10 Apr
2015
10 Apr
'15
12:57 p.m.
On Apr 10, 2015, at 3:35 PM, John Ames
<commodorejohn at gmail.com> wrote:
Back in November I dropped in on a list member's moving giveaway and
came away with some DEC stuff, among which was a DEC Professional 350
with keyboard and monitor. As the previous owner informed me, the
video isn't working; there's no picture on the monitor, but there's
visible sync lines, and the diagnostic lights on the back of the unit
indicate an error with the bitmap graphics card. I'm pretty sure it's
an issue with the card and not the slot, since the error moves with
the card when I install it in one of the other slots, but I'm not sure
what to look for on the card itself - nothing is socketed, so it's not
chip creep, and the card connector looks to be in good shape.
Does anybody have any advice for diagnosing and repairing this?
Nothing from personal experience, unfortunately, but a few random notions:
I don?t remember if schematics for the -350 exist on-line, but the Technical Manual will
at least give you detailed block diagrams. It?s on Bitsavers.
If you have a console cable (which is basically a printer cable with a pair of pins on the
PRO end jumpered together) you could try to boot an OS that will talk to a console
terminal, then you might be able to use that to talk to the CSRs and dig deeper. RSTS
could do that but it?s not generally available; RT11 might, I?m not sure. If you have
some ODT-like program, you could poke around the CSRs and see what those tell you.
paul