To provide a technique which can easily and effectively prevent the fraudulent action using an auto-play adapter.

The invention consists in keeping the power from the backup power to the random access memory (RAM) of the main control substrate, at the time of shutting off of the power source, furnished through the harness connecting the door substrate and the main control substrate. By doing so, even if someone tries to memorize RAM a favorable game condition to a player (such as internal winning of a bonus winning combination) by attaching the auto-play adapter instead of the door substrate, when the auto-play adapter is removed and returns to the door substrate, the power supply from the backup power to RAM shuts off and the RAM data is cleared off. As a result the machine can prevent the fraudulent action using an auto-play adapter.

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