I'm mailing to the entire group because I've had such an outpouring of
helpful suggestions and responses. My Shims are good as new...thanks to
< $10 in components and the schematics from Acorn, Inc. What happened
is a flaky regulator and 2 dead op-amps (which had the output latched at
max).
The _surprising_ thing is that the shims are OK, even though the base of
the RT-shimset was so hot we could have fried breakfast on it!!?? All
18 shims control as they should with no apparent cross-talk...nothing
seems to have fused inside the windings.
I now have the RT shim supply plugged into a latching-relay which will
not allow things to power back up until manually reset. I already had
one of those powering my transmitters...I almost paid dearly for not
including the shims in that curcuit (I mistakenly thought I was safe
since I don't have any DACs to worry about).
Thanks again to all!
Rich S.
-- Richard Shoemaker, Ph.D. Phone--(402) 472-6255 Instrumentation Director, Chemistry FAX---- -6964 Research Associate Professor, Chemistry University of Nebraska-Lincoln URL: http://www.chem.unl.edu/nmrlab.html