DOWNLOAD LG 42LH20D (CHASSIS:LB91A) Service Manual ↓ Size: 5.09 MB | Pages: 65 in PDF or view online for FREE

THE    SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATES
SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM X-RADIATION.
FILRE AND ELECTRICAL SHOCK HAZARDS, WHEN SERVICING IF IS 
ESSENTIAL THAT ONLY MANUFATURES SPECFIED PARTS BE USED FOR
THE CRITICAL COMPONENTS IN THE    SYMBOL MARK OF THE SCHEMETIC.

R980

0

32"UP_IR_KEY

L957

BLM18PG121SN1D

D956
5.6V

AMOTECH

LED_ON/LED_R

P953

12507WS-12L

32"UP_IR_KEY

EAG58732902

1

SCL

2

SDA

3

GND

4

KEY1

5

KEY2

6

5V_ST

7

GND

8

WARM_ST

9

IR

10

GND

11

3.3V

12

PWR_ON

13

GND

L953

BLM18PG121SN1D

32"UP_IR_KEY

D952

26"UNDER_IR

C976

0.1uF

32"UP_IR_KEY

C983

0.1uF

32"UP_IR_KEY

L952

26"UNDER_KEY

LED_ON/LED_R

L956

26"UNDER_IR

D954

5.6V

AMOTECH

26"UNDER_KEY

D951

5.6V

26"UNDER_IR

L955

26"UNDER_IR

C975

0.1uF

16V

IR

KEY2

C980

0.1uF

16V

32"UP_IR_KEY

D955
5.6V

AMOTECH

32"UP_IR_KEY

D958

5.6V

AMOTECH

32"UP_IR_KEY

L954

26"UNDER_KEY

L951

32"UP_IR_KEY

D959

5.6V

R978

0

32"UP_IR_KEY

C978

1000pF

50V

R973

4.7K

+3.3V_ST

R972

100

KEY1

C972

0.1uF
16V

26"UNDER_KEY

R979

0

OPT

C981

1000pF

50V

32"UP_IR_KEY

C973

1000pF

26"UNDER_IR

LED_G

D953

5.6V

AMOTECH

26"UNDER_KEY

SUB/AMP_SDA

SUB/AMP_SCL

R974

4.7K

L958

BLM18PG121SN1D

32"UP_IR_KEY

D957

5.6V

C979

100pF

50V

+5V_ST

POWER_ON/RL_ON

C977
0.1uF
16V

26"UNDER_KEY

R971

100

C974

1000pF

26"UNDER_IR

L959

BLM18PG121SN1D

P951

12507WS-08L

26"UNDER_IR

EAG58732904

1

KEY1

2

KEY2

3

GND

4

5V_ST

5

GND

6

IR

7

LED_B

8

LED_R

9

.

Q910

2SC3052

OPT

E

B

C

R985

47K

OPT

Q911

2SC3052

OPT

E

B

C

R983
10K

OPT

R981

22

OPT

+5V_ST

R982

47K
OPT

+5V_ST

IR_OUT

R984

47K
OPT

C982

0.1uF

16V

32"UP_IR_KEY

R986

10K

32"UP_IR_KEY

+3.3V

LED_G_SUB

R987

0

OPT

P952

12507WR-03L

26"UNDER_KEY

1

KEY1

2

KEY2

3

GND

4

GND

MDS61887701

M2

SMD GASKET-MEMORY1

MDS61887701

M1

SMD GASKET-LVDS

MDS61887701

M3

SMD GASKET-MEMORY2

R976

100

32"UP_IR_KEY

R975

100

32"UP_IR_KEY

IR

11

10

EAX59793902(0)

2009.01.31

CONTROL & IR & LED

AUS_LH20/LH35

For LH20_LH35 MP

EAX59793902(0)_AUS_MERCURY

Normal 

audio

Y

N

Move to No 
video/No audio

No video
Normal audio

Check Back Light
On with naked eye

On

Y

N

Check Power 
Board
12v,5v  etc.

Normal 

voltage

Y

N

Replace Main Board

Replace T-con 
Board or module

OR

Repair Power 
Board or parts

Check Power Board 20V or 24v output

Normal
voltage

Y

Replace Inverter 
or module

N

Repair Power 
Board or parts

End

Always check & record S/W Version and White 
Balance value before replacing the Main Board

Replace Main Board 

Re-enter White Balance value

※Precaution

(Main B/D↔ Power B/D, LVDS Cable,Speaker Cable,IR B/D Cable,,,)

1

Check various 
voltages of Power 
Board ( 5V,12V,20V 
or 24V…)

No Video/
No audio

Check and 
replace 
MAIN B/D

Y

Replace Power 
Board and repair 
parts

N

2