MIMF

Hi,

I picked up a NAD 3020A amp. When I turn it on, a loud hum sound comes through the speakers for a second and then fades off. The problem is in the preamp section, as the amp is dead quiet when I pull the amp/preamp jumpers and turn it on. All of the pots have been cleaned. The amp works fine after the hum goes away. Someone suggest me the pre-out muting fets leak. J111 is generic so I looked here https://www.icrfq.com/part/2000795-J111.html for J111 and I got it here. I do not have a schematic for this unit. How many fets should I purchase, and where do they go?

Any suggestion will be appreciated.

I have retired from servicing industrial electronics for 39 years. With that said. Unless you understand the safe handling of static sensitive components (most are ) and have a static safe work area. Good soldering skills are also needed. leave the replacement of those components to the pros.

Daryl's advice is good

You might have more luck at the music electronics forum but last I checked NAD made home audio equipment so you might have even better luck at a home audio electronics forum. MEF is here: http://music-electronics-forum.com/forum.php
Check out http://audiokarma.org/forums/index.php? ... ds.426532/

Thanks for sharing. It's a very nice information for me!

David King wrote:Daryl's advice is good

You might have more luck at the music electronics forum but last I checked NAD made home audio equipment so you might have even better luck at a home audio electronics forum. MEF is here: http://music-electronics-forum.com/forum.php
Check out http://audiokarma.org/forums/index.php? ... ds.426532/

I have used MEF for a long time and can comment on how great some of the users there are. That place is a wealth of information.