> > 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.
Err, have you priced the screw-terminal 'computer grade' electolytic capacitors that were used in these PDP11 power supplies. They are not cheap, if you can find them at all. And of course NOS ones might be as good or bad as the one that's already there. Conversely when I had a major disaster in a DEC power regulator brick some years ago (blew almost all the transistors and the 723) the replacement parts were easy to get (exact replacements, not just equivalents) and were not expensive. [...] > 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). Odd... I know plenty of people who restore old valve radios and audio stuff and not one will blanket-replace all the aluminium electrolytics. There is a capacitor that I (and they) would check very carefully, but that's not an electrolytic. I refer of course to the coupling capacitor to output valve grid. In a lot of radios this is connected to the anode (plate) of the audio ampilfier triode so if it leaks it puts a +ve voltage on the output valve causing far too high an anode current there. But even then I (and everyone else I know) would test it, not just replace it. Some of those capacitors are very reliable and the replacements you get not any better. I probably would replace certain safety-related capacitors in live chassis sets, like ones that isolate external sockets, using class Y replacements. But that;s about it. Incidentally, do you shotgun-replace 7805s and other 3 terminal regulators? If not, why not? They can fail, and if they do they do a lot more damage than a failed capacitor. -tony