(Topic ID: 284962)

Target Alpha releasing Reset Control Relay AX

By srcdube

4 months ago

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  • 4 posts
  • 3 Pinsiders participating
  • Latest reply 4 months ago by srcdube
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Target Alpha Player Unit cams (resized).jpg
AXR reset path (resized).jpg

#1 4 months ago

Continuing to document my Target Alpha relays. Trying to understand what actually releases the Reset Control (AX) relay.

Added confusion with how the Hold Relay (R) is actually in opposite state than shown on the schematic, because power is off. In diagram attached, R should be open when power is on (Hold relay is on after game is reset)... then when tripped by a hard tilt/slam, it will trigger the Last Ball interlock (no more balls for you!), and apparently release the AX interlock as well (come to that again later).

So... assuming no slams for now, then the path to trigger releasing the Reset Control Relay AX after startup sequence should be a pulse on 4C, going through both P5A and First Ball Relay (DX).

First Ball interlock is set up during the startup sequence, so it should be closed as shown.

I'm not totally clear on what P5A is, and when it is on / off. I believe it's "player 5"... ie. the end sequence "after player 4 finishes their last ball". Is that correct? I'm also assuming it's normally closed until P5A is activated after end of player 4 last ball, but during startup it could possibly still be open from previous game if not reset yet.

So... is AXR actually being released as soon as the First Ball Interlock DX is set, or is DX interlock set but AXR not released until something happens to close the P5A switch later during startup sequence. What is the sequence of closing switches... DX>>P5A>>Motor 4c or P5A>>DX>>Motor4c ?

Also... what is the purpose of the slam triggering the release of AXR? If someone slams the machine during the startup sequence, it stops the startup sequence by releasing the Reset Control Relay immediately?


AXR reset path (resized).jpg
#2 4 months ago
Quoted from srcdube:

I'm not totally clear on what P5A is, and when it is on / off.

On the player unit, there are a set of five cams. The cam closest to the rivet board is cam 1. It determines when the scoring goes to player 1. The next cam behind it is cam 2, and that cam determines when the scoring goes to player 2. The same goes for the next cam back (cam 3) for player 3, and the cam behind that (cam 4) for player 4. All of these cams are white plastic. And then we finally get to the last cam, cam 5, which is black plastic.

So the "P" in P5A refers to the player unit, and the "5" refers to cam 5 (not player five). And, the "A" refers to the first switch (that is, the one closest to the cam) on the switch stack that is actuated by cam 5. So when you see a switch labeled P2B for example, you know it's the second switch (B) on the switch stack riding cam (2) of the player unit (P).

Cam 5 has exactly one lobe, and that lobe actuates the switch stack for cam 5 only when the player unit is at the player 1 ball 1 position. On the schematic, the P5A switch is shown closed because Gottlieb schematics are always drawn with the game fully reset and ready for player 1 ball 1. In other words, the P5A switch will always be open except when the player unit has stepped around to the game start position (player 1 ball 1). Then the P5A switch closes, the AX reset coil is energized, the AX relay drops out, and that is what takes the game out of the reset state and allows it to begin play.

The switch on the R relay that allows the AX relay to come out of reset is there in case someone slam-tilts the game while it is resetting. When the R relay drops out, it causes the DX relay to latch as part of the logic that forces the machine into a valid game-over state. That causes a problem because then the DX switch that normally allows the AX relay to come out of reset will be open, and the game will be stuck in reset forever. So the R relay switch bridges the part of the circuit left open by the DX switch, and that allows the game to complete its reset cycle even if it gets slam-tilted while resetting.

If you are wondering why the DX switch is in the AX reset coil circuit in the first place, that is done to ensure that the player unit will step all the way around one time every game reset, even if a new game is started when the player unit is already sitting at the player 1 ball 1 position. The player unit always needs to step around once on every game start to ensure that all the player scores get reset back to zero.

I also just want to mention that, on this game, the DX (1st ball) interlock relay is reset on game start, and is latched as soon as the game is no longer in the 1st ball state. This is kind of confusing, because you might expect a relay that is called the 1st ball relay to be latched during the 1st ball state, and reset otherwise. But for whatever reason, GTB did it the other way around.

- TimMe

#3 4 months ago

Here's the visual from the Target Alpha manual to accompany TimMe's excellent explanation.
Target Alpha Player Unit cams (resized).jpg

#4 4 months ago

Wow! Great stuff folks. A bit of a duh moment for me cause I do remember looking through that section and the naming/numbering schema at the bottom. It does help a lot to have it explained though. I’ve been spending most of my time under the hood and figuring out how the main motor switches work with the other relays because the scoring wheels all seems to be working fine and most of the niggling inconsistencies have been in the relay rack and scoring motor switches. There’s enough non-score wheel stuff back there though that I guess it’s time to learn more about it. Thanks again!

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