Quote:
Originally Posted by Robert Grant
It seemed to me that when I took up the hobby of fixing discarded television sets from curbsides (circa 1978) that a TV repairman told me that the 23EGP was, in reality, a 21" tube! And that the tubes were made from the shells of dud 21" monochrome picture tubes (how did they ever get to add two inches to the claimed diagonal measure?).
Any truth to that?
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This doesn't make sense.
1) Picture tube sizes were for a long time specified by outside diagonal. When the requirement for designation by viewable diagonal came in, designations added the letter "V," which was eventually dropped for new tubes when the tubes had been specified that way for some period of time.
2) I have read that the 23EGP22 envelope was based on a monochrome envelope design, but that does not mean it had no added features, was assembled in the same order or was made from duds.
Monochrome tubes could be complete assemblies of faceplate, funnel, and neck before the phosphor was applied. A color tube faceplate had to have locating details to mount the shadow mask in precisely the same location at least four times in a row: once for each color phosphor and then before mating the faceplate and mask to the funnel. So, there are details missing or confused in this story.
The process of removing and replacing the mask for each phosphor application is why monochrome rebuilds could include replacing the phosphor, but color tube rebuilds could not. Once the faceplate/mask assembly was fritted to the funnel, there was no removing it.