Electrical Troubleshooting Guide; Power Check Flow - NAD M55 Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

1. Power check flow

A.
No VF+
Is 5VD section working?
YES
Check D910
No
Replace D910
NO
No 5VD
Check FH900
Is there a AC voltage at
one terminal of RT900?
YES
Is there a DC voltage At
(+) terminal of B900?
YES
Replace U900.
3-3
B.
No 5VS
NO
Is 5VD section working?
YES
NO
Is 5VD present at input
of U911?
YES
Replace U911.
YES
NO
Replace RT900.
YES
NO
Replace B900.