NAD 3020A Amplifier Hum

  • Thread starter Thread starter Sumo098
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Sumo098

Sumo098

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Sumo098
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Sumo098
A few months back I scavanged a disused NAD 3020A from my father's garage and it sounds absolutely marvellous. I do however have an issue I would like to address if possible.

The thing hums whenever it's powered on and the volume and tone knobs do absolutely nothing to affect it (unless it's on the phono channel and gets boosted by the extra gain). It's not so loud that I can hear it over the audio I put through, but it is loud enough to bother me when I have nothing playing.

Some Googling has suggested that it might be the caps on the power supply at fault. But I'd like to get as much info as possible in the problem before replacing something unnecesarily. I can take a video of it if that would help make things clearer.
 
No, no no no! If it's power caps don't even think of doing it yourself because you will inevitably die. That's not a joke, give it to someone who does electronics repair for a living.
 
neema_t
No, no no no! If it's power caps don't even think of doing it yourself because you will inevitably die. That's not a joke, give it to someone who does electronics repair for a living.
Click to expand...

I understand that much. It'll be handed to a technician if that's the problem.
 
Ok, just checking, wouldn't want anyone catching that death thing that's going around. But I would agree that it's likely the power supply caps. They age poorly and leak electrolytic fluid so the capacitance drops, that means the power supply voltage will be rippling at a constant 50/60Hz so it follows that you get a low frequency hum. The fact that the various knobs do nothing suggests as much because it's the power to the amplifier itself that's rippling so the input is unaffected, but the knobs only affect what's going in to the amplifier and not what's coming out. I'm not an audio expert by any means, though, it could also be mains hum or a ground problem.

But my money is on those caps.
 
It certainly seems like the most likely issue. I'll try and get one of the audio technicians at college to have a look at it. Maybe then I can get this thing silenced for the time being.
 

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