Dear People:

        We have a rare but intermittent problem with our Mircomass Optima.
The source head will turn itself off, and cannot be turned on through the
Optima software without first doing a hardware reset.

        Doing such a reset results in the loss of the running standard gas,
and the consequent need for rerunning standards again.This only happens one
to three times a year, but is rather a nuisance, especially when a sample is
so small that it can't be rerun.

        The shutdown occurs mainly during the time the system is sitting
idle with standard running gas entering the source. This has occurred with
tank hydrogen, tank nitrogen, tank carbon dioxide, and tank 3% argon in
nitrogen. The weather outside, seems to play no role in this perturbation.

        Some of the electronics people have suggested removing the old surge
protection devices and replacing them, since the instrument is over five
years old.

        Comments would be appreciated.

        Thank you.

Glen Martin, School of Natural Resource Sciences, Water Science Laboratory
        University of Nebraska, Lincoln, Nebraska, USA 68583-0844