Replacing MicroVAX II PSU With a Modern PSU

[Robert Jarratt]

Thanks Mark,

I probably don't have space for another one really, and yours is the one in the big enclosure anyway (like this: http://www.trailingedge.com/comphave.html?theKey=deccmicrovax2&byCompany=0), if I remember right, which has a different PSU. 
Mine is one of these: http://www.cosam.org/images/uvaxii/front.jpg

We should try to get that one of yours working at the next Legacy. Have you thought about whether to go for April?

Regards

Rob

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Mark
> Wickens
> Sent: 24 November 2015 23:52
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: Replacing MicroVAX II PSU With a Modern PSU
> 
> 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.
> If you need another dead MV2 let me know, the one I collected is still sat in the
> garage.
> 
> Regards,
> Mark.
> 
> On 20 November 2015 at 00:00, Robert Jarratt <robert.jarratt at ntlworld.com>
> wrote:
> 
> > While I look into what is wrong with my H7864, I'd like to use a
> > modern PSU to power my machine (actually an rtVAX 1000).
> >
> >
> >
> > I think I would need to deal with the following problems:
> >
> >
> >
> > 1.       Finding the right connectors (ideally, I am sure I could rig up
> > something more temporary).
> >
> > 2.       A way to power the fans, which I believe are 15V, perhaps they
> > would run on 12V as I wouldn't run the machine for long periods
> > anyway, or I could just use PC fans.
> >
> > 3.       Emulate the DC OK and P OK signals, I suspect these would be
> > simple
> > +5V signals which could perhaps just come from the +5V of the PSU
> > +anyway
> > (unless there is a problem with that).
> >
> > 4.       The most difficult bit, I suspect, would be the PSU LTC signal ,
> > which I believe is some kind of clock. I don't know what the spec of
> > the signal is, but I will get a scope on a working one to see (NB
> > don't want to risk a working PSU on this machine in case it was a
> > problem with the machine itself that caused the first PSU to fail, I
> > don't mind sacrificing a modern PSU if need be).
> >
> >
> >
> > Has anyone done this before?
> >
> >
> >
> > Regards
> >
> >
> >
> > Rob
> >
> >