Electrical Troubleshooting Guide; Power (Smps) Circuit - NAD L55 Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

1. POWER (SMPS) Circuit

No LED
Is 5.2V applied
to CN62 Pin 5 ?
NO
Check R622, R623
Is 5.2V applied
to PT61 Pin 1 ?
NO
Check D601-D604
Check Q626, D609
NO FLD
Is -24V applied
to CN62 Pin 3 ?
YES
END
YES
Check FRONT Circuit
YES
Check L620, R620
No 8V
Check Q622, Q623, R632
Check D625, IC62
NO
Check IC64, D628, D621
No 5V_D, 5V_A
NO
Is High State applied
to CN63 Pin 2 ?
Check Q620, Q625, R625
Check IC67, R609
2-2
YES
No 3.3V