LG CM9730 Service Manual page 53

ELECTRICAL TROUBLESHOOTING GUIDE
B
IC600
Pin28,29,35,36 FL/FR±
signal OK?
YES
IC601,
IC602 FL/FR audio signal
OK?
YES
Check IC601,IC602
Pin13 of
IC700,IC701,IC704,IC705 FL/FR
audio signal OK?
YES
IC701, IC704, IC705.
±40 V,-28 V,
±5 V power voltage
OK?
YES
Q700,Q701,
Q702,Q703,Q714,Q716,Q719,
Q720 OK?
YES
Check Q701,Q702,Q703,
Q704,Q714,Q716,Q719,Q720.
NO
Check IC600.
NO
NO
Check IC700,
NO
Check SMPS.
NO
Check speaker cable connection.
NO
Check IC600.
NO
Check IC603,IC604
NO
Check IC702,
IC703, IC706, IC708.
NO
Check SMPS.
NO
Check Q704,Q705,Q708,
Q709,Q721,Q722,Q723,Q724.
OK
3-36
IC600
Pin26,27,31,32 SWL/SWR±
signal OK?
YES
IC603,
IC604 SWL/SWR audio
signal OK?
YES
Pin13 of IC702,
IC703,IC706,IC708 SWL/SWR
audio signal OK?
YES
±40 V,-28 V,
±5 V power voltage
OK?
YES
Q704,Q705,
Q708,Q709,Q721,Q722,Q723,
Q724 OK?
YES