Buzzing - Vibrating Transformer - How to stop it?

I have an old Adcom amp that I use in my keyboard rig and like it. Lately, it developed a buzz that comes and goes (it stops after 1/2 hour or so of operation). The buzz is not coming through the speakers, but a physical, 60Hz vibration. I suspect it is a transformer.

So, how do I stop it? Hot glue (will that melt when the amp is hot?)? Jam a piece of something under it to wedge it?

It operates fine. A few years ago, I upgraded the power supply with a kit from some guy on the internet. I soldered it up and installed it fine. I am not sure if this is the section of the amp that is buzzing as I have not opened the thing yet. I will do it in the next day or so, but I want to be prepared to repair it before I open it.

Ideas for stopping the buzz? Ideas for diagnosing? Since it is a physical vibration, I figured I would just pull the cover and use my ears and a non-conductive poker to find the offender.

Peace
Bruce in Philly

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Often the bolt holding the transformer to the frame needs to be tightened having worked itself loose over time.

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Hmmm… that seems too easy! I hope so. Thanx!

Peace
Bruce in Philly

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Fingers crossed.

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Thanx man… that is all that it was. Actually I don’t think the screws moved, but I think there is a rubber pad or some insulator under this huge toroidal transformer and maybe it is breaking down over the years?? maybe?

I dunno, I did tighten up the four corners and it apparently worked.

Thanx

Peace
Bruce in Philly

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Excellent!

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Nice call, Elk. Hang on to that Adcom amp, Bruce. It’s good for another 20 years. Adcom was my introduction to high power SS amplification. Built like a tank.

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Ditto. Foolishly (well ignorantly, which becomes foolishly with time) sold my Adcom amps.

I had a bad transformer in an old ARC amp, and all the screw-tightening in the world wouldn’t stop its hum🥲

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Apparently, according to those tech illuminati of the internet, this amp had a less than perfect power supply. So there are kits out there and I soldered one up… and I did a three-prong plug… cheap fun. Interesting that this amp still has a following after all these years.

I never put this amp in my big home audio rig so I am not real sure how it sounds… You would thing a geek like me would have tried it out but I guess I just don’t like all that work. For my keyboard setup, it sounds really good.

Peace
Bruce in Philly

Every got-dang amp and component has a less-than-ideal power supply. And Caps. And Input transformers or Output transformers. And/Or overall design. Not to mention Parts Budget.

But have to say that the Adcoms weren’t some Lost Holy Grail. They were generally good. Mostly didn’t suck. Which is - surprisingly - saying something.