NAD 3020 with loud hum. A couple of simple questions.

[planet10]

I am not a pro when it comes to electronics...

dave

[mjf]

hello.
this is an old amp,so handle it with care and patience.
have you read all posts in this thread carefully?
does the amp work,can you hear music?
at first i would clean all contacts (power switch,input selector,pots,fuseholder,....) with a contact cleaner(spray).
after this you can begin to change parts (the electrolytics........)
greetings

[whizgeek]

The phono section has a habit of amplifying any lo freq sounds. (what it supposed to do)
so thats why hum is louder on phono selector. however it could be the phono section on its own generating the noise, and bleeding thro to the power amp section.
short the phono inputs and see if there's a difference.
there's good reason to replace the caps suggested anyway first.
I had something like this, where a piece of jewelry bridged the input to case metalwork

[tvrgeek]

Mine started out that way. It was a failure of the power supply rail switching. Parts not available. These things are getting very old. ( and a long history of failures) As nice as they were, might troll e-bay for something built this century. Caps get old. Silicon generates micro flaws due to substrate impurities and fails, pots get noisy, connectors oxidize. If you get ten years out of anything electronic, consider it free after that and don't be upset when it needs replacing.

Deal, You may have more than one problem.

[bcarso]

Originally Posted by gbh001

I have the same issue with my NAD 3020 which I started using after many years of storage because I re-discovered how good it was with vinyl. After a few weeks of use it started humming/buzzing as described in this thread. The hum is not affected by the volume control.

I replaced the 4 big 2200mf power supply capacitors as I suspected them and because they had oozed orange goo! But I still have the problem.

I tried isolating the pre amp by removing the jumpers and connecting my CD player to the power amp. It still hummed so I guess not the caps there.

I'd really appreciate any advice as to what to look at next. I'm no expert but I realize it must be something in the power supply side.

Many thanks

My 3020 started to have some hum as well. It wasn't the bulk caps however, rather one of the two auxiliary supply caps. I replaced both of them and it fixed the problem. I purchased replacements for the bulk caps just in case they start to go, but I saw no point to changing them out right now, as the ripple voltage on both pairs was quite reasonably low.

I must say that amp has been an incredible deal. It was recommended to me by Keith Johnson many years ago, who gave it his ultimate KOJ endorsement: "I didn't have to do anything to it to make it sound right." The switches wear out and the pot gets worn and dirty. As I use the power amp section now alone (the wonderful ideal of providing a direct PA input serves well) I just don't worry about switching, and my source (a Roland RD-500 keyboard) provides the level control. I use the amp to drive AKG K1000 headphones.

Oh---also: the orange goo is probably not ooze. Rather it is adhesive, to prevent the parts from breaking loose from the board.

Brad Wood