Mercury TV-220A restoration

[Jeffhs]

I noticed the aquadag coating on the CRT bell was flaking off (there is a large bare spot where the coating should be, even though most of the rest of the dag is still on the tube). I'd replace the tube, as it could be very weak--especially if the TV was made in the 1950s and was used a lot by its former owner(s). There could be high-voltage issues as well if the dag coating (or any part thereof) is missing, including arcing or even no raster. Because the dag is one part of a large HV capacitor in all CRT TVs, it is very important that the coating is intact over the entire surface of the tube bell.

Edit: I just looked at some other posts in this thread and found that Bob had recoated the CRT bell, thereby restoring the tube to normal, or at least as close to normal as one can come with a 1950s-era CRT. I was not aware (until just now) that flaking aquadag could be replaced, but I learned something tonight when I saw the references to Slip-Plate and the other compound mentioned.

BTW, the picture on the newly-recoated CRT looks good from here. Bob said there were still some issues with the image the tube produces, but from what I can see, the picture is pretty darn good. I would think defects in the raster, etc. would show up more prominently on a crosshatch pattern than on a standard program picture anyway.