Symbolics 3620 screen issues

From: Bob Shannon <>
Date: Sat Mar 23 18:19:30 2002


I used to fix lisp machines for a living. They use custom monitors.

The problem described is a common problem of reflections on the video signal
transmission line, and this accounts for the doubling of the video.

Tony Duell wrote:

> >
> > On 22 Mar, Tony Duell wrote:
> >
> > > Is the monitor based on a standard chassis that we might be able to find
> > > documentation on?
> > Aha. I see. You never seen a Symbolics (monitor) from inside. These
> No. Now, if somebody wants to give me a Symbolics... :-)
> > console monitors are very special and very strange things. Mono screen,
> > some audio stuff in it, keyboard and mouse controller, ... and it is
> > connected to the machine with a single cable. They are completely
> > different from everything else on the world.
> That, actually, doesn't mean a darn thing...
> Consider the portrait monitor on my PERQ 2T1. It's got 3 physical cables
> back the host, which actually form 1 'logical cable' -- video (no syncs)
> : BNC, power : 3 pin DIN, everything else (syncs, keyboard/tablet power
> and signals, audio, etc) : DA15.
> The keybaord and mouse/tablet plug into the back of the monitor.
> But inside the monitor there's a custom connector bracket which links up
> all the connectors, the speaker, and so on. And a standard KME monitor
> PCB.
> The PERQ 3a monitor has a PCB in the base with all the interface
> circuitry on it (for things like the keyboard, speaker, etc) and an
> almost-identical KME PCB on top.
> The Moniterm landscape monitors used on PERQ 2T2s have much the same
> connector bracket as the T1 portrait monitor, a simple (very simple) PSU,
> and a standard Moniterm monitor PCB.
> So the fact that the monitor unit is custom doesn't mean the PCBs inside
> are. In fact most companies did use standard monitor PCB.
> Do you know the PCB in the Symbolics monitor is totally custom?
> -tony
Received on Sat Mar 23 2002 - 18:19:30 GMT

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