A friend and I are working on Game Plan Old Coney Island! machine. Initially when we got the machine it would boot, but not much else. After replacing a few fuses and bringing it back to some state of running we noticed many things not working one of which was the wrong coils firing. For example when hitting the bottom left kicker one of the mushroom bumpers fires. Another example is another of the mushroom bumpers fires the kick-out hole coil instead of it's own.

So to try and correct this and many other issues we ended up re-doing the playfield connectors. After changing 300+ molex pins the game is alive again. Someone had lubricated a few of the connectors and they all were very corroded. The newly cleaned and re-pinned connectors fixed most of the issues we were experiencing except the misfiring coils.

Running a coil test doesn't add much information. Several coils don't fire during the test, but will fire during game play. The MPU has been repaired and the battery replaced with a capacitor but the board is rough. The connectors on the boards look in decent shape.

What to try next? Could it be on the SDU? Is it possible/likey that the MPU is programmed for the wrong game? You never know the history of a used machine. Thanks for any insight!

So, working on the assumption that the issue is indeed the roms. I ordered up 3 new roms chips for OCI from a reputable source. I swapped all 3 chips. Once I turned it on, it did nothing on the MPU zero flashes, but the soundboard did make the start up noise. After putting in the old chips the MPU booted again just fine. I then replaced the chips one by one, and got the board to boot using a new A and C rom, with the old B rom. It seems the new B rom I received was bad. So now with a known correct A and C rom chips, the same problem persists. I am awaiting a replacement B rom before trying that.