Quoted from jasonspoint28:
Just a thought, but if you supply 6 volts to a lamp socket, is it possible that the voltage will reach the transformer, which would step the voltage up to 120? I’m wondering if the power switch was turned on, would there be 120v at the wall plug?
Excellent point. If you apply 6 volts AC to a light socket that is connected directly to the game's transformer (a GI light socket for example) you can get 120 volts on the other transformer winding and at the wall plug.
A transformer is a pretty simple device. It's just some coil windings and an iron core that magnetically couples them all together. Usually 120 volts AC is applied to the primary winding which is stepped down to safer voltages used in the game (e.g. 25 or 50 volts and 6 volts) that appear on the secondary windings.
If instead you applied 6 volts AC to the 6 volt lugs of the transformer it would step it up to 120 volts on the primary winding and 25 or 50 volts on the other secondary winding too. Since the transformer is just coils of wire there is nothing that enforces the direction of the energy transfer so it works in both directions.
Note that there wouldn't be much current available at the generated 120 volts but the voltage would be there.
I actually tried this out after reading your question. I tied the 6 volt lugs of a Gottlieb transformer to the 6 volt lugs of a Bally transformer and sent 120 volts into the primary winding of the Gottlieb transformer. I got 120 volts on the Bally primary winding and 50 volts on the other Bally secondary winding.