LG 75SJ857A Service Manual page 22

Standard Repair Process
symptom
First of all, Check whether all of cables between board is inserted properly or not.
(Main B/D↔ Power B/D, LVDS 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
Error
No video/ Normal audio
☞A1
Y
Check Back Light
On with naked eye
Check Power Board 20V output
☞A18
☞A18
Y Check Power
On
Board
20V, 13.2V etc.
N
Replace Inverter
Normal Y
or module
voltage
N
Repair Power
Board or parts
Replace Main Board
1
Established
date
Revised date
Y
Normal
Replace T-con/Main
voltage
Board or module
N
Repair Power
Board or parts
End
Re-enter White Balance value
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