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.
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!
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.
An externally hosted image should be here but it was not working when we last tested it.
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!
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.
The 60Hz hum I find is usually caused by the tubes heater wiring.
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.
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?
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.
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.
Yes, that's probably the multi-section can cap, you should be able to read the values directly off that can.
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?
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.
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.
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?
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?
Antique Electric Supply has all the capacitors you need. Search on "CE Manufacturing". The 80/40/30/20uF 525VDC cap should work well as long as the 60uF is not the first cap after the rectifier (if it has a tube rectifier.) A voltage greater than the original is fine and a little more capacitance will be fine also. The 50uF 25V can be a separate cap tucked in underneath. You could connect the 30uF and 20uF in parallel to make a 50uF cap giving you 80/50/40 @ 525V for the main power supply.
Thanks for the info Palustris. As for the rectifier tube, I did a quick search and 5y3 came up, which the amp does have, 1 of them, so I am guessing that it does indeed have a rectifier tube. How would I tell if the 60uf cap is the first cap after the rectifier? trace the wiring from the rectifier tube and see if it is hooked up to the 60uf post on the cap?
As for the CE manufacturing cap, what you are saying is use that cap for the first 3 caps, then get a standalone 50uf 25v cap and use that where it is needed? I assume those exist somewhere? I looked at Antique Electric supply and found a 50uf/50VDC, but no 25.
As for the CE manufacturing cap, what you are saying is use that cap for the first 3 caps, then get a standalone 50uf 25v cap and use that where it is needed? I assume those exist somewhere? I looked at Antique Electric supply and found a 50uf/50VDC, but no 25.
The first capacitor has a connection from pin 8 of the 5y3. Most can caps were marked with triangles, squares,etc identifying the values associated with the value desired. Look on the side of the can.
The 50uf/50VDC will be fine . Higher voltage rating is a plus.
The 50uf/50VDC will be fine . Higher voltage rating is a plus.
the can has the symbols on it, the 60uf is a half circle. and pin 8 from the rectifier tube is connected to that pin on the can. it is not a straight connection though. the wire from pin 8 connects to a post that has a 200 ohm 5w resistor i am guessing? It looks like a cardboard box. Then from there it connects to the 60uf post on the can. the other end of that resistor, or whatever it is is connected to the 50uf/25v post of the can. does this complicate matters?
Contact member Tom Bavis, who has an EXTENSIVE schematic collection. Chances are good that Mr. B. has your amp's "map".
Schematics are on their way. If I don't get them today I will post some pics tonight. I appreciate all the help!
That can cap is $40! Call me cheap but that seems a bit absurd for 4 electrolytic capacitors.
I don't set the price. If you want a quality multi section can capacitor made in the USA that fits the space properly and is reproduced To exact Mallory specifications that's the price. I am sure you can find a cheap one made in China for less if that's the quality you are after.
I wasn't personally attacking you.
It's a valid option, just expensive. I couldn't find any datasheets on them so I can't be impressed by the specifications enough to pay that much money. Especially if they are using old equipment and old tech ("reproduced to exact Mallory specifications") to make them. All I am saying is with a little ingenuity you can save some money and have good performance. Cost effective options don't necessarily hinder performance, I never said I was after "cheap Chinese quality".
Gut the old can cap and stuff it with good ones is always an option.
It's a valid option, just expensive. I couldn't find any datasheets on them so I can't be impressed by the specifications enough to pay that much money. Especially if they are using old equipment and old tech ("reproduced to exact Mallory specifications") to make them. All I am saying is with a little ingenuity you can save some money and have good performance. Cost effective options don't necessarily hinder performance, I never said I was after "cheap Chinese quality".
Gut the old can cap and stuff it with good ones is always an option.
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