Scanning Electron Microscope - Filament
The filament is the source of the electron beam
and has a very limited lifetime. Replacement is fairly straight-forward.
The filament is housed in an "electron gun assembly" and is mounted in
the electron gun housing, which is of the "flip top" design. Here
is a picture (actually, this is after the filament was replaced).
The electron gun cartridge unplugs from the housing, exposing the contacts
(three sockets for the filament connections and a spring loaded finger
to contact the shell of the cartridge).
Removing two screws from the electron gun cartridge exposes the filament,
four more set screws hold and center the filament under the cap.
Here is an exploded view of the dirty cartridge and burned out filament.
A new filament (I have about a dozen that came with the 'scope) was
installed in a clean gun cartridge (four extras came with the 'scope),
the filament tip centered under the hole in the cap using the four set
screws, the two cap ring screws tightened and the cartridge plugged into