LG SJ5 Service Manual page 42

3. PROTECTION ERROR
No display or No Sound.
3-1. D(DC) PROTECTION
3-1-1. Solution
Replace MAIN board.
3-1-2. How to troubleshoot (Countermeasure)
1) Check DC Voltage of speaker out FL+/-, TWL+/- (CN703 pin1, 2, 3, 4)
and FR+/-, TWR+/- (CN704 pin1, 2, 4, 5).
2) Check resistor crack, cold solder of PWM IC out (AR601, AR602)
3) If PWM IC out is ok and speaker out (FL+/-, FR+/-, TWL+/-, TWR+/-) has DC voltage,
replace MAIN board.
3-1-3. Service hint (Any picture / Remark)
IC600 IC600
ONE POINT REPAIR GUIDE
AR601 AR601
AR602 AR602
< MAIN board top view >
3-13
CN703 CN703
CN704 CN704