Hello,
Guncon 2 require a csync signal to operate. In my setup i use an extron vga switcher, that "buffer" the two sync pin to 5v.
Also i use my mister in direct video, and my dac output sync at 3.3v, i suppose it's the same for vga out of the addon board.
Anyway 3.3v and 5v are probably too much for the csync input of the guncon 2, if i remember correctly csync level for consumer tv use 1v max. I did plug my guncon 2 at the output of my extron, they were working but i stop doing it when i realize this, i suppose it could harm them over time. Also i suppose this kind of addon use a resistor to get csync at the right level : https://ultimatemister.com/product/gunc ... or-mister/
Just wanted to create a topic to discuss this. I suppose i need to tinker a cable to include a resistor.