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I think my 15GP22 red gun is either bad or sick.
At low brightness, not all that much lower than I remember it when I got it,
maybe the same per old versus recent photographs made with my Canon
7D in "raw" mode and therefore with the raw data available to compare,
it still produces reasonable pictures with good color.
I do think that the 1.8K resistor in the CRT divider chain may be a bit high;
bridging the high end of it and the wiper of the brightness control with a
5K resistor makes the brightness control no need to be almost all the way up.
BUT ... the red screen control, while generating the correct voltage range,
has very little effect. Not NO effect, in fact it does seem that there is a bit
more red when it is all the way DOWN. But not the huge effect of the
green and blue screens. I find it hard to believe this is
normal. Is it possible that it is disconnected inside the tube? I measured
pin to pin capacitances on the tube plug and the red screen is in fact a little bit
higher than the blue and green ones, a fraction of a pF. I tried resoldering the
tube pin with no change; it did have only a little solder on it.
If you've adjusted a CT-100, and remember playing with the red screen,
did it work like the other two? Until recently I had never turned it
down below 80% up because I was always told to to set it
almost all the way up.
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