Sylvania Hybrid D16 - low h-drive

[DaveWM]

I suspect the VDR is clamping too much, since I get almost no waveform there, D14 show 1300v p-p come from the fly via a 560 pf. Need to double check if the fly is installed correctly


Something odd there for sure about the 1300v pp being so low.
IF pulling the VDR does not resolve (with a pot replacing it), that is you cant get the 1300v pp then maybe its the scope, I presume you are using a 10x prob? I don't think it would take much to load it down.

Looking at the schematic I can see how the HV control would not effect the drive directly, just too much resistance in series with the pot to have any real effect. Clearly its designed to impact the feed back pulse and not the grid drive.

Nice tough dog, hang in there.