> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Jon Elson > Sent: 25 November 2015 02:05 > To: gene...@classiccmp.org; discuss...@classiccmp.org:On-Topic 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: http://home.windstream.net/engdahl/powerup_reset_circuit.htm, 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. Regards Rob
