Hi @RGB, how do you implement your buffered CSync?Just slight differences. After many tests I decided to drop the EL1883 sync separator in favor of ISL59885. This means there is no potentiometer anymore. In its place there is a switch to select "regenerated" or "buffered" CSync (but buffered only via a Schmitt Trigger instead of sync separator like in V3). I also used THT capacitors this time, because the SMD ones in V3 were too painful to solder (lesson learned).
CSync from JAMMA goes to one gate in the 74HC14 and the output goes to another gate to re-invert the signal. It's a simple way to buffer TTL CSync, also serves as a CSync distribution.