LG SN4A - Protection Error

3-13
Copyright © 2021 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
ONE POINT REPAIR GUIDE
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), 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)
< MAIN board top view >
IC600
IC600
CN703
CN703
CN704
CN704
AR601
AR601
AR602
AR602