LG 42LN549C / 42LN549E (CHASSIS:LJ3AC) Service Manual ▷ View online
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TROUBLE SHOOTING
Power-Up Boot Fail Trouble Shooting
Check P1201 All
Voltage Level (5V, 12V, 16V)
Check Power connector
OK ?
Replace Power board
Y
N
Y
Check Q706 OUT
Voltage Level 3.3V
Replace Q706
Recheck
Y
N
Check
IC706(3.3V),IC705(3.3V),IC7
09(2.6) ,IC710(1.25V) OUT
Voltage Level
Replace
IC706,IC705,IC709,IC710
Recheck
N
Y
Check X100 Clock
12MHz
Replace X100
Y
N
Replace IC105 Flash
Memory
N
N
Redownload or replace
Flash Memory IC105
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No OSD Trouble Shooting
Check P1201
Voltage Level ST5V
Check
Power connector
Replace Power board
Check LVDS Cable
Check LCD Module
Control board
Y
N
Y
Y
Check Q706 OUT
Voltage Level 3.3V
Replace Q706
Y
N
Replace Cable
N
Digital TV Video Trouble Shooting
Check RF Cable
Check IIC Signal
TU400 #7, 8 Pin
Maybe Tuner(TU400) has
problems
Check LGDT3304 Output
Clock(R404),
Data(AR436,437), Sync(R441)
Y
Y
N
Check Tuner 5V Power
IC701
Replace IC701
Y
N
Y
Maybe LGDT3304(IC400) has
problems
N
Maybe LGDT3304(IC400) has
problems
Check LD400 color
Bad Tuner. Replace Tuner.
None
red
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Analog TV Video Trouble Shooting
Check RF Cable
Check CVBS signal
TU100 #16 Pin
Maybe Tuner(TU400) has
problems
Y
N
Y
N
Y
Maybe FI-8668(IC506) has
problems
Check Tuner 5V Power
IC701
Replace IC701
Check IIC Signal
TU400 #7, 8 Pin
Maybe Tuner(TU400) has
problems
N
Y
Component Video Trouble Shooting
Check signal format
Is it supported?
Check signal
R615,R616,R617(Y,CB,CR)
Replace it.
Y
N
Check JK601
Replace connector
Y
N
Y
Maybe LGE1854C(IC100) has
problems
Y
Check Component Cable
- 19 -
RGB Video Trouble Shooting
Check signal format
Is it supported?
Check signal, Hsync, Vsync
R604,R601,R602,R631,R632
Replace it.
Y
N
Check JK605
Replace connector
Y
N
Y
Check RGB Cable
Y
Maybe LGE1854C(IC100) has
problems
AV Video Trouble Shooting
Check signal format
Is it supported?
Check signal
Rear – R612 (Composite),
R622 , R623 (S-Video)
Side – R676 (Composite),
Replace it.
Y
N
Check JK600 (Rear)
Check JK606 (SIDE)
Replace connector
Y
N
Y
Check AV Cable / S-Video Cable
Y
Maybe LGE1854C(IC100) has
problems
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