It looks like disaster has struck during our lab move. Attempts to energize
our 20 year old 400/52 after it was moved (warm) and resealed have failed.
Charging starts OK but we cannot get any more than 3 amps into the coil
before it seems to become resistive. At this point the magnet sits and
boils off He. The sc-switch seems to work, but after it is re-opened the
power supply voltage takes off like the coil current is lower than the
supply.
We have tried about a dozen variations (different power supplies, cables,
polarity etc.) with no difference. Our last hope is warming it up and
trying again, but I am pessimistic about any chance. Has anyone out there
seen this type of failure? If anyone out there has any advice I would be
happy to accept it.
Right now I am trying to formulate contingency plans. Replacing the magnet
seems like the only choice. If any one has a surplus narrow bore 400
collecting dust, please contact me to negotiate a deal (803) 777-2088.
Thanks.
+++====+++
Perry J. Pellechia
Director of NMR Services
University of South Carolina
Department of Chemistry and Biochemistry
Columbia, SC 29208
[mailto:pellechia_at_sc.edu]
http://homer.chem.sc.edu/perry
+++====+++
Received on Mon Jul 17 2000 - 18:15:09 MST