RCA 21-D-7177 Horz Drive Issues

[Penthode]

Hi Kevin,

I suppose I am now a little confused. I recall the original problem was that the center of the horizontal scan is to the right. This means that the left side is stretched and at the same time the right side is compressed. Is that correct?

By the width control being all the way out, does this mean the core of the width coil is out so you have minimum width? Then I suppose overall you have the necessary width adustment range but the left side is still stretched.

This would suggest to me you have too much horizontal drive, even with the trimmer capacitor tighted right down. Is this correct?

The Horizontal drive control is part of a capacitive divider. Perhaps there is something wrong with the trimmer? You should be able to adjust the trimmer so that as it is tightened, the left side of the raster slightly compresses and the CRT will dim slightly as the HV drops.

Maybe you should test the trimmer? Or as a test to reduce drive more, you could put a small capacitor (50 to 80 uufd) in parallel with the horizontal drive trimmer?

Terry