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
You can see that one or two of the other 80V caps are ready to pop.

Run too close to the voltage limit. they were getting gassy.

A manufacturer of those caps was absolutely full of it, or a parts supplier for that capacitor company was full of it, or..NAD was penny pinching and purchased dicey product, or the capacitor manufacturer flat out lied their face off about their quality standard.

Or some combination thereof. All I can say is that some of the decisions made, from/during that time period, have really hounded the company. eg, the 370 and associated power amp design...I’ve seen far too many of them with the same failure. Additionally, with shorted/dead caps, from the same company/source. Four in one year. I expect to see more.

It is many years down the road, though, so not really all that predictable. But there is a time to be careful about expenditure and a time to throw the penny pinching accountants out the nearest window.

My Best quick guess is that someone decided to try and save a nickel on capacitor costs, and took a shot, they took a swing, they took a flyer... and it worked.

For a while. for about a decade. Now that accounting decision has come back to bite them a bit...

Anyway, no one is perfect, and other than this blip, NAD has done really well. Sooner or later all manufacturers get bit by this sort of thing. It is just a matter of time, but is also tied to design and parts decisions. and it is not always the engineer or designer at fault. It can be accounting that is tied to parts costs, which can make iffy decisions. To do the right hing and satisfy customers who know little about the insides.. but.. a lot about prices they pay. It's a difficult balance at best.
I had an Innersound amp completely melt down.  Luckily it was in a pretty heavy chassis so the fire stayed inside and didn't burn my house down.  Innersound was out of business so no recourse but on something like that NAD should just get you set up with a new amp, doesn't matter if it's in warranty or if you bought it used.  That should not happen and if it does they should cover it, they are a big company.  Let us know what they say. 
The local line voltage is 110
The unit is rated 120v. Nominal is ±5% - 114v to 126v.

Running on 110v increases cap ripple if load high current delivery is required. Ripple increases heat. By chance did the unit smell hot?

Diodes usually fail open circuit
ESD often causes devices to fail as a short. A puddle of molten silicon makes an excellent conductor.

The only caps I've ever seen 'blow' have been due to reversed polarity. 

Failure analysis is often pure speculation... unless someone 'fesses up <:-0


I won't derail the thread, but .... this is the perfect example of why you should never remove the ground pin on an AC plug.

Failures are rare but they do happen.

This case wasn't probably caused by a bad ground pin, but this kind of failure can happen and you want the chassis to be grounded by a big beefy conductor when it does.