Electrical Troubleshooting Guide; Power(Smps) Circuit - NAD T512C Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

1. Power(SMPS) Circuit

A.
No VF+
Is 5.2VA section working?
YES
Is oscillation present at the
anode of D109?
YES
Replace D109.
NO
NO
No 5.2VA.
Check R127, 128.
(SHUTDOWN CKT)
Is 5.2V applied to IC102
Pin 1?
NO
Check Fuse(F101).
YES
Is there a DC voltage at the
(+) terminal of BD101?
Replace IC101.
3-2
B.
No 5V_D
or 5V_A .
NO
Is 5.2VA section working?
YES
NO
Is oscillation present at the
Base of Q108?
YES
Replace Q108.
YES
Check L103.
NO
Replace BD101.
(Bridge rectifier)