Re: power supplies, was Re: NetBSD/vax

[sadness <vampire%ipv7.net@localhost>]

Il 22/03/2020 23:48, Maciej W. Rozycki ha scritto:

>  The capacitors I have seen fail in this PSU were actually Chemi-Con SXF 
> line ones (1800µF/25V as you say) and according to my notes there ought to 
> be five rather than four actually.  I would highly recommend chasing the 
> fifth one and replacing it too.

Thanks for the (very) accurate description of the problem, I can confirm
that the failed caps where 5 and not 4 as I mentioned in my previus
message, maybe I was low on coffee.

>  Other reputable makes and lines of capacitors of the time also suffered 
> from the said problem, e.g. I saw Nichicon PL parts leak in the H7826 PSU 
> used with some DECstation 5000 machines.

In my 3100 the failed caps was all Nichicon PL, also I've seen this
problem in many other psu (non only DEC).
Speaking of Nichicon caps just today I've found that all the Nichicon SE
used in my VLC psu (330uf 25v, 4 of them) wasn't leaking but they're ESR
value went up and the measured capacity was below specs, all the other
caps in the psu checked out ok (still replaced them all, this particular
vlc is running non-stop from november 2000, it was just the right time
for doing some maintenance).

-- 
Giuliano Paolo Brunetti
http://www.flickr.com/photos/31231773@N02/sets/
Italian hobbyist DECnet network - http://decnet.ipv7.net