20 Feb
2004
20 Feb
'04
9:48 p.m.
On Fri, 2004-02-20 at 23:18, Tony Duell wrote:
Oh, right...
Can you please re-describe the 2 faults and the machines they occur on --
I was under the impression I was considering a PERQ 1 (VMI monitor) with
a small picture all round...
Well the 2T1 is the one I'll try and sort out first, as that one
certainly appears to have a healthy (or almost-healthy) system unit.
So, the 2T1 has a standard KME as you say - it looks to have correct
horizontal and vertical drive, with the exception that it skips every
few lines, leaving a blank horizontal gap. I can see what look to be
That does _not_ sound like a monitor problem. You're getting missing
video every few scan lines, right? In which case, either you've got some
Analogue signal that's blanking the display _and_ which is locked to the
vertcial sync signal, or you've got a problem with the memory board
(middle board in the cardcage) in the PERQ.
How far does it get through the self-tests? What's the final number on
the DDS display (front of the CPU box) when it tries to boot?
Just to confirm, we're talking about a PERQ 1 here
-- it's confusing to
me wether this is a PERQ 1 (verically-mounted SA4000 hard disk at the
left side, monito connects on a single DC37 connector) or a PERQ 2T1
It's a 2T1, vertical drive mounted at the back. characters on the display, but they're not at all
readable. Difficult to
tell if it's scrambled pixels (suggesting a system fault) or an analogue
problem (suggesting the monitor). The display has an unstable shimmering
right margin to it, which definitely looks analogue in nature.
That may be normal. There's some marginal timing in the vidro circuitry,
and often the right few pixels are a bit unstable :-( At least one of my
PERQs does that...
Onto the PERQ 1. Standard monitor as you say - only that one is
*totally* stuffed. The picture (such as it is) is collapsed into maybe
2" vertically, and about 80% of the screen width horizontally. It's
extremely non-linear; left and right margins weave all over the place. I
can see beam traces all over the shop within the squashed picture too.
It's actually quite a work of art! Not sure if there's more than one
fault going on here, or whether some critical point isn't getting to the
right voltage and that's causing the whole thing to fail.
I will ook at the VMI manuals... This one does sound to have some kind of
monitor problem...
OK, back to the T1. I think it's the machine
I worked on some years ago
(don't worry, everything is 'stock', apart from the fact you may find the
odd IC in a socket if I replaced it).
Ahh, yes it will be. I checked all the connectors and reseated the
boards plus chips - I remember seeing a few socketed ones that didn't
look like they would have originally been socketed.