best way to recondition Rifa caps after long storage
Hi guys, I have just been given a pile of Rifa PEH169 some 3300u/63v stud mount (about 20) and some 15000u/40v. the 3300 date codes put them at 15 years old, they are unused and appear to be in good nick, but the stated shelf life is 10 years @ 40c, now I know they were kept well packed in a cool but not cold place.
the 15000uf/40v (14 of them) i'm yet to look up the date code (BAO) but these also appear fine and were stored together with the others.
I have many things I would love to do with these great caps, not least build an adjustable supply for testing and an F5X, but I do not want to put myself in jeopardy. there datasheet explains to expose them to close to their rated voltage and about double their leakage current for an hour to recondition them before use, is this a good idea at this point? or should I regretfully dispose of them?
I suppose the words suck it and see come to mind, try the reconditioning thing and if they survive that unscathed, step up the current a bit using them in a fairly undemanding power supply and again if they survive, use them as intended for the next 70000hrs?
your advice and comments are much appreciated :) it would be a crying shame to throw these away and given they have been stored at 10-20c (probably somewhere 15-20 for the vast majority) well protected and wrapped, i'm probably fine, but thought I would ask just the same
Old electrolytics can often be re-formed successfully. Just do it gradually. The minimum you need to do this is a DC power supply, a resistor and a voltmeter. There is plenty on the web about this, although much of it is aimed at higher voltages. The principle is the same for lower voltages.
If they have dried out or the film has deteriorated too much then they won't reform. Anyway, give it a try - nothing to lose.
thanks yeah thats what I figure, seen the stuff on the net, but thought I would ask 'my people' who may have even had experience specific to these very caps. considering the PEH169 is branded and promoted as an 'ultra long life' electrolytic I figure its about as good a candidate as possible. and since they are branded as such and guaranteed to live 70000hrs in use in much harsher environments than i'll put them through after such a period, they probably cover themselves too.
so i'll be doing just as you say and first winding them up slowly with ~50-55vdc (for the 63v) and a few ma from a resistor and take it from there. will then have to come up with a cooker to do them in batches after that. i've used much older NOS caps and blackgates that must be getting on a bit regularly and they arent designed to last forever like these are.
thanks for the advice
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