Power supply question - test-drb@ccmp.vtda.org

12 May 2001

From: ip500 &lt;ip500(a)home.com&gt;

...
  Would a "modern" switching supply ie: a
cheap, generic PC supply
have enough output to run a vintage machine? I had considered doing that 

At best the answer is maybe.  Reason is I have no idea of the specific
vintage machines power needs.

For example the average PC power supply can run from 145-350 watts
and that alone covers a lot of ground.  Ther other problem is most of the
PC power supplies outout is +5 and some +12, some of the vintage
machines may have heavier needs for +12 or maybe -12.  Another
example is the PDP-8/f I have, a 250W PC supply would easily
satisfy the +5v needs but would fail badly as the PDP-8 wants
+15 and -15 something a PC supply cannot do.

...
 faulty memory] the HP drew about 20 amps or so on the
+5 line. Shouldn't
be too hard to pull a couple of the faulty cards to make room for the
much smaller [physically] supply. Might be a problem with lack of decent
air circulation for cooling though.
 Again from memory ... even the CE's really didn't want to fool with
repairing the PS units on these. When I bought a bunch of HP gear there
were 8 or 10 dead supplies that had been stashed away to maybe fix
"someday'. 

Many people are scared of PS units.  Switch mode PSUs are harder
to fix than linear.  Then again I fixed a BA123 supply by replacing a
failed internal fuse!  So first testing and deciding how bad the failed
 unit is likely first order of the day.

Allison