LG CMS9540F Service Manual page 55

ELECTRICAL TROUBLESHOOTING GUIDE
B
Pin28,29,35,36
of IC600, FL/FR± signal
OK?
YES
Check IC600.
IC601, 602
FL/FR audio signal
OK?
YES
Check IC601, IC602.
Pin13 of
IC700,IC701,IC704,IC705
FL/FR audio signal
OK?
YES
IC700, IC701, IC704, IC705.
±40 V, -28 V, ±5 V
power voltage OK?
YES
Check SMPS.
Q700,
Q701,Q702,Q703
Q714,Q716,Q719,Q720
OK?
YES
Check Q701,Q702,Q703,Q704
Q714,Q716,Q719,Q720.
NO
NO
NO
Check
NO
NO
Check speaker cable connection.
OK
3-34
NO
of IC600, SWL/SWR± signal
Check IC600.
NO
SWL/SWR audio signal
Check IC603, IC604.
NO
IC702,IC703,IC706,IC708
Check
IC702, IC703, IC706, IC708.
NO
Check SMPS.
NO
Check Q704,Q705,Q708,Q709
Q721,Q722,Q723,Q724.
Pin26,27,31,32
OK?
YES
IC603,604
OK?
YES
Pin13 of
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