LG 42LH35FD (CHASSIS:LJ91A) Service Manual ▷ View online
Power-Up Sequence
¾
Measured Waveform
All power have enough ramp up time (4 ms > minimum 100us)
RESET is negated after last power is ramped up (115 ms > minimum 10ms)
3.3V, 2.6V, 1.2V power sequence requirement of MPEG encoder is satisfied.
2.5V, 1.8V, 1.2V, RESET
3.3V, 2.5V, 1.8V, 1.2V
1. Power-Up Boot Fail Trouble Shooting
Replace Power board
N
Y
Check Micom IC407
Redownload or replace
Check P800 All Voltage Level
(20V, 12V, 5V_ST)
Check Power connector
Y
Check Voltage Level 3.3V at L815
N
Replace one of
IC807/IC802/L815/L823/L810/L826
& Recheck
Y
N
Check Voltage Level 2.5V at L827
N
Replace one of IC803/L824/L827
& Recheck
N
Y
Check Voltage Level 1.8V
at IC804 #6 pin
N
Replace one of IC804/L825
& Recheck
N
Y
Check Voltage Level 1.2V at L803
N
Replace one of
IC809/IC800/L803/L816/L819/L801
& Recheck
N
Y
Check X201 Clock 54MHz
N
Replace X201
Y
Check signal transition
at IC101 #9 pin
N
Maybe BCM3556 has troubles
Replace IC101 Flash Memory
Y
Check All Voltage Level
at L804/L807/L808
N
Replace one of L804/L807/L808
& Recheck
Y
2. No OSD Trouble Shooting
Replace Power board
N
Y
Check 12V Voltage Level
at P800 #13 Pin
Check Power connector
Y
Check 12V Voltage Level at L903
N
Replace one of
Q900/Q901/Q902/L903
& Recheck
Y
Check P903
#16(TXAC-), #17(TXAC+),
#32(TXBC-), #33(TXBC+)
N
Y
Check LVDS Cable
N
Replace Cable
Y
Check Voltage LCD Module
Check 12V Voltage Level
at L902
N
Replace one of L804/L902
& Recheck
Y
Maybe BCM3556(IC100)
has troubles
3. Digital TV Video Trouble Shooting
Check RF Cable
Y
Check TP Clock, Data, Sync
R1114, R1103, R1102
N
Maybe Tuner(TU1101) has
problems
Y
Maybe BCM3556(IC100)
has problems
Check Tuner(TU1101) Power
(5.0V, 2.5V, 3.3V, 1.2V)
N
Replace one of
L1108/L1105/L1100/L1107/L1109
& Recheck
Y
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