Hello all,
I want to thank everyone who responded with advice and suggestions. Just to
follow up about the resolution of this problem. At this point it is pretty
clear that our optical encoder for one and maybe two motors have failed. I
was able to switch out the protune box with a spare I had from an older
instrument and that has fixed the issue for now but I will be replacing the
encoders on the old Protune module to keep a working backup around. Several
people pointed me to the correct part to replace which can be found here:
https://www.usdigital.com/products/encoders/incremental/kit/e2/
Again, thanks to everyone who helped diagnose this problem.
Best,
David O.
________________________________
> From: David O
> Sent: Tuesday, October 5, 2021 11:37:51 AM
> To: ammrl_at_ammrl.org <ammrl_at_ammrl.org>
> Subject: Issue with Protune moving in only one direction
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 Fri Oct 08 2021 - 11:47:03 MST