Dear BUMmers,
I subscribed many years ago, but this is my first help request. Thanks a
lot to everyone who can share experience !
After about twelve years of very satisfactory experience on an AC-200 in
year 2002 our dept. acquired, as a new NMR to share with the glorious
(and still working, thanks God) Aspect-based AC, a new AVANCE 300, with
direct multinuclear probe, automated tuning & matching (ATMA), Z-gradients,
temperature control unit, PC Computer (WinNMR 3.0 software).
After installation (curiously, field INCREASED after some weeks of
stabilization, shifting 1H frequency from 300.13 to 300.15 ! what about
thermodinamics ?), we experienced troubles with the SGU 400 unit, which was
removed, temporarily substituted and retuned repaired in guarantee.
After some 1.5 years (last summer) we begun having troubles with the
heteronucleus SGU unit, in that it stochastically showed malfunctions,
losing phase, frequency matching and power. The symptoms usually are : no
FID signals, extremely noisy Tuning&Matching signal (you can't distinguish
the "dip" in the noise), stochastic efficiency of pulses (so the gradshim
routine runs completely crazy), spykes in the tuning signal etc.
Substitution of the heteronucleus channel SGU (with TWO different SGU !)
gave no results, in the sense that strange error codes appear at the
configuration step ("cf" command routine), the card is not "recognized" by
the system, and nothing can be done. The Bruker engineeer himself (a very
good, competent and bright guy, nothing to say on him) has offered no
explanation but to continue using the original SGU (when working), waiting
suggestions from the manufacturer's staff.
Usually, switching off the consolle, waiting some time (from minutes to
hours) and restarting the system has been a good workaround, but in the
last days this was needed some three times a day, and an NMR utility can't
go on this way.
At the moment, the engineer hypotesis is a problem in the electrical power
supply of the SGU cards (the 1H card too has started to fool up), and we
are awating for spare parts to make new tests next week.
Has anyone experienced the same story we have here ? If so, wich were the
solutions ? Are you able to give suggestions ?
Great thanks to anyone who can help to solve the problem, at the moment the
instrument is out of use (grr....) !
Stefano Antoniutti
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dr. Stefano Antoniutti Voice : +39 041 / 2348555
Dipartimento di Chimica Fax : +39 041 / 2348917
Universita' Ca'Foscari
di Venezia
Dorsoduro 2137
I-30123 VENEZIA e-mail: anto@unive.it
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