Video Asylum

Posted by GrandpaBobby (A) on March 11, 2004 at 09:47:37

In Reply to: TV image too large--how to fix? posted by djprobed on March 08, 2004 at 09:04:22:

dj...
All crt based sets incorporate many (a dozen or so, at least) controls which determine the placement of the image on the faceplate (screen). Most of these controls are interactive, meaning multiple iterations of the adjustment procedure are required to obtain the most accurate results.

Since the electron beam is magnetically deflected, some of the adjustments are the moving of physical components (coils and magnets). Other adjustments involve compensating for the differing physical position of the electron guns in the picture tube.

Doing a total convergence and alignment adjustment involves centering the image, controling its dimensions, adjusting for both horizontal and vertical linearity, (Ever seen lines of scrolling credits squeeze or expand at the top or bottom the the picture?), convergence, focus, grey scale tracking. Ideally you will need a source of test patterns, from a single dot to cross hatch to color bars.

With factory service manual, a signal source and a half day, you might be able to DIY, but... it might also look worse. Good luck.

robert