Training Manual

LCD TelevisionsModels: KLV-26HG2

KLV-32M1

Diagnostics and Troubleshooting

Course: CTV-33

Training Manual

KLV-26HG2 KLV-32M1

CTV-33 i

P-Board ................................................................................ 9

H1-Board ........................................................................... 10

H2-Board ........................................................................... 10

H3-Board ........................................................................... 10

Chapter 2 - LCD Panel Assembly ......................................11

LCD Panel Assembly Schematics ..................................11

LCD Panel Assembly Troubleshooting .......................... 16

Backlight Inverter Board Troubleshooting ...................... 16

Inverter Board Shut Down ................................................. 16

Inverter Board Not Powering Up ........................................ 17

Inverter Board Detecting Defect ........................................ 17

Non-Functioning Inverter Board ......................................... 17

Defective LCD Panel ......................................................... 17

Backlight Inverter Outputs and Inputs ........................... 18

LCD Logic Board Troubleshooting ................................. 21

Light Raster Display ........................................................... 25

Video or Sync Distortion .................................................... 25

Chassis Disassembly KLV-26HG2 ............................... 32

Chassis Disassembly KLV-32M1 .................................. 38

Chapter 3 - Power Supply Overall Blocks ....................... 43

Overview ........................................................................ 43

Power ON Sequence and Output Voltages ................... 46

Power Supply Troubleshooting ...................................... 47

Chassis DC Voltage Map ................................................... 47

Introduction .......................................................................... 1

Course Overview ............................................................. 1

KLV-26HG2 Features ........................................................... 2

KLV-32M1 Features ............................................................. 2

Chapter 1 - Overall Block Diagrams ................................... 3

KLV-26HG2 Overall Block Diagram ................................. 3

LCD Panel Assembly ........................................................... 5

A1-Board .............................................................................. 5

B-Board ................................................................................ 5

G1-Board ............................................................................. 5

MSB-Board .......................................................................... 6

MS-Board ............................................................................. 6

MSX-Board .......................................................................... 6

UD-Board ............................................................................. 6

TU-Board ............................................................................. 6

U1-Board ............................................................................. 6

H1-Board ............................................................................. 6

H2-Board ............................................................................. 6

H3-Board ............................................................................. 6

KLV-32M1Overall Block Diagram .................................... 7

LCD Panel Assembly ........................................................... 9

ULU-Board ........................................................................... 9

AU-Board ............................................................................. 9

GL-Board ............................................................................. 9

BL-Board .............................................................................. 9

Table of Contents

CTV-33 ii

Table of Contents

Basic Checks ..................................................................... 48

Confi rm Operation of Standby 5V Power Supply ......... 48

Confi rm Operation of Primary Power Supply ............... 48

Confi rm Operation of Secondary Power Supply .......... 49

Detailed Power Supply Diagrams and Operations ........ 50

Standby 5V Power Supply ................................................. 50

Troubleshooting ................................................................. 52

Primary Power Supply ................................................... 53

Switching Power Supply Operation ................................... 55

Secondary Power Supply .............................................. 57


Chapter 4 - Video Processing ........................................... 59

Video Circuit Descriptions ............................................. 59

Wega Engine (CCP2) ........................................................ 59

Digital Reality Creator (DRC) ............................................. 59

Scan Converter (PW166) ................................................... 59

LCD Drive (Bolt) ................................................................. 59

V-Chip ................................................................................ 59

Video Processing Circuit Troubleshooting ..................... 60

Overview ............................................................................ 60


Loss of a Single Video Source ..................................... 63

Loss of Multiple Video Sources ................................... 63

Loss of all Composite Video Input Sources (Only) ...... 64

Chapter 5 - Audio Processing ........................................... 66

KLV-26HG2 Overview .................................................... 66

Troubleshooting ............................................................. 68

No Audio Output from Single Audio Input .......................... 68

No Audio Output at the Speakers ...................................... 68

No Headphone Audio, Speaker Audio OK ......................... 68

KLV-32M1 Overview ...................................................... 69

Troubleshooting ............................................................. 71

No Audio Output from Single Audio Input .......................... 71

No Audio Output at the Speakers ...................................... 71

No Headphone Audio or Audio Var/Fix Output,

Speaker Audio OK ....................................................... 72

Chapter 6 - Protection Circuits ......................................... 73

Circuit Descriptions and Troubleshooting ...................... 73

KLV-26HG2 Protection Circuits .......................................... 74

KLV-32M1 Protection Circuits ............................................ 74

Video Processing ......................................................... 78

Power Supply ............................................................... 78

LOW 16.5V .................................................................. 79

Panel Assembly ........................................................... 80

Temperature ................................................................. 81

Video Processing ......................................................... 81

Power Supply ............................................................... 81

Panel Assembly ........................................................... 82

Temperature ................................................................. 83

16.5V Over-Voltage Protection .................................... 83

CTV-33 1

Introduction

Course OverviewThis course covers troubleshooting and repair of both the KLV-26HG2 (2003 model) and the KLV-32M1 (2004 model). Both of these units are Color Liquid Crystal Display (LCD) Direct view models, which incorporate an Active Matrix Thin Film Transistor (TFT) LCD panel and backlighting to display video images. The main focus of this course is to determine whether the defect exists in the LCD Panel or in the supporting circuitry (e.g. Power Supply, Video, or Audio circuits). To make this determination this manual provides detailed troubleshooting procedures, which include diagrams, voltages and waveforms for the LCD Panel function and all the major supporting circuits.

The LCD display technology has been highly successful in the computer display industry; especially in the fast grow laptop computer market. The LCD display technology was not considered a suitable display for movie and broadcast video in the past due to its slow response time when attempting to display moving video, and its low contrast ratio as compared to other display technologies such as CRT and Plasma. LCD display is quickly becoming the display technology of choice in the TV industry due to key advances in technology.

Sony’s LCD Panel Driver Large Scale Integration (LSI) minimizes motion blur caused by slow response time of the LCD Panel by improving the response time in the middle Luminance range resulting in smoother images on the screen.

TFT technology is used to improve the contrast ratio of the LCD panel. The TFT technology enables the LCD panel drive circuits to more accurately control the voltage at each individual pixel to a higher level of detail and stability. The TFT and an associated capacitor are the key components at each individual pixel to achieve higher contrast ratios, in some cases achieving a contrast ratio of 1000:1, which now enables LCD technology to directly compete with the other display technologies in the TV industry.

The picture quality is further enhanced by the Direct Digital Circuitry (DDC), which increases the Signal-to-Noise ratio during the analog to digital signal conversion process just before the signal is applied to the Digital Reality Creation (DRC) circuit. The DRC circuit enhances the picture by converting the Standard Defi nition signal to a High Defi nition (HD) quality signal; this is accomplished through an increase in the lines of resolution from standard to high defi nition.

CTV-33 2

Introduction

KLV-26HG2 Features

• 26" Direct View LCD WEGA™ Television

• All-In-One side speaker design

• Digital Reality Creation™ Circuitry

• Direct Digital Circuitry

• WOW™ Audio Effect brings life to low and mid range frequencies

• Memory Stick® media playback*

• Choose Wide Screen Modes with Remote Control

• Sony’s LCD Panel Driver LSI

• DVI-HDTV Input

• Front A/V INPUTS

• Resolution: 1280 (h) x 768 (v)

KLV-32M1 Features

• All-In-One Bottom Speaker Design: Built-In Speakers, Pedestal and NTSC Tuner

• Screen Size: 32"

• Direct Digital II Circuitry

• Digital Reality Creation™ Circuitry

• CineMotion Reverse 3:2 Pulldown Technology

• TruSurround® SRS® Audio Processing (10w x 2)

• HDMI-HDTV Input

• Sony’s LCD Panel Driver LSI

• Resolution: 1366 (h) x 768 (v)

CTV-33 3

Chapter 1 - Overall Block Diagrams

KLV-26HG2 Overall Block Diagram

FIGURE 1-1

KLV-26HG2 OVERALL BLOCK DIAGRAM

� 3.3VRegulator

MSB Board

LCD Panel

� DVI Interface& Processing

UD Board

� Video 1

U1 Board

� Video 2� Headphone

Output

H2 Board

� Tuner

TU Board

� LED� IR Sensor

H3 Board

� Power Switch� Function Keys

H1 Board

� Memory StickProcessing

MS Board

� Memory StickInterface

MSX Board

� 5V StandbyPower Supply

� Primary PowerSupply

G1 Board

ACInput

LCDBacklight &

Inverter

Component 1Video Input

R

L

A1 Board

� AV Switching� Audio Processor� Audio Amplifier� Secondary Power

Supply

B Board

� MainMicroprocessor� Chroma Decode� DRC� LCD Drive� Scan Converter

Power &Control Data

Power

Power

PictureData

Power

Power

AVData

Power

Power

Video

ControlData

ControlData

AV

AV

AV

AV

AV

ControlData

AVData

Power

PowerKeysSIRCS Power &

LEDs

Logic Board

LCD Panel Assemble

CTV-33 4

1. Overall Block Diagram

BacklightInverter Board(under Sheild)

U1-Board

MSB-Board

MSX-Board

TU-Board

A1-Board

LCD Logic Board(under G1-Board; Under sheild)

H2-Board

H1-Board

H3-Board MS-BoardB-Board UD-Board

G1-Board

Backlight Return Lines

FIGURE 1-2

KLV-26HG2 BOARD LOCATION

CTV-33 5


LCD Panel Assembly

The LCD assembly includes the LCD Panel, LCD Logic board, CCFT

Backlights, and High-Voltage Backlight Inverter board.

The LCD Logic board receives the video data from the B-board and

performs the necessary pixel addressing, charging, and timing to display

the video images on the LCD Panel.

The High-Voltage Backlight Inverter receives 16.5V from the Primary

Power Supply (via the A1-board) and develops between 1000Vrms to

1100Vrms, which is used to activate and illuminate the CCFT Backlights.

A1-Board

All audio and video input switching is performed on the A1-board. (The

only video input that does not go through the AV Switcher on the A1-board

is the Memory Stick video which goes directly to the Chroma Decoder on

the B-board. However, the Memory Stick audio does go through the AV

switcher on the A1-board via the B-board. More on these signal paths in

the video and audio sections.

All audio processing (treble, bass, volume, and effects) and amplifi cation

are performed on the A1-board.

Also located on this-board is the Secondary Power Supply which produces

the D3.3V, D5V, +9V, and +12V supplies.

The Speakers and the Component 1 input are also connected directly to

the A1-board

B-Board

The Main Microprocessor (IC1006) is located on the B-board which

performs all control functions for all devices on the chassis.

All video processing (D/A Conversion, Chroma Decoding, and DRC

Processing) is performed on the B-board.

The Scan Converter and LCD Drive circuits are located on the B-board.

The fi nal video data is fed to the LCD Logic board (not repairable; comes

with LCD Panel) over a Low Voltage Differential Signaling (LVDS) cable.

G1-Board

The AC input is applied directly to the G1-board.

The G1-board houses the 5V Standby switch mode power supply. Also

located on the G1-board is the Primary Power Supply which produces

the LCD Backlight voltage (16.5V), unregulated 12V for the audio circuits,

unregulated 6V used to produce D5V, and unregulated 33V for the Tuner

channel tuning function.

CTV-33 6


MSB-Board

The MSB-board houses a single 3.3V regulator. The regulated 16.5V

from the Primary is supplied to the MSB-board which then outputs a highly

regulated 3.3V to power the Memory Stick circuits on the MS-board.

MS-Board

All Memory Stick video and audio processing is performed on the MS-

board, including the Memory Stick User Interface screen.

MSX-Board

The MSX-board is the Memory Stick interface board. The Memory Stick

plugs directly into this board.

UD-Board

All Digital Visual Interface (DVI) uncompressed High-Defi nition (HD)

video data processing is performed on the UD-board. These are no audio

signals transmitted over the DVI interface. Audio for the DVI must be

supplied to the auxiliary RCA analog audio jacks. The DVI connector

interfaces directly to this board.

TU-Board

The NTSC tuner is mounted directly to the TU-board, and the TU-board is

mounted directly to the A1-board.

U1-Board

The Video 1 jacks are mount directly to the U1-board.

H1-Board

The Power Switch and Function Keys are mounted on the H1-board.

H2-Board

The Video 2 and Headphone jacks are mounted on the H2-board.

H3-Board

The Power, Standby/Timer, and Memory Stick LEDs and the IR sensor

are mounted on the H3-board.

CTV-33 7


KLV-32M1Overall Block Diagram

ULU Board

P Board

AU Board

H2 Board H1 Board

GL BoardAC

Input

� Audio Processor� Audio Amplifier� Secondary Power Supply� Tuner

� AVSwitching

� HDMIInterface

� Power Switch� IR Sensor

� 5V Standby PowerSupply

� Primary Power Supply

� FunctionKeys

H3 Board

� Headphone output� Video 2

BL Board

� Main Microprocessor� Chroma decoder &

3D Comb Filter� DRC� LCD Drive� Scan Converter

Power

Power

Video

Audio

ControlData

ControlData

TunerVideo

Power

R L

ControlData

A/V

VideoAudioHPAudio

HPAudio

KeysSIRCS Keys Power &LEDs

LCDPanel

LCDBacklight &

Inverter

Power

PictureData

Control

Backlight Control

Power

Power

Center SpeakerAudio Input

Audio Var/FixOutput

HD/DVD 4 InputComponent

Video 3 InputS & Composite

Video 1 InputS & Composite Logic

Board

LCD Panel Assemble

FIGURE 1-3

KLV-32M1 OVERALL BLOCK DIAGRAM

CTV-33 8


Backlight InverterBoard (under

shield)

GL-Board

ULU-BoardH1-Board

H2-Board(behind ULU-Board)

H3-Board

P-Board(under shield)

AU-Board

Backlight ReturnLines

(under shield)

LCD Logic Board(under shield) BL-Board

FIGURE 1-4

KLV-32M1 BOARD LOCATION

CTV-33 9


LCD Panel Assembly

The LCD assembly includes the LCD Panel, LCD Logic board, CCFT

Backlights, and High-Voltage Backlight Inverter board.

The LCD Logic board receives the video data from the BL-board. It then

performs the necessary pixel addressing, charging, and timing to display

the video images on the LCD Panel.

The High-Voltage Backlight Inverter receives 16.5V from the Primary

Power Supply (via the AU-board) and develops between 1000Vrms to

1100Vrms, which is used to activate and illuminate the CCFT Backlights.

ULU-Board

All video and audio switching is performed on the ULU-board. Only the

Center Speaker input and Audio Output Var/Fix are not switched on the

ULU-board, they go directly to or come from the AU-board respectively.

AU-Board

All audio processing (treble, bass, volume, and effects) and amplifi cation

is performed on the AU-board.

The speakers are also connected directly to the AU-board.

The Secondary Power Supply is located on this board which produces

the D3.3V, D5V, and Panel 5V supply voltages. Also, located on the AU-

board concerning power sources is two 9V and one 5V regulators.

The NTSC tuner is mounted directly to the AU-board.

NOTE: The audio and video signals are basically separated on the ULU-

board, with the audio going to the AU-board and video going to the BL-

board for the respective signal processing.

GL-Board

The AC input is applied directly to the GL-board.

The GL-board houses the 5V Standby switch mode power supply. Also

located on the GL-board is the Primary Power Supply which produces the

LCD Backlight voltage (16.5V), unregulated 10.5V for the audio circuits,

unregulated 30V for the audio amplifi er, and unregulated 33V for the Tuner

channel tuning function.

NOTE: There is a feed-through path for the Backlight control signal on the

GL-board. Therefore, when troubleshooting a suspected backlight defect

confi rm the connections on the GL-board.

BL-Board

The Main Microprocessor is located on the BL-Board which is the only

microprocessor on the chassis for all control functions.

All video processing (D/A Conversion, Chroma Decoding, and DRC

Processing) is performed on the BL-board.

The Scan Converter and LCD Drive circuits are located on the BL-board.

The fi nal video data is fed to the LCD Logic board (not repairable; comes

with LCD Panel) over a Low Voltage Differential Signaling (LVDS) cable.

NOTE: The audio and video signals are basically separated on the ULU-

board, with the audio going to the AU-board and video going to the BL-

board for the respective signal processing.

P-Board

All High Defi nition Media Interface (HDMI) video and audio processing is

performed on the P-board. The HDMI is an enhanced version of the DVI.

The HDMI transmits both uncompressed High-Defi nition video and audio

data. The HDMI is backwards compatible with the DVI with the proper

connector conversion adapter. The HDMI connector interfaces directly to

this board.

CTV-33 10


H1-Board

Function Keys are mounted on the H1-board.

H2-Board

The Power Switch & Power LED, Standby/Timer LED and the IR sensor

are mounted on the H2-board.

H3-Board

The Video 2 and Headphone jacks are mounted on the H3-board.

CTV-33 11

Chapter 2 - LCD Panel Assembly

LCD Panel Assembly SchematicsRef. Figure 2-1 and 2-2

The LCD Panel assembly includes the LCD Panel, Backlight (16 Cold Cathode Fluorescent Tubes CCFTs), Backlight Inverter board, and LCD Panel Logic board. When troubleshooting either the KLV-26HG2 or the KLV-32M1 the priority is to determine if the defect is in the LCD Panel assembly or in the supporting power, video, or audio circuitry. This chapter concentrates on troubleshooting the LCD Panel assembly for proper operation. The LCD Panel assembly operation for the KLV-26HG2 and KLV-32M1 are identical. There are only a couple of physical layouts and one voltage difference between the two models (Ref. Figure 2-1 and 2-2). Note that the Panel Voltage between the two models is different. KLV-26HG2 is 12V and KLV-32M1 is 5V. The only other difference is the layout for the panel-return lines between the two models.

CTV-33 12

2. LCD Panel Assembly

A1-Board

LCDBacklightInverter

LCD Panel & Backlight System

8 2 Line

Connectors

16 Lamps

Lamp Return Lines

LCD Panel Assembly

CN8001

CNT1

G1-Board B-Board

CN6004 CN58013 4 5 CN46041 2 3 4 5

1 2 3 4 5 11 12 13

16.5V

Dimmer

Backli

ght

Panel D

etect

(PD)

16.5VPD

Backli

ght

Dimmer

3.3V4V

1 2 5 6 8 9 11 12 14 15 17 18

1 2 5 6 8 9 11 12 14 15 17 18

Panel 12V

Panel12V

1.2VdcPer Video

Line

LVDSCable

RX+RX- RX+ RX- RX+ RX- RX+ RX- RX+ RX-

TX+ TX- TX+ TX- TX+ TX- TX+ TX- TX+ TX-

2.8V (Standard Picture Mode)

RGB RGBRGB RGB/SyncNot

Used

LCD Logic Board

FIGURE 2-1

KLV-26HG2 LCD PANEL SCHEMATIC

CTV-33 13


LCDBacklightInverter

LCD Panel & Backlight System

8 2 Line

Connectors

16 Lamps

Lamp Return Lines

LCD Panel Assembly

CN8001

CNT1

CN652 CN450111 12 131 2 3 4 5

1 2 3 4 5 11 12 13

16.5V

Dimmer

Backli

ght

Panel D

etect

(PD)

16.5V

Bac

klig

htD

imm

er

2.8V (Standard Picture Mode)

3.3V4V

26 - 30 5 6 8 9 11 12 14 15 17 18

26 - 30 5 6 8 9 11 12 14 15 17 18

Panel5V

Panel5V

1.2VdcPer Video

Line

LVDSCable

RX+RX- RX+ RX- RX+ RX- RX+ RX- RX+ RX-

TX+ TX- TX+ TX- TX+ TX- TX+ TX- TX+ TX-

Control Data

1 2 3BL-BoardGL-Board

1 2 3CN653

Pan

el D

et.

Dimmer

Back

light

PD

CN1004

RGB RGB RGBRGB/SyncNot

Used

LCD Logic Board

FIGURE 2-2

KLV-32M1 LCD PANEL SCHEMATIC

CTV-33 14


LCDInverterBoard

CN8001LVDSCable

CNT1

LCDLogicBoard

Connector to BL-Board CN5801

FIGURE 2-3

KLV-26HG2 LCD PANEL ASSEMBLY PHOTO

CTV-33 15


LCDLogicBoard

LCDInverterBoard

Connector to GL-Board CN652

CN8001

LVDSCable

CNT1

Connector to BL-Board CN4501

FIGURE 2-4

KLV-32M1 LCD PANEL ASSEMBLY PHOTO

CTV-33 16


LCD Panel Assembly TroubleshootingAreas to check when troubleshooting the LCD Panel assembly are:

1) Inverter Output Lamp Drives (Ref. 2-1, 2-2, 2-3 Waveforms)

2) Inverter Board Input Power Supply (16.5V)

3) Inverter Board Control Signals (Panel Detect, Backlight, and Dimmer)

4) Logic Board Power Supply or Panel Voltage (KLV-26HG2 12V, and KLV-32M1 5V)

5) Logic Board Input Video/Sync Data Signals (Ref. 2-4, 2-5, 2-6 Waveforms)

This section discusses the symptoms and troubleshooting methods for determining defects in the three major areas of the LCD Panel assembly.

• LCD Panel

• Backlight Inverter board

• LCD Logic board

Due to the similar physical and circuit design of the KLV-26HG2 and the KLV-32M1 models the troubleshooting methods are almost the same. The differences is the board reference numbers, and the Panel voltage value which is applied to the LCD Logic board. Before continuing to the next section reference fi gures 2-1 and 2-2 to view the differences between the two models.

Because the Backlight Inverter and LCD Logic board can only be replaced as part of the LCD Panel assembly, only the input voltages and signals need to be confi rmed to determine if these components are defective.

Backlight Inverter Board Troubleshooting(Ref. Figure 2-1 KLV-26HG2 and Figure 2-2 KLV-32M1 for all the following symptom troubleshooting)

The fi rst thing to note when troubleshooting a possible defective Backlight Inverter is the AC current draw on the VAC (Variable AC Power Supply) at initial power up and ON states. The two states are as follows.

1) Initial Power Up 0.2A

2) After approximately 5 seconds the current will jump to 1.38A (Backlight ON, Standard Picture Mode, Backlight Adjustment MID range)

This is a quick indication if the Backlight Inverter is functioning. The AC current should jump to 1.38A to indicate a properly operating Backlight Inverter. NOTE: This does not indicate proper operation of the lamps themselves. The Inverter can be operating properly with a defective lamp or lamps (or dark screen).

Inverter Board Shut Down

(AC Current OK on initial power up, but unit shuts down)

If the unit is shutting down and going into protection mode after the AC current has momentarily jumped to 1.38A before shutting down, this indicates that the Inverter board is powering up, and something else is causing it to shut down. The most likely cause for the Inverter to shut down in this manner is:

1) One or more Backlights are defective. Check the amplitude of the Inverter output waveform at each output connector as describe in the “Backlight Inverter Outputs and Inputs” section. If the amplitude is excessively low as shown in waveform 2-3 the lamp is defective. Consequently, the complete Panel Assembly must be replaced.

CTV-33 17


Inverter Board Not Powering Up

(AC Current Low on power up and unit shuts down)

If the AC current does not jump to 1.38A, and remains at 0.2A and shuts down, this indicates that the Inverter board is not powering up. Check the following voltages at CN8001 on the Inverter board.

1) 16.5V supply voltage CN8001/pns 1 - 5

2) “Backlight” control signal CN8001/pin 12 (3.3V)

Inverter Board Detecting Defect

(Video and Audio are momentarily seen and heard, but unit

immediately shuts down)

The most likely cause of this symptom is a defective lamp or lamps, or an individual Inverter output drive is low or missing. The inverter is powering up and there are some lamps working because video is being displayed. This also indicates that the logic board is working (outputting video). The Inverter board is detecting a defective lamp, or individual inverter output drive. Make the following checks.

1) One or more Backlights are defective. Check the amplitude of the Inverter output waveform at each output connector as describe in the “Backlight Inverter Outputs and Inputs” section. If the amplitude is excessively low as shown in waveform 2-3 that individual lamp and/or the individual Inverter drive output is defective. Consequently, in either case the complete Panel Assembly must be replaced.

2) To confi rm the Inverter board is detecting a defective lamp check the “Panel Detect” line on CN8001/pin 11, which is typically 4V. This is an output signal from the Inverter board to the Main Microprocessor. This line will monetarily go to 4V and immediately go to 0V if a defect is detected.

Non-Functioning Inverter Board

(Audio is momentarily heard, but No Video is displayed and

the unit immediately shuts down)

In this case the most likely culprit is a non-functioning Inverter board (all outputs missing). Either the Inverter circuit itself is defective or there is a missing power source or control line. If the Inverter circuit is defective the complete Panel assembly must be replaced. Check the following to determine if the problem is in the Inverter or the supporting circuits.

1) 16.5V supply voltage CN8001/pns 1 – 5

2) “Backlight” control voltage CN8001/pin 12 (this 3.3V voltage turns the Inverter circuit and consequently the Backlights)

If the 16.5V supply is missing, check for open connections or a defective primary power supply on the G1-board (reference the chapter on Power Supply for details). If the ‘Backlight” control signal is missing, check for open connections and trace signal back to Main Microprocessor.

If both of these voltages are present and all Inverter outputs are missing, then the Inverter circuit is defective and the complete Panel Assembly must be replaced.

Defective LCD Panel

(Missing Row(s) or Column(s) of Pixels)

Only a defective LCD panel can cause Missing Row(s) or Column(s) of Pixels. Since no supporting circuitry would cause this type of defect, when this symptom occurs the complete panel assembly must be replaced

CTV-33 18


Backlight Inverter Outputs and InputsRef. Figure 2-1 KLV-26HG2 and Figure 2-2 KLV-32M1

NOTE: If the unit is shutting down due to a defect, the following measurements can be momentarily observed just prior to the unit shutting down and going into protection mode.

1) Confi rm Backlight Inverter board outputs (refer to Waveform 2-1, 2-2, 2-3). The actual output of the Inverter board is approximately 1100Vrms. Therefore, it is best to measure these voltages by bringing the oscilloscope probe in close proximity to the output connector and individual wire, or rest the probe on the outer coating of the individual wire. Access the connectors by removing the rear cover. The connectors are vertically aligned down the left side of the chassis (viewed from rear of unit). Reference fi gures 2-5 and 2-6 for connector locations. The connectors with the two black wires are the output high-voltage connectors. The other connectors are the return lines (pink and white wires). Set the oscilloscope setting as shown on waveforms 2-1, and hold the probe close to the connector. Because of the plastic cover over the connectors hold the probe as close as possible and directly over the individual black wire. NOTE: The probe should be directly over the particular black wire being measures to get maximum reading. There are two output wires per connector, if the probe is held between the two wires the reading will be somewhat lower then the display shown in waveform 2-1.

a. Waveform 2-1 or 2-2 should be observed on all connectors if the Inverter is working properly.

b. If waveform 2-3 is observed the single output (single black wire) that the probe is measuring is defective. The low reading that is displayed is from the adjacent output. Moving the probe over the adjacent output should increase the amplitude of the waveform. In the case of a single defective output the Backlight Inverter board is defective. Consequently, the complete LCD Panel Assembly most be replaced.

WAVEFORM 2-1

KLV-26HG2 INVERTER OUTPUT

WAVEFORM 2-2

KLV-32M1 INVERTER OUTPUT

WAVEFORM 2-3

LOW INVERT OUTPUT

CTV-33 19


Inverter Outputs:� Eight Connectors� 16 Lamps� One Black Wire per Lamp

FIGURE 2-5

KLV-26HG2 INVERTER BOARD

CTV-33 20


Inverter Outputs:� Eight Connectors� 16 Lamps� One Pink Wire per Lamp

FIGURE 2-6

KLV-32M1 INVERTER BOARD PHOTO

CTV-33 21


2) Confi rm Backlight Inverter Control and Detection Signals (reference Figure 2-1). If, as discussed in step one, all the output waveforms are completely missing, then the Inverter circuit may be defective, or one of the input voltages or control signals is missing.

a. Check for the presents of the 16.5V supply on CN8001/pins 1-5. This voltage is developed by the primary power supply on the GL-board.

b. Check the following detect and control signals on CN8001 on the Inverter board.

i. Panel Detect – In normal operation 4V, which indicates a properly functioning Inverter circuit and lamps.

This is an output signal from the Inverter board that goes to 0V when it detects a failure in the Inverter circuit or in one or more lamps.

ii. Backlight - 3.3V

This is an input signal to the Inverter board, which comes from the main microprocessor IC1006 on the B1-board to turn ON/OFF the Inverter circuit and illuminate the lamps.

iii. Dimmer - 1V to 5V depending on the Picture Mode selected (Pro, Standard, or Vivid)

This is an input signal to the Inverter board, which comes from the main microprocessor to control the luminance (or Dimmer) level of the Backlight.

LCD Logic Board TroubleshootingRef. Figure 2-1 KLV-26HG2 and 2-2 KLV-32M1

A defect on the LCD logic board will affect the video displayed and/or timing of the LCD panel.

1) Panel Voltage KLV-26HG2: Confi rm the Panel 12V on CN5801 pins (26 – 30) on the B-board, and that the voltage is at the LCD logic board connector. This voltage is developed by the secondary power supply on the A1-board (not shown).

2) Panel Voltage KLV-32M1: Confi rm the Panel 5V on CN4501/pins 1 & 2 on the BL-Board, and that the voltage is at the LCD logic board connector. This voltage is developed by the secondary power supply on the AU-board (not shown).

3) Video/Sync Data Signals KLV-32M1: Confi rm the (TX+/TX-) signals on CN4501 BL-board (Ref. Waveforms), and that the signals are applied to the Logic board connector (RX+/RX- signals). This is the LVDS cable connection between the BL-board and the logic board.

4) Video/Sync Data Signals KLV-26HG2: Confi rm the (TX+/TX-) signals on CN5801 BL-board (Ref. Waveforms). and that the signals are applied to the Logic board connector (RX+/RX- signals). This is the LVDS cable connection between the B-board and the logic board.

NOTE: Apply a White Raster generator signal to the unit to the display the signal as shown in the following waveform diagrams.

CTV-33 22


WAVEFORM. 2-4

RX+/RX- WAVEFORM

CNT1/IN 5

WAVEFORM. 2-5

RX+/RX- WAVEFORM

CNT1/PIN 11

WAVEFORM. 2-6

RX+/RX- WAVEFORM

CNT1/PIN 17

NOTE: Reference the “Chassis Disassembly” sections for details on separating the chassis assembly from the LCD Panel assembly for access to the Logic board and CNT1 connector.

CTV-33 23


Logic BoardCNT1

LVDS Cable

CAUTION: Lift chassis slowly when accessing theLogic board. The LVDS cable has little slack at the

B-board connector. Raise chassis only enough to gainaccess to Logic board CNT1 connector

FIGURE 2-7

KLV-26HG2 LOGIC BOARD ACCESS

CTV-33 24


LVDS Cable

Logic Board

Inverter Cable

CNT1

CAUTION: Lift chassis slowly when accessing theLogic board. The LVDS cable and Inverter cable aretaped down, and must be untaped to provide cable

slack to raise the chassis. Raise chassis only enoughto gain access to Logic board CNT1 connector

FIGURE 2-8

KLV-32M1 LOGIC BOARD ACCESS

CTV-33 25


Light Raster Display

(Unit Powers Up with No Video, Constant Light Raster Only,

and Audio OK)

The most likely cause of this symptom is the loss of the 12V Panel voltage on the KLV-26HG2, and the 5V Panel voltage on the KLV-32M1. The unit will power up normally, but only a light white raster will be displayed and audio will be present. The unit remains ON and does not trigger a protection mode shutdown. Confi rm the 12V on CN5801/pins 1 & 2 on the KLV-26HG2 model, and the 5V on CN4501/pins 26 – 30 on the KLV-32M1 model.

Video or Sync Distortion

The following fi gures (2-9, 2-10, 2-11, and 2-12) illustrate the affects (or symptoms) of possible video distortions due to a LVDS Cable defect. The LVDS cable transports video and sync information from the B-board to the Logic board on the KLV-26HG2, and between BL-board and the Logic board on the KLV-32M1. The text associated with each picture describes the distortion and the possible cause.

CTV-33 26


FIGURE 2-9

COLOR DISTORTION

CTV-33 27


FIGURE 2-10

COLOR & LUMINANCE DISTORTION

CTV-33 28


Figures 2-9 and 2-10 illustrate the video distortions caused by an open circuit on the LVDS cable, which carry video RGB video information. Figure 2-9 illustrates a loss of signal on CN5801/pins 5 or 6 (KLV-26HG2), and CN4501/ pins 5 or 6 (KLV-32M1). These two lines carry strictly RGB information (no HS or VS sync information). Therefore, a loss of signal on these lines causes a loss of a primary color. In this case it is a loss of primary blue and/or green, causing the reddish coloring of the picture.

Figure 2-10 illustrates a loss of signal on CN5801/pins 17 or 18 (KLV-26HG2), and CN4501/ pins 17 or 18 (KLV-32M1). These two lines also only carry RGB information (no HS or VS sync information). Therefore, a loss of signal on these lines causes a loss of a primary color. In addition, a defect on these lines also affects the luminance. The affect is a black-and-white picture with a solarization or blooming aspect. In this case it is a loss of primary blue and/or green, causing the reddish coloring of the picture.

CTV-33 29


FIGURE 2-11

SYNC DISTORTION

CTV-33 30


FIGURE 2-12

SYNC DISTORTION

CTV-33 31


Both fi gure 2-11 and 2-12 illustrate a loss of signal on CN5801/pins 11 or 12 (KLV-26HG2), and CN4501/ pins 11 or 12 (KLV-32M1). The signal on these pins contains the blue video information along with the HS and VS sync information. Therefore, if there is an open circuit on these pins on the LVDS there will be a complete loss of picture synchronization displayed on the screen.

CTV-33 32


Chassis Disassembly KLV-26HG2 Remove the plastic rear cover and pedestal. The boards and panel can be separated as two complete assemblies, for easy access to the LCD Panel Assembly.

FIGURE 2-13

KLV-26HG2 CHASSIS AND PANEL ASSEMBLY

1) Figure 2-13 shows the KLV-26HG2 chassis completely assembled with the plastic back cover, pedestal bracket, and pedestal removed.

CTV-33 33


2) Remove the pedestal bracket by removing the four screws as shown in Figure 2-13. (Note: This picture has the speakers, key function board, and MSX board removed.)

Screw Screw

ScrewScrew

FIGURE 2-14

KLV-26HG2 PEDESTAL BRACKET REMOVAL

CTV-33 34


3) Once the pedestal bracket is removed all boards are exposed as shown in Figure 2-15. NOTE: Most boards and connectors are accessible for signal and voltage checks. The pedestal can be reattached to stand the unit upright when troubleshooting.

To separate the Board Chassis from the Panel Assembly remove sixteen screws and disconnect eight connectors (LVDS Cable Inverter Cable, Speakers Wires, U1-Board connectors, A1-Board connector, H3-Board connector), then remove the MSX-Board (Ref. Figure 2-15 and Figure 2-16).

Screwon side

2 Screw

2 Screw2 Screw

2 Screw

Screw Screw

Screw underMS-Board

Screw underP-BoardScrew

on side

Screwon side

Screwon side

FIGURE 2-15

KLV-26HG2 SCREW REMOVAL

CTV-33 35


Screw underthe MS-Board

Screw underP-Board

DisconnectConnector

RemoveMXS-Board& Function

Switchboard

DisconnectConnectoron Inverter

Board

DisconnectConnector

DisconnectConnector

DisconnectConnector

DisconnectConnector

Disconnect TwoConnector

DisconnectLVDS Connector

FIGURE 2-16

KLV-26HG2 DISCONNECTION

CTV-33 36


4) Figure 2-17 shows the complete KLV-26HG2 Board Assembly

FIGURE 2-17

KLV-26HG2 CHASSIS ASSEMBLY

CTV-33 37


5) Figure 2-18 shows the Panel Assembly (including the LCD Panel, Logic Board, and Inverter Board) with the Board Assembly removed. The complete Panel Assembly can be lifted out of the plastic front bezel by grasping any two corners tabs and lifting.

Grab Corner Tabsto Remove Panel

assemble

FIGURE 2-18

KLV-26HG2 PANEL ASSEMBLY

CTV-33 38


Chassis Disassembly KLV-32M1 Remove the plastic rear cover and pedestal. The boards and panel can be separated as two complete assemblies, for easy access to the LCD Panel Assembly.

1) Figure 2-19 shows the KLV-32M1 chassis completely assembled with the plastic back cover, pedestal bracket, and pedestal removed. To separate the Board Chassis from the LCD Panel Assembly remove eight screws and four connectors (Ref. Figure2-19). NOTE: Most boards and connectors are accessible for signal and voltage checks. The pedestal can be reattached to stand the unit upright when troubleshooting.

CTV-33 39


2 Screws 2 Screws

2 Screws2 ScrewsDisconnect

LVDS Connector

DisconnectConnectoron Inverter

Board

DisconnectSpeakers

Connector

DisconnectConnectors

FIGURE 2-19

KLV-32M1 CHASSIS AND PANEL ASSEMBLY

CTV-33 40


2) Figure 2-17 shows the complete KLV-32M1 Board Assembly

FIGURE 2-20

KLV-32M1 CHASSIS ASSEMBLY

CTV-33 41


3) To separate the LCD Panel Assembly from the front bezel, remove the edge brackets. There are fi ve screws on each side and six screws on both the top and bottom of the assembly that must be removed. (Ref. Figure 2-21)

5 Screws

6 Screws

5 Screws

6 Screws

FIGURE 2-21

KLV-32M1 PANEL ASSEMBLY

CTV-33 42


4) After removing the brackets the LCD Panel Assembly can be separated from the front bezel. (Ref. Figure 2-22)

FIGURE 2-22

LCD PANEL

CTV-33 43

Chapter 3 - Power Supply Overall Blocks

OverviewThe KLV-26HG2 and the KLV-32M1 both incorporate three power supplies: (Ref. Figures 3-1 and 3-2)

• Standby 5V Power Supply: This is a switch-mode power supply, which uses an eight-pin (A6169SK401) type converter IC to produce the standby 5V. The standby 5V output is applied to the Main Microprocessor as long as AC is applied to the unit.

• Primary Power Supply: This is a switch-mode power supply, which uses the MCZ3001 converter IC to produce the 16.5V, 6.8V, 17V, and 33V for the KLV-26HG2 unit, and 16.5V, 10.5V, 30V, and 33V for the KLV-32M1 unit. The Primary power supply is turned ON using the Power 1 control line for the Main Microprocessor.

• Secondary Power Supply: This is a switch-mode power supply, which uses the MCZ3001 converter dual-package IC. The IC used for the secondary power supply actually has two MCZ3001 converter ICs in one package, which produces the D3.3V, 12V Panel Voltage, and Reg. 9V output voltages for the KLV-26HG2, and D3.3V, 5V Panel Voltage, and D5V output voltages for the KLV-32M1. The Secondary power supply is turned ON using the Power 3 and Power 4 control lines for the Main Microprocessor. The 12V Panel voltage is turned ON separately using the Power 2 control line from the Main Microprocessor. The IC specifi c troubleshooting methods in the previous courses (TVP-18 and C31P15) can be applied to the dual-package IC confi guration.

The power supplies are basically identical in both the KLV-26HG2 and KLV-32M1 units as illustrated in fi gures 3-1 and 3-2. Therefore, the following circuit descriptions and troubleshooting procedures can be applied to either model. Any differences that exist between the two models will be noted throughout the text.

The Standby 5V and the Primary Power supplies are both located on the G1-board for the KLV-26HG2, and on the GL-board for the KLV-32M1. The Secondary Power supply, and associated regulator circuits are located on the A1-board for the KLV-26HG2, and on the AU-board for the KLV-32M1.

CTV-33 44

3. Power Supply Overall Blocks

A1 BoardG1 Board

ACInput

Power 1 (ON)from B-Board

STBY 5Vto B-BoardMain Micro

To InverterBoard

F601 IC6002PrimaryPowerSupply

IC6001Standby

5VPowerSupply

16.5V

17V

6.8V

33V

16.5V

17V

PS4601

IC4601Secondary

PowerSupply

TunerBoard

5V Reg

D5V to B-Board

3.3V toB-BoardMemory

Stick

AudioCircuits

D3.3V to B-Board

12V Panel Volageto Logic Board

9VReg

9V to B-BoardPS4602

30V Reg

PS6450

9VReg

PS7001

AudioAmplifier

Power 3from B-Board

Power 4from B-Board

Power 2 from B-Board

MSB Board3.3V Reg

13

5\71\2

11

1\5

CN6004

CN6003

CN6006

13

24

25

5\7

1\2

11

CN4601

CN2801

CN4601

11

1

8

9

CN4603

CN2801

CN4603

PH6001

1

3

Q6007

Q6007

3.2V

3.2V

3.2V

3.2V

D6000

STBY5V

Q4605

Q460623

FIGURE 3-1

KLV-26HG2 POWER SUPPLY

CTV-33 45


AU-BoardGL-Board

Power 1 (ON)from BL-Board

STBY 5Vto BL-BoardMain Micro

To InverterBoard

IC621PrimaryPowerSupply

10.5V

30V

33V

16.5V

17V

IC7002Secondary

PowerSupply

Audio Amplifier

Tuner

IC661Standby

5VPowerSupply

PH662

Power 3from B-Board

Power 4from B-Board

AU9V(Audio)

Reg 9V to BL-Board

Reg 5V to ULU-Board

9V Reg

9V Reg

5V Reg

Q681

Q661

Q7002

Q70033.2V

3.2V

3.2V

3.2V

D3.3V to BL-Board

5V PanelVoltage

D5V to BL-Board

Power 2from B-Board

STBY5V

PS7000

PS8500

PS7001

F601ACInput

D6000

RY601

TH601

1\5

5\8

1\2

12

15

14

CN652

CN651

5\8

30V Reg

1\2

12

15

14

B38

A38

CN7000

CN5504A47

A43

B39

B45

B44

17

A39

A50

CN5504

CN5504

CN5500

STBY 5V

FIGURE 3-2

KLV-32M1 POWER SUPPLY

CTV-33 46


Power ON Sequence and Output VoltagesRef. Figures 3-1 and 3-2

1) AC is applied directly to the G1-board (KLV-26HG2), or the GL-board (KLV-32M1), through the main fuse F601. The AC is rectifi ed and fi ltered and applied directly to the Standby 5V power supply circuit and the Primary power supply circuit. The Standby 5V power supply starts immediately after AC is applied and outputs the Standby 5V, which is then applied to the Main Microprocessor on the B-board (KLV-26HG2), or the BL-board (KLV-32M1) to activate the standby mode of operation (or Sleep-Mode). The RED LED on the front panel of the unit when lit will indicate a properly function Standby 5V power supply. As long as AC is applied to the unit, the LED should glow red.

2) To turn the unit ON after the Standby mode is established the Power 1 (ON) signal must go high (3.2V) to activate the Primary power supply. The Power 1 signal comes from the Main Microprocessor after the Power Button on the front panel or on the remote has been depressed. The Primary power is now active and outputs the voltages shown in Figures 3-1 and 3-2 for both models. One notable difference between the models is the presents of the AC input relay RY601 in the KLV-32M1 models. This relay along with the thermistor TH601 is actually used to limit the inrush current during initial power up. The thermister absorbs the initial surge current until the Primary power supply 16.5V output is produced. The 16.5V is applied to the relay, which activates and bypasses the thermistor in the ON-mode.

3) Once the Primary power supply 16.5V output is produced on both the KLV-26HG2 and the KLV-32M1 models and the main microprocessor sends the Power 3 and Power 4 signals to turn ON the Secondary power supply. The main Microprocessor monitors the 16.5V signal on the DCIN-ALERT line located at CN4603/pin 21 (KLV-26HG2), and CN5504/pin B40 (KLV-32M1).

4) The fi nal DC voltage to be switched ON is the 12V Panel voltage. Once the D3.3V is produced the main microprocessor sends the Power 2 signal to turn the 12V Panel switch ON and pass the 12V to the Logic board.

CTV-33 47


Power Supply Troubleshooting

Chassis DC Voltage Map

Main Micro

AV Switcher

Tuner

ComponentSwitcher

DVI or HDMI

LCD ScanConverter

Wega Engine

DRC

LCD Driver

REGSTBY 5V

9V

33V

3.3V

30V

D5V

REG

REG

3.3V

3.3V

2.5V

REG 3.3V

D3.3V

REG

REG

2.5V

2.5V

REG 1.8V

REG 2.5V

REG

PanelLogic Brd

PanelInverter Brd

AudioProcessor

AudioAmplifier

Memory StickBoards

(KLV-26HG2) Panel 12V(KLV-32M1) Panel 5V

16.5V

AU 9V

(KLV-26HG2) MS 3.3VMSB-Brd

(KLV-26HG2) 17V(KLV-32M1) 30V

FIGURE 3-3

CHASSIS DC VOLTAGE MAP

CTV-33 48


Figure 3-3 is a complete chassis DC voltage map that shows how the various DC voltages are distributed throughout the KLV-26HG2 and the KLV-32M1 models. Both chassis DC distribution layouts are basically the same except for those that are noted with the specifi c model in parenthesis next to the differing attribute.

Figure 3-3 can be very helpful in the troubleshooting process. The key aspect to note exactly what circuits use what voltages. This information, along with the noted symptoms of a defective unit, will be extremely helpful in determining the area to focus troubleshooting efforts.

For example, note that the 9V only applies to the Tuner and AV Switcher. Therefore, if the 9V line is lost only those two circuits are affected. In this case the unit will probably power up OK but have no video. However, the Component, DVI, and Memory Stick video inputs are functional to test the video circuits and panel.

For another example note that the D3.3V main powers all the video processing circuits. In the case of a missing D3.3V there would obviously be no video, however, audio would be OK. Furthermore, the unit will probably power up OK with a light raster displayed.

Basic Checks

Ref. Figures 3-1 and 3-2

Confi rm Operation of Standby 5V Power Supply

1) The fi rst thing to take notice of is whether the RED LED is illuminated on the front panel. As long as AC is applied the RED LED should be illuminated.

2) Check for 5V on CN6006/pin 1 (KLV-26HG2) and CN651/pin 14 (KLV-32M1)

3) Check F601

4) Check TH601 (KLV-32M1 Only)

5) Disconnect CN6006 (KLV-26HG2), or CN651 (KLV-32M1), to unload the Standby 5V power supply, and apply AC input. If 5V output is OK unloaded, check for short circuit condition in the connecting circuits. If 5V is still not present after unloading, then the standby power supply circuit is defective.

Confi rm Operation of Primary Power Supply

1) Confi rm Standby 5V power supply operation. This is a necessary step because the Primary power supply converter IC requires the 17V for its VCC, The 17V is produced in the Standby 5V power supply .

The RED LED when illuminated indicates a properly functioning 5V Standby power supply.

2) Confi rm rectifi ed DC from D6000 is applied to the Primary power supply.

3) Does GREEN LED illuminate?

a. If GREEN LED does illuminate after pressing the Power button, then this indicates that the main microprocessor has received the ON command and is working properly.

b. If the GREEN LED does not illuminate after pressing the Power button, then there is a problem with the Main Microprocessor and this is the area where troubleshooting should be focused.

4) Confi rm Power 1 (ON) signal is going high (3.2V) at CN6006/pin 3 (KLV-26HG2) and CN651/pin 15 (KLV-32M1).

5) Confi rm all voltage outputs

a. 16.5V, 6.8V, 17V, and 33V (KLV-26HG2)

b. 16.5V, 10.5V, 30V, and 33V (KLV-32M1)

CTV-33 49


Confi rm Operation of Secondary Power Supply

1) Confi rm Standby 5V power supply operation. This is a necessary step because the Primary power supply converter IC requires the 17V for its VCC, The 17V is produced in the Standby 5V power supply .

The RED LED when illuminated indicates a properly functioning 5V Standby power supply.

2) Confi rm Primary power supply operation because it requires the 16.5V and 6.8V supplies (KLV-26HG2), or 10.5V (KLV-32M1), from the Primary power supply to start and function properly.

3) Check PS4601 and PS4602 (KLV-26HG2 only)

4) Confi rm Power 3 and Power 4 signals are going high (3.2V) at CN2801/pins 24 & 25 (KLV-26HG2), or CN5504/pins B38 & A38 (KLV-32M1).

a. Power 3 controls the half of the dual MCZ30001 converter package that develops the D3.3V.

b. Power 4 controls the half of the dual MCZ30001 converter package that develops the 12V, which is used for the 12V Panel voltage (KLV-26HG2) and also to drive the 9V regulator, or the 5V (KLV-32M1), which is used for the 5V Panel voltage and the D5V

5) Confi rm all voltage outputs

a. D3.3V, 12V, 9V (KLV-26HG2)

b. D3.3V, 5V, D5V (KLV-32M1)

CTV-33 50


Detailed Power Supply Diagrams and Operations

Standby 5V Power Supply

IC6001STR-A6459

8 7 6 5

1 2 3 4

1

3

6

4

T60019

8

ACInput

1

2

R6026

C6008

R6054

R6030

C6030

D6015

D6000CN6006

To B-BoardCN1009

G1 Board

StartSwitching

FBVC1OCP

4.7ohm

21KHz

0.02V

+

KLV 26HG2

IC681Ref.

3

1

2

R6040D6010

D6011

R6032

R6045R6047

R6052

R6053

D6007

C6023STBY 5V

Volts/Div: 100VTime Base: 20us

Waveform 3-1

0.25V

17V

C6008

FIGURE 3-4

KLV-26HG2 STANDBY 5V POWER SUPPLY SCHEMATIC

CTV-33 51


IC661STR-A6169

8 7 6 5

1 2 3 4

6

4

2

1

4

3

1

2

IC681Ref.

3

1

2

T661

PH651

9

8

ACInput

14

13

R660

C612

C661

R667D663

C665R661

D661C662

R666

R680

R1925

C682

D681

D601CN651

To AU-BoardCN7000

GL Board

StartSwitching

FBVC1OCP

4.7ohm

242V95KHz

0.02V 21V0.6V

+

0.6V

0V

4.5V

3.5V

KLV-32M1 St db 5V P S l

R681

R682

R683

R684

STBY 5V


Waveform 3-2

FIGURE 3-5

KLV-32M1 STANDBY 5V POWER SUPPLY SCHEMATIC

CTV-33 52


The Standby 5V power is a switch-mode power supply. IC661 (STR-A6169) is the converter that produces the switching function. When the TV is plugged in AC power is applied directly to the rectifi er D601. Therefore, as long as AC is applied to the TV the Standby 5V power is active and outputting 5V.

The AC input is rectifi ed and fi ltered, approximately 242Vdc is applied to IC661/pin 5 (Start), and IC661 begins the switching function. At the same time the initial rise of the 242Vdc signal is applied to T661/pin 6, and coupled over to the coil connected to T661/pin 2; the output at T661/pin 2 is rectifi ed and fi ltered to produce the VC1 voltage at IC661/pin 2 this sustains the switching function of IC661 after the initial DC supply to IC661/pin 5. Approximately 21Vdc is applied to IC661/pin 2. This can be considered IC661’s running power supply because once IC661/pin 2 is up to 21V the internal circuits of IC661 turn off the input form IC661/pin 5.

To provide output regulation, a feedback signal is necessary. The 5V output is monitored using IC681 (Reference) and PH651 (Optic Coupler). The 5V output will vary depending on the load on the secondary of T661 (or CN651). A feedback voltage of approximately 0.6V is applied to IC1900/pin 4 through IC1901 and PH1902. As the load changes, the feedback voltage will change, and the frequency of the switching functions at IC661/pins 7 & 8 will change, which will regulator the 5V output.

IC661/pins 7 & 8 switches the low side of the coil at T661/pin 4 at approximately 95KHz. As the 5V output decreases the switching frequency will increase, and as the 5V output increases the switching frequency will decrease.

Troubleshooting

Ref. Figure 3-5

NOTE: Use local ground at IC1900/pin 3 as the reference for all

measurements.

1) Confi rm 242Vdc at IC661/pin 5. This voltage is necessary to start the switching function of the IC.

2) Confi rm 21Vdc at IC661/pin 2. This voltage should remain constant. If this voltage rises and immediatly falls, the switching function of IC661 is not occurring.

3) Confi rm switching frequency at IC661/pins 7 & 8. This should be a constant 95KHz. If this frequency is much higher or lower than 95KHz then there is a secondary loading problem or feedback problem.

4) Confi rm 0.6V at IC661/pin 4. In normal operation this voltage should be 0.6V. This voltage is directly proportional to the 5V output. Consequently, if the 5V is loaded down (short circuit) the feedback line will be lower than 0.6V, and if there is an over-voltage problem the feedback line will be higher than 0.6V. Also, if there is an open circuit in the feedback line (no feedback to IC661) the output frequency will be at its highest level.

5) This power supply can be tested unloaded when an external problem is suspected (e.g as a shorted condition).

Turn the unit OFF and disconnect CN651. Re-apply AC to the power supply and confi rm all output voltages in the unloaded condition. Confi rm steps 1 through 4.

CTV-33 53


Primary Power SupplyFigure 3-6 is the schematic diagram for the Primary power supply in both the KLV-26HG2 and KLV-32M1 models. The reference numbers shown in Figure 3-6 are for the KLV-26HG2, just change the reference numbers to apply the diagram to the KLV-32M1 model. The operations between the two models are identical except for differences in a couple of output voltages.

CTV-33 54


TO IC6000 PIN 22

1

21

17

14

V-SENSE

VB

VC2

TIMEROCP

IC6000IC621

MCZ3001

23

22

720

VG(H)

VS

VG(L)

F/B VCI2 15

5

R6061

16

13

12

10

13

IC6005Ref.

3 1

2

R6031

D6012

C6036 +

R6062

R6034

R6044

R6063

PH6002

R6070

T6001

Q6005

Q6006

R6033

R6039

R6038

11

D6015

8.3V

0V

19V1.8V

10.4V

120V

2.5V124V

130V

5V

230Vp-p60kHz

R6037

Grnd

D6004

D6009

D6014

D6013

D1621

15V

15V

15V

15V

(15V)

18

C6017+ 9

D6018

D6020

D6019

C6047

C6042

C6044

C6049

+

+

+

+

R6072

C6005+

C6035

From D1611

AC Input

16.5V

12V

6V

3.3V

4 1

23

9.4V

2.5V

247V

5

7

T6002

17V fromStandby 5V

Power Supply

PH6001

17V

STBY 5V

Power 1 (ON)

Q6007

Q6003

Q6004

G1-BOARD

GL-BOARD (KLV32M1)

(KLV26HG2)


Waveform 3-3

FIGURE 3-6

KLV-26HG2 & KLV-32M1 PRIMARY POWER SUPPLY SCHEMATIC

CTV-33 55


Ref. Figure 3-6

Both power supplies use the same converter IC (MCZ3001) as the heart of their separate switch-mode power circuits, along with two drive MOSFETS and associated components. MCZ3001 contains all the needed circuitry necessary to function as a switching power supply: (except for the Power Switching MOSFETS)

• Control circuitry

• Oscillator/Oscillator control

• Output Driver transistors

• 10V regulator

• Soft-Start / Delay Shut-Off Timer

• Over Current Protection

• Over and Under Voltage Protection

The same basic circuit Theory of Operation, and Troubleshooting Procedures describe in the following paragraphs can be applied to either of the Power Supply circuits.

NOTE: The KLV-26HG2 Primary Power Supply component reference numbers will be used in the following circuit description and troubleshooting procedures, just change the component reference numbers to apply the descriptions and procedures for the KLV-32M1 Primary Power Supply.

Switching Power Supply Operation

Ref. Figure 3-6 for the following circuit description.

This procedure can be applied to either the KLV-26HG2 or KLV-32M1 Primary or Secondary Power supplies.

AC signal is applied to the rectifi er block D601. The AC component is fi ltered-out and multiplied by the fi lter circuit (not shown). A DC voltage of

250V is produced at the output of the fi lter circuit. The following process continues from this point:

IC1606 Startup Sequence

1) Turn ON voltage: The 250Vdc from the fi lter circuit fi rst passes through fusible link resistor R6031 and then is voltage divided by R6037, R6038, R6039, and R6033 down to 2.5Vdc. This voltage is applied to IC6000/pin 1 (Vsense) and IC6000 turns ON. IC6000/pin1 (Vsense) is also used for OVP protection (IC6000/pin 1 > 8V will trigger OVP).

2) Internal Circuit Start Voltage: The 250Vdc from R6031 is also connected directly to the Drain of Q6005 and serves as the High-side FET power source.

Internal circuits initially powered in IC6000

• Internal drive transistors for the output FETS Q1614 and Q1613

• Oscillator

• Control circuit

• 10V regulator (IC6000/pin 17)

Note: The 10V output at IC6000/pin 17 passes through D6012 and is then fed back into IC6000/pin 21 supplying power to the internal driver transistor for the Low & High side output FETS Q6005 and Q6006

3) Output Oscillations: At this point, initial square-wave oscillations of approximately 60KHz are output at IC6000/ pins 23 and 20. Normal operation frequency is approximately 60KHz.

CTV-33 56


4) Regulator Feedback: The feedback line is connected to the Set 12V secondary output. Once IC6000 is turned ON and oscillations begin, the secondary winding at T6001/pins 13 and associated circuitry produces 12V. The 12V is applied to IC6005/pin 1 (Ref. IC).

IC6005 controls the voltage at the PH6002/pin 2, which controls the current output of the optic-coupler PH6002. The amount of current supplied to IC6000/pin 2 depends on how hard PH6002 is turned ON. In normal operation, a voltage of 1.8Vdc (which is proportional to the amount of current) is present at IC6000/pin 2. The feedback loop is now complete.

5) IC6000 normal operating (or running) power supply (VC1):

The 17V at IC6000/pin 15 (VC1) is produced by the Standby 5V power supply. The 17V is applied to IC6000/pin 15 through a switching circuit consisting of Q6003, Q6004, and PH6001. The switching circuit is controlled by the POWER 1 (ON) signal, which is a function ON/OFF button or the ON/OFF from the remote controller. Therefore, this is the power ON switching circuit. All of IC6000’s internal circuits are powered from the 17V at IC1606/pin 8.

Over Current Protection (OCP):

Ref. Figure 3-6

The current fl owing through the switching MOSFETS (Q6005 & Q6006) also passes through T6001/pins 5 and 7, C6035, R6061, and then to ground. The same current also passes through the parallel resistor circuit of R6034 and R6044. This current is directly proportional to the current through the switching MOSFETS. The voltage across R6044 is applied to IC6000/pin 16. The OCP is activated when the voltage at IC6000/pin 16 exceeds 0.2V.

Over Voltage Protection (OVP) and Under Voltage Protection (UVP): The voltage at IC6000/pin 15 (VC1) is monitored by circuitry inside IC16000 for Under-voltage and Over-voltage conditions. The two conditions are as follows:

OVP – greater than 33V

UVP – less than 8V

If either of these two conditions occurs at IC6000/pin 15, the unit will go into protection mode.

CTV-33 57


IC4601IC7002

1

3

13

15

29

27

22

30

16

19

17

Q4601Q4602

Q4603

Output 1H

Output 1L

Output 2H

Output 2L

Internal5V Reg.

VCL1

VCL2

D3.3V

12V

FB

FB

Soft Start

Soft Start

10 STBY 2Power 4

9 STBY 1Power 3

From MainMicro


3.2V

3.2V

5V

0.8V

0.8V

5V

3.4V

9V

2.5V

30

16

VCH2

VCH2

8V

9.9V

24 VCC16.5V10.5V

(KLV26HG2)(KLV32M1)

PS4601PS7001

R4616R7011

R4620R7014

R4617R7017

R4621R7015

Waveform 3-4

FIGURE 3-7

KLV-26HG2 & KLV-32M1 SECONDARY POWER SUPPLY

Secondary Power Supply

CTV-33 58


Troubleshooting

1) Confi rm the 16.5V (KLV-26HG2), or 10.5V (KLV-32M1), VCC power supply at pin 24.

2) Confi rm Power 3 and Power 4 signals (both 3.2V) at pins 9 and 10 respectively. These are the unit Turn-ON signals from the main microprocessor and should be a constant 3.2V in the ON mode.

3) Confi rm the Internal 5V regulator is functioning properly. Check 5V at pin 22. Also check for 5V at pins 30 & 16.

4) Confi rm the output signals at pins 29 & 27 for the D3.3V converter, and pins 19 & 17 for the 12V converter. The signal that should be observed at these outputs is the waveform shown on the Figure 3-7.

5) If VCC, Power 3 & 4, and the internal 5V are OK, but no output then either the converter IC or the MOSFET outputs transistors are defective.

a. Unsolder pins 29, 27, 19, and 17. If output signal is now present replace output MOSFETs (Q4601, Q4602, and Q4603).

If the output is still missing, then replace the converter IC (IC4601 or IC7002).

CTV-33 59

Chapter 4 - Video Processing

Video Circuit DescriptionsThe core video processing section of KLV-26HG2 and the KLV-32M1 are identical and consist of the following integrated circuits:

Wega Engine (CCP2)

IC3007 KLV-26HG2 IC2006 KLV-32M1

The CCP2 performs A/D conversion, 3D Comb fi ltering (or Y/C separation), Chroma decoding, Image Quality processing (e.g. sharpness), Noise Reduction, and Sync Separation.

Digital Reality Creator (DRC)


The DRC performs Interlace to Progressive Scan conversion, 480i Up-conversion to 480p, further Noise Reduction, and it also performs D/A conversion for inspection of the internal video signals at the test points (KLV-26HG2: J3307. J3308, J3309; KLV-32M1: J3007. J3008, J3009).

Scan Converter (PW166)


The PW166 performs horizontal and vertical image up and down scaling, supporting NTSC 4:3 and 16:9 aspect ratios. Auto optimizing circuitry provides sharp full-screen images centered on the screen. This IC also produces the User and Service Mode ON-Screen-Displays (OSD).

LCD Drive (Bolt)


The Bolt performs further image processing to produce a high quality picture on the LCD screen.

V-Chip


This IC performs all processing for the Closed Caption (CC1, CC2, etc), Text (Text 1, Text 2, etc), and Parental Lock functions. VID line supplies the video signal for processing these various feature.

The only difference between the to models is the addition of the Memory Stick feature on the KLV-26HG2 model. Because of the identical nature of the circuits, the following section on troubleshooting can effectively be applied to either model. Exceptions will be noted in the text when a procedure only applies to a particular model.

CTV-33 60

4. Video Processing

U1-Board

H2-Board

TU-Board

IC2803Switcher

Video 1

Video 2

IC2511Switcher

Y/CV

C

A1-Board B-Board

UD-BoardDVI

Component

IC2505Switcher

Y

CB

CR

C/CB

CR

VIDVID

IC3600V-Chip

IC3007CCP2

R G B

IC3302DRC

IC7503Scan

Converter

IC5802LCD Drive

LCD Panel Assemble

IC5804LVDS TX


MS Board


MSX Board

480i

1080i, 720p, 480p

User & ServiceMode OSDGenerator

Memory StickOSD

Generator

V-Chip OSD

RF

(MS) Digital ComponentSignal

IC1006MainMicro

CCP_SW

I2C

I2C

J3307B-Y

J3308R-Y

J3309Y

X500114.32MHz

X580133MHz

X5802100MHz

MS MS

Y/CV

UART

3.3V

3.3V2.5V

3.3V2.5V

9V

5V

9V

3.3V

3.3V

2.5V

NOTE: DRC1.8V & 3.3V

Video Processing Circuit Troubleshooting

Overview

FIGURE 4-1

KLV-26HG2 VIDEO PROCESSING BLOCK DIAGRAM

CTV-33 61

4. Video Processing

IC9602Switcher

Video 1

Video 2

IC9801Switcher

Y/CV

C

ULU-Board BL-Board

Y/CV

C/CB

CR

VIDVID

IC2003V-Chip

IC2006CCP2

R G B

IC3002DRC

IC4007Scan

Converter

IC4502LCD Drive

LCD Panel Assemble

IC4504LVDS TX

480i

1080i, 720p, 480p

User & ServiceMode OSDGenerator

V-Chip OSD

P-BoardHDMI

Component Input

IC9800Switcher

Y

CB

CR

H3-BoardVideo 3

TunerRF

AU-Board

CCP_SW

I2C

IC1002MainMicro

I2C

J3007B-Y

J3008R-Y

J3009Y

X400114.32MHz

X450133MHz

X4502100MHz

UART

9V

5V

9V

3.3V

3.3V2.5V

3.3V

3.3V

2.5V

3.3V2.5V

NOTE: DRC1.8V & 3.3V

FIGURE 4-2

KLV-32M1 VIDEO PROCESSING BLOCK DIAGRAM

CTV-33 62

4. Video Processing

The video-circuits can be neatly divided into three distinct and separate sections for ease of troubleshooting. The separate sections are as follows (Ref. Figures 4-1 and 4-2).

• Switching Section

• Video Processing Section

• LCD Panel Section

The Switching Section handles all the composite, s-video, and component signal selection functions. As illustrated in fi gures 4-1 and 4-2 IC2803 (KLV-26HG2), or IC9602 (KLV-32M1) perform the composite video signal selection. Video 1, Video 2, Video 3 (KLV-32M1 only), and Tuner are all inputs to the composite video switcher. Losses of a single or multiple video sources are typical symptoms when a defect occurs in the video switcher section. For example, a missing Video 1 signal only would point to a possible defective composite switcher IC.

IC2505 (KLV-26HG2), or IC9800 (KLV-32M1), perform the component video signal selection. The component and DVI (KLV-26HG2) or HDMI (KLV-32M1) are inputs to the component video switcher.

The output of both the composite and the component switchers are applied to an analog switcher IC2511 (KLV-26HG2), or IC9801 (KLV-32M1), for further selection processing. At this point composite, s-video, or component video can be selected for further processing and display.

The Video Processing Section handles all A/D conversion, Signal fi ltering and separation, Scan-rate up and down conversion, picture quality, and noise-reduction processes. Reference the previous section for details on the specifi c integrated circuits that perform the various functions. Complete losses of video and luminance/color distortions are typical defects associated with the video processing section. For example, a loss or distortion of a 480i input signal only (component 1080i signal OK) would point to a possible defective DRC circuit.

The LCD Panel Assembly includes the LCD Panel, Logic board, and Backlight Inverter board. The LCD Panel produces the actual pixel timing and charging functions (Logic Board) to properly display the video on the

screen. The Panel Assembly also produces the necessary AC signals (Backlight Inverter Board) to activate and maintain proper backlighting for the LCD Panel. The operational description and troubleshooting procedures for the LCD Panel Assembly are discussed in detail in Chapter 2. In most cases a defective LCD Panel Assembly will cause a complete loss of video. On rare occasions a defective LCD Panel Assembly may cause a stationary defective row(s) or column(s) of pixels.

Troubleshooting

Ref. Figures 4-1 & 4-2

With the Switching, Video Processing, and LCD Panel sections in mind a divide and conquer type troubleshooting method can be employed to effectively and effi ciently determine the defective circuit or component. The following symptom/solution scenarios will be used to illustrate this troubleshooting method.

Unit powers up with a constant light white raster (No Video)

The unit powers up normally with only a light white raster displayed, and the unit does not shut down and go into protection mode. Check for the proper function of the 33MHz crystal connected to the LCD drive IC5802/X5801 (KLV-26HG2) or IC4502/X4502 (KLV-32M1).

Unit powers up and makes three attempts to display video; only a light raster is displayed three times

The unit powers up and dsplays a light white raster fl ashes on the screen three times. The unit shuts down, and the LED fl ashes a 2sec ON / 2sec OFF protection mode sequence indication.

Check the crystal X4001 (14MHz) connected to the scan converter IC7503 (KLV-26HG2) or IC4007 (KLV-32M1). If there is no crystal waveform check for 2.5Vdc on the crystal terminal. If there is 2.5V present then the scan converter IC is good, and the crystal is defective.

However, if 2.5V is not present the scan converter IC is defective and the BL-board (KLV-32M1) or B-borad (KLV-26HG2) must be replaced.

CTV-33 63

4. Video Processing

Loss of a Single Video Source

1) Confi rm the proper display of other video sources. For example, for a loss of Video 1 source, check Video 2 or Component Input sources for proper display.

2) Loss of single composite source(s)

a. Confi rm 9V to IC2803 (KLV-26HG2, A1-board), or IC9602 (KLV-32M1, ULU-board)

b. Confi rm data communications on I2C bus

3) Loss of single component source(s)

a. Confi rm 5V to IC2505 (KLV-26HG2, A1-board), or 6V IC9800 (KLV-32M1, ULU-board)

b. Confi rm data communications on I2C bus to IC2505 KLV-26HG2, A1-board), or 6V IC9800 (KLV-32M1, ULU-board)

Loss of Multiple Video Sources

(No Composite and Component; Memory Stick and V-Chip OSD OK)

1) Confi rm 9V power supply to IC2511 (KLV-26HG2, A1-board), or IC9801 (KLV-32M1, ULU-board)

2) Confi rm data communications on I2C bus to IC2511 (KLV-26HG2, A1-board), or IC9801 (KLV-32M1, ULU-board)

3) (KLV-26HG2 only) Confi rm Memory Stick video source can be displayed. This will determine if the defect causing the loss of video source is in the Switching Section or the Video Processing Section.

a. No Memory Stick Video defect is in Video Processing Section. Go to Loss of Multiple Video Sources (No Composite, Component, Memory Stick, or V-Chip OSD)

b. Memory Stick Video OK defect is in the Switching Section. Troubleshoot IC2511 (KLV-26HG2, A1-board), or IC9801 (KLV-32M1, ULU-board).

4) (Both KLV-26HG2 and KLV-32M1) Confi rm the V-Chip OSD (CC or Text features) can be displayed. This will determine if the defect causing the loss of video source is in the Switching Section or the Video Processing Section.

(No Composite, Component, Memory Stick, or V-Chip OSD)

1) Confi rm User & Service Mode OSD, which is produced by the Scan Converter IC7503 (KLV-26HG2, B-board), or IC4007 (KLV-32M1, BL-board)

CTV-33 64

4. Video Processing

a. User & Service Mode OSD OK

Defect is in the CCP2 or DRC integrated circuits. Replace B-Board (KLV-26HG2) or BL-Board (KLV-32M1).

b. No User & Service Mode

i. Confi rm LCD Panel Assembly operation. Go to Chapter 2 for detailed LCD Panel Assembly troubleshooting procedures. This step will quickly determine if the defect is on the B-Board (KLV-26HG2) or BL-Board (KLV-32M1) or on the LCD Panel Assembly.

ii. If LCD Panel Assembly checks OK, check the power supplies (3.3V and 2.5V) and crystal operations (33MHz and 100MHz) for IC7503 and IC5802 (KLV-26HG2, B-board), or IC4007 and IC4502 (KLV-32M1, BL-board).

Loss of all Composite Video Input Sources (Only)

NOTE: This problem can be caused due to a defect in the Switcher Section (IC IC2803 (KLV-26HG2, A1-board), or IC9602 (KLV-32M1, ULU-board)) or in the Video Processing Section, specifi cally the DRC circuit (IC3302 (KLV-26HG2, A1-board), or IC3002 (KLV-32M1, ULU-board)). Notice that the composite signal (480i) is the only signal that passes through the DRC circuit. All other signals (1080i, 720p, and 480p) physically bypass the DRC circuit.

1) Confi rm 9V to IC2803 (KLV-26HG2, A1-board), or IC9602 (KLV-32M1, ULU-board)

2) Confi rm data communications on I2C bus

3) Confi rm component video (1080i, 720p, and 480p) can be displayed

a. Component video OK, No Composite Video. Defective DRC circuit. Replace B-Board (KLV-26HG2) or BL-Board (KLV-32M1).

b. The test points J3307 – 3309 (KLV-26HG2), or J3007

– 3009 (KLV-32M1), can also be probed to confi rm the DRC circuit is operating properly. Waveforms 4-1, 4-2, and 4-3 should be viewed at these test points. If these waveforms are not present the DRC circuits is defective. If the waveforms are present, but still no composite video can be displayed, then there maybe a defective LCD Drive input (this would be a extremely rare defect) IC5802 (KLV-26HG2, B-board), or IC4502 (KLV-32M1, BL-board)

COMPONENT SIGNALS

0.5V per div.10us per div.

WAVEFORM 4-1

Y-SIGNAL

CTV-33 65

4. Video Processing


WAVEFORM 4-2

R-Y SIGNAL


WAVEFORM 4-3

B-Y SIGNAL

CTV-33 66

Chapter 5 - Audio Processing

KLV-26HG2 OverviewRef. Figure 5-1

The KLV-26HG2 is a completely analog system from input to output. Therefore, the audio signal can be easily traced through the circuit using an oscilloscope if needed. The complete audio system consists of the input switching circuit (IC2801, IC2802, and IC2803). IC2801 and IC2802 perform the audio selection function for the component, DVI, and Memory Stick audio inputs. IC2803 performs selection function for the Video 1 & 2 and Tuner Inputs, along with the resulting component audio selection from IC2801 and IC2802.

The selected audio signal is then applied to IC7002, which performs the Volume, Bass, and Treble functions. After IC7002 the audio signal is routed to three separate circuits, IC7011 Audio Processor, IC7002 Headphone Amplifi er, and IC7400 Variable/Fixed Audio Output. The audio processor IC7011 performs processing for audio special effects (SRS WOW for the KLV-26HG2). The resulting audio is then applied to the audio amplifi er and the speakers.

The various audio muting circuits illustrated on Figure 5-1 are as follows.

• Q7007 mutes the main speaker audio output by turning off the output amplifi er

• Q7018 & Q7019 mute the audio amplifi er input circuit for elimination of DC popping in speakers when unit is turned ON & OFF

• Q7001 & Q7002 mute the headphone output circuit

• Q7005 & Q7006 mute the headphone input circuit

CTV-33 67

5. Audio Processing

U1-Board

H2-Board

TU-Board

IC2803Switcher

Video 1

Video 2

A1-Board

UD-BoardDVI

Component

IC2801Switcher

RF

IC2802Switcher


MS Board


MSX Board

R

R

R

L

L

L

L/R

L/R

L/R

R

L

IC7002Audio

Control

R IC7007Audio

Amplifier

IC7011Audio

ProcessorL L

R

IC7400Comparator

IC7002HP Amp

� HeadphoneOutput

H2Board

J7004Var/FixOutput

RL

R L

SP-MuteFrom B-Board

Q7007

Q7005Q7006

HP-MuteFrom B-Board

Q7001Q7002

P-MuteFrom Secondary

Power SupplyIC4601

Q7018Q7019

5V

9V

9V

9V

9V

9V

12V

12VPS7001

FIGURE 5-1

KLV-26HG2 AUDIO PROCESSING

CTV-33 68

5. Audio Processing

TroubleshootingRef. Figure 5-1

The fi rst aspect of the audio circuit to notice is where the audio for the headphone and audio variable/fi xed outputs is tapped off. The audio for these circuits is tapped off immediately after IC7002 the audio control circuit, which divides the audio circuit in half. This would be the prime area to check fi rst with any audio problems (check headphone and/or the audio variable/fi xed output for audio and any distortions). This type of troubleshooting method will be applied in the following symptom/resolution scenarios.

No Audio Output from Single Audio Input

1) Is the missing audio from a composite or component input? This will determine if there is a problem with IC2803 (composite & component switcher) or IC2801 and/or IC2802 (component only switcher).

2) If missing a composite audio input confi rm the 5V supply to IC2803 switcher. NOTE: In most cases if there is a missing composite audio input, the component audio input will most likely be missing also because both sources are switched through IC2803.

3) If component audio inputs are missing and composite inputs are OK, the problem is in the IC2801 and IC2802 circuit. Confi rm the 9V power supply to both IC’s.

No Audio Output at the Speakers

1) Check audio output at the headphone and/or the audio variable/fi xed outputs.

a. No audio at headphone or audio variable/fi xed outputs. The problem is in the switching circuit (most likely IC2803) or the audio control IC7002.

i. Check audio output of the switcher (IC2803) and audio control (IC7002) with an oscilloscope.

ii. Check 5V supply to the switcher (IC2803), and the 9V supply to the audio control (IC7002).

b. Audio OK at the headphone and audio variable/fi xed outputs. The problem is in the audio processor (IC7011), audio amplifi er (IC7007), or the speakers.

i. Confi rm speaker connections

ii. Check audio output of the audio processor (IC7011) and audio amplifi er (IC7007) with an oscilloscope.

iii. Check 9V supply to the audio processor (IC7011), and the 12V supply (PS7001) to the audio amplifi er (IC7007).

iv. Check for shorted condition on muting transistors (Q7018, Q7019, and Q7007).

No Headphone Audio, Speaker Audio OK

1) Confi rm connections to H2-Board

2) Check audio variable/fi xed output.

3) Check 9V supply to headphone amplifi er (IC7002).

4) Check for shorted condition on muting transistors (Q7001, Q7002, Q7005, and Q7006).

CTV-33 69

5. Audio Processing

KLV-32M1 OverviewRef. Figure 5-2

The KLV-32M1 is a completely analog system from input to output. Therefore, the audio signal can be easily traced through the circuit using an oscilloscope if needed. The complete audio system consists of the input switching circuit (IC9602, IC9600, and IC9601). IC9600 and IC9601 perform the audio selection function for the component, DVI, and Memory Stick audio inputs. IC9602 performs selection function for the Video 1, 2, 3, and Tuner Inputs, along with the resulting component audio selection from IC9600 and IC9601.

The selected audio signal is then applied to IC8001, which performs further audio switching between main audio and center speaker audio. After IC8001 the audio signal is routed through an amplifi er (IC8002) and then to the audio processor (IC8100). The audio processor IC8100 performs all audio signal processing and effects including Volume, Bass, Treble, and special effects (Trusurround for the KLV-32M1). The resulting audio then branches off to the main audio path amplifi er (IC8301), headphone amplifi er (IC8601), EQ circuit (IC8300), and Audio Var/fi x (IC8660).

The headphone audio is sent to the H3-board and the headphone output jack, via the ULU-board. The audio output of the amplifi er (IC8301) and the EQ circuit (IC8300) is applied to a switching circuit consisting of IC8302 and IC8303, which will pass either the audio from the amplifi er or the EQ circuit. NOTE: The EQ circuit is turned active (or turned ON) when the Center speaker feature is selected (or turned ON). The audio then proceeds through another amplifi er (IC8500), and then to the audio output amplifi er (IC8501) and the speakers.

The various audio muting circuits illustrated on Figure 5-1 are as follows.

• Q8700 mutes the main speaker audio output by turning off the output amplifi er

• Q8300 mutes the audio amplifi er input circuit for elimination of DC popping in speakers when unit is turned ON & OFF

• Q8603 & Q8604 mute the headphone output circuit

• Q8601 & Q8602 mute the headphone input circuit

CTV-33 70

5. Audio Processing

IC8001Audio

Selector

RIC8100

AudioProcessor

L

IC8600Switch

IC8601HP Amp

R L

Q8601Q8602

HP-MuteFrom BL-Board

Q8603Q8604

TU-BoardIC9602Switcher

ULU-Board

P-BoardHDMI

Component

IC9600Switcher

RF

IC9601Switcher

R

R

L

L

L/R

R

L

AU-Board

Video 1L/R

Video 2 L/R

L/RH3-Board

Video 3

HeadphoneOut

CenterSpeaker

Input

R L

TB9300

J9302

IC8602Amp

IC8002Amp

IC8301Amp

IC8501Audio

Amplifier

IC8500Amp

SP-MuteFrom BL-

Board

Q8700

Q8300

Mute

Mute

Mute

Audio Var/FixOutput

CenterSpeaker

SW2

IC8300EQ

IC8302Switch

IC8303Switch

EQ SWFrom BL-Board

9V

9V

9V

9V

9V9V

9V

9V

9V

9V

9V

30VPS8500

Q8001

9V 9V

CenterSpeaker

SW1Q8002

FIGURE 5-2

KLV-32M1 AUDIO PROCESSING

CTV-33 71

5. Audio Processing

TroubleshootingRef. Figure 5-2

The fi rst aspect to notice about the audio circuit illustrated in fi gure 5-2 is how the various output and inputs can be used to divide the circuit into separate sections thereby passing specifi c circuits while testing others. The various outputs and inputs to be mindful of are as follows.

• Audio Var/Fix Output: Monitoring this output will basically test the output of the switching circuit (IC9602, IC9600, and IC9601) on the ULU-Board, and the Audio Selector (IC8001) and the Audio Processor (IC8100) on the AU-board. This output bypasses all the circuitry after the Audio Processor (IC8100).

• Center Speaker Audio Input: This input can be used to completely bypass the switching circuit, basically bypassing the ULU-Board. The input is applied directly to the audio selector (IC8001). NOTE: When the Center Speaker feature is turned ON the audio also bypasses the amplifi er (IC8301) immediately after the Audio Processor (IC8100).

• Headphone Audio Output: Monitoring this output will basically bypass the audio output circuit immediately after the audio processor (IC8100) thereby testing the switching and audio processing circuits.

• EQ or Main Audio: By turning the EQ circuit ON and OFF the audio through the EQ (IC8300) and main audio amplifi er (IC8303) can be tested.

No Audio Output from Single Audio Input

1) Is the missing audio from a composite or component input? This will determine if there is a problem with IC9602 (composite & component switcher) or IC9600 and/or IC9601 (component only switcher).

2) If a composite audio input is missing confi rm the 9V supply to IC9602 switcher. NOTE: In most cases if there is a missing composite audio input, the component audio input will most likely be missing also because both sources are switched through IC9602.

3) If component audio inputs are missing and composite inputs are OK, the problem is in the IC9600 and IC9601 circuit. Confi rm the 9V power supply to both IC’s.

No Audio Output at the Speakers

1) Apply audio to the Center Speaker Input and select Center Speaker in Menu.

This will divide the audio circuit into two distinct halves one being the switching circuits on the ULU-board and the other half being the audio processing circuits on the AU-board.

a. Audio OK at speakers with center speaker audio applied. Troubleshoot switching circuit (ULU-Board)

i. Check 9V supply to the switching circuit.

ii. Check audio output of the switcher (IC9602)

b. No Audio at speakers with center speaker audio applied. Troubleshoot audio processing and audio output circuits (AU-Board). Go to next step (#2)

2) Check for an audio signal at the Audio Var/Fix Output jack (J9302) or the Headphone Output via IC8601. This will determine if the problem is in the audio output circuits

CTV-33 72

5. Audio Processing

immediately after the Audio Processor on the AU-board or in the audio processing circuits on the AU-Board (IC8100 and IC8001).

a. No audio at Audio Output from either Audio Var/Fix or Headphone.

The problem is in the audio processing circuits IC8100, IC8002, or IC8001.

i. Check 9V supply to the audio processing circuits.

ii. Check audio output of IC8001, IC8002, and IC8100 with an oscilloscope.

b) Audio OK at the Audio Var/Fix and Headphone Output. The problem is in the audio output circuits (IC8301, IC8302, IC8303, IC8500, or IC8501) or the speakers. NOTE: If the Center Speaker is on the audio will go through IC8300 and bypass IC8301.

i. Confi rm speaker connections

ii. Check audio output of the Amplifi er (IC8501) with an oscilloscope.

iii. Check 30V supply through PS7001 to the audio amplifi er (IC8501).

iv. Check for shorted condition on muting transistors (Q8700 and Q8300).

v. Turn EQ circuit ON and OFF to bypass the amplifi er (IC8301)

No Headphone Audio or Audio Var/Fix Output,

Speaker Audio OK

1) Check audio output at Audio Var/Fix output

a. If OK go to next step (#2)

b. If no audio troubleshooting IC8600 and IC8602 audio switcher and audio amplifi er for the Audio Var/Fix output

i. Check 9V supply

ii. Check audio output of IC8600 and IC8602 with an oscilloscope

2) Confi rm connections to H3-Board

3) Check 9V supply to headphone amplifi er (IC8601).

4) Check for shorted condition on muting transistors (Q8603, Q8604, Q8601, and Q8602).

CTV-33 73

Chapter 6 - Protection Circuits

Circuit Descriptions and TroubleshootingThe KLV-26HG2 and the KLV-32M1 both have basically four protection shutdown and indication failure types with various voltage and functions failures that can trigger these modes. Table 6-1 (KLV-26HG2) & Table 6-2 (KLV-32M1) lists the Monitored Item, Flash Sequence (after shutdown), and the failure type (or area affected). The major failure types are Video Processing, Power Supply, LCD Panel, and Temperature.

Column one of Table 6-1 (KLV-26HG2) & Table 6-2 (KLV-32M1) lists the reference names for each major protection circuit, and column two provides the voltages and signal actually monitored by each protection circuit. Column three gives the RED LED fl ash timing associated with each protection mode.

CTV-33 74

6. Protection Circuits

KLV-26HG2 Protection Circuits

Monitor Point RED LED Flash Timing Area of Failure

IC7503 UART Communications RED LED 2.0sec. ON / 2.0sec. OFF Video Processing

Panel 12V at Q4605 RED LED 1.5sec. ON / 0.5sec. OFF Power Supply

9V Regulator IC4602 RED LED 1.5sec. ON / 0.5sec. OFF Power Supply

IC4601/pin 12 RED LED 1.5sec. ON / 0.5sec. OFF Power Supply

16.5V from IC6002 RED LED 1.5sec. ON / 0.5sec. OFF Power Supply

16.5V from IC6002 RED LED 0.5sec. ON / 1.5sec. OFF Power Supply

Inverter Board & Backlights RED LED 0.5sec. ON / 1.5sec. OFF Panel Assembly (Invert Board or Backlights)

IC1002 (I2C bus) Unit Temp. RED LED 1.0sec. ON / 1.0sec. OFF LCD Drive IC5802

TABLE 6-1

KLV-26HG2 PROTECTION CIRCUITS

KLV-32M1 Protection Circuits

Protection Reference Name Monitor Point RED LED Flash Timing Area of Failure

Scan Converter IC7503 IC7503 (UART) Communications RED LED 2.0sec. ON / 2.0sec. OFF Video Processing

5V ALERT 5V Regulator IC7005 RED LED 1.5sec. ON / 0.5sec. OFF Power Supply

3.3V ALERT IC70002 D3.3V Output

Q7003 Panel 5V Output

RED LED 1.5sec. ON / 0.5sec. OFF Power Supply

DC-IN ALERT IC7001 9V Regulator

IC7000 AU9V Regulator

RED LED 1.5sec. ON / 0.5sec. OFF Power Supply

16.5V OVP Primary Power Supply Output RED LED 1.5sec. ON / 0.5sec. OFF Power Supply

Panel Detect Inverter Board & Backlights RED LED 0.5sec. ON / 1.5sec. OFF Panel Assembly (Invert Board or Backlights)

Temperature IC1007 (I2C bus) Unit Temp. RED LED 1.0sec. ON / 1.0sec. OFF LCD Drive IC5802

TABLE 6-2

KLV-32M1 PROTECTION CIRCUITS

CTV-33 75


IC1006MainMicro

A1-Board

B-Board

IC1002Temp

IC7503Scan

Converter

I2C

IC4601Scondary

PowerSupply

Q460312V Reg

Q4605Panel 12V

Switch

IC46029V Reg

5V ALERT

3.3V ALERT

IC46035V Reg

16.5V DC IN_ALERT

BacklightInverterBoard

G1-Board

IC6002Primary Power

Supply

Backlight

Panel Detect

LCD PanelAssemble

Q4604D4607

D4611

D4612

R4643

R4642

R4644

13V3.3V

4V

12

16

16.5VUNREG 6V

3.1V

3V

2.75V

20

21

19

25

24

CN4603

UART

CN6003

4 3CN4604

5 - 7 13

5 - 7 13CN4601

PowerGood

DriveOutput

6

5

7

1

2

CN1003

R4645

FIGURE 6-1

KLV-26HG2 PROTECTION CIRCUITS

CTV-33 76


IC1002MainMicro

AU-Board

BL-Board

IC1002Temp

IC7503Scan

Converter

I2C

IC7002Scondary

PowerSupply

Q7001D5VV SW

5V ALERT

3.3V ALERT

8.5V DC-IN ALERT

Backlight

Panel Detect

LCD PanelAssemble

D10025.6V

3.2V

4.8V

29

19

AU9V

UNREG 10.5V

3.3V

A41

B40

A47

D7026.2V

IC70019V Reg

D5504

R5583

R5580

9V

IC70009V Reg

IC70035V Reg

PS7000 IC70055V Reg

R5582

R5505

UART

17

27

Q7000D3.3V

SW

D5505 R5581

D70035.6V

D70023.9V

Q7003Panel 5V

SW

Panel 5V

GL-Board

IC621Primary Power

Supply11

12

BacklightInverterBoard

5 - 8 1 2CN651 CN653

CN652

A43

2

1

CN1004

CN1001

4.9V

3V

FIGURE 6-2

KLV-32M1 PROTECTION CIRCUITS

CTV-33 77


GL-Board

IC621Primary Power

Supply

Q681PH662Q661Power 1 (ON)from BL-Board

Main Micro

16.5Vto BacklightInvert board

T62116.5V

3.2V

D68322V

R691 D682

C685

Q682

Q683

R689

15

1/5

CN651

CN652

0.1V

16.5V

FIGURE 6-3

KLV-32M1 16.5V OVER-VOLTAGE PROTECTION CIRCUIT

CTV-33 78


Video Processing

(RED LED 2.0sec. ON / 2.0sec. OFF)

Ref. Figure 6-1

The video processing protection circuit monitors the operation of the Scan Converter IC7503. If this IC fails, then the unit shuts down and the RED LED will fl ash continuously with a timing sequence of 2.0 seconds ON and 2.0 seconds OFF. Check the following items:

1) Check 3.3V and 2.5V power supplies to IC7503

2) Check the crystal X5001 14.32MHz for proper operation

3) Check for data communications on the UART interface between IC7503 and the main micro IC1006

Power Supply


Ref. Figure 6-1

The power supply protection circuit can be triggered by three different failures, all of them relating to a complete or partial power supply failure.

The 5V ALERT circuit monitors both the Panel 12V output of Q4605 and the regulated 9V output of IC4602. If either of these outputs fails, D4611 or D4612 will forward bias and cause CN4603/pin 20 to go low. If this occurs the unit will shut down and the RED LED will fl ash continuously with a timing sequence of 1.5 seconds ON and 0.5 seconds OFF. Note: If the regulated 12V output of Q4603 fails, then both Panel 12V and 9V will not be developed causing the same protection indication. Check the following items:

1) Check for 3V at CN4603/pin 20

a. If missing proceed to step 2

b. If OK, check for poor connections between A1-Board and B-Board

2) Check for 12V at the output of Q4605

3) Check for 9V at the output of IC4602

4) Check for 12V at the output of Q4603

5) Check for good drive output at IC4601/pin 16 (Ref. Chapter 3 Power Supply Overall Blocks)

The 3.3V ALERT circuit monitors the 3.3V developed by the secondary power supply IC4601. IC4601/pin 12 (Power Good) is a sample of the 3.3V output, which is monitored directly by the main microprocessor IC1006. If the 3.3V line goes low or absent, IC4601/pin 12 will follow and the unit will go into shutdown protection mode. If this ocurs the RED LED will fl ash continuously with a timing sequence of 1.5 seconds ON and 0.5 seconds OFF. Check the following items:

1) Check for 2.75V at CN4603/pin 19



2) Troubleshoot the Secondary power supply (IC4601) operation (Ref. Chapter 3 Power Supply Overall Blocks)

The DC-IN ALERT monitors the 16.5V from the Primary power supply (IC6002) directly. If the 16.5V goes low or is absent the unit will go into shutdown protection mode, and the RED LED will fl ash continuously with a timing sequence of 1.5 seconds ON and 0.5 seconds OFF. Check the following items if this indication is experienced.


a. If missing go to step 2

CTV-33 79





b. If OK, check for poor connections between G1-Board and A1-Board

3) Troubleshoot the Primary power supply (IC6002) operation (Ref. Chapter 3 Power Supply Overall Blocks)

LOW 16.5V


Ref. Figure 6-1

The 16.5V line from the Primary power supply on the G1-Board is monitored by D4607 and Q4604 for a low or absent voltage condition. If the 16.5V drops below 13V (as designated by the zener diode D4607), the zener diode D4607 will turn OFF and Q4604 will turn ON placing a ground on the Backlight control line and turn the Backlight OFF. Although this is, in most cases, caused by a power supply defect, a Backlight failure indication (RED LED will fl ash continuously with a timing sequence of 0.5 seconds ON and 1.5 seconds OFF).

The reason for this is due to the fact that when the Low 16.5V circuit activates the Backlight line to the inverter board is pulled low turning the Backlight OFF and the Panel Detect will also go low notifying the main microprocessor that a panel assembly failure has occurred. Check the following items:

1) The fi rst step is to determine if the shutdown was caused by an actual Backlight failure or a 16.5V failure.

a. Monitor the 16.5V line during initial unit power up.

i. If the 16.5V comes up to proper level (16.5V) before shutdown, then the problem is in the Panel Assembly (reference Chapter 2 Panel Assembly Troubleshooting)

ii. If the 16.5V does not come up to the proper level, then the problem is in the power supply (go to step 2)






b. If OK, check for poor connections between G1-Board and A1-Board. NOTE: Also confi rm that the protection circuit’s components (D4607 and Q4604) are not defective.


CTV-33 80


Panel Assembly


Ref. Figure 6-1

The operation of the Panel Assembly is monitored by the main microprocessor directly using the Panel Detect signal coming from the Inverter board, which is included in the Panel Assembly. The Panel Detect voltage (4V) will go low if a failure occurs in the Inverter or Backlight section of the Panel Assembly. Failures that will cause the Panel Detect line to go low are as follows:

1) One or more CCFT backlights fail

2) One or more Inverter CCFT backlight driver outputs fail

3) Lose of 16.5V power supply to the Inverter board

4) Lose of Backlight control voltage to the Inverter board

If there is a Backlight or Inverter failure the unit will go into shutdown protection mode, and the RED LED will fl ash continuously with a timing sequence of 0.5 seconds ON and 1.5 seconds OFF. Check the following items:

1) Confi rm that the problem is truly a Backlight or Inverter failure not, a 16.5V failure. Reference the previous Low 16.5V troubleshooting for details.

2) Monitor the Backlight control voltage at CN4603/pin 24 and the Panel Detect voltage at CN4603/pin 25 before unit shutdown

i. If the Backlight control voltage goes to 3.3V (turning ON the Backlight), and the Panel Detect voltage goes low and the unit goes into protection mode, then the problem is on the Panel Assembly (CCFT, Drive to CCFT, or 16.5V failure). (Ref. Chapter 2, LCD Panel Assembly Troubleshooting for details.)

ii. If the Backlight control voltage does not go to 3.3V (not turning ON the Backlight), then the problem is either a poor connection between the A1-Board and the B-Board or the main microprocessor Backlight signal output has failed (highly unlikely that a single output would fail)

CTV-33 81


Temperature


Ref. Figure 6-1

The unit’s internal temperature, and specifi cally the temperature of the LCD driver (IC5802) are monitored using IC1002. The main microprocessor IC1006 will communicate over the I2C bus to check the temperature. Because of IC1002’s close proximity to the LCD driver circuit the temperature of the LCD driver (IC5802) is specifi cally monitored. Because the LCD Panel is obviously the largest device in the unit, and consumes the most power, it will determine the level of the internal temperature. Therefore, the temperature of the LCD Panel is indirectly monitored. NOTE: The internal temperature will also be affected by the external temperature conditions. If the unit is placed in a high temperature environment, the temperature protection circuit may trigger causing a unit shutdown. Therefore, fi rst confi rm proper external temperature conditions before troubleshooting for an internal failure.

The protection circuit trigger temperature is 80 degrees Celsius

The protection circuit will reset when the temperature falls below 75 degrees Celsius

If there is an excessive internal temperature condition the unit will go into shutdown protection mode, and the RED LED will fl ash continuously with a timing sequence of 1.0 second ON and 1.0 second OFF. Check the following items:

1) Confi rm that the temperature in the immediate area of the unit is not excessive (above 80 degrees Celsius)

2) Confi rm LCD Panel temperature by touch (the LCD Panel should only be slightly warm)

3) On most cases the failure will be on the B-Board (replace B-Board)

Video Processing


Ref. Figure 6-2

The video processing protection circuit monitors the operation of the Scan Converter IC4007. If this IC fails, then the unit will shut down and go into protection mode. The RED LED will fl ash continuously with a timing sequence of 2.0 seconds ON and 2.0 seconds OFF. Check the following items:

1) Check 3.3V and 2.5V power supplies to IC4007

2) Check the crystal X4001 14.32MHz for proper operation

3) Check for data communications on the UART interface between IC4007 and the main micro IC1002

Power Supply


Ref. Figure 6-2

The power supply protection circuit can be triggered by three different failures, all of them relating to a complete or partial power supply failure.

The 5V ALERT circuit monitors the regulated 5V output of IC7005 (indirectly the output of IC7003 and the Primary Power Supply). If the 5V output is missing, CN4603/pin 20 will go low. If this ocurs the unit will shut down and the RED LED will fl ash continuously with a timing sequence of 1.5 seconds ON and 0.5 seconds OFF.

1) Check for 3V at CN1004/pin A41


b. If OK, check for poor connections between AU-Board and BL-Board


CTV-33 82



4) Check continuity of PS7000

5) Check for 10.5V at CN651/pins 5 through 8 from the Primary power supply (if missing reference Chapter 3 Power Supply troubleshooting details)

The 3.3V ALERT circuit monitors the 3.3V developed by the secondary power supply IC7002. IC7002/pins 29 and 27 drive Q7000 to develop the 3.3V supply, which is monitored directly by the main microprocessor IC1002. If the 3.3V line goes low or absent the unit will go into shutdown protection mode, and the RED LED will fl ash continuously with a timing sequence of 1.5 seconds ON and 0.5 seconds OFF. Check the following items:

1) Check for 3.3V at CN1004/pin A47


b. If OK, check for poor connections between Au-Board and BL-Board

2) Troubleshoot the Secondary power supply (IC7002) operation (Ref. Chapter 3 Power Supply Overall Blocks)

The DC-IN ALERT monitors the 9V output of IC7001 and the AU9V output of IC7000 directly, and the 10.5V output of the Primary power supply indirectly. If the 9V, AU9V, or 10.5V goes low or is absent, the unit will go into shutdown protection mode, and the RED LED will fl ash continuously with a timing sequence of 1.5 seconds ON and 0.5 seconds OFF. Check the following items:

1) Check for 8.5VV at CN1004/pin B40


b. If OK, check for poor connections between AU-Board and BL-Board

2) Check for 9V output from IC7001

3) Check for AU9V output from IC7000

4) Check for 10.5V at CN651/pins 5 through 8


b. If OK, check for poor connections between GL-Board and AU-Board


Panel Assembly


Ref. Figure 6-2

The operation of the Panel Assembly is monitor by the main microprocessor directly using the Panel Detect signal coming from the Inverter board, which is included in the Panel Assembly. The Panel Detect voltage (4.8V) will go low if a failure occurs in the Inverter or Backlight section of the Panel Assembly. Failures that will cause the Panel Detect line to go low are as follows:

1) One or more CCFT backlights fail

2) One or more Inverter CCFT backlight driver outputs fail

3) Lose of 16.5V power supply to the Inverter board

4) Lose of Backlight control voltage to the Inverter board

If there is a Backlight or Inverter failure, the unit will go into shutdown/protection mode, and the RED LED will fl ash continuously with a timing sequence of 0.5 seconds ON and 1.5 seconds OFF. Check the following items:

1) Monitor the Backlight control voltage at either CN652/pin 12, CN653/pin 2, or CN1004/pin 2 and the Panel Detect voltage at either CN652/pin 11, CN653/pin 1, or CN1004/pin 1 before unit shutdown

a. If the Backlight control voltage goes to 3.3V (turning ON the

CTV-33 83


Backlight), and the Panel Detect voltage goes low and the unit goes into protection mode, then the problem is on the Panel Assembly (CCFT, Drive to CCFT, or 16.5V failure). (Ref. Chapter 2, LDCD Panel Assembly Troubleshooting for details)

b. If the Backlight control voltage does not go to 3.3V (not turning ON the Backlight), then the problem is either a poor connection between the GL-Board and the BL-Board or the main microprocessor Backlight signal output has failed. (It is highly unlikely that a single output of the microprocessor would fail.)

Temperature


Ref. Figure 6-2

The unit’s internal temperature, and specifi cally the temperature of the LCD driver (IC4502), are monitored using IC1007. The main microprocessor IC1002 will communicate over the I2C bus to check the temperature. Because of IC1007’s close proximity to the LCD driver circuit the temperature of the LCD driver (IC54502) is specifi cally monitored. Because the LCD Panel is obviously the largest device in the unit, and consumes the most power, it will determine the level of the internal temperature. Therefore, the temperature of the LCD Panel is indirectly monitored. NOTE: The internal temperature will also be affected by the external temperature conditions. If the unit is placed in a high temperature environment, the temperature protection circuit may trigger causing a unit shutdown. Therefore, fi rst confi rm proper external temperature conditions before troubleshooting for an internal failure.

The protection circuit activatives when external temperature is 35 degrees Celsius

The protection circuit will reset when the temperature falls below 35 degrees Celsius

If there is an excessive internal temperature condition, the unit will go into shutdown protection mode, and the RED LED will fl ash continuously with a timing sequence of 1.0 second ON and 1.0 second OFF. Check the following items:

1) Confi rm that the temperature in the immediate area of the unit is not excessive (above 80 degrees Celsius)

2) Confi rm LCD Panel temperature by touch (the LCD Panel should only be slightly warm)

3) On most cases the failure will be on the B-Board (replace B-Board)

16.5V Over-Voltage Protection

Ref. Figure 6-3

The 16.5V supply for the Inverter board is monitored for an over-voltage condition using D683, R691, D621, and latch circuit Q681 and Q682. If the 16.5V rises above 23V (as designated by the zener diode D683, diode D682, and Q683), the latch circuit will activate and pull the Power 1 (ON) line low, turn OFF the Primary power supply, and turn OFF the unit.

If there is an excessive 16.5V condition, the unit will go into shutdown/protection mode, and the RED LED will fl ash continuously with a timing sequence of 1.5 second ON / 0.5 second OFF. Check the following items:

1) Check for 16.5V at CN652/pins 1 through 5


b. If OK, check the components (D683, D682, and the latch circuit Q683 and Q682) of the protection circuit for defects

2) Troubleshoot the Primary power supply (Ref. Chapter 3, Power Supply Troubleshooting details)

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Reproduction in whole or part without written permission is prohibited. All rights reservedCTV-33 4/8/05

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