14 Jul
2012
14 Jul
'12
1:55 p.m.
On Sat, 14 Jul 2012, Chuck Guzis wrote:
On 14 Jul 2012 at 0:34, Tothwolf wrote:
Who's the maker of the original cap? I'm curious now given what Will
mentioned if it might very well have been a custom made part for HP. I
think I've actually seen 950uF before but I can't remember where.
Capacitors with axial leads have been getting harder and harder to find,
and when you can actually find them, they tend to be so much more
expensive than an equivalent radial too. If all you need is an 85C rated
part, I think Nichicon still has them in their VX series. According to my
Nichicon book, the P/N for a VX series 1000uF 50V in a 16x31.5mm case
would be TVX1H102MCD. I don't know of anyone who currently makes an axial
leaded 105C rated part though, which is what I generally prefer for
radials in SMPSU rebuilds.
I replace odd value capacitors all the time in
older SMPSUs and as
long as the values are close, substitutions are generally not a
problem. The hard part I've found is finding modern parts with the
same lead spacing. Sometimes you have to go up a case size and/or
voltage rating to find an electrolytic that will fit the existing
location without putting excessive bends in their leads. This is
especially true with old 3-lead "computer grade" capacitors (typically
two ground leads).
My error--it's a 950 uF cap, not 940 and it still is 40 VDC.
Fortunately, it's an axial-lead cap, so replacement with a physically
smaller size won't be an issue.
It seems to be a filter cap on the +22 supply line, so it's not
critical as regards timing. But the odd value had me wondering--I've
been placing 1000 uF filter caps virtually since there were
transistors. I'd never seen a 950 uF before.