Contrast set too high on vintage sets.

[marty59]

Always my rule of thumb..."the less you drive the CRT the longer you will prolong its life".

We've talked abouit optimizing the controls for the best picture, gray scale etc. but from a black and white perspective I will turn both brightness and contrast down to minimum and bring up the brightness enough to show a uniform, low light raster and then bring in the contrast without overdriving while providing detail. A little touching up at this point is okay after observing. If this can't be achieved then verify AGC adjustments and repeat, providing we're working on a normally functioning set.

On some sets, the AGC may be more sensitive than on others and affecting both brightness and contrast.