LG DP271, DP271B, LPA-837 Service Manual page 19

MAIN ELECTRICAL TROUBLESHOOTING GUIDE
B. AUDIO OUT ABNORMAL
Audio out abnormal
Check Audio jack & mode
Check +9V
Check signals from MPEG
Replace IC(U504)
D. AUDIO IN/SPEAKER ABNORMAL
Audio in/speaker
abnormal
YES
Check Audio jack &
mode S/W
YES
Is Q501
and Q503 OK.
YES
Is speakers OK.
Replace
YES
Replace IC(U502)
YES
YES
YES
YES
NO
Replace
Q501 and Q503
NO
Speakers
C. VIDEO OUT ABNORMAL
Video out abnormal
Check Video jack & mode
Check Video signals from MPEG
Check IC(U501)
E. VIDEO IN ABNORMAL
Video in abnormal
YES
Check Video jack
& mode
YES
Is U501 OK.
YES
Check
R203, R202, C202
YES
Refer to LCD part
3-12
YES
YES
YES
YES
Check LC filter
NO
Replace
(U501 IC)