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NAD 7020 DC Offset of 2.4v

superjb

superjb

Active Member
Hello Guys,
I've bought a Nad 7020 for nothing. I recaped it with Panasonic FM/FC and Wima mks.
I've powered it and it's sound nicer that before i was able do listen the difference directly.
By hearing a pop when changing from A to B i decided to check the DC offset and i got 2.2v.
In which direction should i look ?

It's the Nad 7020 first version.

Thanks a lot
 
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guessing turning it the other way did nothing, or was it already fully down? Is this on both channels equally or just one ?

dc offset is usually either some problem with the differential pair, or maybe off-value resistors around it. I can't download the svc manual from here to see if its something odd though. I had problems with a very old Sherwood that were caused by multiple seriously off-value resistors, though those were 1960s parts that are well known for being trash. I wouldn't normally expect to see significant value drift on parts inside this but who knows.


if this did not have offset issues before, maybe worth confirming the polarity of the caps that were installed.
 
gadget73 said:
guessing turning it the other way did nothing, or was it already fully down? Is this on both channels equally or just one ?
Click to expand...
Initially was fully turn anticlockwise. By turning it clockwise it was increasing slowly and I stopped when it reached 2.5v because ive seen it was not going in the right direction.

I will also look at the polarity of caps and the resistor values. Thanks a lot.
 
gadget73 said:
dc offset is usually either some problem with the differential pair,
Click to expand...
Both channels the same? Would point to single fault in common area like power supply. Only one channel affected then look at power amp diff pair and...
 
mbz said:
Both channels the same? Would point to single fault in common area like power supply. Only one channel affected then look at power amp diff pair and...
Click to expand...

exactly, which is why I asked. Wasn't clear from the initial post if both channels were checked or not.
 
Yes both channel with approximately the same value.
So I will look at the power supply.

Thanks a lot !!
 
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