Help me understand the 630 horizontal circuit

[miniman82]

Im very familiar with synchroguide, if that's what this was I wouldn't even be here. What's throwing me off was that reactance tube, but I guess it's not a whole lot different from the later stuff when you think about it. Just a different way of accomplishing the same thing, and the waves look a little different.


Here's what I've been able to find out, so far there are nice sine waves arriving at the 6AL5 and everything looks normal- that is still I put the plate cap back on the HO tube!

Here's h-drive and h-sine with the plate cap removed and no signal input to the chassis, everything looks normal:




And now with the plate cap on:



See that little hump? Apparently the flyback is causing it to show up, so effectively it's self triggering because that pulse has more amplitude than a regular sync pulse does- so any sync pulses from a normal video signal applied to the chassis simple gets drowned out.

I'm still waiting for the flyback tuning capacitor to show up from mouser, so I won't know if the lack of it is what's causing this till it arrives. I really hope that's it, because I'm out of ideas here.