MC2300 power transformer BUZZ

nbndtrain

Well-Known Member
How loud is your MC2300? Mine is very audible from a few feet away. I am talking about mechanical/physical buzz, NOT through the speakers. It's all from the power transformer. I've ensured all is tightened down and definitely verified it is a bit subdued with the top bell off the transformer. How loud are these things, and is it worth the blood, sweat, and tears to do something about it?
 
Hmmm ... Never heard that's before. I've had a few dozen over the years and never experienced that. I have a pair still, both are quiet.

My ex wife has a spare power transformer ...
 
That would be a expensive transformer......in more than cash I would bet.....

To the OP....is the transformer under stress? A failing shorting out bridge rectifier or filter cap can draw a lot of current before blowing the fuse causing the transformer to make a racket before the fuse blows......
 
That would be a expensive transformer......in more than cash I would bet.....

To the OP....is the transformer under stress? A failing shorting out bridge rectifier or filter cap can draw a lot of current before blowing the fuse causing the transformer to make a racket before the fuse blows......
I've recapped everything but the power supply. I do have caps to replace the multi-cap, but all voltages match the schematic within a volt. The amp sounds great... through the speakers. Maybe I just need to take the cover off the transformer and line it with silicone or something. Seems like its mostly coming from the bell top.
 
I would go through a comprehensive, systematic evaluation of the electrical path from the transformer to the power supply caps, within your comfort level, in dealing with voltages that could easily stop your heart.
 
I would go through a comprehensive, systematic evaluation of the electrical path from the transformer to the power supply caps, within your comfort level, in dealing with voltages that could easily stop your heart.
I tested the voltages at the caps and one of the output cards, so pretty sure all is well. Maybe that isn't enough though? I haven't tested the rectifiers directly. My gut is saying it's just an old transformer making some noise, or maybe DC on my AC lines?
 
It isn't bowing my test bench so all is just conjecture....
Yeah, I'm ready to be done working on this beast. I'll mess with mounting the cap on top of the transformer and see if I can quiet it down. Is there supposed to be anything between the cap and the two brackets it connects to on the transformer? Maybe I'm missing something causing it to buzz more than normal.
 
The power supply transformer on my '2105 did that, years ago. Couldn't really hear it until I walked up to the equipment rack but it really bugged me. I did the standard thing of making sure the bolts were snug but, of course, that wasn't it.

Cleaned out the multicap on the bottom of the chassis,replaced with some Panasonic axial caps and changed a couple of diodes (those little ones) that are part of the power supply section. And, glory be, that did nothing to fix it. Exactly the same before/after.

Not sure what else to do, I just sorta forgot about it and a few weeks later I noticed that it wasn't doing it anymore. :shrug:

Murray
 
I've seen transformers where the windings came loose from the core. I have an adjustable dc power supply that does that. The more load I place on it the louder it gets. I've wedged pieces of cardboard under the windings, and/or epoxied them in place. Never had an amplifier do that before, but I suppose it's possible.
 
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