> On Aug 28, 2019, at 2:07 AM, Guy Dunphy via cctalk <cctalk@classiccmp.org>
> wrote:
> An extremely common problem with all old electronics from around that era.
> The mains filter caps are commonly 'RIFA' brand metalized polyester film,
> encapsulated in a clear-honey-coloured resin.
> The problem is that the resin embrittles and shrinks with age, resulting in
> many small cracks. (And sometimes large pieces falling off.)
> The cracks let in moisture, which absorbs into the insulating film.
I suspect those notorious Rifa brand capacitors would not be so problematic if
they had polyester film dielectric. But if I'm not mistaken, they don't; they
have *paper* dielectric!
Aside from that one correction, I agree with everything else you wrote about
the likely failure mechanism of these evil little rectangles of compressed
smoke and fire.
--
Mark J. Blair, NF6X <n...@nf6x.net>
http://www.nf6x.net/
