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Old 5th February 2015, 07:11 PM   #1
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Default Should Output Transformers be replaced

Good day all,

I am starting down a long and winding road to rebuild a vintage tube amp from a Voice of Music console stereo.

The output transformers look a little nasty and I am wondering if these should be replaced. And if so, where would be the best place to look for replacements?

Pic is below.

Click the image to open in full size.

I cant really say that there is an issue with the transformers themselves, but there is quite a bit of 60 hz hum coming out of the amp.

Any assistance is appreciated!
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Old 5th February 2015, 07:26 PM   #2
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Can you upload a schematic and maybe some pictures of the layout?

The 60Hz hum I find is usually caused by the tubes heater wiring.
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Old 5th February 2015, 07:30 PM   #3
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I will.... once I get the schematic. It is on order. Not sure if this helps but it is a V-M 20051 model amp. It has a 6bq5 and 5y3 on each channel and a 6eu7 at the front of the unit next to the volume control.
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Old 5th February 2015, 07:32 PM   #4
BZed is offline BZed  United States
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I would replace the power supply cap first. That's the most likely cause of the him.
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Old 5th February 2015, 07:39 PM   #5
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Thanks BZed. I am a newbie at this so please forgive what may be dumb questions. I will be able to see the capacitance and voltage specs when I get the schematics. When I took the covers off the amp, I could not really see something that looked like the caps I saw on parts express for example. There is one large silver can looking thing in the amp, it is probably 3 or 4 inches long and 2 inches in diameter. Would that be what I am looking for?
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Old 5th February 2015, 07:46 PM   #6
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You could probably draw up a schematic and get answers before your order arrives, it can't be terribly complex.

Replacing the power supply caps is a good idea, but thats usually 120Hz hum from the full wave rectifier. If you are positive that it is 60Hz then it is probably the heater wiring. Does it have a humdinger pot? If it doesn't have a humdinger or a real center tap you can create a virtual one with two 100 ohm resistors.
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Old 5th February 2015, 07:48 PM   #7
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Quote:
Originally Posted by brandoh73 View Post
There is one large silver can looking thing in the amp, it is probably 3 or 4 inches long and 2 inches in diameter. Would that be what I am looking for?

Yes, that's probably the multi-section can cap, you should be able to read the values directly off that can.
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Old 5th February 2015, 08:47 PM   #8
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yep, that is it. the top number, which may be the model is 12172-2, then we have 60 MFD - 450 VDC, 40 MFD - 450 VDC, 20 MFD - 450 VDC, 50 MFD - 25 VDC. then under the numbers is CAN COM NEG, then under that is 10816221 then what looks to be 85 degree C. Would replacing this be a good first step?
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Old 5th February 2015, 09:16 PM   #9
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Replacing the filter caps is always a good first step.

If there is lots of room you can leave the can cap alone to keep it looking original and just put fresh caps under the hood. In my opinion those can caps are really expensive to replace. Another alternative if there is no room in the chassis is to gut the can cap and put modern caps inside of it, I have done this on occasions with good results.
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Old 5th February 2015, 09:27 PM   #10
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again, forgive my newbie ignorance, so I can open up that cap can and replace the caps inside of it? I dont really care about keeping it original looking as it will be put back in a console stereo and no one will ever look at it again. I just want it to sound good!

I started a search online to find cap can's with that particular specification but have had no luck yet. Is there a more common specification that would be able to replace it, or do the values have to match exactly?
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