> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Robert > Jarratt > Sent: 19 December 2015 17:20 > To: 'General Discussion: On-Topic and Off-Topic Posts' > <cctalk@classiccmp.org> > Subject: RE: VAX 4000-500 PSU Overload? > > > > > -----Original Message----- > > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Mouse > > Sent: 19 December 2015 16:09 > > To: cctalk@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
Rob, Seeing as it already seems to have over current sensing, I guess it has some small resistors in there so perhaps it is possible to measure the current. I notices one looks like this:- http://uk.farnell.com/welwyn/oar1-r020fi/resistor-1-0r020/dp/1200359 Dave