VAXstation 3100 power supply

Peter Hicks peter.hicks at
Mon Jun 8 09:10:23 CDT 2020


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?



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