Hi,
I've been trying to track down an intermittent digital glitch in
our 6 yr. old Varian Inova 500 MHz console. A year ago we had about 4 of
these Acquistion Bus Trap Errors in about 6 weeks time which caused longer
(overnite) acquisitions to crash. I ran the "tip hardwire" diagnostic and
didn't see anything, and the problem just sort of went away. I just
figured it was one of those "ghost in the machine" type of things that
crop up once in awhile. A couple of weeks ago the problem came back with
a vengenance; for a week solid we couldn't run an experiment longer 2-3
hrs. without the experiment crashing due to Acquistion Bus Trap Errors (a
total of 10 failures in 7 days). I told my users the instrument was no
longer reliable for experiments longer than 2 hrs. and started
troubleshooting the problem. Tip hardwire this time showed an STM error:
20:42:29 [IntContxt]: 'stmObj.c' line: 258, Error Interrupt(Vec:0xb0,
active rcvr #: 0): status inconsistent 0x112.
After talking with our local Varian Service Engineer and sending a help
request to AskTAC, it looks like it's either the DAC (data acquisition
control) or DTM (data to memory) board. So I started to get ready to
purchase a replacement board. But a couple of nites ago a user was
running a short 3 hr. experiment from 4-7 PM, and I figured, what the
heck, test the board one more time, and queued up a longer overnite
version of the same experiment. This time a 14 hr. experiment ran to
completion. So last nite I had the user whose experiments failed 10
times in a week try to rerun his experiment, and, alas, it failed after
5 hrs. So I have a couple of specific questions for this august body if
anyone has time to ponder my dilemma:
1. The ill-fated user whose experiments are failing is running a carbon
HSQC (it's a version that we've adopted from a Bruker pulse sequence
("Ah!, say all the Varian loyalists, "There's your problem." ... Kidding
.. Really)). The 14 hr. acquisition that ran successfully to completion
a couple of nites ago was just a Varian gtnnoesy experiment. I've just
been assuming that this was a problem in the digital card cage, and had
nothing to do with the pulse sequence being run, Right? Maybe
statistically given the error rate that the DAC or DTM board is
experiencing, there's a small chance (<5%) that a 12 hr. acquisition will
run to completion, and that 1:20 chance just happened when I ran a
different pulse sequence. I know thinking the pulse sequence might be
causing the problem is grasping at straws, but I've seen stranger things.
2. Any way I could tell more specifically which board (the DTM or DAC) is
failing? The reason I ask is that Varian charges a 15% restocking fee,
and the board is either $4.5k (DTM) or $7k (DAC). 15% of either of these
costs is about what I pay for a helium fill (assuming I can get the
helium), so it's kind of real money. I guess I could swap and test since
I have two other Inova consoles in the lab, but they're a 600 and an 800,
both with cold probes and heavily used (500 that's giving me problems
doesn't have a cold probe and is the least used of the three magnets, so
it would kind of be like taking the battery out of your Porsche to get
your VW minivan running again).
Thanks for the time it took to read this rather detailed (long winded)
account of my problem, and for any suggestions which might help get this
resolved.
Sean
Sean Moran
Bio-NMR Facility Manager
Dept. Biochem. & Cell Biol.
Rice Univ.
Houston, TX 77005
(713)348-3475 (lab)
(713)348-4255 (off)
(832)398-4208 (cell)
(713)348-5154 (fax)
seamus_at_rice.edu
Received on Mon Aug 27 2007 - 11:44:20 MST