Re: AMMRL: Acquistion Bus Trap Error on Varian Inova #2

From: David Live <dlive_at_ccrc.uga.edu>
Date: Tue, 28 Aug 2007 19:55:25 -0400

A point worth adding to Rob Duchesne's suggestion is that the voltage should be checked at the backplane of the digital and analog card cages and not just at the front panel test points for the power supply. There can be a drop in the voltage across the leads from the power supply that necessitates boosting the adjustment on the power supply to actually get the required voltage at the modules.


David Live
Complex Carbohydrate Research Center
University of Georgia
315 Riverbend Rd.
Athens, GA 30602

Phone: 706-542-6262


----- Original Message -----
From: Rob Duchesne
[mailto:robert.duchesne_at_varianinc.com]
To: Ivan
Keresztes [mailto:ik54_at_cornell.edu],
ammrl_at_ammrl.org
Cc: seamus_at_rice.edu
Sent: Mon, 27
Aug 2007 21:55:23 -0400
Subject: Re: AMMRL:
Acquistion Bus Trap Error on Varian Inova #2


> 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 Wed Aug 29 2007 - 12:27:08 MST

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