SHARP LC-20B2H, LC-20B2M Service Manual

LC-20B2H LC-20B2M

SERVICE MANUAL

S01B5LC-20B2H

LCD COLOUR TELEVISION

LC-20B2H

MODELS

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.

LC-20B2M

CONTENTS

Page Page

» IMPORTANT SERVICE SAFETY

PRECAUTION ................................................... 2

» SPECIFICATIONS ............................................. 3

» OPERATION MANUAL ...................................... 4

» DIMENSIONS .................................................... 5

» REMOVING OF MAJOR PARTS....................... 6

» ADJUSTING PROCEDURE OF

EACH SECTION................................................ 9

» TROUBLE SHOOTING TABLE ....................... 13

» CHASSIS LAYOUT .......................................... 16

» BLOCK DIAGRAM........................................... 18

» DESCRIPTION OF SCHEMATIC DIAGRAM .. 20 » SCHEMATIC DIAGRAM

OPERATION and R/C RECEIVER UNIT .. 21

MAIN UNIT ................................................ 22

TERMINAL UNIT ....................................... 30

JACK UNIT ................................................ 34

INVERTER-A and INVERTER-B UNIT...... 35

» PRINTED WIRING BOARD ASSEMBLIES ..... 36

» PARTS LIST

ELECTRICAL PARTS ................................ 41

INVERTER-A UNIT.................................... 41

INVERTER-B UNIT.................................... 41

MAIN UNIT ................................................ 41

TERMINAL UNIT ....................................... 44

OPERATION UNIT .................................... 47

JACK UNIT ................................................ 47

R/C RECEIVER UNIT................................ 47

CABINET PARTS LIST........................ 47, 50

CABINET AND MECHANICAL PARTS ..... 48

ACCESSORIES PARTS ............................ 50

PACKING PARTS ...................................... 50

» PACKING OF THE SET................................... 51

SHARP CORPORATION

LC-20B2H

LC-20B2M

IMPORTANT SERVICE SAFETY PRECAUTION

Service work should be performed only by 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 ONL Y WITH SAME TYPE FUSE. F3701 (1.6A, 250V), F3702 (1.6A, 250V) F3703 (2.0A, 250V), F3704 (2.0A, 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 and 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 1 10~240 volt AC 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 having 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 and etc.) and measure the AC voltage drop across the resistor. All checks must be repeated with the AC cord plug connection reversed. (If necessary, 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 milliamp. 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, wattage and 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

Specifications

ITEMS ...................................................... 20" LCD COLOUR TV, Model: LC-20B2H/M

LCD panel...............................................................................................19.7" TFT LCD

Number of dots ................................................................................. 921,600 dots VGA

Video colour systems....................................................................... World multi system

TV Function

TV Standard (CCIR) .................................................................................I/DK/M/BG

TV Turning System..................................................................... Auto preset turning

STEREO/BILINGUAL .....................................................NICAM-BG, I, DK/IGR-BG

Universal R/C for TV only ....................................................................................Yes

AUTO PRESET ...................................................................................................Yes

CATV ....................................................................................................~Hyper Band

4-LINE DIGITAL COMB FILTER ..............................................................................Yes

Brightness.......................................................................................................430 cd/m

Lamp life ................................................................................................... 60,000 Hours

Viewing angles.......................................................................................H: 160° V: 160°

Audio output........................................................................................................2.5Wx2

Speakers................................................................................................... 5 cm ø 2 pcs.

Terminals

AV1 ...................................................................... Composite Video, S-Video, Audio

AV 2 IN/OUT........................................................................ Composite Video/Audio

Component ....................................................................................... Y, PB, PR/Audio

Headphone Jack...........................................................................3.5 mm ø jack (Rear)

OSD LANGUAGE ..................................................................... English/Chinese/Arabic

Power requirement .................................................... DC 13 V, AC110-240 V, 50/60Hz

Weight........................................................................................ 8.2 kg w/o accessories

Accessories ...............................................R/C, Batteries, Cable clamps, AC adapter,

LC-20B2H LC-20B2M

AC cord, Operation manual, Antenna cable

Specifications are subject to change without prior notice.

LC-20B2H

LOCATION OF USERS CONTROL

Main unit (front view)

Speaker

SLEEP indicator

The SLEEP indicator lights up red when

the SLEEP TIMER is set to on.

Speaker

Upper control panel

Remote sensor window

(The actual location is not visible.)

To change the vertical

angle of the LCD TV set,

tilt the screen up to 10

degrees forward or 20

degrees backward. The

TV set can also be

rotated 90 degrees

horizontally. Please adjust

the angle so that the TV

set can be watched most

comfortably.

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).

VOL CH MENU TV/VIDEO MAIN POWER

PRESET

■

TV/VIDEO, CH (

)/( ), and VOL (+)/(–) 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 with the remote

control.

Note:

VOL (+)/(–)

CH (

)/( )

TV/VIDEO

MAIN POWER

Auto Preset Details are

described on page 14.

Main unit (rear view)

ANT.

VIDEO

AUDIO

HEAD

PHONE

POWER

INPUT

DC13V

AV-IN 2/OUT

COMPONENT

VIDEO

S-VIDEO

AUDIO

AV-IN 1

Antenna terminal

AUDIO (L)

AUDIO (R)

HEADPHONE

POWER INPUT

(DC 13V)

AUDIO (L)

AUDIO (R)

VIDEO

RPB

AV-IN 2/OUT

COMPONENT

AUDIO (L)

AUDIO (R)

VIDEO

S-VIDEO

AV-IN 1

LC-20B2M

Operation Manual

Dimensions

VOL CH MENU

TV/VIDEO

MAIN POWER

60.5

54.5

78.9

379

POWER

SLEEP

626

403.28

401.3

298.8

300.8

474.5

384.590

VIDEO

AUDIO

HEAD

PHONE POWER

INPUT DC13V

AV-IN 2/OUT

COMPONENT

AV-IN 1

VIDEO

AUDIO

S-VIDEO

100

51.5

15.5

43141414141414141314

3.5

151516

ANT.

VIDEO

AUDIO

S-VIDEO

95.2

60.5

18 12.5

65.5163.9

229.4

295.8

467.8

172

136 0.5

LC-20B2H LC-20B2M

(Unit: mm)

LC-20B2H

LC-20B2M

REMOVING OF MAJOR PARTS

1. Remove the back cover.

2. Remove the table stand fixing screws (4 pcs.).

3. Remove the cabinet B fixing screws (15 pcs.) and detach the cabinet. (3 : XBBSF30P06000, 3 : XEBSF40P16000)

4. Remove the reinforcement angle fixing screws (4 pcs.).

5. Release the wire holders at 3 locations.

6. Detach the connector from each PWB.

Cabinet B

Back cover

Table stand

Reinforcement angle

SC1201

P2004

Main PWB

SC1202

P4005

R/C Receiver PWB

P2003

Terminal PWB

SC3403

P3501

P3500

P4004

SC2001

P3602

P3601

P3702

P3701

P3401

Wire holder

Operation PWB

Inverter-A PWB

P6751

Jack PWB

P5001

Inverter-B PWB

P6551

P6755

P6555

7. Remove the terminal PWB fixing screws (4 pcs.).

8. Remove the jack PWB fixing screws (2 pcs.).

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

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

11. Remove the inverter-B PWB fixing screws (2 pcs.).

12. Remove the R/C receiver PWB fixing screws (2 pcs.).

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

14. Remove the PWB frame fixing screw (1 pc.).

LC-20B2H LC-20B2M

Main PWB

Operation PWB

Terminal PWB

Inverter-A PWB

Inverter-B PWB

Jack PWB

R/C Receiver PWB

LC-20B2H

LC-20B2M

» 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 electroconductive mat.

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

15. Remove the two lock screws from the front of the LCD display unit and the four lock screws from its back. Detach the shielding plate.

16. Detach the two reflection sheets.

17. Detach the top and bottom fluorescent lamps.

18. Remove the light guide plate.

19.Detach the diffusion sheet.

20. Detach the prism sheet and reflection/deflection sheet.

LCD Display Unit (Front)

Light Guide Plate

(PGiDM0065CEZZ)

Diffusion Sheet

Fluorescent Lamp (Top)

(KLMP-0110CEZZ)

Shielding Plate

Reflection Sheet-1

(PSHEP0250CEZZ)

Reflection Sheet-2

(PSHEP0251CEZZ)

LCD Display Unit

Prism Sheet

Reflection/deflection Sheet

Fluorescent Lamp (Bottom)

(KLMP-0111CEZZ)

LC-20B2H LC-20B2M

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.

1.Preparation for Adjustments

(1)Use the exclusive-use AC adapter or stable DC power supply.

AC adapter: UADP-0219CEZZ DC power supply: 13 ± 0.5V 3.5A

[1] Adjustment Procedure

1-1. Adjusting the checker

Turning on the power (initialization) ) Setting the model and size in inches ) Transferring the model-specified data to the E2PROM (I2C) ) Calling the adjustment process mode ) Starting the adjustment (+B)

1-2. Adjusting the finish process

Reassembling the set ) Turning on the power ) Calling the adjustment process mode (using the remote controller) ) Adjusting the counter bias, TV contrast and white balance

[2] Calling the MAIN adjustment process mode

There are the following two ways to choose from.

• Set KEY 4 and KEY 5, pins (81) and (82), respectively, on the microprocessor to the "L" level. Now turn on the power.

• For servicing, hold down the INPUT SELECT and MENU keys at once, and turn on the POWER switch. (Make sure the process mode "K" appears at the top left of the screen.) Then press the CH DOWN and VOL DOWN keys at once. (Make sure the adjustment process mode screen shows up.) To quit this mode, turn off the power. (Or turn off the POWER switch or use the remote controller’s OFF key.)

[3] Using the keys for the adjustment process

Selecting a reception channel

• Using the CH UP/DOWN key, turn up and down reception (broadcasting) channels. Just click on the key, and channels are selected on by one. Hold down the key, and the next receivable channel is searched up and down.

• Adjustment items Adjust each of the items by using the MENU SELECT, CURSOR UP/DOWN, CH UP/DOWN and VOL UP/ DOWN keys (on the set or on the remote controller).

• Select an adjustment item using the CURSOR UP/DOWN key.

• An adjustment item is toggled on and off by activating the MENU SELECT key (next item). Let’s suppose that the item at the bottom of a page is now selected. When the MENU SELECT key is activated here, the item at the top of the next page will be selected.

[4] Initialization

4-1. Set pins (81) and (82) of IC2001 (microprocessor) to GND. Turn on the power. 4-2. Select a model number ( C2H, B2H ). 4-3. Select a size in inches ( 10, 13, 15, 20 ).

[5] Adjustment

5-1. +B adjustment (R3760 Variable resistor)

1) Receive the colour bar signal.

2) Adjust the voltage at SC3403 (pin (38)) to 5.00± 0.02 V.

Note: The 5.0 V level is used as reference for all the line voltages. Make this adjustment as precisely as

possible.

5-2. Counter bias adjustment: COM BIAS on page 2

Adjust the "COM BIAS" setting until the contrast gets optimum (the black portion blackest). The adjustment guideline is around 106 for Model LC-20B2H/M.

LC-20B2H

LC-20B2M

5-3. TAMP adjustment

1) Feed the color bar pattern signal.

2) See if the "Y" reading on adjustment process page 2 is within the range shown below. If not, adjust the "NTSC TAMP" setting to bring the "Y" reading within the specified range.

Model LC20B2

Adjustment value BB ~ CA

3) If the "NTSC TAMP" setting has been readjusted, write down its new setting in the "PAL TAMP", "SECAM TAMP", "PAL-M TAMP" and "PAL-N TAMP" items manually.

(Page 2 of adjustment process OSD)

Y data 75% White

5-4. White balance adjustment

1) Feed the monoscope pattern signal.

2) Adjust the “RCUTOFF” and “BCUTOFF” settings on adjustment process page 2 to achieve the color at the same level as with the standard set.

Note: Keep the “RCUTOFF” and “BCUTOFF” settings as an odd number, whenever possible, in the range below.

• • • -9, -7, • • • -1, +1, • • • +7, +9 • • • If set to an even number, horizontal streaks may occur with a specific-gradation monochrome signal.

[6] Lamp error detection

6-1. 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.)

6-2. Countermeasures 6-2-1. 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 9, page 1 of the adjustment process is 1 or more. If it is 1 or more, it indicates the lamp error detection was executed.

6-2-2. 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 9, page 1 of the adjustment process and set the number to 0 using the volume button.

LC-20B2H LC-20B2M

Page 1 of the adjustment process

+ B – A D J 160 M O D E L B2H I NCH I S I ZE 20 N T S C P W M F R E Q 0C0 P A L P WM F R E Q 0BD NTSC PWM DUTY 0 P AL PWM DUT Y 0 T V G A I N OFF ERROR NORESET 5 PUBLI C MODE ON

B 2 H V E R 1 . 0 0

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

Reset 0

[7]. Public mode

• How to enter into PUBLIC MODE

1. Turn off TV by pressing MAIN POWER switch.

2. While pressing at same time VOL(+) key and CH(])key, press MAIN POWER switch for more than 2 seconds. TV will turn on, and you will see the screen display a setting of PUBLIC MODE.

LC-20B2H

LC-20B2M

• Setting screen of “PUBLIC MODE”

PUBLIC MODE MAXIMUM VOLUME [ 60] VOLUME FIXED [VARIABLE ] REMOTE CONTROL [RESPOND ] USER CONTROL [RESPOND ] ON SCREEN DISPLAY [YES ] AV1 INPUT [NORMAL ] RESET ENTER

1()2() •()59()60

VA RIA BL E()FIXED RESPOND()LIMITED RESPOND()NO RESPOND YES()NO

NORMAL()START()AV 1 FI X E D

Factory setting

Adjust setting

1. You can select each item of functions by pressing cursor UP/DOWN keys on the remote control or CH]/[ keys on the LCD TV. The letter of selected item turns to yellow colour when you selected it.

2. The setting position of each item of functions are made by pressing cursor RIGHT/LEFT keys on the remote control or VOL (+)(-)keys on the LCD TV.

3. Select ENTER position after you set all functions , and press cursor RIGHT/LEFT keys on the remote control or VOL(+)(-)keys on the LCD TV for confirmation. Unless otherwise you make ENTER confirmation, the settings will not be memorized.

6-functions of Public Mode settings expand for public application

1. MAXIMUM VOLUME (1—————60)

You can set the maximum volume at your desire level.

2. VOLUME FIXED (VARIABLE / FIXED) You can fix the sound volume at your desire level. When you set to "FIXED",the sound volume which you just set is fixed.

3. REMOTE CONTROL (RESPOND / LIMITED) If you set "LIMITED", remote control keys of POWER,CH]/[,VOL(-)/(+) and BRIGHT keys are responded, but other keys are not responded. This is a position that you can not make MENU adjustments.

4. USER CONTROL (RESPOND / NO RESPOND) "NO RESPOND" means that the TV does not respond when you press a user control buttons except main power button on the main unit.

5. ON SCREEN DISPLAY (YES / NO) If you set “NO”position,OSD will not appear.

6. AV1 INPUT (NORMAL / START / AV1 FIXED) Some application use DVD or VCR connecting to AV1 input of our monitor and you will not want to change it to other mode,such as Component or AV2 input. You can set the position of input "AV1 FIXED" For other application that you want to start AV1 every time when you press power button, and you may select other input mode after then, set it at "START" position.

7. RESET You can cancel all Public Mode settings. (It returns to the factory setting.)

8. ENTER You make sure after you have specified all functions, then press the enter key. Unless otherwise you press the enter key, all positions that you have selected will not be set.

No picture

at all

Yes

Are inputs

and outputs

of IC801 as

specified?

Check all the settings on the microprocessor’s adjust process menu.

No picture

Check IC801

and its

peripheral

parts.

Yes

Are inputs

and outputs

of IC1201 as

specified?

Check

IC1201 and

its peripheral

parts.

Check LCD

panel voltage

and

waveform.

No TV and

VIDEO 1

output

Are inputs

and outputs

of IC402 as

specified?

Check IC402

and its

peripheral

parts.

Is input at Pin

(73) of IC801

as specified?

Check IC801,

AV1 line and

their

peripheral

parts.

Yes

No TV

output

Yes

Are voltages

at Pins (6),

(7) and (9) of

tuner as

specified?

Check the

power line.

Yes

Is output at

Pin (19) of

tuner as

specified?

Check the

tuner and its

peripheral

parts.

Is input at Pin

(3) of IC402

as specified?

Check the

line in

question.

Yes

Check IC402

and its

peripheral

parts.

Yes

Are Pins (2)

and (4) of

IC402 at “H”

and “L”

respectively?

Are Pins (65)

and (66) of

IC2001 at “H”

and “L”

respectively?

No VIDEO

1 or 2

output

Yes

Is input at Pin

(1) of IC402

as specified?

Check the

line in

question.

Yes

Are Pins (2)

and (4) of

IC402 both at

“L” or Pins (4)

of IC402 at

“H”?

No S

VIDEO

output

Are inputs at

Pins (71) and

(72) of IC801

as specified?

Check P5001,

SY line, SC

line and

peripheral

parts.

COMPONENT

output

Is input at

Pins (4), (5),

(6) and (75)

of IC801 as

specified?

Check J3404,

J3405, J3406,

DVD-Y line,

PB line, PR

line and

peripheral

parts.

Are Pins (65)

and (66) of

IC2001 both

at “L”or Pins

(66) of IC1201

at “H”?

Check IC402

and its

peripheral

parts.

Yes

Check the

line in

question.

Yes

Check the

line in

question.

TROUBLE SHOOTING TABLE

LC-20B2H LC-20B2M

LC-20B2H

No picture and sound

No color

No TV color

No S-VIDEO color

Yes

Do F3701, F3702, F3703

and F3704 function?

Check all the settings on the microprocessor’s adjust process menu.

Are secondary outputs

(+38V, +16V, +9V, +5V, -8V)

of T3701 as specified?

Yes

Are the oscillation waveform

at T3701’s primary side as

specified?

Yes

Disconnect F3701, F3702,

F3703 and F3704. Is the

load side short-circuited?

Yes

Is any of T3701’s primary

side, Q3700 and S4701 short-

circuited?

Check J3701, its peripheral

parts and connection cable.

Replace F3701, F3702,

F3703 and F3704.

Check S4701 and

connection cable.

Check the secondary-side

load of T3701.

Fluorescent lamp

Yes

Does F3703 and F3704

function?

Yes

Is Pin (34) of IC1201 at “H”?

Yes

Are the oscillation waveforms

at the primary side of T6551-3

and T6751-3 as specified?

Yes

Replace F3703 and F3704.

Is input at Pin (71) of IC801

as specified?

Check P5001, SC line and

peripheral parts.

Yes

Check the line, IC1201 and

its peripheral parts.

Check Q6551-2, Q6555,

Q6751-2, Q6755, T6551-3,

T6751-3 and their peripheral

parts.

Replace the fluorescent lamp

and check the oscillation

waveform again.

No VIDEO color

Check all the settings on the microprocessor’s adjust process menu.

No COMPONENT color

Is input at Pins (4) and (6) of

IC801 as specified?

Check J3405, J3406, PB line,

PR line and peripheral parts.

LC-20B2M

TROUBLE SHOOTING TABLE (Continued)

+ 31 hidden pages