JEOL Probe Users Listserver

Moderator: Ellery Frahm, [log in to unmask],
Electron Microprobe Lab, University of Minnesota

Post a message: send your message to [log in to unmask]

Unsubscribe: send "SIGNOFF PROBEUSERS" to [log in to unmask]

On-line help and FAQ:


Hey probe folks;

It's me once again, and once again on the scrounge for a part.  My venerable
JEOL 733's CRT high voltage power supply appears to have kicked the bucket -
come in one morning to find the CRT doesn't work.  Probe works great (beam,
detectors, can image on the computer, no problems), CRT won't light up.
Sure enough, measure the power supply and instead of 13kV/4kV/400V it's
putting out 3.4 kV/0kV/0V, despite running really hot.  I had a look inside
mr. gold box and it looks pretty burned up inside.  Boo.

For interests' sake, here's a couple of pictures.

Here's the box I'm talking about:

Here it is in its natural habitat, just inside the front panel in front of
the HT tank:

Here's the inside of mr. golden box, board uh... somewhat discoloured:

I hate working on high voltage stuff, given my propensity to accidentally
attempt to kill myself.    The inside of our friend is all HV
cables/insulators that are all epoxied up to keep them from arcing (and
electrocuting, I'm sure).  Given how hot it was running and the voltages my
suspicion is that the transformer part is not functioning correctly, but I
haven't been able to confirm that.

Does anyone have a "spare" (ha) one of these boxes of gold they'd like to
part with?

As an aside, this thing was wonderful when I opened it up to look inside.
Board looks pretty discoloured (overheating?), all the ceramic standoffs and
shims have crumbled and rotted away, all the cable straps have become
brittle and broke, the insulation on the wires is as stiff as a board.  One
of those "I wonder how long it's been like that" feelings.

My little tip of the day: If you ever have to open this box up, turn it
upside down first and lift off the lower cover.  In my case with all the
ceramics crumbled away the circuit board and transformer bits were hanging
off the wires when I lifted it up and out.

Have a nice day.

Best regards,
Steven Cogswell

University of New Brunswick