Shaker motor installation

9.5.2005:

Please note that this modification includes connecting extra wires and parts to your game circuitry. If you are unsure about doing this, then don't. There is a risk in damaging your game if done incorrectly.

The shaker effect is done with a motor that has a misbalanced wight attached to its shaft. When the motor runs it shakes the whole machine.

In games that are not equipped with a shaker motor from factory, there is naturally no driver output directly suitable for one, but usually one of the flasher outputs can be used. The shaker then runs when the selected flasher is flashing. Play a few test games and try to locate a suitable flasher. In STTNG, it is probably best to use the shield flashers at mid playfield. When the Enterprise gets hits and damage, the shields flash and now the game also shakes. Shaker effect is best when used sparingly, try to select a flasher that doesn't flash very often.

You can probably get a complete shaker motor assembly as a (expensive) spare part. But old copy machines and dot matrix printers are a good source of suitable size DC motors. I used a 12V motor from a junk printer. To the motor shaft, I attached a large nut and some washers. The more you put on weight, the more it shakes. Find the correct amount by experimenting. Don't overdo it, you don't want the machine to start walking around!


Motor with misbalanced weights.

The motor should be attached to game cabinet quite firmly, or otherwise only the motor shakes but not the game. My motor was already attached to an aluminum plate, so it was easy to just screw the plate onto cabinet inside wall behind the cashbox. It would also be easy to mount the motor with exhaust pipe clamps.


Motor attached to cabinet.

Connecting the motor requires some electronics. It is not wise to try and connect the motor directly to the flasher driver although it might work. It would create excessive load for the driver transistor, possibly damaging it, and the very short flasher pulse might not be long enough to make the motor run at full speed. Instead, a PNP transistor is used as a buffer and pulse stretcher.


Schematic for those willing to experiment.

You can mount the components on a small perforated board or just glue them to the motor. Since my motor had plate for mounting, I attached the transistor to that plate, which acts as a heatsink. The transistor will probably be OK without a heat sink, but it depends on how often your shaker runs.

Almost any 12-24 volt small motor can be used as long as it doesn't take more than a couple of Amps current. My 12V motor, running on 20V, took a little under 2 amps while running with the weights. It runs for only short periods, so there will be no problems even though the voltage is a bit high for a 12 volt motor. To avoid loading the flasher driver transistor, a BDW94 transistor is connected as a buffer. The diode and capacitor lengthen the driver pulse somewhat, to let the motor start and run from a brief flasher pulse. Diode across motor terminals prevents spikes caused by motor inductance.

If you use a very powerful motor, it might be wise to put a 1-5 ohm 9 Watt power resistor to one of the motor wires, to reduce startup current and keep the 20V line fuse (5 amp) from blowing. Also the shakers power can be adjusted with this resistor. And if the motor doesn't have time to start quick enough, you can increase value of the 4.7 uF capacitor, to 10 uF or more.


Connection of the ground wire.


Connection of the +20 V wire.


Connection of the control wire.

The three wires coming from your motor assembly are +20V, ground and control. They are connected to suitable places in your game. Ground can be found near the motor, from transformer secondary wiring harness, it is the green wire. Power, +20 V is found in all WPC games, at backbox connector J106 pin 5, the red/white wire. Connecting the control wire depends on the game and flasher selected. Look at your game manual to locate the connector pin for that flasher. In STTNG, control is connected to shield flasher driver J125 pin 8, the blue/violet wire.

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