Dear friends,
Our Inova-500/Vnmr61C console has a rather weired behaviour recently:
when we change probes and run the proton NMR for the first time after
probe change, the sensitivity is terrible (almost no signal). This did
not happen before and does not happen everytime time, but happened about
4 times during the last 6 probe changes. In the past few times, the
sensitivity gets back after I reboot the acquisiton CPU. But this
afternoon, I reboot the CPU, no help; reboot whole console, no help;
reboot sun station, no help. The sensitivity is about 2~3.
I have not put my scope on it to trace the problem since it is too late
today. I just want to know if anybody has experienced similar problems
and if there is any quick fix while I am waiting for Varian's engineer
to come. I did all the necessary changes in vnmr, i.e. change probe
file, reset pfg, read shims. The lock signal is normal, gradient
shimming works good, and tuning is good for all channels, so I think
that it must be either the transmitter or the receiver.
Thanks
Wei Li
Received on Tue Sep 16 2003 - 17:44:22 MST