19 Jul
2015
19 Jul
'15
9:31 p.m.
Well, all I can say is that my experience differs. I have had newer capacitors fail, and
old ones, too, of course, but nothing points to wholesale replacement as a cost or time
effective strategy, especially on something like an Altair. FWIW, I don't run my
vintage machines all that often. Of course reforming a bad capacitor, whatever the
failure mode, is going to be useless.
Tothwolf <tothwolf at concentric.net> wrote:
On Fri, 17 Jul 2015, Jay Jaeger wrote:
On 7/17/2015 1:33 PM, Rich Alderson wrote:
Replace - no, I don't agree - especially not for those of us who don't
have the kind of budget that your organization has. In my experience,
for equipment of this quality and vintage, 95% or more of the time an
hour to a few hours of re-forming is all that is necessary - and as Tony
has pointed out, even that is not often really necessary.
Replace - yes, *especially* if you don't have a big budget. Aluminum
electrolytic capacitors are CHEAP and easy to obtain. Replacement
semiconductors by comparison are expensive and can be quite difficult to
find.
While it might be worthwhile reforming a special purpose NOS electrolytic
that isn't much older than 15-20 years old, reforming 20-30 year old
heavily used (read: past usable service life; evaporation of the
electrolyte, corrosion of the foils and especially foil to terminal
junctions, etc) is a complete and total waste of time.
Ironically, 20-30 years ago this same mindset used to persist with people
who collected vacuum tube (valve) based radios and television, however
that attitude no longer seems to be present in those communities today
(not worth risking an irreplaceable transformer or inductor over
$5.00-$10.00 worth of aluminum electrolytics). It is
generally a good idea to re-form electrolytic capacitors in
power supplies, and to bench check the power supplies (under some kind
of load) before actually applying power to the whole unit.
It is always a good idea to replace electrolytic capacitors in power
supplies. The rest of the advice is sound.