So updates:
I received
@meybarra 's v3 HAS today and it works perfectly with my BVM. No changes, exactly the way he sent it:
I also grabbed an Extron RGB 201 Rxi. using the HD15 out straight cable to 201 in, and 4x BNC RGBS to 129X. The only setting that gets any picture is Serration Pulses. With all the DIP switches off but SERR I can get an accurate picture on the BVM, however dim. The level/boost knob brightens it up to normal. After a few minutes, the BVM blips or clips out every few seconds and seems to happen more as I play through a round of 3rd strike.
I can't tell if it starts as it warms up or if the signal is bleeding through and losing sync from time to time. It looks like the crt is powering down and back on in a split second, picture stays in sync, but it is unusable in this fashion.
Focusing on the v3 working and the v4.2 not, seems like the right way to continue.
@RGB
is there a v3 instruction manual available so I can see what the jumpers do in this configuration?
and do you have any ideas what may be happening with the sync circuit from v4.2? If you identify an issue, I don't see an easy way to rewrite the firmware on the atmega. I could pop it out and breadboard it I guess. A little ahead of myself, I guess.
thank you to everyone for helping,
-Dan