NAD M3C
Manual de Servicio

ELECTRICAL TROUBLESHOOTING GUIDE
1.Power Check Flow Power switch on

Amber LED ON?

NO

5V is Right ?

NO

Check S1 and its cable Check F901 Check the standby Transformer Check IC1 on the standby board

YES

YES

Press the standby button

Check the MCU on the keyboard Check U84 and Q82 Check the D81

Hear the relay�s click?

NO

Check the MCU on the keyboard Check Q91 Q92 and OP91 Check if the main transformers has been plugged in

YES
Check F902 and F903 Check the main transformer Check B603 B604 B703 B704 Check D602 D603 D702 D703 Check PSU PCB

+/-70V un-regulated power supply is correct?

NO

YES

+/-20V power supply is correct?

NO

Check R648 R649 R748 R749 Check B605 B705

Check IC603 IC604 IC703 IC704 Check the PCB track

YES

+/-18V power supply is correct?

NO

Check the sockets and plugs Check 1Q21 1Q22 2Q21 2Q22

YES

A
3-2