Replacing MicroVAX II PSU With a Modern PSU

Robert Jarratt robert.jarratt at
Wed Nov 25 01:34:21 CST 2015

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of Jon Elson
> Sent: 25 November 2015 02:05
> To: General at; Discussion at and Off-
> Topic Posts
> Subject: Re: Replacing MicroVAX II PSU With a Modern PSU
> On 11/24/2015 05:52 PM, Mark Wickens wrote:
> > I haven't looked into this at all and I suspect it's probably quite
> > tricky indeed. I did look around a while back drew a blank.
> >
> I built up a Micro-VAX II system out of boards, backplanes and assorted junk.  I
> made my own power supply.  The power supply is actually easy, just +5 and
> +12, with a touch of
> -12 for serial I/O.
> The only tricky thing is the power-OK and reset logic, which really wasn't all
> that tricky, either.
> I had a power and thermal safety control panel on it repurposed from the
> original 3rd party IBM mainframe memory box that would shut it down if there
> was an abnormal voltage or cooling failure.
> Jon

Thanks Jon. I think standard PC PSUs only do +5 and +12, so how did you do -12?

For P OK and DC OK I found this:, but just for test purposes I assume I could connect the +5 direct to P OK and DC OK.

Thanks for the other email, sounds like I wouldn't need to do anything with LTC.



More information about the cctech mailing list