EVOX RIFA X2 capacitors

Mark J. Blair nf6x at nf6x.net
Sun Jun 12 14:40:58 CDT 2016

Those Rifa paper-dielectric caps are very common in the Astec power supplies that I have found in most of my TRS-80 gear. After having one cook off on me in my Model 12, I replace them all on sight with Panasonic safety-rated poly film caps. My hypothesis is that moisture gets into the paper dielectric through the visible cracks that I have seen in the outer case of every single 80s-era Rifa cap I've looked at. Since poly film caps are supposed to be much less prone to absorbing moisture than paper dielectric caps, even when their outer seal fails, I expect the poly film caps to last much longer.

I can look up the part numbers from Digi-Key that I used if necessary. I think that any safety-rated poly film caps with suitable lead spacings, same or higher voltage ratings, and similar capacitance should be fine.

Mark J. Blair, NF6X <nf6x at nf6x.net>

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