Electrolytic capacitors and other picture postcards.

From: Bill Sudbrink <bill_at_chipware.com>
Date: Mon Feb 7 18:32:45 2000

Well, my OSI C3D is currently non-functional. Here's
what happened:

I've been testing and repairing a number of OSI 48-pin
bus cards using the C3. This has required a large number
of power cycles. Also, several cards caused the PS fuse
(2A, 250 volt, glass cartridge) to blow. In each case, this
problem was corrected by replacing the electrolytic caps on
the offending board. OSI used 47 microfarad, 16 volt ecaps
(ecaps... is this a good abbreviation? I'm getting tired of
typing "electrolytic") pretty much exclusively. I could not
find a source for these, so I used 47mf, 36 volt ecaps as
replacements. This seemed to work OK. I finished working
on the other cards and tried to bring up the machine with
just the original cards. The fuse blew. Grrr... I pulled
all of the cards, replaced the fuse and tried them one at a
time. Sure enough, the CPU card (the model 510, triple CPU
card with 6800, 6502 and 8080) was the culprit. I replaced
its two ecaps as per above. It came up, rebooted once OK,
started to get flakey and now won't come up at all. Is my
understanding of ecaps correct? That is, as long as the
capacitance is correct, the voltage is greater or equal to
the required load and it is installed "right way around"
it should be OK? There is so much logic on this board, a
lot of it 8Txx, I hope I haven't blown a chip. It would
take me a month to find it and who knows if I could get a
replacement.

Thanks,
Bill Sudbrink
Received on Mon Feb 07 2000 - 18:32:45 GMT