LG OLED77ZXPTA Service Manual page 21

Standard Repair Process
Error
symptom
First of all, Check whether all of cables between board is inserted properly or not.
(Main B/D↔ Power B/D, VX1 or EPI Cable, Speaker Cable, IR B/D Cable,,,)
No video
Normal
Normal audio
audio
N
Move to No
video/No audio
※Precaution
☞A4 & A2
Always check & record S/W Version and White
Balance value before replacing the Main Board
A. Video error
No video/ Normal audio
☞A1
Y
Check Vx1 lock
voltage
☞A9
Check Power Board output to Module (23.5V)
Repair Power
Board or parts
☞A9
Check Power board
Y
On output to Main.
(12V, 20V)
N
Y
Normal
Replace Module
voltage
N
Replace Main Board
1
Established
date
Revised date
Y
Normal
Replace Main Board
voltage
N
Repair Power
Board or parts
End
Re-enter White Balance value
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