Sentinel 430 restoration

[bandersen]

Originally Posted by miniman82

Thread jack: That's a pretty simple mod, I'd like to use it on my Philco which shows retrace lines at high intensity. Problem is on the Philco, the pic tube cathode is used for brightness and the grid is driven by the video amp tube. How could I change this simple circuit to work with the grid vice the cathode, if that's even possibe? I assume I'd need a phase inverter, and a coupling cap at the very least.

I'm glad you asked - I had the same problem with this set!
What I did was feed the vertical pulse into the cathode along with the brightness control and leave the video grid alone. It wasn't working at first because the 0.05 cap on the cathode was filtering it out. So i cut that down to 0.02 and reduced the resistor to 3.9K.

I hope this helps.