Techno Stuff
How They Work - Reset

Every game with a has similar circuits for power-on reset and starting a machine cycle. Well take a look at each circuit in detail.

Replay Reset

replay reset
big show
replay register reset
at power-on
The circuit for replay register reset is highlighted. Our goal is to get a closed circuit path from wire #30 (fat black line at top of the image) to the replay reset relay coil at the bottom of the image.

If you aren't familiar with schematics or electricity, take a look at electricity and reading the schematic.

Starting at wire #30 and walking down the green circuit, we can see that we go through some switches, and as usual, you need to just figure out which wires these switches are connecting together at any point in time.

When the game is first powered-on, we get 50V passed through the search index 17B and CU cam 3A switches at the top. Both these switches stay closed all the time during replay reset.

Next we reach the replay register zero switch. If the replay register has credits, the switch is connecting along the green line and we get to a parallel circuit with an anti-cheat relay switch and a replay reset relay switch. One of these two branches has to be a closed circuit path if we want to keep going down the circuit.

The replay reset relay switch branch on the left is open and stays open until the replay reset relay closes, so we can ignore that circuit and look at the other branch through the anti-cheat.

The anti-cheat relay closes during the first machine cycle (coin played) and stays closed forever unless the power is removed. When the anti-cheat relay is open, the switches direct the 50V along the green line and we power the replay reset relay coil. As soon as this happens, the state of the anti-cheat doesn't matter, as that switch we were ignoring above in the left branch is now closed and it will hold the replay reset relay closed until the replay register reaches zero.

While the replay reset relay is closed, the mixer motor is turned on (that's why there is a 120V switch set on the replay reset relay, so be careful poking around on it) and the 16 pulse cams are generating a stream of pulses to the replay register reset coil. The additional replay register zero switch down by the replay register reset coil simply prevents the coil from being powered when there are no credits on the replay register (when a coin is played). This prevents the replay register reset coil from constantly yanking the number wheels against their zero stops. The register cannot roll-under from 000 to 999 due to the mechanical design of the unit, but Bally didn't want the unit to be stressed during coin play.

When the replay register reaches zero, the replay register zero switch up near the top opens and cuts off the power to the replay reset relay. Now the game sits there waiting for a coin to be deposited to start the first machine cycle.

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