> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of tony duell > Sent: 17 July 2015 19:56 > To: General Discussion: On-Topic and Off-Topic Posts > Subject: RE: PDP 11 gear finally moved > > > > > Perhaps. But not all of it, certainly. I'm currently four for four > > fixing dead flatscreens by re-capping their power supplies; I imagine > > others have similar experiences. It's not a huge stretch to imagine > > This could be taken to show that modern capacitors are not reliable, and given > that there are plenty of 40-year-old ones still in use in various classic > computers here it would be better to leave them as-is > > More seriously, a lot of modern consumer stuff seems to have marginally-rated > capacitors (and the use of 85 degree ones doesn't help). Possibly on those it is a > good idea to replace them. But the ones in PDP11s were good quality at the > start and were over-spec'd in general. > > > that other power supplies may have similar issues; even if it turns > > out to not be the case, there is probably at least a little "can't > > hurt anything, right?" running around. > > Ah but it can hurt. Damage to the PCB (unlikely, sure), the new part might be > faulty and thus introduce more faults, you might make an error fitting it, and so > on. I prefer to only replace that which needs replacing. > > -tony > =
When I repaired my VT100s I had to replace all the electrolytic caps on the monitor control board to cure the screen wobble. Before doing so I had reformed them all and I had tested them all for ESR and they had all tested fine so I was unable to determine which of them was the bad one. Perhaps there is other more professional test equipment I could use that would have helped, I don't know. I did keep all the original caps though (somewhere). Regards Rob
