Chris,


    We have had this problem before. Check the components on the power
supply board. We had one of the capacitors on that board blow after a
power outage. There was no visual sign that it went bad. We simply
replaced all 8 of them (of various types) and then things started
working again. We had also replaced the bridge rectifier (as per
ThernoFinnigans suggestion) as well as the Q1 Drive Transistor, prior
to replacing the capacitors. So they may have been bad as well.

Good luck!

Bernie Genna

> ISOGEOCHEMers:
>
> We have a Delta Plus that recently lost source HV and emission (but not
> high voltage) for an unknown reason.  After fixing the vacuum system, we
> were still unable to restore emission.  We have tried replacing the
> filament, checked the source leads, checked the filament on the board
> (J48/49), board fuse looks good and source ceramics are all intact.
> We've even tried just powering down the instrument and that didn't work
> any magic.
>
> Any ideas?  We're fresh out right now, and any help would be most
> appreciated.
>
> Thanks,
>
> Chris Yarnes
>
> --
>
> Chris Yarnes, Ph.D.
> SIRF Manager
> Dept. of Earth and Space Sciences
> University of Washington
> Seattle, WA 98195
> 206.543.6327
>