29 Oct
2005
29 Oct
'05
8:53 a.m.
IBM never released the schematics, even to internal IBM sites wanting them.
Early on, we learned that there was a optoisolator that often died.
There WERE aftermarket schematics available for about $40 in the mid-80's;
I don't
think I have any?? A friend still at IBM may.. I'll ask when I see him.
The XT versions were a lot more reliable; I have 8 XT's that get turned on
only once or twice a year, now, and I've never lost a power supply or
system board.
Regards, Terry King ...On The Mediterranean in Carthage, Tunisia
terry at terryking.us
29 Oct
29 Oct
4:49 p.m.
IBM never released the schematics, even to internal IBM sites wanting them.
Maybe because IBM never had them (after all, the PSUs were not designed
by IBM), or because there were so many versions.
As an aside, the TRS80 M3 and M4 used Astec PSU boards. ASTEC did not
normally release schematics, but Radio Shack sold techncial manuals for
these machines. The PSU schematic in there was clearly reverse-engineered
by Radio Shack, and is almost hilarious. It bears little relation to any
of the PSUs I've seen in these machines (there are at least 2, 115V only
and 115/230V), or indeed to any working SMPSU.
Early on, we learned that there was a optoisolator that often died.
There WERE aftermarket schematics available for about $40 in the mid-80's;
I don't
think I have any?? A friend still at IBM may.. I'll ask when I see him.
The PC, PC/XT and PortablePC supplies are all very similar designs. No,
you can't intercahnge them, but if you had a schematic for one, you could
find your way round any of them
I've traced out schecmatics for the ones in my machines. I've offered to
get the PortablePC one scanned. Do you want me to see if I can get the
others done sometime.
-tony
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ard＠p850ug1.demon.co.uk -
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