Interesting hack repair on a CTC-5, your thoughts?

[drh4683]

I started looking into this chassis again. One thing that is really holding me back is the ability to set this chassis up on a test jig, the repeated pulling of the chassis in and out of the cabinet is very annoying. I noticed one thing, from a cold start up, all guns cut off and after about 3 minutes, the green slowly starts to brighten up, even with all screen, background and brightness controls fully ccw. However, within that 3 minute warmup period when things seem to be working correctly, I can get the controls to properly light up the screen and then extinguish.
I think the only thing I can do now is reverse the boost leads on two guns of the crt to see if the green still lights up. Should green light up if say blue and green boost leads reversed, then I know the crt is at fault and Im out of luck. Should the other gun light up, then I know the trouble is in the green circuit. The boost circuit is simple though, since all other guns are working right, the correct voltages are there. The only thing I can think of is that perhaps the resistance of the background or sreen pot changes value as the set warms up.
This is a real fun one to say the least...