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 <a...@p850ug1.demon.co.uk> wrote: > > > > > 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. > > 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 >