Samsung la20s51 service manual

TFT-LCD TV

Chassis Model SP20SO LA20S51B

Manual

SERVICE

TFT-LCD TV CONTENTS

1. Precautions

2. Product Specifications

3. Disassembly & Reassembly

4. Alignment & Adjustments

5. Troubleshooting

6. Exploded View & Parts List

7. Electrical Parts List

8. Block Diagram

9. Wiring Diagram

10. PCB Layout

11. Schematic Diagrams

12. Panel Description

2 Product Specifications

2-2

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15

2-2 Pin Assignments

RCA Green

RCA Blue

RCA Red

RCA White

RCA Red

GND

Pb (Cb)

GND

Pr (Cr)

GND

Audio L

GND

Audio R

GND

2-2-1 DVD

RCA White

RCA Red

CVBS

Audio L

GND

Audio R

GND

2-2-3 A/V

RCA Yellow

Separate

1 2 3 4 5

GND

C GND GND

2-2-2 S-Video

Separate

Red

Green

Blue

GND

GND (DDC Return)

GND-Red

GND-Green

GND-Blue

No Connection

GND-Sync / Self Test

GND

DDC Data

H - Sync V - Sync

DDC Clock

2-2-4 D-SUB

2 Product Specifications

2-3

Separate Sync

2-3 Timing Chart

This section of the service manual describes the timing that the computer industry recognizes as standard for computer-generated video signals.

C D

Video

Sync

Video

R S

A : Line time total B : Horizontal sync width O : Frame time total P : Vertical sync width C : Back porch D : Active time Q : Back porch R : Active time E : Front porch S : Front porch

H/V Composite Sync

Sync-on-Green

79.976

12.504

1.067

1.837

9.481

0.119

75.025

13.329

0.038

0.475

12.804

1280/75Hz,50Hz

1280x1024

1024/75Hz

1024 x 768

60.023

16.660

1.219

2.235

13.003

0.203

75.029

13.328

0.050

0.466

12.795

0.017

78.750

Positive Positive

Separate

31.469

31.777

3.813

1.589

26.058

0.318

70.087

14.268

0.064

0.858

13.155

0.191

28.322

Negative

Positive

Separate

µ µ

IBM

640/75 Hz,

60Hz, 72Hz

640 x 480

800/75 Hz, 56Hz,

60Hz, 72Hz

800 x 600

1024/60Hz

1024 x 768

VGA2/70 Hz

720 x 400

VGA3/60 Hz

640 x 480

Table 2-1 Timing Chart

31.469

31.778

3.813

1.589

26.058

0.318

59.940

16.683

0.064

0.794

15.761

0.064

25.175

Negative Negative Separate

37.500

26.667

2.032

3.810

20.317

0.508

75.000

13.333

0.080

0.427

12.800

0.027

31.500

Negative Negative Separate

46.875

21.333

1.616

3.232

16.162

0.323

75.000

13.333

0.064

0.448

12.800

0.021

49.500

Positive Positive

Separate

48.363

20.677

2.092

2.462

15.754

0.369

60.004

16.666

0.124

0.600

15.880

0.062

75.000

Negative Negative

Separate

Mode

VESA

Timing

3 Disassembly and Reassembly

3-1

3 Disassembly and Reassembly

This section of the service manual describes the disassembly and reassembly procedures for the LA20S51B TFT-LCD TV.

WARNING: This monitor contains electrostatically sensitive devices. Use caution when handling these

components.

3-1 Disassembly

Cautions:1. Disconnect the monitor from the power source before disassembly.

2. Follow these directions carefully; never use any metal instrument except provided jig to separate the cabinet.

1. Place monitor face down on cushioned table and r emove 6 screws and remove stand.

2. Lift up the rear cover and remove 7 screws from the power board.

3 Disassembly and Reassembly

3-2

3. Remove 8 screws from the main board and disconnect cables.

4. Lift up the power board and main board.

5. Remove 6 screws from the BRKT and lift up the BRKT.

3 Disassembly and Reassembly

3-3

1. After confirm there is nothing on the desk, turn the LCD module over and put it on a flat desk set to the ground.

2. Remove 2 screws for the lamp unit.

3-2 Replacement Order of Lamp Assemblies

5. Lift up the panel.

3 Disassembly and Reassembly

3-4

3 Disassembly and Reassembly

3-4

3-3 Reassembly

Reassembly procedures are in the reverse order of disassembly procedures.

4. Please fix the new lamp units on the LCD module : opposite process 2 and 3.

3. Slide the lamp unit out. Please take out the lamp unit from the LCD module.

Slide the lamp unit out.

4 Alignments and Adjustments

4-1

4 Alignments and Adjustments

4-1 General Alignment Instuction

1. Usually, a color LCD TV needs only slight touch-up adjustment upon installation. Check the basic characteristics such as height, horizontal and vertical sync.

2. Use the specified test equipment or its equivalent.

3. Correct impedance matching is essential.

4. Avoid overload. Excessive signal from a sweep generator might overload the front-end of the TV. When inserting signal markers, do not allow the marker generator to distort test result.

5. Connect the TV only to an DC power source with voltage and frequency as specified on the backcover nameplate.

6. Do not attempt to connect or disconnect any wire while the TV is turned on. Make sure that the power cord is disconnected before replacing any parts.

7. To protect aganist shock hazard, use an isolation transform.

4-2 Factory Mode Adjustments

4-2-1 Entering Factory Mode

1. To enter “Service Mode” Press the remote -control keys in this sequence :

- If you do not have Factory remote - control

- If you have Factory remote - control

4-2-2 Factory Mode Tree

4 Alignments and Adjustments

4-2

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