17 Jul
2015
17 Jul
'15
11:55 a.m.
I suspect part of the "swap'em ALL out" mentality comes from the 90's
when
some botched industrial espionage had some of the bottom-tier cap
manufacturers using a dodgy electrolytic formula for their caps. These
caps would have a frequent failure rate..
While not an issue for pre-90's electronics, it has fostered the mentality
of full replacement for 'newer' electronics i.e. arcade/pinball machines
Todd Killingsworth
On Fri, Jul 17, 2015 at 2:42 PM, tony duell <ard at p850ug1.demon.co.uk> wrote:
supplies.
Could you, please, explain why? And how often should this be done? Every
week, every month, every year, or what?
FWIW, the number PSU elecrtrolytics I have replaced can be counted on the
fingers of
one hand -- in unary. Well, perhaps both hands. But it's <1% of all the
PSU electrolytic
capacitors I own.
Only 2 cases spring to mind :
The PSU in my 11/44 had a high ESR capacitor on the +36V rail (all other
caps in the machine
were fine)
I changed the 2 mains smoothing capacitors in my HP120 not because they
were electrically
defective (they tested fine) but because one was bulging a little on top
and had it exploded it would
have hit the neck of the CRT with all the problems that would be likely to
cause.
I do find this witch-hunt against capacitors to be curious, given how few
I've found to have
failed. I suspect a lot of it comes from audiophools who think this is the
way to fix anything...
-tony
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