They are on the main board in the backbox.
Actually stern seem to have made it more complex on that you need a small board that enables headphone control - that they want $100 for! It connects to this
I might have a go at wiring it direct and see what it gives… as the stern part uses the dollar bill slot which we dont have in the U.K.
I’m using the headphone out on my GB which is spike 1 for streaming and it works great.
I imagine it would be line level and you wouldn’t want to plug most headphones directly into that without some sort of attenuation. If this is the case, there are a boatload of simple DIY headphone amp designs (I’d look at the Cmoy project probably) that could be built on some perfboard and mounted to the coin door for about $20.
I think the goal here was streaming rather than offering headphones, so line level ends up being a win over an amplified output.
try this encoder:
I’ve managed to use a lot of bizarre resolutions with it, not sure if it will work with the resolution you need but it works with the output resolution of the CGC HDMI out on AFMR (and pretty sure It will work with MMR too). It also does DVI in which is useful for Alien (lol)
Is the screen that Stern uses standard (!) LVDS pins for input?