D(Dc) Protection - LG LAS454B Service Manual

7. D(DC) PROTECTION

7-1. Solution
Replace IC703 (AMP IC) on MAIN board.
7-2. How to troubleshoot (Countermeasure)
1) After MAIN SET power off, check Red LED blink at intervals of 1 sec. (D Protection or S Protection)
2) Turn MAIN SET power on again.
3) Check DC Voltage of speaker out FL+/- (CN703 pin1, 2), FR+/- (CN704 pin1, 3).
4) Check resistor crack, cold solder of PWM IC out (R751, R753, R759, R761).
5) If PWM IC out is ok and speaker out (FL+/-, FR+/-) has DC Voltage,
Replace IC703 (AMP IC) on MAIN bottom board.
7-3. Service hint (Any picture / Remark)
ONE POINT REPAIR GUIDE
CN704 CN704
< MAIN board top view >
IC703 (AMP IC) IC703 (AMP IC)
< MAIN board bottom view >
R761, R759 R761, R759
R753, R751 R753, R751
3-8
CN703 CN703
IC701 (PWM IC) IC701 (PWM IC)