Techno Stuff
How They Work - Score extra step pulse generator
OK, let's start with the pulse generator switch itself. It is squashed in between the two metal cams. One of the cams has a series of bumps on it, and a little roller under the switch rides up and down the bumps to close and open the switch.
surf club |
| pulse generator switch inside a cam sandwich (rotated 90 degrees) |
|---|
For some bizarre reason, it easier to see the bumps when the picture is rotated 90 degrees clockwise. I'll be back after I fill up the scotch glass...
one scotch later....
So we see from above that we want that switch to travel over the bumps. That means that the cam with the bumps or the cam with the switches must be moving while the other one is held still (ok, so in theory they both could be moving at different rates or opposite directions, but let's not get silly and make this worse).In fact, both cams do turn, but an index arm stops one of them the same way that the spotting wipers are held in place. When the unit is reset, the top cam in the above pic is rotated such that the "big pin" sticking down is touching the "big pin" sticking up from the bottom cam. While in this reset position, the two cams spin as one unit on the shaft when the score extra step index arm releases them.
The score extra step index coil is powered usually by a switch on the same timer cam as the mixer latch coil, so this sandwich spins around for a variable length of time determined by the drag arms. When the score extra step index coil loses power, the fun begins.
surf club |
| index arm engaging small tooth cam |
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In the above picture, the score extra step index arm has grabbed one of the teeth on the small tooth cam. Since the assembly is reset and the big pins are touching, stopping the small tooth cam also stops the "other cam". With both cams stopped, the pulse switch doesn't get to ride the bumps and no pulses are generated.
surf club |
| index arm engaging other cam |
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Suppose you are lucky enough that the index arm plopped down on the other cam. The teeth of the smaller cam are outlined in blue. Now we have a situation where the index arm is going to hold the other cam still, and the small tooth cam is free to rotate.
Why is it free to rotate? Because the teeth on the small cam are not long enough to catch on the index arm. Trust me.
surf club |
| ok, don't trust me |
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The small tooth cam will continue to turn, and since the pulse switch is attached to it, it goes for a ride over the bumps.
The small tooth cam stops turning when:
the big pin rotates
all the way around and hits the other big pin
- or -
when one of the small square pins attached to the side of the
small tooth cam hits the index arm.
The square pin on later
games opens a switch when it stops against the
index arm. This switch is cleverly labelled "square pin switch"
on the schematic, and you'll go nuts trying to find it in the manual.
If it's in the manual, it'll be in the switch chart describing the mixer
switches.
overview | pulse generator | score extra step relay | summary
