Req: Help/Advice on Cromemco System

[Roy J. Tellason]

On Friday 17 October 2008 12:21, Dave McGuire wrote:
> On Oct 17, 2008, at 10:15 AM, Granz wrote:
> > I have most of the stuff to put together a System 3.  I have the
> > card cage with the 21-slot motherboard and a bunch of cards.  The
> > manuals I got with the system include the Cromix manual, I have
> > more than 1 64-K RAM card and at least one TPU, so I believe that
> > mine was a multi-user system.  I would like to put this back to
> > near-original, but need a case and power supply.
> >
> > Since I have been unable to find any power supplies which provide
> > the +/- 8 and +/- 16 volts, I just thought of an idea the other day
> > of using a PC power supply and shorting out the on-board voltage
> > regulators to allow them to work at the +5V and +12V of the power
> > supply.  In order to do that though, I would need a small (3-5
> > slot) motherboard to test a couple of cards together.
>
>    I don't think it's going to be possible to short around the +5 and
> +12 regulators in a PC power supply, as they're not discrete in that
> way.

I don't think that's what he was talking about there.  I remember some S-100 
cards coming with regulators (all of them did,  early on),  and later the 
input and output points where those regulators _had been_ were connected with 
a wire jumper in the assumption that a switching power supply of some sort 
with regulated outputs would be used instead of the original S-100 
unregulated supply.

The catch,  though,  is that the System 3 needs a +24V supply as well,  for 
the FDD.  I have one,  and it uses an oddball connector,  too,  which is one 
of the reasons I haven't gotten around to fixing the drive yet (which has 
problems),  I need to make an extension power cable for the drive so it can 
be powered up and out in front of the case.

(Snip)

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