SilverNAD
New Member
Hi There Folks, and seasons greetings to all from here in Australia.
I thought I’d share my experience curing a fairly common problem in the NAD 3020 family - low level but obvious transformer hum. This is a sort of DIY so if Mods want to move then please do, but as it addresses a specific issue, I thought I’d post here. It may also be relevant to other models/brands.
The culprit was a 3020 Series 20 with the second configuration of transformer mounted to the rear panel, rather than the earlier version which was mounted to the base of the chassis. Note these are both Series 20, which precedes the A-I suffixes that followed.
The hum was loud enough to be annoying without any source playing and I have heard in older amps this can possibly be a slight delamination of the plates. In any case, quite a few people have suggested isolating the transformer from the chassis and this is what I did, with excellent results. Hum has vanished.
The best part was it took about an hour and 10c worth of rubber washers. These I sourced from some corrugated roofing screws. (See pic)
Start by unplugging amp and letting it drain down. Remove top cover and locate transformer mounting screws on back plate. With a combination of a phillips head screwdriver and a 7mm socket, remove four screws and nuts. CAREFUL not to drop the nuts- there are crevices from which they will never emerge…
Also, in this case the nuts had a dollop of sealant on the end which made first few turns difficult. I found that starting by rotating the screw left and right broke the seal and allowed enough movement to get the socket over the nut.Fiddly but not difficult.
I then juggled the rubber washers into place between the transformer feet and the back plate. (See before and after pics) Do all four loosely (nut just on) in this way, starting with the bottom two. You will have to wiggle screw through the washer and through transformer feet but it’s quite possible just (again) fiddly.
When you come to final tightening of screws and nuts (which you’ll need to do with Philips and socket) DON’T overtighten. Just enough so the feet bite into the washer. This allows the movement of the rubber to better absorb the vibration.
Cover back on and job done. As I say, the difference for me was amazing, so I hope it can help some other people.
I thought I’d share my experience curing a fairly common problem in the NAD 3020 family - low level but obvious transformer hum. This is a sort of DIY so if Mods want to move then please do, but as it addresses a specific issue, I thought I’d post here. It may also be relevant to other models/brands.
The culprit was a 3020 Series 20 with the second configuration of transformer mounted to the rear panel, rather than the earlier version which was mounted to the base of the chassis. Note these are both Series 20, which precedes the A-I suffixes that followed.
The hum was loud enough to be annoying without any source playing and I have heard in older amps this can possibly be a slight delamination of the plates. In any case, quite a few people have suggested isolating the transformer from the chassis and this is what I did, with excellent results. Hum has vanished.
The best part was it took about an hour and 10c worth of rubber washers. These I sourced from some corrugated roofing screws. (See pic)
Start by unplugging amp and letting it drain down. Remove top cover and locate transformer mounting screws on back plate. With a combination of a phillips head screwdriver and a 7mm socket, remove four screws and nuts. CAREFUL not to drop the nuts- there are crevices from which they will never emerge…
Also, in this case the nuts had a dollop of sealant on the end which made first few turns difficult. I found that starting by rotating the screw left and right broke the seal and allowed enough movement to get the socket over the nut.Fiddly but not difficult.
I then juggled the rubber washers into place between the transformer feet and the back plate. (See before and after pics) Do all four loosely (nut just on) in this way, starting with the bottom two. You will have to wiggle screw through the washer and through transformer feet but it’s quite possible just (again) fiddly.
When you come to final tightening of screws and nuts (which you’ll need to do with Philips and socket) DON’T overtighten. Just enough so the feet bite into the washer. This allows the movement of the rubber to better absorb the vibration.
Cover back on and job done. As I say, the difference for me was amazing, so I hope it can help some other people.
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