LG 28LM4 0B-PU Series Service Manual page 31

Standard Repair Process
Error
symptom
Check user
No audio
menu >
Screen normal
Speaker test
C. Audio error
No audio/ Normal video
A19
Y
No sound
N
Adjust Volume or mute to unmute
Check
Speaker
disconnection
Established
date
Revised date
A20+A18
Check audio 12.5V
Normal
of Power Board
voltage
N
Replace Power Board and repair parts
N
Replace MAIN Board
Disconnection
Y
Replace Speaker
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Y
End
2019
8/13