VAX 4000-500 PSU Overload?

[Robert Jarratt]

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Mouse
> Sent: 19 December 2015 16:09
> To: cctalk at classiccmp.org
> Subject: Re: VAX 4000-500 PSU Overload?
> 
> > But getting something in series to measure load is going to be really
> > awkward, [...]
> 
> As in, you don't have any such thing to put in series, or you don't see a
good
> way to get it in series?  I've got a couple of 0R1 resistors which work
nicely for
> that in conjunction with a voltmeter that can handle millivolt
measurements;
> you might be able to get something similar.  Mine are 10W, and, while they
> are designed for bolting to a heatsink, they can probably handle at least
2 or 3
> watts, which means some 5-6 amps, in free air.  (Though that then drops
> about half a volt, which can be a problem when you can't put it on the
input
> side of the
> regulation.)
> 

I think the suggestion was to put an ammeter between the PSU and the
backplane. That would be awkward to make all the connections with the PSU
out of the machine. Also difficult is to make a dummy load for a bench test
that draws enough current to test that it can sustain its rated output at
full load (or some decent proportion of full load at any rate).

Regards

Rob