Hi all,
Running into a strange issue after users of our Varian 400 reported it was
unable to tune to any X nuclei (probe is a Auto X type). For some reason
the X-match stick is only being moved in a single direction by protune. I
have checked that I can manually tune and match myself both by using the
black knob on the back of the protune box (and I can see the match stick
turn and watch the tuning dip respond) and by manually tuning with the
flexible shaft disconnected altogether and rotating by hand. Moving the black
knob feels "clicky" like all the other motors, there is no extra resistance
or apparent slippage in either direction. Same is true of the drive shaft on
box. However, when I tell protune to move the drive connected to that rod,
both the (-) and (+) buttons rotate the match stick in the same direction!
Obviously it will never properly tune like this. Has anyone had this issue
before?
Things I've tried:
1. Indexing the motor
2. Tightening the locking stick on the drive side and re-indexing the motor
3. Using the reset on the protune box
4. power cycling the box entirely.
5. Opening up the side panel to look inside for obvious signs of mechanical damage (found none)
Any advice would be greatly appreciated. I do have a spare protune box of the
same vintage from a decommissioned instrument that I can swap out, but since
these things are notorious for breaking probes I want to use that as a last resort.
Best,
David O.
Dr. David Onofrei
NMR Facility Manager
Dept. Chemistry
San Diego State University
Work: chem-nmr_at_sdsu.edu<mailto:chem-nmr_at_sdsu.edu>
Received on Tue Oct 05 2021 - 08:38:05 MST