Quote:
Originally Posted by SwizzyMan
Everything looks good except for the bottom right corner of the CRT. There is a green tint over everything in the bottom right corner. I've tried purity setup and deguassed the CRT multiple times and it won't go away. Is the shadow mask bent too much?
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Do you get a pure red field when doing the purity setup, or is it discolored in the bottom right? The early tubes with "positive guard band" (the holes in the shadow mask are smaller than the phosphor dots) could have white field impurity even when the individual color fields were OK. A really precise purity setup would involve viewing the beam landings with a telescopic microscope (RCA WG309A microscope) to see if they were in the center of the phosphor dots.
The later "negative guard band" tubes (Zenith Chromacolor, for example) where the holes are larger than the phosphor dots, would illuminate the phosphor dots evenly even if the purity adjustment was slightly off, eliminating white field impurity problems.