Brightness control inop. Contrast ok. CRT is good and has no H-K short --Now what?

[jpdylon]

Got this set as a freebee. The CRT has very low hours on it. Its been sitting in a garage for 15 years since it developed its problem.

The previous owner said the brightness control stopped working. It still doesn't work. The contrast, color, tint, and sharpness controls work fine. The sub-brightness control in the video section has no effect either. it just seems that the brightness is always at minimum.

The control itself is fine, as are the lines from the control panel to the chassis. The resistance from the high side of the pot to ground is 3k ohms, so i do not believe a short in a control is causing the problem. The sub brightness control is ok as well. I haven't been able to discover anything obvious that could be causing the problem. There is an IC on the video board that may be part of the luminance circuit, but I don't know for sure without any literature.

I would like to save the set just for the shop since its small and I can put it up on a shelf. --Any thoughts?