Fast forward two years later, some more issues crop up with the SEM. First, the scan starts having problems and eventually dies. Second, the last filament blows. The scope only came with one spare filament which died early. New filaments are somewhere around $500 for a box of 10 and are not sold individually. Around this time my friend finds a seller in California posts a couple SEMs for sale on eBay, a Jeol 6300F FESEM and a Jeol 8600 Microprobe. They sit on ebay for quite a while constantly dropping in price. Eventually my friend makes him an offer and they are his. To make room for the new scopes I get the old Hitachi and stick it in my garage.

The first thing I need to deal with is the filaments. I really don't want to spend $500 on a box of filaments for a machine that I don't even know if I can repair. Some of the parts in the machine are obsolete and just about impossible to get ahold of. A friend at Portland State University says we can rebuild the filaments, they are easy. I order some .089mm tungsten wire off ebay and he shows me how to weld them up with his Unitek capacitive discharge spot welder. In about 30 minutes I have two rebuilt filaments for my SEM.

I get a new filament installed and I I get an image. So far so good, the rapid scan mode does not work, the image goes off the screen. Eventually even the normal slow scan modes die too, the image tearing off the edge of the screen.

Luckily I do have schematics for the SEM, a college sent us a copy of their manual for the SEM. I put the acrylic window back and fluorescent stub in the chamber and find I still have a good raster scan for the e-beam. The CRT and the san could for the column share the same scan generator signal source so I can rule out the scan generator as the source of the problem. I start tracing down the signal from the scan generator on the CRT, everything looks fine, a nice sawtooth pattern up until I get to the scan amplifier module. I put the scope on the output and it looks like a mess. I compare it to the vertical scan output which is very close to it's input leading me to believe the scan amp is toast.

A bit of video of the input and output of the scan amp, I am using my little Hitachi battery powered scope just in case there are any ground loops.

The scan amp in these modules is actually a STK070 audio amplifier. Whatever works, I guess. I luck out, there was a new spare that came with the machine. I install that and it brings it back to life. I need to make a few pot adjustments to get the image centered but everything is working as it should.