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NAD 7020 question

hamraisin

hamraisin

variable optimist
Picked one up recently, worried it would be a bit underpowered but it sounds great to my ears.
However, when I turn it on there is a burst of white noise for about 2-3 seconds like radio static, not electrolytic static, and then it goes away (just drops off), prolly after a protection circuit kicks off most likely.
It doesn't hurt anything but damn it's annoying
Anyone have any thoughts? This is the org. version sans "e"
 
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I think before anything else, I'd treat all the controls / switches to a decent deoxit cleaning - once they're clean, if the problem still persists, troubleshooting will at least be easier.
 
I de-oxited the bejesus out of it (true) but didn't hit the power button. It feels like a different issue but that is a good point, will get in there with the spray
 
hamraisin said:
and then it goes away (just drops off), prolly after a protection circuit kicks off most likely
Click to expand...

The only 'protection' if you like (normally called 'muting') is at the exit of the pre-amp / entry to the amp- try powering the amp up with the 2 jumpers pre-out / main-in jumpers removed - do you still hear the 'white noise'?
 
Common cause of this in NAD 7020 is the power switch itself. What you hear is arcing. The switch has to be replaced or disassembled and cleaned (flushing it with deoxit won't help, you'll need to open it).
 
Cleaning isn't good enough. It must be replaced, else your house will eventually burn down.
 
The obvious way to check if it's the switch or not, is just to leave the amp switch on, and use a switched mains outlet to turn the amp on instead - just be sure to compare 'like to like', e.g., reproduce all other conditions the same.
 
Its definately the switch - I have the TT on a breaker and when I flip that on and off there is none of the white noise. I guess I gotta take that sucker apart then...thanks guys!
 
Well I went as far as I was comfortable into that switch and hosed it out by prying up parts of the top (didn't want to unsolder the thing) to no effect - same "whoosh" of soft noise powering on and then a smaller whoosh when powering off.
I'll just wait until something else breaks and then get it looked at I guess - I can live with it, or if it starts to drive me crazy, I'll buy a new switch.
 
There are threads on replacing the power switches here. For both the 3020, 7020 I believe.
 
I have a similar issue with mine, only, it's a hum at startup, not white noise. It dies down after a minute or two and is completely quiet. I always chalked is up to needing a cap job.
 
4300, hum is a different issue, possibly caps.

hamraisin, like we said, flushing the switch (open or not) with deoxit won't help, it's either disassembly and sanding contacts or a new switch.
For now, you can simply power the NAD with speakers off and turn them on a minute later to avoid the noise. Or use power strip to turn it on/off.
 
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