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What capacitors to buy to refurbish old RCA amp?

Posted by maxhifi (A) on February 9, 2016 at 16:58:34

Figured it's time to refurbish my old RCA mono amplifiers (MI-12188A). These are rather large 70W PPP 807 amplifiers, with a big choke input power supply, and regulated screen supply.

Right now the coupling capacitors are a motley assortment of originals and replacements. The replacements are more or less whatever I had on hand when the originals failed.. I've never been one to fix something which isn't broken, but would like to "normalize" the amplifiers so they're both the same.

Now, I don't really want to use either orange drops, or the ever present yellow film caps. Each amp needs four 0.1uf capacitors, three at 400V and one at 200V. I also need one 0.5uf at 1000V, and a couple of fairly low value electrolytics. I'd also like to try and get "made in USA" parts if at all possible, it seems a shame to use China parts in 65 year old US equipment. So for the electrolytics I guess Sprague Atoms are the only real option.

I'm also on the fence about replacing the filter capacitors - 8uf 1000V rectangular can paper in (probably PCB) oil capacitors. They seem to be working fine.. no heating and no hum in the audio. I don't own a capacitor tester which is capable of putting high voltage on them, but maybe there is some sort of pass/fail test I can use to make absolutely sure they're okay.

What sort of capacitors do you guys use in vintage sound equipment which you care about?

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