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Re: 3458A Schaffner Mains Filter


 

Funny you mention the clear encapsulation.

So I have some RIFA's I ordered and received from digikey in 2018. I
saved them for a project in the original antistatic bag in a cardboard
box in the unlite closet. So no UV exposure. I keep my office
relatively temperature controlled because of the test equipment there.
Imagine my fascination when I opened the box last year and found that
they had cracked. Keep in mind this isn't a large sample size it's
just 3 or 4 capacitors but to me it says a lot. I don't believe the
failure mode for the RIFA's is heating and drying out or whatever.
IMHO the encapsulation failure is the root cause. I suspect the
acrylic has a lot of internal stress from a rapid curing process used
by RIFA.

-Evan Foss

On Tue, Sep 6, 2022 at 4:44 AM Carsten Bormann <cabocabo@...> wrote:

On 2022-09-06, at 10:58, Adrian Nicol <Adrian@...> wrote:

Any 'stand alone' yellow Rifa caps you find serving as input filters should be changed with extreme prejudice on sight however!
Yes. The point about Schaffner filters is that X caps of this type (reportedly from WIMA, not RIFA) were use in their line filters up to some point, which (together with the fact that they make a somewhat sealed enclosure) is the reason they explode.

The question really is when Schaffner stopped using the ¡°clear epoxy blob¡± type of X cap and switched to caps that didn¡¯t have that fatal flaw.

Your data seems to suggest mid-1990s or earlier.

Can we get more precise?
Maybe obtain a statement from the horse¡¯s mouth?
(Somebody in this mailing list must have worked for Schaffner¡­)

Gr¨¹?e, Carsten





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