27 Mar
2006
27 Mar
'06
10:17 a.m.
Julian asked:
Okay, so I was thinking, would it be possible to
replace the
regulators and
whatnot in a BA11 with several standard PC power
supplies? Obviously
there
would be adjustments that need to be made, but
considering the DEC
units are
now 20+ years old and the out-of-service modules may
have dried up
caps,
would this not be a possible option?
"BA11" covers a lot of chassis/backplane combinations, both Q-bus and
Unibus and not really any bus. I suspect you're talking about the 10.5"
high Unibus box. Dried up caps in the modules are far from a fundamental
difficulty. Compare that with re-doing the power bussing on the
backplanes
and replacing a couple of caps seems downright easy :-).
Not all the backplane signals are drop-in compatible with PC-clone power
supplies, but when third-party manufacturers used PC-clone power
supplies
for Q-bus chassis the extra signals were easily generated with a little
board.
On the Unibus, you probably need at least a token 15V supply and maybe
one that can give substantial currents (depending on what boards you've
got.) Some of those will run off +12V just fine, but others won't
Look at Strobe Data's Unibus backplane for an example of one way to
approach the problem: http://www.strobedata.com/home/ubus.pdf
One warning: few "350W" PC clone power supplies are actually capable of
pumping out half that much power. There are good PC-clone supplies but
at
that price point the "industrial" switchers are not too far off in price
(and are
far more flexible in terms of configuration.)
Tim.