Subject: WFD
From: Christopher Orth (corth@budoe.bu.edu)
Date: Wed Oct 06 1999 - 09:27:23 EDT
Ciao Nicola (cc macro-gs),
I have no new suggestions, at least none that don't require you
find a really big hammer... But maybe talking about some old suggestions
will help someone think of something:
I think it is clear the problem is NOT the WFD card. It could be
the slot, the crate and supplies, the computers, or the ribbon cable(s),
or even the start/stop signals.
The problem comes and goes without intervention, so it is
probably not cables.
While the run is going, please make sure the WFD appears to be
running okay. Maybe there are some visual clues. Are there errors on the
uvax console? Are some of the WFDs not stopping and starting with the
rest? Are you seeing readout (orange lights) while the WFD lights are
green?
Is the Nat Longley module working for this crate? Does removing
it help? This module was designed to read the voltages where it matters
-- at the backplane. The test points on the back of the crate measure the
voltage at the supply and there is a substantial current draw and voltage
drop by the time power reaches the cards. It could be that some essential
power line is really on the edge. There are test points provided on the
VME monitor which just run right to the backplane. Check those.
Are we having problems every run, or every few runs? If it is
happening all of the time, maybe we can try things like removing half of
the cards from the module and from the camac list. If the problem is
power related, it should be better with less current draw. This kind of
test isn't very helpful if the problem isn't constant though (did you fix
the problem or did it fix itself).
How much spare hardware do we have? You might try swapping in VIC
8250 modules. The same module type goes both on the system crate and the
WFD crate, but there are many switches and jumpers that have to be
changed. You could also try simply moving the VIC8250 on the system crate
-- maybe the slot it is in there is flaky. Check the voltages on the
system crate while you are at it, maybe there is some line that only the
8250 uses.
Another possible fix - find a strong oak stick, and tap the WFD 3
times with the stick. Walk around the WFD clockwise 3 times, then 3 times
counterclockwise. Then raise your hands in the air and make a prayer to
the god or saint of your choice.
What can I say, I'm feeling desperate.
Good luck,
Chris
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