In part 1 and part 2 of Understanding Protection Devices I covered varistors, fuses and how they protect your games against excessive voltage and amperage draw so I thought now would be a good time to cover power and give an example of how your game uses it.

Power is expressed in watts. Volts times amps equals watts. Going back to the 6 volt 15 amp power supply reference, 6 volts X 15 amps = 90 watts. So that 6v 15a power supply would be rated at 90 watts. If it was a 12v 15a power supply it would be rated at 180 watts and so on.

Taking it a step further, a pinball machine made for the USA is designed to run on ~120 VAC and is typically fused for 8 amps. That means your game can use up to 960 watts of power. Now it’s probably rarely ever drawing that much and if it is it’s most likely for very short amounts of time.

Have your ever wondered (or even noticed) that games made for countries that use 240 VAC are only fused at 4 amps? That’s because a watt of power is a watt of power no matter how you look at it. 240 VAC X 4 amps = 960 watts.

Volts and amps are disproportionate to each other. When volts go up, amps go down and vice versa.

This may help explain how, in early Bally games for example, the power supply is able to generate +190 VDC to power the displays from a 120 VAC wall outlet. The transformer steps the voltage up to about 230 VAC and sends it to the power module where it’s rectified and sent to the power driver board for filtering and regulating down to +190 VDC.

When voltage is raised, the available amperage is reduced. The display power output is only fused for 3/16 of an amp, that’s less than a quarter of an amp. The circuit is high voltage, needs a lot of pressure, but just a fraction of an amp to operate.

I hope you found this simplified explanation on power helpful and informative. If you did then please share it and comment below.

Frank