11-12-2013, 02:56 AM
That's actually not an ion burn. The electron gun is bent so both ions and electrons shot out the side of the neck. The external magnet bends the electrons back towards the screen while the ions being much more massive are barely affected.
What happened is the CRT was operated with the yoke removed so the intense electron beam was focused on one small spot and it destroyed the phosphor coating. The same thing can happen over time when a set is shut off many times and the image reduces to a bright dot.
You'll only see an ion burn on a CRT with a straight gun and no aluminized coating. That's pretty much only pre-war TVs and a few very early post-war sets. It looks like a dim spot in the center of the picture. (That stuff running down is the old CRT gasket)
[Image: http://farm9.staticflickr.com/8495/83723...c067_z.jpg]
What happened is the CRT was operated with the yoke removed so the intense electron beam was focused on one small spot and it destroyed the phosphor coating. The same thing can happen over time when a set is shut off many times and the image reduces to a bright dot.
You'll only see an ion burn on a CRT with a straight gun and no aluminized coating. That's pretty much only pre-war TVs and a few very early post-war sets. It looks like a dim spot in the center of the picture. (That stuff running down is the old CRT gasket)
[Image: http://farm9.staticflickr.com/8495/83723...c067_z.jpg]
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