LG 75SM9400PTA Service Manual page 44

Standard Repair Process
Error
symptom
No audio
Screen normal
C. Audio error
No audio/ Normal video
☞A12
Check user
menu > Off
Speaker off
Y
Cancel OFF
Check Speaker
disconnection
☞A13+A9
N
Check audio 20V
of Power Board
Replace Power Board
and repair parts
N
Disconnection
Y
Replace Speaker
9
Established
date
Revised date
Y
Normal
voltage
N
Replace MAIN Board
End
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