Transformer hum ...

[Aja097]

I have several receivers or amplifiers having hum (noise) coming from main transformer. This hum is coming from vibrations of the transformer plates. Is there any tricks to reduce or stop these vibrations ?

 

[ryuuoh]

You can try tightening the fasteners on the transformer.

 

[larryderouin]

Some manufacturers advocate flipping the power plug to the way that is quieter with regards to hum. +1 on ryuuoh's suggestion.

Larry

 

[laatsch55]

Do it all the time on PL 400's and 700's. Every one I get have loose tranny bolts.

 

[Aja097]

Good suggestions ! but tightening the fasteners is not enough. Maybe something else such as using some varnish to avoid vibrations ?

 

[ryuuoh]

Many transformers are mounted on rubber grommets to isolate vibration. In old gear, these grommets will likely be as hard as a rock.

 

[Watthour]

SEARCH the forum archives. There are several threads regarding removing rust, applying Glyptal, and shimming the windings in the cores.

 

[BinaryMike]

Sometimes power transformers are noisy because the AC line is especially noisy or line voltage is higher than normal. Noise on the AC line can be caused by appliances or machinery that consumes more or less current on different portions of the sinewave.

 

[shelby1420]

Sometimes power transformers are noisy because the AC line is especially noisy or line voltage is higher than normal. Noise on the AC line can be caused by appliances or machinery that consumes more or less current on different portions of the sinewave.

Took me three days of vacation to finally figure out it was the Fridge in the garage causing noise in my 2A3 amp, drove me friggin crazy!!!

 

[Aja097]

Thanks for the suggestions ! Tried to connect them to several different AC lines, but no changes. I will follow Watthour idea to use that Gyptal stuff (seems to be quite difficult to find in France, but there is certainly some alternatives ...)