LG SJ5 Service Manual page 60

POWER ON ERROR
Fundamental power check points.
1-3. 3.3 VA
1) Check 3.3 VA at pin1 of WIC703.
2) Check 3.3V_PWM at pin6 of WIC703.
3) 1), 2) is NG  Replace WIC703.
If you can't check PVDD voltage, then replace the PCB board.
WIC703 WIC703
ONE POINT REPAIR GUIDE
< Woofer SMPS & AMP board bottom view >
4-5