I'm working a 6A mpu I picked up recently. It runs with Leon's test chip and all the ram tests pass but it will not run the game roms. It has a combo game chip at IC14. According to some of the repair sites the chip select jumper has to be in at J3 not J4 in order to use IC14. This board has the jumper at the J3 location that appears to be from the factory. I then checked my Gorgar that has a 6A with all the original proms and where IC14 not used but it has the J3 jumper installed and the game works fine.

So my question is which jumper should be in? Or should neither be used?