Injecting composite video into a Hot Chassis set?

[Jon1967us]

The TV I'm troubleshooting, 1957 portable Trav-ler is a nice little set, with a good CRT, is worthy of restoration but has some video sync issues. I'm attempting to feed a composite signal from my BK 1249A into either the video amp grid or the 1st IF grid, as a way of process of elimination.

I haven't done this before (I've only restored a couple sets) and was wondering if

A. It's safe or possible to inject a signal onto a hot chassis set, feeding the signal from the generator onto the grid of the Video Amp, and ground to chassis. I remember reading something about this and suspect this isn't a wise idea.

B. If not, is there an alternative way to bypass the tuner, and inject signal somehow?


I assume we're connected to the "Video" output with "IF" selected.



And injecting into pin 7?