Recently we had to power off our Inova 600 MHz system for several days. After
powering up the system, we discovered that the required setting for Y1 has shifted
by close to a 1000 dac units. Using H2 gradient shimming on the doped water sample,
it appears that only Y1 shifted and that the shmd2o experiment still meets lineshape.
All of the shim power supply leds are still green suggesting that the voltage
regulation is operational. Y1 seems stable at this new value at the moment. Has
anyone seen this behavior and what is the likely culprit in the shim power supply
unit? I don't have a spare 40 channel shim power supply to exchange boards with but
I do have a 23 channel shim power supply from a Inova 400 which can be used for
testing any common internal components that can be swapped between the two units.
Thanks in advance for any advice.
Jack
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Jack W. Howarth, Ph.D. 231 Albert Sabin Way
NMR Facility Director Cincinnati, Ohio 45267-0524
Dept. of Molecular Genetics phone: (513) 558-4420
Univ. of Cincinnati College of Medicine fax: (513) 558-8474
Received on Wed Jan 11 2012 - 08:23:21 MST