We got a Bruker DPX300 with z-gradient broadband probe. Some
time ago we started seing spikes to appear in the lock signal
during the acquisition of X-detected heteronuclear experiments. The
problem is intermittent in the sense that we can go for weeks
without seing anything. When it appears, the lock signal moves up
or down to the top or bottom of the screen and persists even with
the X- and H-1 cables disconnected from the probe, i. e. the
problem originates already in the console. In order to get rid of the
problem one has to type ii 3 or four times (doing one before each
acquisition does not always prevent occurrence of the glitch), or
performs a reviveccu, which in most cases solves the problem. In
any case, proton observation (with or without X-decoupling) never
exhibits this problem.
It almost sounds like a stuck relais or switch to me. Has anybody
experienced a similar problem or has a suggestion where to search
for the source of the problem ?
Any help is greatly apprechiated.
Holger Foersterling
F. Holger Foersterling, Ph. D.
Director of NMR Facilities
Department of Chemistry
University of Wisconsin-Milwaukee
Milwaukee WI 53211
Phone: (414)-229-5896