Joe;
However your symptoms suggest swabbing using the giant kimwipe q-tip method
may have blocked the tiny holes used to hover the spinner. These holes are
inside 4 c-shaped millings recessed below the air-bearing surface. Without
full disassembly you might only smear the greasy material over the holes if
there is a lot in there.
To disassemble the UB hold the bottom of the UB unit tightly between your
knees while sitting. Use one hand to hold the top o-ringed assembly from
rotation while rotating the long aluminum cylinder with the other counter-
clockwise. It has very fine threads and might take more than 10 turns. Take
care not to disturb the connections to the transducer because they are only
supported by a dab of silicone glue and a piece of tape.
Once it is separate clean the little c-shaped millings and bearing surface
with a real q-tip and you might need a thin wire to un-block the holes.
>From there you can clean the business end of the transducer too. Where the
air lines connect there is a port body held on by a single Phillips screw.
Remove that to clean and flush out any debris created unplugging holes.
What's nice about doing it his way is you can get most of the assembly into
a 400mL beaker, soak, clean and flush-out everything with alcohol.
I make sure there are no metal filings in the threads by using an old
toothbrush. Teflon tape on the fine threads makes disassembly next time
easier. Reassemble in reverse order Taking care not to thread the cylinder
between a hose or transducer line. Once assembled I also wrap over the
transducer a few layers of Teflon tape to replace Varian's cellophane tape.
Before inserting the UB into the magnet loosen the PROBE set screws first.
Push down HARD the UB cylinder so it seats. If your probe height is too
high it will force it to move down. If too low you will be able to push up
on the probe without moving the UB center cylinder. Since Alcohol is
hydroscopic and the passages are tiny, it may take some time to completely
dry so leave the lift air on for an hour or so and turn VT on to maybe 40C.
Don't forget to clean spinners too.
Regards,
Robert Harker
Engineer
University of Florida
Department of Chemistry
NMR Laboratories
Gainesville, Florida 32611-7200
352-392-4650 Business Hours (no voice mail)
-----Original Message-----
> From: barchi_at_helix.nih.gov [mailto:barchi_at_helix.nih.gov]
> Sent: Saturday, December 11, 2004 10:58 AM
> To: ammrl_at_ammrl.org
> Subject: Spinner problems
Hi all,
I suppose none of us are immune to spinner problems and we are no
exception. This latest one prompts me to write. In between probe changes
on our routine-use Varian INOVA 400, we performed our yearly upper barrel
(UB) cleaning (alcohol-wet kim wipes ramrodded through until clean, purge
with N2 gas for several min). After replacing everything, the sample would
not spin. We tried all the usual suspects: clean and use different
spinners, increase supply gas, reboot system, remove and reseat UB, insure
all connection were made, increase bearing flow and general fiddling to no
avail. Both Varian 4-nuc and Nalorac probes had same result. If I plug the
UB with my hand to momentarily build pressure on the UB and "pop" the
sample up slightly, the sample spins nicely in this "levitated" position.
You can remove the rotation air inlet at the top of the UB and the sample
remains spinning (suggesting the bearing supply is OK?). If the spinner is
turned off and hence the sample returns to the standard position in the
UB, spin stops and does not start. Is this a bearing gas problem or is
there some "duh" thing that I am missing?
Thanks for your time,
Joe
--
Joseph J Barchi, Jr, Ph.D.
National Cancer Institute, Frederick
376 Boyles Street, PO Box B
Bldg 376, Rm 209
Frederick, MD 21702
301-846-5905 (Voice)
301-846-6033 (FAX)
barchi_at_helix.nih.gov
Received on Tue Dec 14 2004 - 08:40:22 MST