Sharp LC-20B4E Schematic

LC-20B4E

SERVICE MANUAL

S33Y8LC-20B4E

LCD COLOUR TELEVISION

MODEL

In the interests of user-safety (Required by safety regulations in some countries) the set should be restored to its original condition and only parts identical to those specified should be used.

CONTENTS

» IMPORTANT SERVICE SAFETY PRECAUTION ........................................................................................2

» SPECIFICATIONS ........................................................................................................................................4

» OPERATION MANUAL .................................................................................................................................5

» DIMENSIONS ...............................................................................................................................................7

» REMOVING OF MAJOR PARTS ..................................................................................................................8

» ADJUSTING PROCEDURE OF EACH SECTION .....................................................................................12

» TROUBLE SHOOTING TABLE...................................................................................................................16

» CHASSIS LAYOUT .....................................................................................................................................22

» BLOCK DIAGRAM......................................................................................................................................24

» OVERALL WIRING DIAGRAM ...................................................................................................................26

» DESCRIPTION OF SCHEMATIC DIAGRAM .............................................................................................28

» SCHEMATIC DIAGRAM .............................................................................................................................29

» PRINTED WIRING BOARD ASSEMBLIES................................................................................................54

» REPLACEMENT PARTS LIST....................................................................................................................66

» PACKING OF THE SET ..............................................................................................................................79

LC-20B4E

Page

SHARP CORPORATION

LC-20B4E

IMPORTANT SERVICE SAFETY PRECAUTION

Service work should be performed only b y qualified service technicians who are thoroughly familiar with all safety checks and the servicing guidelines which follow:

WARNING

1. For continued safety, no modification of any circuit should be attempted.

2. Disconnect AC power before servicing.

CAUTION: FOR CONTINUED PROTECTION AGAINST A RISK OF FIRE REPLACE ONLY WITH SAME TYPE F3301(2A, 250V), F3302(1.25A, 250V), F6700 (1.25A, 250V), F6701 (1.25A, 250V), F6702 (1.25A, 250V), F6703 (1.25A, 250V) AND F6704 (1.25A, 250V) FUSE.

BEFORE RETURNING THE RECEIVER (Fire & Shock Hazard)

Before returning the receiver to the user, perform the following safety checks:

1. Inspect all lead dress to make certain that leads are not pinched, and check that hardware is not lodged between the chassis and other metal parts in the receiver.

2. Inspect all protective devices such as non-metallic control knobs, insulation materials, cabinet backs, adjustment and compartment covers or shields, isolation resistor-capacitor networks, mechanical insulators, etc.

3. To be sure that no shock hazard exists, check for leakage current in the following manner.

• Plug the AC cord directly into a 110~240 volt A C outlet, and connect the DC power cable into the receiver's DC jack. (Do not use an isolation transformer for this test).

• Using two clip leads, connect a 50k ohm, 10 watt resistor paralleled by a 0.15µF capacitor in series with all exposed metal cabinet parts and a known earth ground, such as electrical conduit or electrical ground connected to an earth ground.

• Use an AC voltmeter ha ving with 5000 ohm per volt, or higher, sensitivity or measure the AC voltage drop across the resistor.

• Connect the resistor connection to all exposed metal parts having a return to the chassis (antenna, metal cabinet, screw heads, knobs and control shafts, escutcheon, etc.) and measure the AC voltage drop across the resistor. All checks must be repeated with the AC cord plug connection reversed. (If necessar y, a nonpolarized adaptor plug must be used only for the purpose of completing these checks.) Any reading of 0.75V peak (this corresponds to 0.5 mA. peak AC.) or more is excessive and indicates a potential shock hazard which must be corrected before returning the monitor to the owner.

DVM

AC SCALE

50k ohm

10W

0.15 µF

TEST PROBE

TO EXPOSED METAL PARTS

CONNECT TO KNOWN EARTH GROUND

234567890123456789012345678901212345678901234567890123456789012123456789012345678901234567890121

SAFETY NOTICE

Many electrical and mechanical parts in LCD television have special safety-related characteristics. These characteristics are often not evident from visual inspection, nor can protection afforded by them be necessarily increased by using replacement components rated for higher voltage , w attage , etc. Replacement parts which have these special safety characteristics are identified in this manual; electrical

and shaded areas in the

Schematic Diagrams.

For continued protection, replacement parts must be identical to those used in the original circuit. The use of a substitute replacement parts which do not have the same safety characteristics as the factory recommended replacement parts shown in this service manual, may create shock, fire or other hazards.

components having such features are identified by “ å”

234567890123456789012345678901212345678901234567890123456789012123456789012345678901234567890121

Replacement Parts Lists and

LC-20B4E

Precautions for using lead-free solder

1 Employing lead-free solder

"All PWBs" of this model employs lead-free solder . The LF symbol indicates lead-free solder, and is attached on the PWBs and service manuals. The alphabetical character following LF shows the type of lead-free solder. Example:

L Fa

Indicates lead-free solder of tin, silver and copper.

2 Using lead-free wire solder

When fixing the PWB soldered with the lead-free solder, apply lead-free wire solder. Repairing with conventional lead wire solder may cause damage or accident due to cracks. As the melting point of lead-free solder (Sn-Ag-Cu) is higher than the lead wire solder by 40°C, we recommend you to use a dedicated soldering bit, if you are not familiar with how to obtain lead-free wire solder or soldering bit, contact our service station or service branch in your area.

3 Soldering

As the melting point of lead-free solder (Sn-Ag-Cu) is about 220°C which is higher than the conventional lead solder by 40°C, and as it has poor solder wettability, you may be apt to keep the soldering bit in contact with the PWB for extended period of time. However, Since the land may be peeled off or the maximum heat-resistance temperature of parts may be exceeded, remove the bit from the PWB as soon as y ou confirm the steady soldering condition. Lead-free solder contains more tin, and the end of the soldering bit may be easily corroded. Mak e sure to turn on and off the power of the bit as required. If a different type of solder stays on the tip of the soldering bit, it is alloyed with lead-free solder. Clean the bit after every use of it. When the tip of the soldering bit is blackened during use, file it with steel wool or fine sandpaper.

Be careful when replacing parts with polar ity indication on the PWB silk.

Lead-free wire solder for servicing

Part No, ★ Description Code ZHNDAi123250E J φ0.3mm 250g(1roll) BL ZHNDAi126500E J φ0.6mm 500g(1roll) BK ZHNDAi12801KE J φ1.0mm 1kg(1roll) BM

LC-20B4E

SPECIFICATIONS

Item 20" LCD COLOUR TV LCD panel 20" Advanced Super View & BLACK TFT LCD Number of dots 921,600 dots Video colour system PAL/SECAM/NTSC TV TV-Standard (CCIR) B/G, I, D/K, L

TV-Tuning System Auto preset 200 ch. STEREO/BILINGUAL NICAM, IGR AUTO PRESET YES

CATV ~Hyper Band Brightness 430 cd/m Lamp life 60,000 hours Viewing angles H: 170° V: 170° Audio amplifier 2.5 W × 2 Speakers 5 cm ø 2 pcs. Terminals AV-IN 1 21 pin Euro-SCART

AV-IN 2 S-VIDEO, VIDEO, AUDIO

OUT AUDIO

Antenna DIN

Headphones 3.5 mm ø jack (Rear) OSD language English/German/French/Spanish/Italian/Swedish/Dutch/Russian Power requirement DC 13 V, AC 110 V – 240 V, 50/60 Hz Weight 8.7 kg w/o accessories Accessories Operation Manual, Remote Control, Batteries (× 2), AC adapter, AC cord,

Cable clamps (× 2)

Specifications are subject to change without prior notice.

OPERATION MANUAL

Controls

Note:

• TV/VIDEO, CH(

)/(

), Volume (–)/(+) and MENU on the main unit have the same functions as the same buttons on the remote control.

Fundamentally, this operation manual provides a description based on operation using the remote control.

TV/VIDEO

Volume (–)/(+)

POWER/STANDBY indicator

A green indicator lights when the power is on and a red

indicator lights when in the standby mode (the indicator will

not light when the main power is off).

Remote sensor window

Remote sensor indicator

A red indicator blinks when the TV set receives the

remote control signal.

Upper control panel

CH (

)/( )

TV/VIDEO

(MAIN POWER)

Speaker

To change the vertical angle of

the LCD TV set, tilt the screen

up to 5 degrees forward or 10

degrees backward. The TV set

can also be rotated 25 degrees

to right and left. Please adjust

the angle so that the TV set can

be watched most comfortably.

Speaker

Terminals

Tilt the display by grabbing onto

the carrying handle while securely

holding down the stand with your

other hand.

How to adjust the angle

Carrying handle

-IN

POWER INPUT DC13V

AV-IN 1

(21pin Euro-SCART)

S-VIDEO

VIDEO

AUDIO (L)

AUDIO (R)

AV-IN 2

Antenna

AUDIO OUT (L)

AUDIO OUT (R)

Headphones

Rear View

LC-20B4E

REVEAL

OLD

END

MENUSOUND

SUBTITLE

SUBPAGE

TEXT

ROTATE

TV/VIDEO

REVEAL

OLD

END

MENUSOUND

SUBTITLE

SUBPAGE

TEXT

ROTATE

OK, Programme Table

SUBTITLE

Displays the Teletext

Subtitle directly.

HOLD

Temporarily holds the

current Teletext page.

(Mute)

Switches the sound on and off.

Yellow,

Timer function Menu

Cyan, Status Display

Turns on the status display

when the menu is not

displayed.

TV/VIDEO

Switches the input source

between AV1, AV2 and

TV mode.

Channel Select

Displays the TV menu.

Volume (+)/(

)

(Flashback)

Returns to the previous

channel.

Red, Picture Menu

Upwards/ Downwards

Selection, zoom display

function (Teletext mode)

END

Returns to normal screen.

TEXT

Displays the Teletext mode

screen.

(Power)

SOUND

Switches the sound

mode.

REVEAL

Displays hidden information

such as solutions to riddles

and puzzles.

Right / Left Selection

SUBPAGE

Displays the Teletext

Subpage directly.

ROTATE

Rotates the display in every

direction.

BRIGHT

Selects the brightness

of the display.

Green, Sound Menu

CH ( )/( )

Displays previous/next page.

(Teletext mode)

Installing Batteries in the Remote Control

Before using the LCD TV set for the first time, install the two R-03 (“AAA” size, UM/SUM-4) batteries supplied in the remote

control. When the batteries become depleted and the remote control fails to operate, replace the batteries with new R-03

(“AAA” size, UM/SUM-4) batteries.

Open the battery cover.

Insert two R-03 (“AAA” size,

UM/SUM-4) batteries.

Replace the battery cover.

■ Position the positive and

negative ends of the

batteries as indicated in

the compartment.

Caution!

Precautions regarding batteries

■ Improper use of batteries can result in a leakage of chemicals and/or explosion. Be sure to follow the instructions below.

• Place batteries with their terminals corresponding to the (+) and (–) indications.

• Different types of batteries have different characteristics. Do not mix batteries of different types.

• Do not mix old and new batteries. Mixing old and new batteries can shorten the life of new batteries and/or cause old

batteries to leak chemicals.

• Remove batteries as soon as they are depleted. Chemicals that leak from batteries can cause a rash. If chemical

leakage is found, wipe it off with a cloth.

• The batteries supplied with the product may have a shorter life expectancy due to storage conditions.

• If the remote control is not to be used for an extended period of time, remove the batteries from the remote control.

■ Engaging the lower

claw with the remote

control, close the

cover.

■ Slide the cover while

pressing the ([) part.

DIMENSIONS

76.1

68.6

LC-20B4E

Unit: mm

TV/VIDEO

420

630

76.1

110.7

295.8

470.3

471.5

188193.590

300.8

403.3

100

AUDIO OUT

51.5

100

AV-IN 1

RGB

AV-IN 2

S-VIDEO

VIDEO

AUDIO

POWER

INPUT DC13V

182.4

30.5

249.6

138

174.5

LC-20B4E

REMOVING OF MAJOR PARTS

1. Remove the stand fixing screws (4 pcs.).

2. Remove the two terminal covers.

3. Remove the terminal section fixing screws (2 pcs.).

4. Remove the cabinet B fixing screws (12 pcs.).

5. Remove the cabinet B after opening from the direction of an arrow.

6. Peel off the tape. Remove the reinforcement angle fixing screws (4 pcs.).

7. Peel off the tape.

8. Detach the connector from each PWB.

Cabinet A

Terminal Cover (S)

Cabinet B

Terminal Cover (L)

Stand

Reinforcement Angle

Tape

SC1204

R/C, LED PWB

SC1202SC1203

Main PWB

P701

P4004

P4001

P2001

SC2002

Tuner PWB

P3601

P3602

P3302

P3301 P3902

Operation PWB

P6705

Inverter-A

PWB

SC3902

P1902

P3303

P3304

P6706

Inverter

-B PWB

Tape

9. Remove the inverter-A PWB fixing screws (2 pcs.).

Inverter-A PWB

Main PWB

Chassis Frame

Chassis Frame Cover

Tuner PWB

Inverter-B PWB

Operation PWB

R/C, LED PWB

10.Remove the inverter-B PWB fixing screws (1 pc.).

11.Remove the main PWB fixing screws (3 pcs.).

12.Remove the 21-pin terminal fixing screw (2 pcs.).

13.Remove the tuner PWB fixing screws (3 pcs.) and detach the chassis frame cover fixing hooks.

14.Remove the R/C, LED PWB fixing screws (2 pcs.).

15.Remove the operation PWB fixing screws (2 pcs.).

LC-20B4E

» Precautions in handling the LCD panels

1. Work in a clean room (with humidities below 50%).

2. Be sure to wear an anti-static armband.

3. Handle the panels on an electro-conductive mat.

4. Be careful not to fall, shake and shock the panels.

16. Remove the LCD panel unit fixing screws (4 pcs.).

17. Remove the ITO earth spring fixing screw (1 pc.).

18. Remove the reflection/deflection, prism, diffusion, ITO sheets and diffusion panel.

19. Remove the lamp fixing holder fixing screws (6 pcs.).

20. Detach the lamp unit-A/B.

21. Remove the reflection mirror fixing screws. (6 pcs.).

Back shield (PSLDM4685CEFW)

Diffusion Panel (PCOVU0107CEZZ)

ITO Sheet (PSHEP0289CEZZ)

Prism Sheet (PSHEP0287CEZZ)

20" LCD Panel Unit

Lamp Fixing Holder (LHLDZ2176CEZZ)

Diffusion Sheet (PSHEP0288CEZZ)

Reflection/Deflection Sheet (PSHEP0286CEZZ)

Reflection Mirror (PMiR-0296CEZZ)

ITO Earth Spring (MSPRP1220CEFW)

Lamp Unit-A (KLMP-0124CEZZ)

Lamp Unit-B (KLMP-0125CEZZ)

Lamp Fixing Holder (LHLDZ2176CEZZ)

LC-20B4E

»Precautions at the time of the side B(back) service of main unit.

1. Remove only SC2002 of the FFC for connection between Main unit(SC2002) and Tuner unit(SC3902), and connect the extended cable (QCNW-A369WJZZ) for service.

2. Peel off the tape.

3. Remove only P701 of the FFC for connection between Main unit(P701) and Tuner unit(P1902), and connect the extended cable (QCNW-B194WJZZ) for service.

4. Remove the main unit fixing screws(2 pcs.), a substrate is reversed.

Main PWB (Side B)

Main PWB

P701

SC2002

SC3902

Tape

Tuner PWB

P1902

Step Part No. Description

1 QCNW-A369WJZZ Extension Cable 50-pin Main (SC2002)-Tuner (SC3902) 3 QCNW-B194WJZZ Extension Cable 12-pin Main (P701)-Tuner (P1902)

LC-20B4E

ADJUSTING PROCEDURE OF EACH SECTION

The best adjustment is made before shipping. If any position deviation is found or after part replace is performed, adjust as follows.

Preparation for adjustments

Use the dedicated AC adaptor or stable DC power supply. LC20B4E AC adaptor: UADP-0241CEPZ DC power supply: 13V 5.4A

1.Adjusting procedure

• Checker adjustment Power ON (Adjustment processing mode) → +B adjustment → Counter bias adjustment → TAMP (Contrast) adjustment → White balance adjustment

2.Entering the adjustment processing mode

There are the following two methods.

• Setting the pin (81)(KEY4) or pin (82)(KEY5) of IC2001 (microprocessor) to GND, turn on the power.

• A “POWER” key is made on with pushing an “TV/VIDEO” and “MENU” keys at the same time.(K of the inspection

process mode is displayed by the upper left of the image plane .) → Next, “CH (Ù)” and “VOL (–)” keys are pushed

at the same time.(It becomes the image plane of the adjustment process mode.).....When it is canceled, it is made

to turn it off.(Even off in the “MAIN POWER” key, off with R/C are good.)

3.Key operation in the adjustment process mode

• The receiving channel UP/DOWN is performed with the “CH (ù)/(Ù)” keys. One push ... The UP/DOWN tuning is performed per channel. Continuous push ... The UP/DOWN search is performed until a next receivable station is found.

• V arious adjustments The adjustment is performed for each item by the “MENU”, “Menu cursor”, “CH (ù)/(Ù)” or “VOL (+)/(–)” keys (LCD TV set and remote control).

• Adjustment item is chosen with the Menu cursor upward/downward keys.

• The adjustment item makes a toggle operation with the “MENU” key input. (Next item) If the “MENU” key is input while the bottom item is selected, it moves to the top item on the next page.

• Press the auto preset button on the remote controller in the adjustment process mode, and the top item of the

next page will show up regardless of which item appears now. Page 1 → Page 2 → ... → Page 57 → Page 1

• Press the manual memory button on the remote controller in the adjustment process mode, and the top item of the same page will show up.

• UP/DOWN of each adjustment vale selected is performed with the VOL (+)/(–) keys input.

LC-20B4E

4.Initialization

When the microprocessor (IC2001) or the EEPROM (IC2008, IC2010) has been replaced or when the EEPROM has been initialized, readjust the each adjustments. 4-1. Connect the pins (81) and (82) of IC2001 (microprocessor) to GND, and turn on the power. 4-2. Select the model name to (A522). 4-3. Select the inch size (20). 4-4. LED changes green from red after setting finish and about 15 seconds, initialization is completed, and it

becomes adjustment mode.

4-5. Writing the model-by-model data

For the Ver.1.10A microprocessor, get it initialized first and then make the settings, listed below, on it. (The microprocessor version is indicated at the bottom of Adjustment Process Page 1.)

Ver.1.10A data reprogramming (INCH SIZE [20])

Adjustment process page

8 13 18 22 26 30 34 41 41 41 41 41 41 41 41 41 41 41 41 41 41

PAL BRIGHTNESS SECAM BRIGHTNESS N358 BRIGHTNESS N443 BRIGHTNESS PAL-M BRIGHTNESS PAL-N BRIGHTNESS PAL60 BRIGHTNESS DPS NLC A6 DPS NLC A8 DPS NLC AA DPS NLC AC DPS NLC AE DPS NLC B0 DPS NLC B2 DPS NLC B6 DPS NLC BA DPS NLC BC DPS NLC BE DPS NLC C6 DPS NLC CA DPS NLC D0

Item

OSD settings

0 → +5 0 → +5 0 → +5 0 → +5 0 → +5 0 → +5

0 → +5 0E → 0B 0E → 0A

18 → 1A 38 → 2A 3C → 30 53 → 3B 4E → 42

07 → 10 15 → 23 39 → 32 40 → 35 07 → 10

15 → 1B

50 → 55

4-6. Precautions in replacing the EEPROMs (IC2008 and IC2010)

When the EEPROMs (IC2008 and IC2010) have been replaced, be sure to replace also the microprocessor (IC2001) with the one "Part No. RH-iXA522WJN1Q". The version of the RH-iXA522WJN1Q microprocessor is 1.20A.

LC-20B4E

5.Adjustment

5-1. +B adjustment...Page 1 +B-ADJ

Adjust the voltage of the pin (4) of P1902 to 5.00 ±0.02V with R3714. Note: Since 5.0V is a reference voltage of all power voltage, adjust it precisely.

5-2. Counter-bias adjustment

Vary the "COM BIAS" setting on Page 2 of the adjustment process mode so that the contrast be sharpest (black looks most sinking).

5-3. TAMP adjustment

1) Receive the upper left of 75% white half colour bar signal.

2) See if the “Y” reading on page 2 of the adjustment process mode is somewhere following. If not, make the “PAL T AMP” adjustment to get the “Y” reading in the range of AE thru BD.

3) If the adjustment of “PAL T AMP” is executed, write its adjustment value to the “SECAM TAMP” manually.

(Screen of the page 2 of the adjustment processing menu OSD)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 0 1 2 3 4 5 6 7 8

10 11 12 13

COM B I AS 9 0 PAL TAMP 21

SECAM TAMP 21 RCU TOF F GCU T OF F

BCU TOF F RGA I GG BGA I

TAMP TAMP

N 0 N

0 0 0

0 0

Y Data

(White 75%)

5-4. White balance adjustment

Adjust “RCUTOFF” and “BCUTOFF” on the page 2 of the adjustment processing so as to obtain the colour of the same level as the standard set.

LC-20B4E

M O D E L A522

V E R R O M 1 . 1 0 A

Reset 0

Afterwards, perform the operation check to confirm that the lamp error detection does not function.

Page 1 of the adjustment process

INCH SIZE 20 ERROR NO RESET 5 PUBLIC MODE OFF EXT CONTROL OFF EXT MODE UART UPDATE MODE NORMAL TEXT RESET OFF

6. Factory Setting

6-1. Perform a factory setting after completing all adjustments. 6-2. A “POWER” keys is made on with pushing an “TV/VIDEO” and “MENU” keys at the same time. 6-3. “K” of the inspection process mode is displayed on the screen upper left. 6-4. CH (ù) and VOL (+) keys are pushed about 2 seconds at the same time. 6-5. Release keys, if “E” is displayed on the screen upper left and “COMPLETE” is displayed on the bottom of it. 6-6. After a while, a power will be in a standby mode and a setup will be finished. Note: “First installation” serves on “Deutsch”.

7. Lamp error detection

7-1. Functional description

This LCD colour television has a function (lamp error detection) to be turned OFF automatically for safety when the lamp or lamp circuit is abnormal. If the lamp or lamp circuit is abnormal, or some other errors happen, and the lamp error detection is executed, the followings occur. 1 The main unit of television is turned OFF 5 seconds after it is turned ON. (The power LED on the front side

of TV turns from green to red.)

2 If the situation 1 happens 5 times sequentially, television can not be turned ON. (The power LED remains

red.)

7-2. Countermeasures 7-2-1.Check when turning OFF the lamp error detection

When television is turned OFF by the lamp error detection mentioned above, it enters the adjustment process with the power LED red. Entering the adjustment process turns OFF the error detection and turns ON TV. This enables the operation check to detect errors in the lamp or lamp circuit. Check whether "ERROR NO RESET" on line 3, page 1 of the adjustment process is 1 or more. If it is 1 or more, it indicates the lamp error detection was executed.

7-2-2.Resetting of the lamp error count

After confirming that the lamp or lamp circuit is normal, reset the lamp error count. Select "ERROR NO RESET" on line 3, page 1 of the adjustment process and set the number to 0 using the volume button.

LC-20B4E

No picture and No sound

Check all the settings microprocessor's adjust process menu.

Do F3301 and F3302

function?

Are T3701's secondary

outputs, +34V, +9V, +5V

and -11V normal?

Remove F3301 and F3302

and check the load side.

Is there short-circuiting?

Is there short-circuiting of

T3701 primary side periphery,

Q3703, Q3704 and S4701.

Replace F3301 and F3302.

Check S4701 and

connection cable.

Is T3701's primary oscillator

waveform normal?

Check T3701's secondary

load.

Yes Yes

No No

Yes

Check J3701 periphery and

connection cable.

Replace F6700~F6704.

Is the pin (120) of IC1201 in

the "H" state?

Is the output of Q3606 in the

state?

Yes

Check the OFL1 line, IC1201

and their peripheral parts.

Check the OFL line, Q3606

and their peripheral parts.

Check T6700~T6709,

Q6700~Q6714 and

connection cable.

Back light lamp failure to light up

Is the primary side of

T6700 ~T6709 periphery

short-circuiting?

Replace the back light lamp

with new one and check

again.

TROUBLE SHOOTING TABLE

No picture (1/3)

Check all the settings microprocessor's adjust process menu.

Is in/output of

IC801 normal?

Is in/output of

IC1201 normal?

Check IC801

and its

peripheral parts.

Check IC1201

and its

peripheral parts.

Check LCD

panel voltages

and waveform.

Yes

No picture

at all

Is voltages at

pins (6), (7) and

(18) tuner

normal?

Is output at pin

(13) of tuner

normal?

Check the

power line.

Check tuner

and its

peripheral parts.

Is input at pin

(16) of IC806

normal?

Is the pin (3) of

IC806 at "H"

state?

Yes

No TV output

Is the pin (48)

of IC2001 at "H"

state?

Yes

Check the its

line.

Check the its

line.

Check IC806

and its

peripheral parts.

Is input at pin

(14) of IC806

normal?

Check V1_V

line and its

peripheral parts.

No VIDEO 2

output

TROUBLE SHOOTING TABLE (Continued)

LC-20B4E

No picture (2/3)

Check all the settings microprocessor's adjust process menu.

Is input at pin

(14) of IC806

normal?

Check the V2_V

line and its

peripheral parts.

No VIDEO 1

output

Check the SY-line,

SC-line and their

peripheral parts.

Is input at pin (9)

of IC806 and pin

(1) of IC803

normal?

No S-VIDEO

output

Check IC1201

and its

peripheral parts.

Yes

No TELETEXT

output

Is input at pins

(136), (137), (138),

and (142) of

IC1201 normal?

Check the R, G

and B line.

Is output at pins

(57)~(59) of IC1601

normal?

Yes

Check V2VO line

and its peripheral

parts.

Is input at pin (21) of

IC1601 normal?

Check IC1601 and its

peripheral parts.

TROUBLE SHOOTING TABLE (Continued)

No picture (3/3)

Check all the settings microprocessor's adjust process menu.

Is output of

R0~R7

normal?

Is output of

G0~G7

normal?

Is output of

B0~B7

normal?

Yes

Colour is

unusual

Is in/output of

SPIO and

SPOI normal?

No picture

image

inversion

Gradation

defect

Is output of U/D

normal?

Yes

Check R1227 and

its peripheral parts.

Check R1235 and

its peripheral parts.

Check IC1202,

Q1204 and their

peripheral parts.

Check R1228 and

its peripheral parts.

Check R1232 and

its peripheral parts.

Is output V0, V7, V21,

V64, V112, V176,

V235 and V255

normal?

Check IC1101 and its

peripheral parts.

LC-20B4E

No sound (1/2)

Check all the settings microprocessor's adjust process menu.

Is the pin (53) of

IC2001 in the

"L" state?

Is output at pins

(27) and (28) of

IC1901 normal?

Is output at pins

(1) and (7) of

IC1905 normal?

Yes

No sound

from front

speakers

Yes

Muting effect is

on. Check the

FSMUTE line.

Check IC1901

and its

peripheral parts.

Check IC1905

and its

peripheral parts.

Is the pin (52) of

IC2001 in the

"L" state?

Is output at pins

(24) and (25) of

IC1901 normal?

Is output at pins

(1) and (7) of

IC304 normal?

Yes

Muting effect is

on. Check the

HP_MUTE line.

Check IC1901

and its

peripheral parts.

Check IC304

and its

peripheral parts.

No sound

from

headphone

TV sound

failure

Is output at pins

(33) and (34) of

IC1901 normal?

Is output at pins

(1) and (7) of

IC3501 normal?

Check IC1901

and its

peripheral parts.

Check IC3501

and its

peripheral parts.

Yes

No sound

from output

line

Check the tuner

and its

peripheral parts.

Yes

Is output at pin

(11) of Tuner

normal?

Is input at pin

(67) of IC1901.

Check IC1901

and its

peripheral

parts.

Check

Headphone Jack

and connection

cable.

Is output at pins

(8) and (12) of

IC3301 normal?

Check IC3301

and its

peripheral parts.

Check front

speaker and

connection

cable.

Yes

TROUBLE SHOOTING TABLE (Continued)

No sound (2/2)

Check all the settings microprocessor's adjust process menu.

Yes

No sound from SCART

SCART sound failure

Yes

Check IC1901 and its

peripheral parts.

Is output at pins (36) and (37) of

IC1901 normal?

Check IC1902 and its

peripheral parts.

Is output at pins (1) and (7) of

IC1902 normal?

Check their lines and their

peripheral parts.

Is input at pins (53) and (54) of

IC1901 normal?

Check IC1901 and its

peripheral parts.

Is output at pins (27) and (28) of

IC1901 normal?

LC-20B4E

CHASSIS LAYOUT

OPERATION Unit

MAIN Unit

TUNER Unit

R/C, LED Unit

87109654321

INVERTER-A Unit

LC-20B4E

INVERTER-B Unit

1716 1918151413121110

LC-20B4E

BLOCK DIAGRAM

SC3901

ANTENNA

SCART

TUNER

(AV1)

AUDIO IN

SC5001

AUDIO OUT

VIDEO OUT

SDA/RXD

SCL/TXD

VIDEOIN

SC_R/G/B

I2C/UART

SY SC

TV_V

V1.SY V

SELECTOR

(AV2) INPUT

J5003

VIDEO

V1_V

SIF1

AI_L/R

I2C

SC_L/RO

TV/AV

IC806

CHROMA

SELECTOR

IC803

AUDIO MAP

IC1902

AMP

IC808

AMP

IC808

(AV2) INPUT

J5001

AUDIO

V1.L/R

ANA_IN1+

SC2_IN_L/R

SC1_OUT_L/R

SC1_IN_L/R

CVBS/SY_IN

R/G/B_IN

SC_IN

MSP

IC1901

VPC

IC801

V2VO

SYNC SEP

IC802

UART

CSYNC

DACM_L/R

DACA_L/R

SC2_OUT_L

PROM

IC2010

MICON

IC2001

(AV2) INPUT

IC2003

REG

J3701

DC13V REG IC2004

+5V

+3.3V

INPUT

PAVCC

REG IC707

REG IC705

+3.3V

+3.4V

Q3707

Q3705

IC3702

+23V +17V

+34V

Q3708

DC/DC

CONVERTER

SIGVCC

T3701

Q3709

REG IC706

PWM IC3701

INVVCC

B12V1A

Q3703

REG IC805

REG IC704

REG IC1602

+9V

+8V

+5V

+1.8V

+3.3V

3.3V

+32V

−11V

VOLTAGE

CONVERTER

IC702

REG IC703

REG IC1607

REG IC1605

87109654321

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