LG CMS9540F Service Manual page 52

ELECTRICAL TROUBLESHOOTING GUIDE
USB play
When insert USB,
IC501 PinU7,U8,A7,A8 USB_D
signal OK?
YES
A
AUX
IC202
Pin7, 8 AUX input signal
OK?
YES
IC202
Pin42,43,44 I2S input signal
OK?
YES
IC202 Pin41
ADC/MIC_data output signal
OK?
YES
A
IC300
NO
USB power +5 VU
OK?
NO
Check audio cable.
NO
NO
3-31
NO
YES
Check IC501.
Replace IC202.
Replace IC300.