Dear friends,
We have a little problem with our Inova-500 running VNMRJ 2.2D/Linux. A user dropped the spinner in the magnet without even inserting his NMR tube in (I don't know how in the world he did that), and my assistant had to take out the probe, and slided the liquid helium level measurement tube to push the spinner out.
Unfortunately, after he did that, the carbon signal is completely lost. We have nice lock signal and no problem with the proton channel at all. When we try to run carbon or P31, all we see is noise. We switched to different probes, same thing. No abnormal LED is on/off, and the voltages on the power supply to the amplifier are all correct. I tried to increase the carbon pulse width from 12 us up to 100 us, still all we get is noise.
I have to say that I am not good in using the scope any more, and we don't have the attenuator. I assume that it could be either the X channel amplifier is dead, or the pre-amplifier is dead. Is there any simple way to identify the problem quickly? If we have to use the scope, where should we measure the frequency/voltage without using the attenuator?
Thanks and wish you all have a great weekend.
Best regards,
Wei Li
--------------------------------
Wei Li, Ph.D.
Associate Professor/Director of NMR Facility
University of Tennessee Health Science Center
847 Monroe Avenue, room 327
Memphis, TN 38163
901-448-7532 (PH)
http://www.uthsc.edu/pharmacy/pharmsci/faculty/wli/
Email: wli_at_uthsc.edu<mailto:wli_at_uthsc.edu>
Or wli.uthsc_at_gmail.com<mailto:wli.uthsc_at_gmail.com> (for large attachment file)
Received on Fri Nov 11 2011 - 13:07:27 MST