AMMRL Group:
I have a question about a Varian Innova 400 that was recently installed
(It is about 1 year old and we had it moved here this winter). One week
ago the installation was just about complete and we had z1 and z2
cryoshims quench. Of interest is that the instrument had passed all
specs including bb decoupled 13C at this point.
Well, this week the engineer returned and reset the cryoshims and
touched up the shim files and was getting ready to go and now we have a
problem that we cannot solve. When acquiring a decoupled carbon the
lock level drops from 90 down to 10 and eventually is unregulated.
Stopping the acquisition leads to the lock signal returning. Running a
coupled spectrum or proton is fine, eg no loss of lock. APT leads to a
loss of lock.
Questions:
Does this sound like we are missing a filter?
Could someone that has observed this behaviour before give me a few
ideas of where to start looking?
Thanks!
Randy Winchester
Department of Chemistry
Grand Valley State University
Allendale, MI 49401
616-331-2387
616-331-3230 (fax)
winchesr_at_gvsu.edu
Received on Wed Apr 21 2004 - 16:02:40 MST