The MPU from the Coney Island worked without problems but the SDU, also from the Coney, gave me some problems. When I first started the game, with the playfield connected, the game start tune was played at the solenoids instead of the sound card. The cause turned out to be the MPU connector end of the cable connecting the MPU to the SDU. One address bit was missing, probably due to oxidation in the connector from the battery leakage. Unfortunately I didn’t have this type of connector in stock instead I solved it by soldering the MPU end to the board.
After the first boot with the playfield connected the sound card started to give a continuous beep, also when starting a game and testing some switches some solenoids was pulled instead of the proper beep from the sound card. The cause of this was that the SDU board was modified at several points by interrupted traces and wire jumpers. It looked like someone made a mistake when writing the software addressing the wrong solenoids and instead of correcting the software they modified the board. I removed the wire jumpers and repaired the traces and then most of the game worked as it should. The Coney SDU wasn’t equipped with all driver transistors and the missing ones were used for the sound and one of the slingshots. Five driver transistors later all was working except for the continuous beep from the sound card. One of the jumper wires I had removed from the SDU connected a solenoid to one of the sound card inputs causing the +24 V to be routed to the sound card through the coil causing a capacitor at the input to be shorted. After replacing the capacitor also the sound worked properly.
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