JEOL 6400 Objective Lens Repair
- From: "Aniruddh" <aniruddh_sarkar@xxxxxxxxx>
- Date: 24 Apr 2005 00:37:16 -0700
Hi,
Our 1990-purchased JEOL6400 SEM recently developed an intermittent
problem of black bands randomly appearing/sliding on its display.
This was traced to an oscillating 24V supply powering, among other
things, its objective lens control board and the objective lens
itself. We found both ends of the objective lens winding were at ~1 ohm
to the the instrument chassis while the coil itself ~2ohm across.
Disconnecting the lens has stopped the supply oscillation etc but
ofcourse now there is no image!
We are guessing that either the condensation due to the running
cooling water or the heating due to lack of it has shorted the
innermost layers of winding to the core.
While we are still hunting for a spare, I would like to enquire people
here for pointers on design & rewinding of electromagnetic lens coils.
The winding looks specially designed - with number of turns decreasing
in each layer in a particular fashion as one goes up the core.
Will just replicating the winding - wire gauge & the turn pattern -
bring it back to function?
Any info/pointers highly appreciated!
--
tia,
Aniruddh
Research Associate
Dept of Electrical Engg
IIT Powai, Mumbai
India
.
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