15 Sep
2013
15 Sep
'13
3:07 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of Peter Coghlan
Sent: 15 September 2013 20:38
To: cctech at classiccmp.org
Subject: Re: VAXstation Monitor Cable Trouble
Fred wrote:
cause
this?
Seems plausable. Finding or making some sort of DA15 breakout device
might be useful to track it down. Disconnecting each of the keyboard and
mouse signals in turn might reveal if one of those is responsible. Just
putting
>I
have a BC18Z I have for connecting the VAXstation to the monitor,
>keyboard and mouse. With this cable, a red hue across the whole
>screen flashes on and off about once a second, the other colours
>are fine and the screen is legible. There is also a thin dark line
>that scrolls up the screen continuously. This happens on two
>different monitors. I don't think it is the VAXstation itself
>either, because swapping with another cable the problem goes away.
On Sun, 15
Sep 2013, Peter Coghlan wrote:
> Me too!
> I have a VAXstation monitor cable that does that too or something
> very like it.
> >I tested continuity of the red wire and it seems fine. Are there
> >any components in the keyboard and mouse connector block that could It's
been a while since I looked at the problem and I don't know
where the cable is now. I think I did a DC comparison between the
bad cable and a working cable and failed to find any difference.
Unfortunately, the only solution I could come up with was the same
one you did, use a different cable :-(
Would that be an issue that DC/continuity checking does not reveal
problems at higher frequencies, such as inductive coupling between
wires, etc.?
a scope on them might show which is a likely culprit.
However, knowing
which signal is responsible won't help much unless it can be disconnected
permanently. There are keyboard and mouse connectors on the system unit
of some models of VAXstation 3100 but not on the VAXstation 2000.
Regards,
Peter Coghlan.
Earlier I had a problem where the screen was flashing on and off about once
a second. I discovered that this was due to a mouse key being jammed in the
clicked position. The frequency of the red flashing is about the same. I
wonder if it is anything to do with the mouse. When I next get the cable out
I will try disconnecting the mouse to see if it makes a difference.
Regards
Rob