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A project log for Hitachi S-450 Scanning Electron Microscope

Getting an old (1980s) SEM running and adding digital capture

Jerry BiehlerJerry Biehler 11/21/2014 at 20:300 Comments

The SEM came with a big transformer to drop the line voltage down from whatever your mains voltage is to the 100v needed by the scope. Big 'ole transformer too, must weigh about 60 pounds. I would rather not use it if I could and looking thought the specs in the manual I find that it says the scope will run off 100 or 120. I get out the schematics and sure enough there are jumpers on the power supplies to switch it to 120v operation. I do that and it works just fine. One less thing to take up space.

With the new configuration of the column sitting 90 degrees from the console I find that the power cable going from the column to the console is not long enough so I extend that, the cable also has the high vacuum interlock for the high voltage supply so I wire that up with a separate wire.

With everything working as it should, more or less, I lowered the console and the column off the carts with the help of a toe jack. The legs of the console are just lengths of square tubing laid flat so I took some adhesive backed teflon tape and coated the bottom of the tubing. This lets me slide it along the carpet pretty easily to get access to the back. I do a similar thing with the console, I bought some furniture sliders at the hardware store and just left it under the column base.

There are a few more bugs to work out. The data display module that overlays the voltage and scaling bar on the CRT is not displaying voltage correctly. I popped it open and even with the manual I have no freaking clue how the thing works. I know someone who might have a spare module that I am hoping to buy from.

I do seem to have a leak in the column someplace. It might be one of the valves on the pumping side of it, I took one of the accessory port covers off and machine it to accept a KF-25 elbow so I could install a pfeiffer PKR-251 full range ion/pirani gauge. With this installed I was able to find out that I was able to get down to about 5x10^-6 torr but after shutting down it would be up to about a torr in a day or so. Not a terrible leak, but something I want to fix. The next step on this will be to connect my RGA/Leak checker to the column and see if I can locate the leak with helium. To connect the leak checker to the column I took a flexible corrugated stainless vacuum line I had and chopped off the 1/2" VCR fittings from the ends and tig welded a KF-25 flanges in their place. I still can't connect to the RGA until I get another KF-16 fitting to replace the one I scavenged off it to hook up the turbo on the SEM. oops!

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