Thank you. It looks like I was mistaken. Sorry for confusing everyone. The sync line comes off the same connector as the sub board for the A/V out, which leads me to believe the sync is actually composite video?
The yellow wire on the left is going from this connector pad directly to the RGB out sync pin (8 pin DIN connector, looks like it’s wired the “standard” way). The black, white and red wires seem to be ground plus left and right audio.
Should I maybe rewire this to use the sync out from the expansion connector, with something on the way? I see that Voultar sells a board for the PC engine with buffering for sync and 75 ohm. The wiring is quite horrible on this mod, and the AMP is just kind of hovering on top of everything, so I’m thinking about redoing the mod anyway.
Here is the RGB amp used in the mod
Here is what is soldered to the expansion pins. Only R, G, B comes off here. Plus +5V and ground.