Read LG 42LH50YD (CHASSIS:LJ91C) Service Manual online
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
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