AMMRL: Z1 shim is going off scale

From: Margaret Eastman <meastman_at_chem.okstate.edu>
Date: Wed, 17 Sep 2008 15:47:14 -0500

Dear AMMRL,
  We have a Varian Inova 600 spectrometer with an older Oxford magnet
(1997). Over the last 11 months, the Z1 shim setting has dropped from about
+2000 to close to the negative maximum value of -32767. I have been looking
into the RT shim driver and shim coils, and believe they are working
properly, so the drop seems to be a change in the Z1 cryoshim. Does anyone
have experience with this phenomenon and know what causes it? I¹m almost
afraid to ask, but how disastrous is this?
Margaret
Received on Wed Sep 17 2008 - 10:51:19 MST