21CT55 #2628 restoration

[Zenith6S321]

Originally Posted by old_tv_nut

Yes, definitely a sign of something in the video during retrace. Does the visibility increase when you turn the brightness up? Can you see the h sync then? This would mean there's insufficient retrace blanking. (Not familiar with this schematic, so don't know what provisions there may be for blanking.)

Yes increasing the brightness does increase the brightness of the white vertical line along with the background brightness. If I lower the brightness so the whole screen just goes dark I can still see the vertical white line as shown on a couple of previous pictures. I could not see anything else, so I guess I do not see the h sync. With the brightness all the way up I do see some slanted retrace lines (like on the 40's BW sets), but they go away just under full brightness. Here is a screen capture of the SAMs showing the vertical blanking signal on the cathode of the CRT. My scope shows the 15V pulse riding on a 142V DC level.