Electricaltroubleshooting Guide; Power Check Flow - NAD M4 Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

1.Power Check Flow

Power switch on
Orange LED ON?
YES
Press the standby button
Hear the relay's click?
YES
+/-13.5V
power supply is correct?
YES
+5.3V
power supply is correct?
YES
+5V power
supply output from U110
is correct?
YES
The End
NO
5V is Right ?
YES
Check the MCU on the FPP board
Check Q300--Q303,U302,U303
Check the cable from J300 to J105
Check the MCU on the FPP board
NO
Check Q112,Q600 and K600
Check if the main transformers
has been plugged in
Check R621 and R622
Check the main transformer
NO
Check D602,Q601,Q603,Q604,
Q605,Q606,Q607
Check PSU PCB
Check R619,R620
NO Check D601
Check U603
NO
Check the sockets and plugs
Check U110
3-2
NO