If the PSU requires too much hacking, you may just want to replace with a modern Mean-Well switcher or two. The Aztec supplies used in those Xerox enclosures are OK but nothing stellar. I recapped mine (it also showed signs of electrolytic leakage) and it did work so I kept it, but if it'd had issues I'd have junked it.
Thanks, Jonathan ------- Original Message ------- On Thursday, October 13th, 2022 at 09:32, D. Resor via cctalk <cctalk@classiccmp.org> wrote: > > > I do understand that these are common film capacitor types. There is one more > smaller .10ufa RIFA branded capacitor hiding near the center of the PWB. > > A couple reasons I'd like to have a circuit diagram is to know what the RIFA > capacitors purpose are. The other is, a couple of the electrolytic capacitor > are double covered with what appears to be rubbery heat shrink tubing, > therefore I cannot read what their value are. > > One of these two electrolytic capacitor appears to have a dried substance > around the top. The over-pressure venting cuts in the top of these two > capacitors are not split. At this point I cannot tell if it is dried > electrolyte, cement to hold the sleeve on, or possibly paper. > > Looking at these two again, it definitely could be dried electrolyte. I have > seen it creep out and up into strange places. > > https://www.dropbox.com/s/18hzfdqe96vmgsr/electrolytics.jpg?dl=0 > > Seems someone was in hurry on the day this PS was tested. I cannot make out > date, is it 1983? > > https://www.dropbox.com/s/zlt2ocpqulil13j/pssticker.jpg?dl=0 > > What type are the diodes, their rating etc.? I seem to remember this type > with a black band were rated at 3 amps, but that's all I remember. > > The TO-3 transistor/regulator has no P/N silkscreened on it. > > Having a circuit diagram helps to cover many bases. Apparently it's an Astec > AA12070. > > Placed the PS board back in the garage to continue airing out! 😉 > > Don Resor > > > > > > -----Original Message----- > From: Joshua Rice via cctalk cctalk@classiccmp.org > > Sent: Thursday, October 13, 2022 4:43 AM > To: General Discussion: On-Topic and Off-Topic Posts cctalk@classiccmp.org > > Cc: Joshua Rice ric...@btinternet.com > > Subject: [cctalk] Re: Xerox 820II U07 Power Supply magic smoke.... > > > You shouldn't need a schematic. These thin film caps are a common failure > mode on a multitude of PSUs. Just replace like for like. Thin film X and X2 > rated caps are easily found from your favorite electronics part retailer. > > If it's gold and got RIFA on it, replace it, though. Just because it hasn't > popped, doesn't mean it wont pop in the near future. > > I've learned now, to always check every PSU or other mains-powered vintage > equipment for these little stinkbombs. If they're present, i'll always > replace. > > Cheers, Josh > > ------ Original Message ------ > From: "D. Resor via cctalk" cctalk@classiccmp.org > > To: "Classic Computer Mailing List" cctalk@classiccmp.org > > Cc: "D. Resor" organlis...@sonic.net > > Sent: Thursday, 13 Oct, 2022 At 12:24 > Subject: [cctalk] Xerox 820II U07 Power Supply magic smoke.... > Where might I find a schematic diagram for the Xerox U07 8" FDD,HDD expansion > cabinet for the 820II, and/or the 105P80450 power supply? > The Xerox Professional Computer Technical Reference Manual I downloaded from > bitsavers.org doesn't seem to have those particular schematic diagrams. > For your enjoyment the part which smoked. > https://www.dropbox.com/s/al9kx3yw9ypwp89/Xerox105p80450.jpg?dl=0 > https://www.dropbox.com/s/al9kx3yw9ypwp89/Xerox105p80450.jpg?dl=0 > > I certainly am glad I have the lid off while testing. Unfortunately these > capacitors which appear to be film type were hidden from view. > The fuse didn't blow, but that .22uf 250v capacitor certainly stunk up the > house. It smelled like burnt popcorn, plastic and the bottom of a coffee pot > which has boiled dry, yech! > I know that if I had pulled the power supply board first I might have seen > the physical cracks in these boxed capacitors. > Wasn't it Marc V. that said in one of his videos, you don't need to shotgun > them all! Oi, lol It's when things like this happen that I most always worry > about not going over vintage equipment fine tooth comb. > Don Resor > > >
