Quoted from jrpinball:Much better solution than dropping the voltage. I don't think that would slow down the motor at all, but would sure make the gameplay sluggish. I have a variac, and have experimented with lowered and raised line voltage. As long as the AC frequency is 60hz, the motor will run at the same speed. It's not a 110v motor. Runs on ~24V from the transformer.
I tried it out with a variac too. I could get it to slow down a tiny bit but not enough to make up the difference between 50 and 60 Hz motors. Below 16-17 volts the motor wouldn't turn at all. Turning the voltage up only made it louder, not any faster. These induction motors aren't designed to have their speed controlled by varying the voltage.
/Mark
Nashua, NH
