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Replacing Amp Caps

I am currently trying to replace the caps in my Bedini 100/100 amp and I am having quite the time trying to find a replacement that will work. I am hoping that someone with more knowledge can give me direction on which way I can go. The amp recently stopped outputting a signal and after all the usual internal checks, with an amp as old as this, cap replacement should be on the list of things to do.

The values and associated numbers on the OEM caps are as follows:


National Cap

85DX

+22000MFD 65VDC

85C USA 8137

 

Screw Terminals

D=2.5"

H=4.0"

Apparently 65VDC caps are something in the distance pass, of the possible replacement values is either 63V or 70V
is there a rule of thumb of which direction this value can go? Since it is for an amp, is there a brand/style I should be looking at? I can find little to no information on National Cap, do I assume they are no longer in business and move to another brand?

I have been searching for five days and fully understand I am out of my element and looking for all the help I can getand open to all suggestions.


SteveA
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Showing 3 responses by stevea11757

stevea11757's avatar
stevea11757 OP
126 posts
 
Great information from everyone, thank you. I will continue looking and see what I can locate in stock. While I have a spare amp I am currently using I would like to try and do this in a timely manner.

The manufacturers names I have seen and assume there will be minor SQ differences between them?

At least I have something to start looking for with more than just an assumption on the caps values to go with.

Just curious gs5556, why the caution as to terminal spacing. They were joined with an aluminum bar (took pics before disassembly) wnd used crimp connectors to terminals. I was figuring that I could either drill out the bar (or go across the street to a fabricator and get a new piece and drill it out) or just use a heavy gauge jump wire instead of the bar. The spacing is one of the few specs that I was having difficulty matching.

And yes, this is not the end of the troubleshooting, I was planning on insulating the wires going to the caps and powering it up to check voltages coming out of the transformers to see if there is an issue there.


 
stevea11757's avatar
stevea11757 OP
126 posts
 
Yes, there are mounting clamps on the bottom plate. I had already figured that they would most likely have to be re-tapped if the new diameter was smaller. Obviously a same diameter cap would be the most ideal situation but from my searches thus far, that did not seem terribly likely to match.
stevea11757's avatar
stevea11757 OP
126 posts
 
https://www.mouser.com/ProductDetail/Nichicon/LNT1K223MSE?qs=%2Fha2pyFadujWNTRYoFZetWFsfOgqQfBavn9UCQaI2cVASAlZVSsWkg%3D%3D

At just 2000 hours for the Cornell-Dubilier getting the above with the higher max temp should extend its life considerably. Any advantage to the other that I am not aware of?

BTW- Mouser has just refunded a previous purchase of a different cap that I was going to use. But due to not reading the data sheet correctly I ended up with a smaller cap with a mounting stud. Emailed about a RMA and got a reply from Customer Service that told me not to bother and return and was crediting me the purchase price. Talk about customer service, will definitely be making the purchase there for the replacements.  
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