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I was surfing around in the Yahoo TekScopes group, as I have an old Tektronix 535 i'm fixing up, and I stumbled acorss a question about an old Tek 547 with an internal graticule. Apparently since the graticule was in the face glass of the tube, Tek bonded a piece of plexiglas to the face with some clear goo for implosion protection. The goo gets cloudy over time. Sound familiar?
Stan Griffiths, one of the resident experts on these older Tek scopes said (among other things):
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Tek used to solve this problem by "repotting" a cloudy CRT at no charge to
the customer. When a scope would come into the Tek Service Center with a
cloudy faceplate, we would change out the black rubber pads to the newer
rusty-brown ones and send the cloudy CRT to Beaverton where the plexiglas
faceplate would be stripped off and replaced by a new one with clear
material. This is not easy to do in the field since it was done in a vacuum
chamber to keep air from being trapped between the glass and the plexiglas
and forming bubbles on the screen.
-----snip-----
So maybe a vacuum chamber is the secret.....
John
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