Hi all:
I am writing to thank the AMMRL for having the best members in the
Universe. I received many wonderful suggestions about fixing my problem
with 120 Hz sidebands. Unfortunately I had to balance repairing the
semi-working instrument with the demands of research so I could not find
the problem until now. Many of the suggestions involved some bad capacitor
in a power supply. The Bruker instrument has numerous power supplies and a
preliminary check looking for ripple and improper voltages found some
problems that were repaired but did not remove the sidebands. Suggestions
about air fluctuations, flourescent lights and grounding problems were
checked but did not seem to cause the problem. One suggestion was exposed
wires is the room temperature shims coils. These exposed wires were
actually present and were repaired with paint on insulation but again did
not solve the problem. A number of people kept pointing to the shim power
supply. A check of all of the voltages and ripple indicated that everything
was fine. Out of frustration I totally remove the shim system from the
instrument and careful checked all of the large filter capacitors. Lo and
behold one of them was dead. Replacing that capacitor solved the problem.
The names of all of the people that sent suggestion would be too long for
this Email but I would like to thank everyone that took the time to respond.
If anyone would like the detailed suggestion that were sent please let me
know and I will compile them for the group.
Many thanks to a great group of people.
Les
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Leslie Gelbaum Phone 404 894-4079
NMR Center Lab Phone 404-894-1827
Georgia Tech Fax 404 894-7452
Atlanta, Georgia 30332 E-mail lg2_at_prism.gatech.edu
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Received on Tue Mar 23 2004 - 17:38:50 MST