Transformer making this (recorded) sound. Intermittent buzzing. Caps?

[godmustuseaboogieman]

HI guys,

Thanks for some ace help in the past.

I've got an old Trace elliot that's making this funky sound. Its a purely acoustic sound, created by transformer, not speakers. There is no input signal and no load connected.

Made a recording on my phone (note that the pop at the end is my finger on the phone case - not the amp)
wav recording here on wetransfer - I cant seem to upload it

It sounds like a slowed down inrush current noise - so I'm wondering could it be 'about to go' reservoir caps?

The amp appears to be fine and reaches full op power with sine.

[MarkusBass]

The link does not work (at least for me). It displays: Get WeTransfer Plus. I don't want WeTransfer Plus :-).

[Bruce / Mission Amps]

I don't want these cookies either it's all BS.

[godmustuseaboogieman]

I don't want these cookies either it's all BS.

My apologies to Bruce and all, it wasn't my intention to irritate. I've managed to attach the file now.

th.mp3

Any suggestions anybody?

EDIT:
Just checked out the link I posted on another machine. I see what you mean.
AFAIK the cookies statement is now EU law - any european website that uses cookies has to state this on their website. It doesn't mean they use any more cookies than any other website or that they'll steal your paypal details(!). Non-EU or older sites simply use cookies without asking (if your browser allows). Clicking agree takes user to the uploaded file. Anyway, sorry to annoy people, wasn't my intention so I've uploaded mp3 above.

Back to the transformer...

[Tom Phillips]

The recording you posted does sound like transformer buzz to me. Transforms can buzz / hum when various parts of the transformer are loose. The loose parts could be the lamination stack, windings, end bells or other mounting hardware. Any such noise will be more noticeable when the current draw is higher. I would not diagnose the problem as "about to go reservoir caps." A good transformer should not buzz like your example even when putting out the maximum available current.

One thing you could check for is loose hardware such as the long bolts that that pass through the lamination stack. Note that there is normally a nut under the chassis that holds the bolt in the transformer then another nut that holds the transformer to the chassis. Make sure all is tight so that none of the laminations can vibrate.

[godmustuseaboogieman]

HI Tom,

Thanks. Its a torroid transformer, so no bolts through lamination stack here. It doesn't sound to me like the vibration of two things rattling against one another, like a loose bolt etc - it sounds just like the sound of a big torroid being turned on with a large inrush - only it's periodic and fades in and out repeatedly. I could be wrong.

This is happening when the amp is idling, no load.

Thanks,

R

The recording you posted does sound like transformer buzz to me. Transforms can buzz / hum when various parts of the transformer are loose. The loose parts could be the lamination stack, windings, end bells or other mounting hardware. Any such noise will be more noticeable when the current draw is higher. I would not diagnose the problem as "about to go reservoir caps." A good transformer should not buzz like your example even when putting out the maximum available current.

One thing you could check for is loose hardware such as the long bolts that that pass through the lamination stack. Note that there is normally a nut under the chassis that holds the bolt in the transformer then another nut that holds the transformer to the chassis. Make sure all is tight so that none of the laminations can vibrate.

[Tom Phillips]

...This is happening when the amp is idling, no load...

Does it ever happen if the transformer itself had no load? I.e. with the secondary windings disconnected completely from the circuit. If it did then that would certainly isolate the problem to the transformer.