2. amps-preamps
  3. 155392-691

Beware of NAD M3 Fire Hazard

My $3k NAD M3 started shooting sparks out the top and burned the shelf that was 8" above. Luckily I was home and not sleeping or the house would have burned down. If anyone has one of these I advise them to unplug it when not in use. I took it to two different repair shops and they said it would be about $800 to just get it running and there may be board issues. They advised not to take the gamble. Anyone have any suggestions on what to do with it?
pwb
pwb OP
14 posts
 
Thanks for the responses. As far as I know the fuses are intact. I stopped the sparks shooting out the top by unplugging it. I took it to the NAD authorized repair facility and they said a faulty power supply caused the round cylinder ( not sure of part name) to explode which probably damaged the board and other parts. I can send pics if anyone wants to see the damage. Thanks.
gs5556
1,250 posts
 
Safety caps do fail short, not enough though to create a fault condition a fuse or breaker can clear. RIFA caps in old Mark Levinson gear are notorious for this. 

If it's the "round cylinder", it is possible that something conductive shorted the power supply cap or caused a voltage reversal. Who knows,  a discarded component lead was dropped inside the unit during production and wiggled its way to a bad spot during shipping/setup.
jea48
4,788 posts
 
Al, that amp has a lot crap in it! How long did it take for you to find the 3 fuses?


pwb said:
I took it to the NAD authorized repair facility and they said a faulty power supply caused the round cylinder ( not sure of part name) to explode

round cylinder in the power supply???

I should have mentioned in my previous post that series arcing will not cause a fuse to blow. In the case of parallel arcing the current may not be high enough to cause a fuse to blow. The arcing can, will, create sparks though.

Jim
.
almarg's avatar
almarg
9,670 posts
 
Al, that amp has a lot crap in it! How long did it take for you to find the 3 fuses?

Not long, Jim. The service manual includes a block diagram, a schematic, and a parts list. Which made it pretty easy to determine what fuses are being used, and where they are located in the circuitry.

And a quick look at rear panel photos that are available on the web confirmed that the fuses are not physically located on the panel.

Best regards,
-- Al
erik_squires
16,895 posts
 
pwb --- The tall round can like things or the donut like things??
More to discover