23 Mar
1997
23 Mar
'97
8:22 a.m.
Yep. I've gone through many of these at work (in
the 70s) and they
always fail the same board. It has lots of analog circuitry on it and I
suspect it is that part of it.
I wonder if it's something as simple as the read PLL failing to lock. That
should be easy to fix.
I have a spare of one of the boards (a mad friend gave it to me along with
some UPP personality boards), but I have no idea if it works, and anyway,
I think it's the digital board with the 3000 stuff on it.
BTW, I am working from memory here, and I've not looked at the schematics
for a couple of months, so don't be suprised if I start talking
nonsense...
The fault is very non-specific. When trying to boot
it just returns a
disk read failure. At that point the rom monitor is the only thing in
charge and it is small. I thing it just says "error". I may try it
Sure. I wondered if you'd tried doing any fault-tracing yet.
again so I can be more specific. When we used them at
work they were on
a service contract, so I never had to mess with them. Just isolate
which board was bad.
Fortunately, I've never had to battle with service contracts.
Board-swapping never seemed satisfactory to me - until you've found the
fault you can never be sure that you've swapped the right board. And if
you've found the fault you might as well solder in a new component.
Dave Mabry dmabry(a)mich.com
--
-tony
ard12(a)eng.cam.ac.uk
The gates in my computer are AND,OR and NOT, not Bill