n a n a l y s i s .

M ID M ult i Im a ge D riv er A cc ep ts bo th 48 0-o r/a nd 96 0- lin ec o m p o n e n t v i d e o i m a g e s ( m a i n / s u b )a n d c o n v e r t s t h e m i n t o a t w i np ic tu re .

The DRC digital circuitry does more than just double the lines, though thatis the primary objective. There are 525 NTSC interlaced lines input (480viewable lines) to the DRC and 960i (i = interlaced) lines leaving. It is themanner in which the extra lines are created that makes the DRC circuitunique. DRC and MID concept explanations are in the pages that follow.

The main picture signal is input to the MID IC directly. The sub picture

signal is converted to a digital signal by A/D Converter IC607 before be-coming the other input for the MID IC.

The MID digital circuitry reduces this sub and the main picture to fit on thescreen at the same time. This coexistence feature is called Twin View.The analog output of the MID IC is low pass filtered by filter 1 to reduce D/A converter noise. Filter 2 is selected in the Japanese version of this TVset when there is a computer signal input to that version. In the USA TV,IC519 is never toggled from the position shown.

Either the main or the Twin View picture is selected by IC528 and thisresultant signal is sent to the next (B) board.


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DRC - Digital Reality Creation

Another picture quality issue has been with us since the dawn of televi-sion. Deeply ingrained in our television system is the question of visiblescanning lines.

All about scanning linesA television picture is painted across the CRT screen by an electronbeam that scans on a horizontal line from left to right. Once the beamreaches the ridge edge, it shuts off and returns to the left edge to startanother line. All told, there are some 525 scanning lines in the AmericanNTSC (National Television Standards Committee) television system, andthey create a new television picture or frame some 30 times a second.

In reality, you dont see the full 525 lines on the screen. Over 40 lines areconsumed by the Vertical Blanking interval. This leaves roughly 480 linesfor the actual picture. And you dont even see the 480 lines all at once.Each video frame is divided into two fields, which last for 1/60 th of asecond. The first field is composed of all the odd-numbered lines (1, 3, 5and so on). The second field fills in with the even-numbered lines. Thistechnique of alternating odd and even fields is called interlacing. TheNTSC system is often referred to as 525/60 (for 525 total scanning lines

and 60 fields per second). It is also called 480I (for 480 net scanninglines, interlaced).

Over the years, the 480i system has worked remarkably well. But withonly 240 lines on-screen at any one time, the scanning lines can becomepainfully obvious, particularly when youre sitting close to a large-screendisplay.

Problem: Visual scanning linesOriginally, television engineers designed the NTSC system so that thepicture would appear seamless when viewed from a distance of 8 timesthe picture height. This worked well in an era when the biggest commer-cially available screens were 12 inches diagonal. But in todays big-screenera, viewers tend to set far closer to their televisions in order to get wrappedup in the action. Under these conditions, the scanning lines becomeblatantly visible.

One solution: Line doublersDemanding home theater enthusiasts, videophiles and video profession-als have long sought a cure for this problem. One solution is to doublethe number of scanning lines with a circuit called a line doubler. Sony hasbeen an active supplier of line doublers, particularly for professional videoprojectors.


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Many line doublers attempt to de-interlace the 480i NTSC signal, display-ing both fields simultaneously in a 480-line progressive scan. Progres-sive scanning combines the separate fields of odd-numbered lines andeven-numbered lines. Progressive scanning displays every line in a framein numeric sequence line 1, 2, 3, 4 and so on up to line 480. Progres-sive scan plays a central role in computer displays where it helps tomake text more legible. Line doublers turn interlaced 480i signals into aprogressive 480P.

This concept works perfectly for still images, because the two fields matchup completely. But on moving images, the even field is captured 1/60th

second later than the odd field. So a car traveling on the screen hasdriven 1/60th second further down the street. And a baseball player hasslid 1/60th second closer to home plate. For this reason, line-doublersrequire elaborate motion-detection, motion-compensation and memorycircuits. This can get expensive, with the better line doublers costing $2,500or more.

A new solution: DRCSonys new Digital Reality Creation (DRC) circuitry is an all-new approachto the problem of visible scanning lines. Not only does DRC create aclearer picture by doubling the number of active scanning lines it alsodoubles the number of pixels on each scanning line. You get four timesthe picture density of standard 480i, making this a significant step towardthe picture quality of true High Definition TV (HDTV).

How it worksThe new DRC circuit is based upon a massive analysis of over tens ofthousands of High Definition TV picture patterns. Because there is a

fixed relationship between NTSC patterns and their HDTV equivalents,Sonys exclusive microprocessor can simply replacethe NTSC signal withits correct DRC counterpart. In operation, the DRC circuit accepts a digi-tally sampled 13.5 M H z input and generates a quadrupled 54.0 MHzdigital output.


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Moreover, with DRC, each field is processed separately, so theres nevera need to compensate for motion between two fields. And while the dou-blers typically produce a scan of 480P, the DRC circuit produces a higherline rate, 960i, for even greater image density.

What it all meansDigital Reality Creation circuitry greatly enhances the television viewingexperience. Now you can sit up close to the screen, immersing yourselfin the magic of home entertainment and still not be bothered by visiblescanning lines. Pictures appear denser and more seamless. And in thecoming world of Digital TV (DTV) broadcasting, televisions with DigitalRealty Creation circuitry will narrow the perceived gap among NTSC ana-log sources, standard definition digital and full High Definition digital video.

Line doublingimproves vertical density DRC doublesboth vertical andhorizontal density


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NOTES

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MID - Multi Image Driver

The world of NTSC has been a simple world. The 480i video camerasgive their signals to 480i video recorders, 480i production switchers, 480ibroadcasting, 480i videocassettes, 480i videodiscs and ultimately 480i

home television receivers. This world is comfortable and compatible, butits already rapidly changing.

A blossoming range of image standardsUnlike entertainment-oriented television, computers have long used pro-gressive scanning to maximize the legibility of on-screen text. For ex-ample, the popular VGA computer standard uses progressive scanning640 h x 480 V pixels. In video terms, thats 480P.

Digital Television (DTV) broadcasting embraces both interlace scanningand progressive scanning. A convergence technology is needed to linkthe two previously separate worlds of entertainment and information.

Sonys solutionSonys new Multi-Image Driver (MID) circuitry contains a special Twin-View function that can display either a High Definition or a Standard Defi-

nition video signal together with any VGA source. This is a proprietaryintegrated circuit based on company expertise in broadcast-quality DigitalMulti Effects systems. Some (but not all) Sony televisions with MID willenable viewers to combine two different signal formats on the same screen.MID works by converting both signals to VGA (480P) display. Supportedsignal combinations include: NTSC + NTSC NTSC + HD VGA + NTSC VGA + HD


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In the digital future, the unique capabilities of the Multi-Image Driver cir-cuitry will open up unprecedented applications. Youll use Picture-in-Pic-ture with High Definition, standard definition and NTSC sources. Youll beable to watch a movie in High Definition, while you visit a website to learnmore about how that movie was produced. And youll be able to see bothimages with exceptional quality and highly advanced Picture-in-Picturefunctionality.

A new generation of PIP functionalityMulti-Image Driver circuitry also delivers powerful picture-in picture ad-vantages, such as:

Flexible Twin-ViewTM Function. Not only can you view two imagesside-by-side, but you can continuously expand either picture, up totwo times its normal size.

New Favorite Channel. Automatically shows your eight favorites orthe last eight channels youve watched.

New Freeze Mode. Lets you freeze a broadcast screen to writedown a telephone number or website URL while the program contin-ues as a side-by-side TwinView picture.

Sonys Multi-image Driver bridges the gap between computing and television. You can surf thenet at VGA resolution while you watch High Definition TV on the same screen.

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Video Process C

The V board is the second board (of four) in the video processing chain.Its purpose is to take the main component video and either reduce thenumber of scanning lines for a Twin View picture or double the number oflines for a picture that will simulate that of an HDTV picture. The signal

path is dependent upon whether a single or twin picture is called for.

Single Picture

The single picture main signal path is through the Digital Reality Creationcircuitry. The output is component video that is selected by switch IC528to feed the Video Processor IC on the next (B) board.

S i n g l e P i c tu r e M a i n S i g n a l P a t h

C o m p o n e n t In p u t O u tp u t P u rp o s e

D R CP r o c e s s i n g

M a i n c om p o n e n tv i d e o i n p u t

C N 5 0 3 / p i n s 7 , 9 ,

1 1 .

S i n g l e( m a i n )p i c t u r e

l in e s d o u b l e d

4 8 0 i t o 9 6 0 il i nes

S w itc h IC 5 28 T w in p ic tu re

S i n g l e ( m a i n )p i c t u r e

C o m p o n e n tv i d e o

S e l e c t s s in g l eo r d o u b l e ( t w in )p i c t u r e

B u f f e rs Q 5 6 4 Q 5 6 6

C o m p o ne nt v id eo C o m p o ne ntv i d e o

C u r r e n ta m p l i fi e r s

Twin View Picture

When Twin View is selected, the main picture path is through the MID IC.This IC uses two external memories (IC501 and IC502) to hold the infor-mation from each picture. When the information is needed, this can be

selected at the right time to produce two pictures on the screen simulta-neously. The second picture comes from the sub picture information in-put at IC506/pins 11-23.

T w i n V i e w P i c t u r e M a i n S i g n a l P a t h

C o m p o n e n t In p u t O u tp u t P u rp o s e

B u f f e r st r a n s i s t o r sQ 5 7 2 - Q 5 7 4

M a i nc o m p o n e n tv i d e o i n p u t

C N 5 0 3 / p in s 7 ,9 , 1 1 .

I C 5 0 9 / p i n s :

7 7 ( Y ) = 2 . 3 V p - p

7 6 ( C b ) = 1 V p - p

7 1 (C r ) = 1 V p - p

S u p p l i e s s u f f i c i e n tc u r r e n t t o d r i v e t h en e x t i n p u t s t a g e .

M u l ti I m a g eD r i v e r

I C 5 0 6

C o m p o n e n tv i d e o f ro m :

M a i n p a t h -B u f f e rt r a n s i s t o r s .

S u b P a t h I C 6 0 7

C o m b i n e d m a ina n d s u b p i c tu r e

i n o n ec o m p o n e n tv i d e o o u t p u t p i n s 7 1 , 7 6 , 7 7 .

R e d u c e s m a i n &s u b p i c t u r e s i z e .

S t o r e s r e m a i n in gi n f o in e x t e r n a lm e m o r ie s .C o m b i n e s b o thp i c t u r e s i n t o o n eo u t p u t (T w i n V i e w )p i c t u r e .

F i l t e r sF L 6 0 4 -F L 6 0 6

T w i n V ie wC o m p o n e n tv i d e o

T w i n V i e wC o m p o n e n tv i d e o

R e d u c e sr e m a i n i n g d ig i t a ln o i s e .

F i l t e r sF L 6 0 8 &F L 6 0 7

T w i n V ie wC o m p o n e n tc o l o r ( C r , C b )

T w i n V i e wC o m p o n e n tc o l o r ( C r , C b )

N o t u s e d in U S Am o d e l.

S w i t c hI C 5 1 9

T w i n V ie wC o m p o n e n t

v i d e o p i n s 1 , 5 ,1 3 .

C o m p o n e n tc o l o r p i n s 2 ,1 2 .

T w i n V i e wC o m p o n e n t

v i d e o

S w i tc h r e m a i n s int h e f i x e d p o s i t io n

s h o w n ( U S Am o d e l) .

S w i t c hI C 5 2 8

T w i n p i c tu r e

S i n g l e ( m a i n )p i c t u r e

C o m p o n e n tv i d e o .

Y = . 8 V p - p ,

C r / C b = . 5 V p - p

S e l e c t s :

s i n g l e o r d o u b l e( t w i n ) p i c t u r e


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Video Block 3

Video Processor IC3005 Inputs

There are several inputs to the Video Processor IC3005. The most impor-tant inputs are:

= Two identical HDTV component video signals from the set-back boxare input (# 4 and 5).

= The RF, DVD or Twin View video component video is input (# 1).= OSD for menu or channel numbers (RGB) OSD input.= IK signal is returned from the CRT cathodes for RGB beam current

balance.The HDTV or main line video input is selected by serial data from the MainMicro (not shown). IC3005 converts the component video selected intoRGB. After the video is converted to RGB format, the OSD information(also RGB format) is inserted.

The closed caption is usually introduced with the OSD signal at this point.However, in this set it is introduced earlier in the video chain (Video Pro-cess 1) so both twin pictures will have their own closed caption informa-tion.

Video Processor IC3005 Outputs

The signal outputs are:

= RGB video output signal is sent to the CRT cathodes (pins 35, 37 and39)

= IK pulses that output the RGB signal lines are used to white balancethe picture (pins 35, 37 and 39)= DTVs component video signal (from the external set-back box) is re-

turned to earlier stages (Video Block 1) for:

RGB Video

The RGB Video Processor signal outputs (pins 35, 37 and 39) are ampli-fied and inverted by the three Video Output ICs IC9001-3. Then they areapplied to the picture tubes cathodes to control electron intensity.

Automatic Cathode Balance (AKB) Circuit

The purpose of the AKB circuit (also known as the IK circuit) is to adjustthe level of the R, G or B drive signal to compensate for picture tube aging.The current drawn by the CRT cathodes is sampled and output pin 5 ofeach output IC. The outputs are multiplexed, buffered and AC coupled(C3072) to the Video Processor IC3005/pin 41 for analysis. The RGB lev-els are adjusted to compensate for a weak cathode.

The AKB circuit starts in IC3005 at turn on by outputting a one-line pulse toeach cathode (from RGB, pins 35, 37 and 39). These three pulses occuron different lines and in the blanking area (above the picture) so they arenever seen. The three drive pulses are output when the video processorIC3005 receives Vcc.

While the picture remains blanked, CRT drive current from these pulsesproduces a corresponding voltage pulse at pin 5 of each video output IC.The three pulses are combined and buffered. These pulses are called theAKB signal and their amplitudes represent the potency of each cathode.

The three pulses are returned to IC3005/pin 41 for analysis and drive sig-nal adjustment. The drive output for example will be boosted to compen-sate for a reduced cathode output so the colors appear equal in perfor-mance. This is why this AKB circuit is commonly called a white balancecircuit.

A loss in a picture tube cathode results in this AKB circuits inability tobalance. However, once the cathode emission is out of operating range,the AKB circuit will not blank the picture like previous AKB circuits. Thefront panel standby light will blink five times, pause and repeat, indicating awhite balance adjustment failure. The standby light will blink with the TVon or off. The circuit is reset when the TV is unplugged, but the light willblink again if the problem persists.

A twin View picture (pins 76-78); or Line doubling if the setback box is receiving a DTV standard defini-

tion picture of 525 lines (480 lines viewable).


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Video Process D

The B board contains the Video Processor IC3005 and the Main Micro (notshown). The Main Micro controls the video processor, TV power and inter-faces with the user. The Video Processor:

1. Selects component video to be input2. Converts component video into RGB voltage for the picture tube3. Monitors picture tube cathode current to adjust RGB drive level (IK,

AKB, or white balance circuitry)4. Adds on screen display (explained in another section)The first two functions are part of the video processing. The third functionis the automatic cathode balance circuit. It has changed dramatically inthis set for ease of servicing. The fourth is for user information such asmenus.

Video Processing

Several inputs are available for selection by the Video Processor IC3005.The selection is based upon serial data from the Main Micro IC3251/pins28 and 31 into IC3005/pins 55-56. The inputs are outlined below:

IC3005 Input Selection

Input Operating Mode

DTV from set-back box at pins13-23.

Pins 13-17 contain identicalinformation as pins 19-23.

Main Micro has instructed the set-back box to tune to a UHF channeland output that channel ascomponent video (Y, R-Y, B-Y).

Single or Twin View pictureinformation from the V boardinto pins 65-69

Either VHF TV, UHF TV, cable TV,Video, or DVD has been chosenfrom the remote control.

Rear panel HD (1080i)component video

HD is selected from the TV/Videoremote control button.

OSD (see the OSD diagram) When menu or display is pressed.

Once the input is chosen by IC3005, this video is internally matrixed intoindividual RGB levels. They output IC3005/pins 35, 37 and 39 for the pic-ture tube (cathodes).

Automatic Cathode Balancing (AKB) Circuitry

The purpose of the AKB circuit (also known as the IK circuit) is to adjustthe level of R, G or B drive signal to compensate for picture tube aging.The AKB circuit starts in IC3005 at turn on by outputting a one-line pulse toeach cathode (from RGB pins 35, 37 and 39). These three pulses occuron different lines and in the blanking area (above the picture) so they are

never seen. The three drive pulses are output as long as the video pro-cessor IC3005 receives Vcc (supply voltage).

While the picture remains blanked, CRT drive current from these pulsesproduces a corresponding voltage pulse at each video output IC. Althoughthese three AKB pulses are combined and buffered, their individual ampli-tudes represent the potency of each cathode.

The three pulses are returned to IC3005/pin 41 to charge their respectivecapacitors at pins 36, 38 and 40. The average charge is used for analysisand drive signal adjustment. For example, a drive output will be boosted tocompensate for a reduced cathode output so the colors appear equal in

performance. This is why this AKB circuit is commonly called a whitebalance circuit.

A picture tube cathode loss results in this circuits inability to balance.However, once the cathode emission is out of operating range, the AKBcircuit will not blank the picture like previous AKB circuits. The standbylight will blink five times, pause and repeat, indicating a white balance adjustment failure. The standby light will blink with the TV on or off. Thecircuit is reset when the TV is unplugged, but the light will blink again if theproblem persists.

The voltages measured at the three capacitors of this sample TV repre-

sent the efficacy of the cathodes. For example, when the red cathode isdisabled, its capacitor voltage rises (see bold).

IK Capacitor Voltages

IC3005/pin Normal R drive shorted CN9001/pin 1 = gnd

36. Red IK voltage 5.6V 6.8V (abnormal)

38. Green IK voltage 5.9V 4.8V

40. Blue IK voltage 5.6V 5.5V


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On Screen Display

OSD Components

The on screen display circuitry consist of the following major parts:

O n S c r e e n D i s p la y P a r t s

P a r ts In p u t O u tp u t P u rp o s eI C 3 2 5 1M a i nM i c r o

V e r t i c a l s y n c p i n 9 5

H o r i z o n t a ls y n c p i n 9 7

R e m o t ec o n t r o l i n p u t p i n 7

R , G , B c h a r a c t e rsp u l s e s f ro m p i n s 3 2 -3 4 .

Y s F u l l b l a n k i n gp u l s e

Y m b l a n k in gm i x i n g p u l s e

G e n e r a t ec h a r a c t e rp u l s e s .

G e n e r a t ec h a r a c t e rw i n d o w p u l s e

I C 3 0 0 5V i d e oP r o c e s s o r

R G Bc h a r a c t e r in f o p i n s 5 0 - 5 2

R , G , B d r i v e

dtv01_high definition tv

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