Samsung LW20M21C Service manual

TFT-LCD TV

Chassis Model
VC17EO LW17M24C
VE20EO LW20M21C

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

1-1-1 Warnings

1. For continued safety, do not attempt to modify the circuit
board.

2. Disconnect the AC power and DC Power Jack before
servicing.

1-1-2 Servicing the LCD TV

1. When servicing the LCD TV Disconnect the AC line
cord from the AC outlet.

2. It is essential that service technicians have an accurate
voltage meter available at all times. Check the
calibration of this meter periodically.

1-1-3 Fire and Shock Hazard

Before returning the LCD TV to the user, perform the
following safety checks:

1. Inspect each lead dress to make certain that the leads are
not pinched or that hardware is not lodged between the
chassis and other metal parts in the LCD TV.

2. Inspect all protective devices such as nonmetallic control
knobs, insulating materials, cabinet backs, adjustment
and compartment covers or shields, isolation resistor­capacitor networks, mechanical insulators, etc.

3. Leakage Current Hot Check (Figure 1-1):

WARNING: Do not use an isolation

transformer during
this test.

Use a leakage current tester or a metering system that
complies with American National Standards Institute
(ANSI C101.1, Leakage Current for Appliances), and
Underwriters Laboratories (UL Publication UL1410,

59.7).

Figure 1-1. Leakage Current Test Circuit

4. With the unit completely reassembled, plug the AC line
cord directly into a 220V AC outlet. With the unit’s AC
switch first in the ON position and then OFF, measure
the current between a known earth ground (metal water
pipe, conduit, etc.) and all exposed metal parts,
including: metal cabinets, screwheads and control shafts.
The current measured should not exceed 0.5 milliamp.
Reverse the power-plug prongs in the AC outlet and

repeat the test.

1-1-4 Product Safety Notices

Some electrical and mechanical parts have special safety­related characteristics which are often not evident from visual
inspection. The protection they give may not be obtained by
replacing them with components rated for higher voltage,
wattage, etc. Parts that have special safety characteristics are
identified by on schematics and parts lists. A substitute
replacement that does not have the same safety characteristics
as the recommended replacement part might create shock, fire
and / or other hazards. Product safety is under review
continuously and new instructions are issued whenever
appropriate.

1 Precautions

LW17M24C/LW20M21C 1-1

1 Precautions

Follow these safety, servicing and ESD precautions to prevent damage and to protect against potential hazards such as electrical
shock.

1-1 Safety Precautions

DEVICE
UNDER
TEST

TEST ALL

EXPOSED METAL

SURFACES

(READING SHOULD

NOT BE ABOVE 0.5mA)

LEAKAGE

CURRENT

TESTER

2-WIRE CORD

ALSO TEST WITH

PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED)

EARTH

GROUND

!

1-2-1 General Servicing

Precautions

1. Always unplug the unit’s AC power cord from the AC
power source and disconnect the DC Power Jack before
attempting to:
(a) remove or reinstall any component or assembly, (b)
disconnect PCB plugs or connectors, (c) connect a test
component in parallel with an electrolytic capacitor.

2. Some components are raised above the printed circuit
board for safety. An insulation tube or tape is sometimes
used. The internal wiring is sometimes clamped to
prevent contact with thermally hot components. Reinstall
all such elements to their original position.

3. After servicing, always check that the screws,
components and wiring have been correctly reinstalled.
Make sure that the area around the serviced part has not
been damaged.

1. Immediately before handling any semiconductor
components or assemblies, drain the electrostatic charge
from your body by touching a known earth ground.
Alternatively, wear a discharging wrist-strap device. To
avoid a shock hazard, be sure to remove the wrist strap
before applying power to the LCD TV.

2. After removing an ESD-equipped assembly, place it on a
conductive surface such as aluminum foil to prevent
accumulation of an electrostatic charge.

3. Do not use freon-propelled chemicals. These can
generate electrical charges sufficient to damage ESDs.

4. Use only a grounded-tip soldering iron to solder or
desolder ESDs.

5. Use only an anti-static solder removal device. Some
solder removal devices not classified as “anti-static” can
generate electrical charges sufficient to damage ESDs.

4. Check the insulation between the blades of the AC plug
and accessible conductive parts (examples: metal panels,
input terminals and earphone jacks).

5. Insulation Checking Procedure: Disconnect the power
cord from the AC source and turn the power switch ON.
Connect an insulation resistance meter (500 V) to the
blades of the AC plug.

The insulation resistance between each blade of the AC
plug and accessible conductive parts (see above) should
be greater than 1 megohm.

6. Always connect a test instrument’s ground lead to the
instrument chassis ground before connecting the positive
lead; always remove the instrument’s ground lead last.

6. Do not remove a replacement ESD from its protective
package until you are ready to install it. Most
replacement ESDs are packaged with leads that are
electrically shorted together by conductive foam,
aluminum foil or other conductive materials.

7. Immediately before removing the protective material
from the leads of a replacement ESD, touch the
protective material to the chassis or circuit assembly into
which the device will be installed.

Caution: Be sure no power is applied to

the chassis or circuit and
observe all other safety
precautions.

8. Minimize body motions when handling unpackaged
replacement ESDs. Motions such as brushing clothes
together, or lifting your foot from a carpeted floor can
generate enough static electricity to damage an ESD.

1 Precautions

1-2 LW17M24C/LW20M21C

1-3 Electrostatically Sensitive Devices (ESD) Precautions

Some semiconductor (solid state) devices can be easily damaged by static electricity. Such components are commonly called
Electrostatically Sensitive Devices (ESD). Examples of typical ESD are integrated circuits and some field-effect transistors. The
following techniques will reduce the incidence of component damage caused by static electricity.

1-2 Servicing Precautions

WARNING: An electrolytic capacitor installed with the wrong polarity might explode.

Caution: Before servicing units covered by this service manual, read and follow the Safety Precautions

section of this manual.

Note: If unforeseen circumstances create conflict between the following servicing precautions and any of the safety

precautions, always follow the safety precautions.

2 Product Specifications

2-1 LW17M24C, LW20M21C Specifications

LCD Panel

TFT-LCD panel, RGB vertical stripe, normaly white, 17-Inch viewable, 0.264 (H) x 0.264(V)mm pixel pitch

TFT-LCD panel, RGB vertical stripe, normaly white, 20-Inch viewable, 0.2125(H) x 0.6375(V) mm pixel pitch

Scanning Frequency Horizontal : 30 kHz ~ 80 kHz (Automatic) Horizontal : 28 kHz ~ 33 kHz (Automatic)

Vertical : 50 Hz ~ 75 Hz (Automatic) Vertical : 50 Hz ~ 70 Hz (Automatic)

Display Colors 16.2 Million colors

Maximum Resolution Horizontal : 1280 Pixels Horizontal : 640 Pixels

Vertical : 1024 Pixels Vertical : 480 Pixels

Input Video Signal Analog 0.7 Vp-p ± 5% positive at 75 Ω, internally terminated

Input Sync Signal Type : Seperate H/V

Level : TTL level

Active Display
Horizontal/Vertical

AC power voltage & Frequency

AC 100 ~ 240V, 50 ~ 60 Hz

Power Consumption 45 W 55 W

Dimensions(W x D x H)

Set

16.44 x 7.59 x 16.72 Inches (417.5 x 192.9 x 424.6 mm)(State of stand installed) 18.86 x 8.85 x 18.07 Inches (479 x 224.8 x 459.1 mm) (State of stand installed)

18.86 x 2.94 x 17.18 Inches (479 x 74.7 x 436.4 mm) (State of stand disassembled)

16.44 x 4.95 x 16.72 Inches (417.5 x 125.7 x 424.6 mm)(State of Wall mount) 18.86 x 5.51 x 20.42 Inches (479 x 139.9 x 518.6 mm) (Without Stand of Wall mount)

Package 21.1 x 7.2 x 20.1 Inches (537 x 183 x 511 mm

)

22.60 x 23.35 x 8.27 Inches (574 x 593 x 210 mm)

Weight

Set / Package 4.95 Kg (10.91Ibs) / 7.0 Kg (15.43 lbs)

7.35 Kg (16.20 Ibs) (State of stand installed) / 10 Kg (22.05 lbs)

Environmental Considerations Operating Temperature : 50 °F ~ 104 °F (10 °C ~ 40 °C)

Operating Humidity : 10 % ~ 80 %
Storage Temperature : -4 °F ~ 113 °F (-20 °C ~ 45 °C)
Storage Humidity : 5 % ~ 95 %

TV System

Antena Input 75Ω, Coaxial Cable

– MAX Internal speaker Output : Right => 2.5W

Left => 2.5W

Sound Characteristic

– Headphone Out: 10mW max (3.50 Stereo Jack 32)
– Output Frequency : RF => 80 Hz ~ 15 kHz at -3dB

A/V => 80 Hz ~ 20 kHz at -3dB

2 Product Specifications

LW17M24C/LW20M21C 2-1

Item

Description

LW17M24C

LW20M21C

337.9 mm(H) / 270.3 mm(V) 408 mm(H) / 306 mm(V)

Tunning Frequency Synthesize

System NTSC-M, PAL/ Secam_L(Euro multi)

Sound MONO, STEREO, SAP, A2/Nicam

2 Product Specifications

2-2 LW17M24C/LW20M21C

1
2
3
4
5
6
7
8

9
10
11
12
13
14
15

2-2 Pin Assignments

RCA White

RCA Red

CVBS

Audio L

GND

Audio R

GND

2-2-3 A/V

RCA Yellow

Pin

Separate

1

2

3

4

5

GND

Y

C
GND
GND

2-2-2 S-Video

Pin

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

1
2
3
4
5
6
7
8

9
10
11
12
13
14
15
16
17
18
19
20
21

No

PIN

Sound R out

Sound R In

Sound L out

GND
GND

Sound L In

Cb

ID

GND

NC

Y

NC
GND
GND

Cr

BL In

GND
GND

Video Out

Video In

GND

2-2-1 Scart

2 Product Specifications

LW17M24C/LW20M21C 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

A

O

E

B

P

Video

Sync

Sync

Video

Q 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

0.013

135.000

Positive

Positive

Separate

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

fH (KHz)

A µsec

B µsec

C µsec

D µsec

E µsec

fV (Hz)

O msec

P msec

Q msec

R msec

S msec

Clock
Freq.
(MHz)

Polarity
H.Sync

V.Sync

Remark

IBM(LW17M24C/LW20M21C)

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(LW17M24C)

Timing

Memo

2 Product Specifications

2-4 LW17M24C/LW20M21C

3 Disassembly and Reassembly

LW17M24C/LW20M21C 3-1

3 Disassembly and Reassembly

This section of the service manual describes the disassembly and reassembly procedures for the
LW17M24C/LW20M21C TFT-LCD TV.

WARNING: This monitor contains electrostatically sensitive devices. Use caution

when handling these components.

3-1-1 LW17M24C

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

2. When IP-BOARD has a defect, the whole PCB ASS’Y, not a single part, should be
replaced.

1. Place LCD TV face down on cushioned table.
Remove 4 screws from the stand.

2. Remove 3 screws from the rear cover and lift up
the rear cover.

3. Remove 13 screws from the boards and remove 2
hold inverter from the boards.
Disconnect inverter cable, speaker cable, control
cable, BRKT AC cable and LVDS cable from the
boards.

4. Lift up the boards. remove 8 screws from the
shield panel.

5. Remove 8 screws from the shield panel.
.Lift up the panel shield. and lift up the panel.

3 Disassembly and Reassembly

3-2 LW17M24C/LW20M21C

1. Place LCD TV face down on cushioned table.
Remove 4 screws from the grip on the stand.

2. Remove 3 screws on stand and disconnect cover
rear after inserting stand completely into stand.
(Note : If stand is loosely inserted into stand, cover
rear can be damaged when disconnected.)

3. Disconnect inverter holder wire from the board and
carefully reomve the silicon glue on the LVDS
cable with a nipper.

4. Disconnect function cable, speaker cable, inverter
cable and LVDS cable from the board.

5. Remove 8 screws from the shield panel and lift up
the panel.

6. Lift up the panel.
This picture shows cover front after disconnecting
the panel from it.

3-1-2 LW20M21C

3 Disassembly and Reassembly

LW17M24C/LW20M21C 3-3

3-2 Reassembly

Reassembly procedures are in the reverse order of disassembly procedures.

Memo

3 Disassembly and Reassembly

3-4 LW17M24C/LW20M21C

4 Alignments and Adjustments

LW17M24C/LW20M21C 4-1

4 Alignments and Adjustments

4-1 General Alignment Instuction

1. Usually, a color TV-VCR 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 LW17M24C/LW20M21C

1. Calibration

1. Calibration

VCTi
PC

2. Option

INFO Menu

3. W/B

4. ADC

5. VCTi 127

6. ACC/ACM

7. Test Pattern 0

8. Bus Stop off

9. Check Sum 0

10. Reset

T- VNC17(20) - PEU-0003 2004/04/20

(1) RF,VIDEO, S-VIDEO :

Factor y Mo de Cal ib r at ion V CTi Enter

(2) PC : adjust in VGA MODE.

Based on Master device

execute Auto Adjustment in Cross Hatch (also called Combination) (Model : 10, Pattern : 25)

(VI DEO SIGNA L GENE RA TOR M SPG- 925F )

After adjusting 16 Gray Pattern (Model : 10, Pattern : 17)

Fac

tory Mode Cal ibr ati on PC E nt e r

(3) check 4.ADC of Factory Mode. Adjustment can be done as below.

Value variation can be 10~20.

+

_

4 Alignments and Adjustments

LW17M24C/LW20M21C 4-3

3. W/B(1)

3. W/B(2)

R level 128
G level 128
B level 128
R gain 127
G gain 127
B gain 127
g Sub Color 0
g Sub Tint 50
Recall

RF RF

[Initial Data] [A d ju st Dat a]

RemarkAdjustment item

Red l evel A DJ[ 0~255] 128 128

Green level AD J[ 0~255] 128 128

Blue level F IX [0~255] 128 128

Red Gain FI X[ 0~255] 128 135

Green Gain ADJ[ 0~255] 128 135

Blue Gain ADJ [ 0~255] 128 135

gSUB Color FI X[ 0~255] 0 0

gSUB Tint F IX [0~255] 50 50

Factor y Rec al l

*A/S : Micom Initial Data Write

2. Option

1. Video Mute O

2. Auto Power On

3. Panel XGA

4. Inch 15

5. Antenna Osd off

6. TTXList/Flof Flof

7. Auto FM On

8. Acc/ACM 1

9. Gamma LUT O

10. ESM

11. System

On
CW

LW17M24C

Blue level 118FIX
Red Gain 162FIX

LW20M21C

Blue level 119FIX
Red Gain 136FIX

4 Alignments and Adjustments

4-4 LW17M24C/LW20M21C

4. ADC

5. VCT

R Drive

255

G Drive

255

B Drive

255

Sub Contrast

44

Sub Bright

0

Sub Sharp

15

Sub Color

7

Sub Tint

50

Sub Coring

5

RF AGC

0

Vpeaking

6

CTI Gain

3

CTI Coring

5

LMIXOFS

6

PKCF

3

AGCADJ1

32

LTI Gain

15

6. ACC/ ACM

Y Max D

7

Y Scl Thr

64

Y Scl A

5

Y Scl B

0

A Ctrl

0

A Snslp

8

T Dixel

12

Lower End

80

Mid Start

30

Mid End

100

Up Start

40

Low Sn Thr

60

Up Sn Thr

0

Y Min

10

Y Max

255

Ym Div Slp

128

Fr Age

1

Fr App

0

Esm Ctrl

127

VCTi PC

Roff set

set

set

set

set

set

FI X [0~127 ] 46 Rof f F IX[ 0~127] 50

Goff F I X[ 0~127 ] 66 G of f F IX [0~127] 54

Boff F IX [0~127 ] 68 Bof f FI X[ 0~127] 44

Rgai n 0

FI X [0~255]

251 Rg ain 0

FI X [0~255]

115

Rgai n 1

FI X [ 0 ~ 1]

0Rgai n1

FI X [ 0 ~ 1]

1

Ggai n0

FI X[ 0~255]

255 Gg ain0

FI X[ 0~255]

120

Ggai n1

FI X [ 0 ~ 1]

0Ggai n1

FI X [ 0 ~ 1]

1

Bgain0

FI X[ 0~255]

253 Bg ain0

FI X [0~255]

114

Bgain1

FI X [ 0 ~ 1]

0Bgain1

FI X [ 0 ~ 1]

1

4 Alignments and Adjustments

LW17M24C/LW20M21C 4-5

7. Test Pattern ( Test Pattern of VCTi)

1) VCTi

2) Toshiba

3) Gray Bar

4) Gray

5) Green

6) Color Bar

7) Cross

8. Bus Stop

- Bus stop is used data communication.

9. Chcek Sum

- Display the current check sum size of the MICOM.

10. Reset

- Initializes the data in the MICOM.

11. T-VNC17(20) PEU-0003 2004/04/20

- Display the MICOM program version.

4-2-3 White Balance

High Low

285, 295 285, 295

x, y x, y

High Low

285, 295 280, 295

x, y x, y

LW17M24C

LW20M21C

LW17M24C/LW20M21C 5-1

5 Troubleshooting

5-1 No Power

Does proper DC 14V/5V
appear at Pin 3. Pin 9 of

CN100?

Check CN803 Pin3, Pin9 in I/P

Board.

Yes

No

No

No

No

No

Does proper DC A5V

appear at FT144?

Check IC101 and IC105.

Yes

Does proper B3.3V

appear at Pin 2 of IC111?

Check IC111.

Yes

Does proper DC B1.8V

appear at Pin 4 of IC112?

Check IC112.

Yes

Does proper DC B8V

appear at FT130?

Check IC109.

1

2

3

4

5

5 Troubleshooting

5-2 LW17M24C/LW20M21C

No

No

No

Check IC704 and IC802.

Yes

Does proper DC 5V_P

appear

at Pin 2 of IC104?

Check IC104.

Yes

Does proper DC 9V_S

appear at FT127?

Check IC110.

Yes

Yes

Does proper DC B5V

appear at FT131?

Check IC108.

6

7

8

5 Troubleshooting

LW17M24C/LW20M21C 5-3

WAVEFORMS

1 2

5

3

6

44

7 8