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How to cure audible hum of a transformer?

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ISO

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Jan 9, 2017
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A transformer of my Yamaha AVR has developed audible hum. It is silent at the beginning and as it gets hot during usage, hum become more and more audible.

I dismantle it to find very poorly designed transformer. Shame of you Yamaha. Lot of air gap is responsible for magnetostrsiction of the core that gives out audible hum.

I dipped hot transformer in Dr. bake transformer varnish and baked it for 24 hours. This solution worked for few days but again audible hum is back to original state.

Any solution to this problem is highly appreciated.
 

gobble

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I think replacing the transformer may be a good way forward. The trick is to source the right one with the right specs ...
 
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ISO

Active Member
Joined
Jan 9, 2017
Messages
267
Points
28
Location
Bahrain/Pune
I think replacing the transformer may be a good way forward. The trick is to source the right one with the right specs ...
Thanks for supporting my thought. Thinking of custom made but will be costly.
 

ISO

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If it is a toroid, DC on the mains can cause it to hum.
No it’s EI core.

 

ISO

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Location
Bahrain/Pune
How to get rid of that . My power amplifier have the issue. The hum is audible through the speakers sometimes , but may be after half an hour it diminishes..any suggestions?
If the hum is coming from speaker clearly means small DC current is passing through speakers. Normally you should not hear hum from speaker at all. When you switch on amp by keep volume zero, do cone of speaker suck in or out slightly? If so indicates DC flowing though speaker. This can happen due to leaky push pull transistor in power amp stage.

In my case hum is fro transformer.
 
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