Hi Dave Superb, thanks - I hadn't thought about the rectifier diodes.
A word of caution for anyone replacing the 470uF/250V electrolytics near the mains side of the board: the Nichicon like-for-like replacements are shorter and wider than the ones they replace and don't actually fit. Peter On Mon, 8 Jun 2020 at 15:30, Dave Wade <[email protected]> wrote: > 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 <[email protected]> On Behalf Of Peter Hicks > via > > cctech > > Sent: 08 June 2020 15:10 > > To: [email protected] > > 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 > > > > > > > > > -- OpenTrainTimes Ltd. registered in England and Wales, company no. 09504022. Registered office: 13a Davenant Road, Upper Holloway, London N19 3NW
