Audio Abnormal (Function Mode) - LG SB74 Service Manual

5. AUDIO ABNORMAL (FUNCTION MODE)

PORTABLE
YES
Check the input
signal of U503 pin7,8
YES
Check the output signal
of U503 pin19,23
CD / USB
Check the input signal of U503 pin3, 4
Check the output signal of U503 pin19, 23
TUNER
YES
Check the input
signal of U503 pin1,2
YES
Check the output signal
of U503 pin19,23
NO
Check the input
signal CN500
YES
YES
NO
Check the output signal
of U101 pin5,6
NO
Check L800, L802
NO
Check the output signal of U703 pin55, 57
and refer to CD troubleshooting
NO
Check the output signal
of C102,C103
3-3
NO
Check R800, R801
NO
Check C810, C811
NO
Check the output signal
of R100,R101