I managed to buy a 'reconditioned' BA23 power supply for my microPDP-11/53. The model number is H7864-A ... some of them seem to be often listed as HP parts, I guess HP now own the rights to all the old Digital stuff. It was delivered today and I installed and tested it. It looked brand new, there was no dust inside. Here I am measuring the 12 volt supply:
This is a switched mode power supply, so it won't show a voltage unless there is a load attached to it. So I have plugged in an old CD-ROM drive to give it something to do. The 5 volt supply measured at 5.08v, and as you can see the 12 volt supply showed 12.11v. The supply voltages were stable during my tests. Here I am getting everything ready to do the tests:
After I did these tests several times and took all the pictures the power supply went bang and gave out a cloud of smoke. Like before, I think that this is a big capacitor on the incoming supply that has exploded. I was quite surprised since the unit was in such good condition and was sold as 'reconditioned'. However, it still seems to work, even after all that. Maybe they are all going to do this - they are quite old afterall.