Difference between revisions of "Twilight Zone Eddy Boards"
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| − | Twilight Zone has two eddy sensors. One is at the ball eject position in the ball trough. The other is located on the under playfield clear trough that feeds balls from the piano and gumball playfield holed to the slot machine eject. | + | Twilight Zone has two eddy sensors to sense magnetic balls. One is at the ball eject position in the ball trough. The other is located on the under playfield clear trough that feeds balls from the piano and gumball playfield holed to the slot machine eject. |
| − | The under playfield sensor is rarely a problem. | + | The under playfield sensor is rarely a problem but the trough eddy sensor is one of the worst problems in the game, second only to the clock. |
| − | + | ==Typical symptoms== | |
| − | + | * Machine says "Powerball" when the powerball is not in play or vice versa | |
| − | Typical symptoms | ||
| − | * Machine says "Powerball" when the powerball is not in play | ||
* A credit dot with a "Switch 26" error. | * A credit dot with a "Switch 26" error. | ||
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| − | ===Failed Optocoupler Output== | + | ===Failed Optocoupler Output=== |
The output signal is driven by an optocoupler across the switch matrix. A short to the switch matrix can destroy the optocoupler transistor. Replace the optocoupler if the LED works correctly but there is no switch signal. | The output signal is driven by an optocoupler across the switch matrix. A short to the switch matrix can destroy the optocoupler transistor. Replace the optocoupler if the LED works correctly but there is no switch signal. | ||
Revision as of 15:34, 1 May 2011
Twilight Zone has two eddy sensors to sense magnetic balls. One is at the ball eject position in the ball trough. The other is located on the under playfield clear trough that feeds balls from the piano and gumball playfield holed to the slot machine eject.
The under playfield sensor is rarely a problem but the trough eddy sensor is one of the worst problems in the game, second only to the clock.
1 Typical symptoms
- Machine says "Powerball" when the powerball is not in play or vice versa
- A credit dot with a "Switch 26" error.
2 Causes
2.1 Connector Spring Failure
The trough eddy board and its sensor are joined by a small cable. With the vibration from the trough, the brass connector pins lose spring and the connection becomes unreliable. There are two solutions. You can solder the wires directly to the boards. Or you can buy or make a new cable.
2.2 Damaged Sensor
The sensor is adjustable, and needs to be within 1/16 of the ball to work. If it is too close, the ball hits it and destroys the plastic. If it gets to the wire, the sensor will permanently fail. Although the sensor may look beaten up, the problem is still usually the cable.
2.3 Out of Tune Circuit
The design doesn't accommodate all variations of parts and conditions, and may end up being too robust and never respond to a close ball - or it may never start up. One fix to try for a stuck red light is to add some twists to the cable, although be careful as the cables/connectors are known to fail easily.
2.4 Failed Optocoupler Output
The output signal is driven by an optocoupler across the switch matrix. A short to the switch matrix can destroy the optocoupler transistor. Replace the optocoupler if the LED works correctly but there is no switch signal.
2.5 How does Twilight Zone keep track of where the powerball is?
The machine discovers the location of the powerball by using a combination of four different methods:
1. By using the eddy sensor in the under playfield tunnel between the piano, camera, powerfield exit and dead end that ends up in the slot. If a ball triggers the piano, camera or dead end switches and then the slot switch triggers *but* the eddy wasn't triggered in between, then we know the powerball must have gone through.
2. By using the eddy sensor in the ball trough
3. By failing to grab a ball successfully on the loop magnets.
4. By counting the powerball as it goes in and out of containers, such as the lock, gumball and trough. So for example if the machine knows there's two balls in the trough and you drained the powerball during single ball play, it'll be out the trough again in 2 balls time. By doing this it's possible for the software to work around broken/failing eddy sensors.