Peter, This is just generic advice based on recent experience. I would replace all electrolytic caps. I had some test pretty good, but PSU worked after I replaced them. Also check all the rectifier diodes as well, and I have had an opto-isolator fail. Dave
> -----Original Message----- > From: cctech <cctech-boun...@classiccmp.org> On Behalf Of Peter Hicks via > cctech > Sent: 08 June 2020 15:10 > To: cct...@classiccmp.org > Subject: VAXstation 3100 power supply > > Hello > > I have a couple of VAXstation 3100s - a M38 which boots but has no output > on the console port, and another model which has corrosion on the > motherboard and a PSU which doesn't power up correctly. > > The voltage on all of the M38 PSU's pins is OK except for pin 7 (brown) which > is +3.5v to +5.25v DC and is floating at about 0.6v with reference to ground. > I > suspect this is why the console port doesn't work (and the LEDs on the read > suggest a RAM problem so I can't tell which chip is faulty), so I've set about > troubleshooting. > > Does anyone have any suggestions above and beyond replacing capacitors? > > > Peter > > -- > > > OpenTrainTimes Ltd. registered in England and Wales, company no. > 09504022. > Registered office: 13a Davenant Road, Upper Holloway, London N19 > 3NW > > >
