DEC Professional 350 - video issues

John Ames commodorejohn at
Mon Nov 24 22:12:11 CST 2014

I went out to Seth's moving-sale giveaway this past weekend and came
away with a few DEC goodies, including a DEC Professional 350 which
was given to me on the understanding that the video didn't work. I set
it up yesterday and sure enough, the video doesn't work. Specifically,
the monitor (a VR201 with BCC02 cable) turns on and displays no
picture, but shows visible sync lines all across and down the screen,
and the diagnostic LEDs indicate a selftest failure on the card slot
that the bitmap card is plugged into.

(I tried moving it to another slot just to check, and sure enough, it
fails there, too. I don't think it's a general CTI bus issue because
the other two cards don't generate a selftest failure code. I did test
the monitor with the Rainbow I also picked up and it's working fine.)

The card itself doesn't have any socketed ICs, so it's not chip creep,
and the ZIF connector looks to be in good shape. Beyond that, I don't
know what to look for in diagnosing the issue - does anybody have any
idea what might be wrong with it, and how it could be fixed? (Is there
a service manual for the card out there somewhere? I couldn't find

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