My grandfather passed away last year and while going through his house I turned on his Williams Tri Zone pinball machine. I remember it working fine and well but as I turned it on and entered a quarter it added no games nor did it make the familiar knocking sound. It already had 4 games ready to play on the display but as I tried to press the begin game button nothing happened.

I have no experience with pinball machines but I really find it hard to let this one breakdown. The only thing I thought to check were the button and quarter connections which seemed to be connecting.

Is there any obvious issues it could be and if there is, can someone like me repair it without much difficulty? These are the only problems and I’m very lucky to have found many spare parts for the machine along with its manuals and technical sheets.
Thank you in advance! You’re helping out a lot!

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The on off on worked! Thought I’d that a permanent fix or is that a more pressing issue with a temporary fix?

As it turns out switching the batteries actually didn’t do much. Not only does the machine usually ignore quarters now but it will also usually start up in the diagnostic mode. Going through the testing programs made the machine accept quarters and work shortly until the next day.

Not sure where the MPU is so I just kinda took a picture of everything. Pretty certain the batteries are in there right and there doesn’t seem to be anything obviously wrong.

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