I would look at the 80 MHz clock signal feeding the digital
card cage. If that is starting to drop out it could cause
some flaky issues with the acquisition. Also, if that is
good look at the 5 VDC power supply for the digital card
cage. The tolerances for the DCC are small and AC ripple can
also wreak havoc.
Good Luck
Rob Duchesne
NMR & MRI Systems
Varian, Inc.
----- Original Message Follows -----
From: Ivan Keresztes <ik54_at_cornell.edu>
To: ammrl_at_ammrl.org
Cc: seamus_at_rice.edu
Subject: AMMRL: Acquistion Bus Trap Error on Varian Inova #2
Date: Mon, 27 Aug 2007 14:38:49 -0400
> Dear All,
>
> The problem described very nicely by Sean in his earlier
> post with the same subject line sounds *exactly* the same
> as the one we have been periodically struggling with over
> the last few years. In our case it occurs on an Inova
> 600. Upgrading to Vnmrj 2.1 changed the error message to
> "Inconsistent DTM error interrupt and DTM status" with an
> occasional "Number of points acquired is [number of
> points] less than np".
>
> I have swapped DTM and DAC boards between the 600 and our
> Inova 400 that is rarely used for long term acquisitions.
> Neither of these swaps fixed the problem. The only
> correlation of any kind may be with number of acquired
> points in t2. The higher the np the more likely that the
> acquisition will fail. Another observation is that any
> particular experiment can be predisposed to failing. We
> had a particular HMBCAD (chempack 4) fail five times in a
> row while other HMBCAD's finished just fine. The problem
> is not restricted to H/X experiments. A number of
> dqcosy's and such failed as well.
>
> I am guessing Sean and I are not the only one to have seen
> this problem and hopeful someone out there has a solution
> for this.
>
> Thanks
>
> Ivan
>
> --
> Ivan Keresztes, Ph.D.
> Director, NMR Facility
> Department of Chemistry and Chemical Biology, Cornell
> University Baker Laboratory, Ithaca, NY 14853.
> phone: (607) 255 0709, fax: (607) 255 4137, email:
> ik54_at_cornell.edu
>
Rob Duchesne
Northeast Region Field Representative
Varian Instruments, Inc.
Office: 650-424-5020 ext 7774
Cell: 978-257-7660
Received on Tue Aug 28 2007 - 10:10:39 MST