Techno Stuff
How They Work - Spin Cycle - Drag Arms and Timing
Not time for that cocktail yet, but grab the ice tongs in preparation.
surf club |
| timing diagram |
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Timer Cams
OK, above is the approximate timing diagram for the timer cams. For many people, it's not going to mean anything, so I better mention that it's easiest to think of it as a map to the lobes on the cams. As an example, let's look at cam 4 (sound familiar?). When the timer cams are locked, the switch stack on cam 4 is lowered. As soon as the cams are released, the stack gets raised (either opening or closing the switches in the stack, depending on the type of switch) and stays raised until about 90 degrees of revolution (4 time periods out of 16), at which time the stack plonks back down again. If you like pictures, the mystic line design flaw timing cam page has an example that shows the cams and the associated timing diagram.According to rumour, switch 4B controls the spotting wipers, and is open when the timer cams are locked (time 0 or 8). When the timer cams release, switch 4B closes quickly and stays closed for 4 time periods. While it's closed, the spotting wipers are free to turn.
The manual actually tells you what each switch on the timer cams is doing. Here's some examples:
| switch | function (per manual) | comment (mine) |
| 3A | drops out start, extra ball start relays and acts as a safety switch during spin | "drops out" means turns off the power. So we see that the start relay, and extra ball start relay turn off pretty quickly after the timer cams get released |
| 4B | energizes score extra step and spotting index | hey! I said that in 60 times more words. |
| 6A | opens game advantage circuits during timing cycle | notice how this switch opens while 4B is closed. This prevents feature step-up pulses from getting generated by/while the spotting wipers are turning. |
| 7B | score unit steps | like 6A but for the score unit step-up circuit |
| 8D | trips corners relay when circuits are all closed on the mixer and spotting disc | we'll look at this later |
| 9A | opens score extra step circuit every other time | stan or kyle on South Park use a phrase whenever kenny gets killed which is appropriate here. What they mean is the every other time you cycle the machine, it is impossible for the scores to increase more than one step. |
| 9B | directs circuit to either hold feature or selection feature steps | hmmm...either the hold feature unit can step-up, or the selection feature unit. Not both for the same coin/credit played. Put another way, if the hold feature unit just stepped-up, and you want it to go further, you gotta play at least two more coins/credits, 'cause it's not happening on the next one. |
Drag Arms
After you've played a bingo a little, you realize that the amount of time that the game is in the spin cycle changes for each coin/credit played. The pieces responsible for this variable timing is are the drag arms. The drag arms lean up against a couple metal cams next to the control unit motor, and they are a fairly clever combination of cams, pins, and interlocking parts that causes the timer cams to stop turning briefly zero or more times during the spin cycle. The number and length of these pauses is determined by the positions of cams 1 & 2 relative to each other, and when the start cycle releases the timer cams.
surf club |
| drag arms |
|---|
In the image above, the drag arms (1) lean up against the cams (a). The leftmost cam (a) is the end of the timer cam assembly. The drag arm stops (2) catch on the pins poking out horizontally and stop the cams from turning. The rightmost unlabeled cam always turns. When the right dram arm is catching a pin on the center cam, it's the unlabelled cam that eventually pushes the arm away and releases the cam to turn again. This process is duplicted for the left arm and the center cam. The left arm drag stop is what holds up the timer cams. You got bandwidth? Watch an mpeg 1 (2.7MB) or an mpeg 2 (6.3MB) video clip of the dragarms in action.
overview
cam/wiper release
drag arms and cam timing
score unit step-up
feature unit step-up
trip relay activation
