13 Oct
2022
13 Oct
'22
7:43 a.m.
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(a)classiccmp.org>
To: "Classic Computer Mailing List" <cctalk(a)classiccmp.org>
Cc: "D. Resor" <organlists1(a)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
