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