Transformer hum problem

nachall
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« on: December 26, 2010, 09:35:01 AM »

First of all marry Xmas.
Hi,
I recently build JCM 800 2204 type amp model. The amp works fine but there is noticeable hum. When you turn preamp pot down you should hear nothing from the speakers, but there is a hum when pull up volume pot.
I think that hum comes from power transformer because I made it by my self. It is old soviet transformer TC-180 I re-winded it.
Maybe some advice how to reduce hum.


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cmoore
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Posts: 351

Re: Transformer hum problem

« Reply #1 on: December 26, 2010, 05:36:25 PM »

I have NEVER wound a transformer, but I know what a complex job it can be. Other than checking/playing with the bolts that hold the lams together, I do not have a clue. Are you sure it is not a lead dress problem. Maybe heater wires or the ground for the heater supply?
Good Luck


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plasticvonaband
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Pickin and Grinnin since 1989

Re: Transformer hum problem

« Reply #2 on: May 19, 2011, 10:03:30 PM »

I have and old sovtek mig 50 that i have had since 1994 and the transformers have ALWAYS hummed. Must be a soviet/russian thing. I should clarify it's not a hum that is heard through the speaker on mine, but the sound of the transformers vibrating. Scary to the uninitiated, but "normal" for stock Sovteks


« Last Edit: May 19, 2011, 10:09:24 PM by plasticvonaband »	Logged

Overdrive is like peanut butter. Some like it crunchy, some like it creamy.
Bluesmaster 50 2x12 combo and some guitars.

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