Has anyone experienced anything like the following with a
Prism II and any tips on fixing the problem or directions to
look in would be greatly appreciated...

The basic issue is that the main 5A fuse, in the source
control box, to the filament keeps burning out...faster after
the HT has been on for several hours.

Recent maintenance having to do with solving this problem has
included fairly detailed cleaning of corrosion from the
inside of the source (which included a soak for the metal
parts in hot H2O2 and further cleaning with 12,000 mesh
paper)...however, the problem persists.

Before the fuse blows, the only signal of an impending
problem is the following...the "source in limit" alarm may
come on for 3-4  seconds along with a drop in focus strength,
followed by the alarm turning off and normal operation.  This
may repeat 3-4 times, over a 15 minute period, before the
fuse blows.  Occasionally, along with the fuse blowing, the
HT and IOn Guage may be tripped.  The fuse will not last as
long if the HT has been powered up for some time and fast
blow fuses might only last a minute.

One track suggested is the transformer...is that a
possibility and might someone know where to find a
replacement?

Again, thanks for any ideas!



Dave Mrofka
University of California, Riverside
Department of Earth Sciences