AMMRL: Spikes in FID on Gemini 2000/300MHz
jtomasze (jtomasze@indiana.edu)
Mon, 05 Nov 2007 14:16:12 -0500
Hi all,
We have another hardware problem that I would like to throw out for
comments if I may.
On our Gemini 2000/300MHz we started getting random spikes in the
FIDs a few weeks ago. Then it was maybe one bad FID in a set of 16.
The frequency has been increasing and some bad scans seem to abort the
experiment and lock up the console requiring a "su acqproc" or reboot.
In the MasterLog file we see "Data Hal returned Exceeds buffer size Exp
ID = #.CP-Exx" where # is the experiment number (since the last reboot),
and xx is some numeric value. The problem is independent of the nucleus
being observed, but there does seem to be some temperature dependence.
Last week, in the mornings when the room temp was ~19.0C or above we had
problems, but in the afternoons, if the temp dropped below 18.5C we
could get some experiments to complete. Today, even with a room temp of
18.0C and an extra fan in the console, I'm lucky to get a single scan
experiment done and they all have the spikes. The temperature
dependence seems odd though, because neither the console nor the CPU are
hot, or even warm for that matter.
I've searched the archives but don't see any similar problem
descriptions. We were thinking maybe a dying CPU or memory chip, or
perhaps something on the ADC board. Anything else we should
investigate? If we start getting boards to swap in for testing from
Varian, does anyone have any thoughts on which board(s) to try first?
Many thanks in advance.
Sincerely,
John
--
John W. Tomaszewski, Ph.D.
IU, Dept. of Chemistry
800 E. Kirkwood Ave.
Bloomington, IN 47405-7102
(812) 855-4478
jtomasze@indiana.edu