Date   : Sat, 27 Sep 2008 14:36:35 +0100
From   : ats@... (Adam Sampson)
Subject: Domesday video problems

Hi all,

I'm currently trying to resurrect a Domesday system:
  http://offog.org/stuff/domesday/25092008119.jpg

This belongs to the Computing Lab at the University of Kent, where I
work. The Laserdisc player had been sitting in our networks lab for at
least the last ten years, and one of our sysadmins found the rest of it
during some recent room moves.

I've got: a Master AIV, a Laserdisc player and remote control, a
trackball, a Viglen dual disc drive, the Domesday, Volcanoes and Ecodisc
discs, the Master, Master AIV and Domesday manuals, keystrips for
View/ViewSheet and the Domesday system, and some sundry cables.  I'm
missing the monitor, video cables, and the manual for the Laserdisc
player -- fortunately, I had an A310 monitor in storage which seems to
work.

It's the cleanest BBC setup I've ever seen -- I'm used to having to
clean sticky crud off cases from machines that have been used in
schools, but this just needed some dust wiping off! The Laserdiscs are
also in good condition: no visible rot, and the only damage is a dent in
(fortunately) the blank side of the Volcanoes disc. Here's the output of
*HELP showing the ROM versions present in the Master:
  http://offog.org/stuff/domesday/25092008112.jpg

So far, I've rebuilt the 1980s-vintage battery pack in the Master and
reset the CMOS settings to those in the AIV manual, set the SCSI ID on
the Laserdisc player back to 0, and made up a replacement RGB cable to
go from the Master to the player (with all six pins connected straight
through).

The system now mostly works: it'll boot off a Laserdisc, and you can
navigate around happily. However, as you can see in the pictures,
there's something wrong with the video output: the overlay graphics from
the BBC are fine, but the genlocked video from the Laserdisc doesn't
appear correctly:
  http://offog.org/stuff/domesday/25092008116.jpg
  http://offog.org/stuff/domesday/25092008118.jpg

I've tried a different monitor with the same result. I've also tried
playing a normal Laserdisc without the BBC attached, and got a similar
effect:
  http://offog.org/stuff/domesday/25092008107.jpg

I believe the Laserdisc player was used as a video source for other
experiments in the early 90s -- the SCSI ID was set differently, two of
the Laserdiscs are marked "stills" and "video", and I've found
framegrabs from them on other old machines. It's therefore plausible
that someone might have fiddled with other settings on the player -- or,
since it's been sitting around for at least ten years unused, that a
capacitor or belt needs replacing...

Since I don't have the Philips manual, I'm at a bit of a loss as to what
to try next. Has anyone seen this problem before? How do you put the
player into diagnostics mode? Is the service manual still available?

The full set of pictures is here:
  http://offog.org/stuff/domesday/g/

Thanks very much,

-- 
Adam Sampson <ats@...      >                         <http://offog.org/>