Restoring a RCA 21CT55

[etype2]

Originally Posted by old_tv_nut

Whoa! Look at Tournament of Roses Parade #2, at 01:26 and following, and 01:58 and following. In these scenes, much of the background is neutral pavement. In the 21CT55 there is a 60 Hz blue hum bar moving slowly upward. The CTC-5 also has a hum bar, but it's weaker and different.

Some portion of these effects could be caused by a beat between the TV video and your camera sensor, but I don't see how your camera could cause two different effects on the two sets like that. It seems like there's some hum in the color circuits or the blue matrix/amplifier, which sometimes makes the bottom bluer and sometimes not. The DC restorer *might* be able to take out hum, but then again maybe not, if the time constants are long.

Besides checking DC restorer operation, maybe you should be looking for the hum.

Eagle eye Wayne! I hadn’t noticed the blue bar only the annoying greenish/yellow bar. The yellow bar is definitely from the camera and possibley the blue bar as well. This video was taken with an iPhone X. The yellow bar still shows up in photos taken by A Sony A6300 at 1/30, 1/40, 1/50.

Here are the frames Wayne noticed.