Convergence Issue

[Penthode]

Wayne, I had the same issue with linearity affecting convergence. The capacitors throughout the vertical sweep circuit had been replaced but could I still could not get it right. Further investigation I found some of the resistors drifted and testing each of the capacitors I had replaced I found some of the new replacements were out of tolerance.

Fixing the linearity helped considerably with convergence. Going over it again and again and again I finally got it right.

[old_tv_nut]

Originally Posted by Penthode

... Further investigation I found some of the resistors drifted and testing each of the capacitors I had replaced I found some of the new replacements were out of tolerance...

Thanks - guess I will have to check values. How much would you say the linearity improved?

[Tim Tress]

Some of those old sets were difficult to get perfect convergence on, especially the early rectangular CRTs. Before trying the procedure again, degauss it.

[old_tv_nut]

Originally Posted by Tim Tress

Some of those old sets were difficult to get perfect convergence on, especially the early rectangular CRTs. Before trying the procedure again, degauss it.

This is an early roundie, with a metal picture tube. Degaussing a metal tube is not simple because it has edge magnets that are adjusted as a final step in obtaining color purity. If you use a degausser after that final adjustment, you will counter it and possibly make it impossible to obtain edge purity. The purity adjustment procedure must be done in correct order completely from start finish, or as a minimum, the edge magnets must be retracted into their shells before using a degaussing coil. Then the edge purity adjustments have to be redone.

Trying to improve convergence by degaussing is futile, as the degaussing, purity and covergence adjustments for the metal tubes have to be done in that order.

[reeferman]

Again, good luck.