1968 Zenith 20Y1C50 chassis - advice needed

[Electronic M]

Originally Posted by joe111671

Thanks Zeno. I got the NOS 6EF7's and they didn't make any difference.

So do I pull the 6EJ7, and lift the anode side of the diode and drive the diode with my source? Or am I just lifting the diode and connecting my source to the IF cable of the set? Or is your suggestion in the context of me having an analyst? I'll search for one and get it if that's what I need to do. Sorry for not understanding 100% but I don't want to make a big mistake.

I'm pretty sure what he means is disconnect the detector diode on whichever side is easiest, hook composite video to the grid of the 1st video amp and see what happens...it's a good signal injection troubleshooting approach. If it gives you video then everything between the ant terminals and detector diode is suspect, but if it doesn't give you video then the video amp stages are suspect.
BTW good idea to not crank brightness too high when looking for video if video is weak you'll see it best with the raster slightly brighter than the minimum brightness needed to perceive that the screen is lit...many properly working sets with strong CRTs will totally wash out the video if brightness is set to max.
If you have video, and good IF voltages but no reception AGC might be improperly adjusted.