Old thread bump - but did you ever figure out the answer to why this changed?

I’m troubleshooting my Space Mission and noticed this same thing while studying the schematics. It’s not really obvious why they made this path only work on those bottom two bonus positions. Hmm?

Also, while I'm asking academic questions about this - what is the point of the ball index relay on Space Mission? My understanding is that it's used to ensure the active ball/player only advance if points have been scored (or if a tilt occurred). But on Space Mission you can't roll through the top lanes without scoring points. So what's the point on this game? It makes sense on a game where you could roll all the way to the outhole without scoring.

Weird. It seems like it would be futile for them to try to cover all the possible failure scenarios like that. Was that a frequent failure on machines? I guess I could see them covering the most common failures / complaints seen in the field.

One other scenario actually happened to me today - plugged in the machine and started a game, and the ball was somewhere on the playfield (instead of the outhole - yanked power in the middle of a game last night). So the ball index relay prevented me from losing that ball atleast.

What’s curious to me is how both of those paths are in series. So the relay only fires if you score points with 0 or 1 bonus advances. Of course in a normal working game, bonus advances always score points .. so it’s still a little odd why they wouldn’t just go by scoring points as before.

I’ll have to double check the logic where the ball index relay switches are used. I can’t think of a scenario where adding that path through the bonus unit makes sense. But I guess there must have been one or they wouldn’t have bothered.

Another academic question - can the match unit on Space Mission actually give an extra ball as a reward? The manual only mentions it giving a credit, and the extra ball adjustment is described for high scores and the alternating outlane specials. But the schematic shows the match output going through that same adjustment jack (even though by the time it fires, you would have already tripped ball advance, player reset, and game over). Not sure why they didn’t connect it directly to the credit path instead. Hmm?

I've heard brief mentions of this, but hadn't read that glossary description before. Interesting trick with using a magnet to lift the gates. I guess this makes another case where the ball index relay comes in handy. It would be interesting to know what all kinds of problems they saw back in the day, and how the games evolved to prevent them.

I've attached the schematic portion that shows this tilt path. Pretty much just what the glossary says - if you close that spinner lane switch, the path through the NC ball index relay switch will fire the tilt relay; otherwise once you score and open that path it won't ever fire.

Space Mission - tilt rollover schematic.PNG

I agree that it's a little more clear to show everything connected to the switch. I'm guessing the schematics would be a spaghetti mess if they did it that way though. I'm pretty happy with the layout of the original schematics except that it needs a list of locations for relay switches (which can atleast be found in the manual) and other switches like this one. I've been working on a spreadsheet to track all this, as suggested by someone in another thread.

DCRand - Interesting problem. It definitely helps if you can isolate exactly what is and isn’t happening when it acts up. A video would be good too if possible. From there we can figure out where to zero in.

You mention that lifting the playfield and stepping the bonus unit fixes it. Do you mean that in all cases the bonus unit is not stepping? It didn’t really sound that way from your initial description (just that it’s stuck in a loop). Is the player or ball number advancing when it gets in this loop? Sounds like not .. I wonder if perhaps your outhole switch is closing (and the open ball index switch we’ve been discussing is causing it to replay the same player/ball over and over - especially if the bonus unit isn’t stepping past zero).

I haven’t charted out yet what order exactly it does everything after a ball drain, although I’ve looked at a lot of the individual steps. I’ve got a loosely related problem now too where it’s going through one extra cycle on game reset before kicking out the ball. Of course that seems to have only started after I was under the hood adjusting switches last night .. sigh

DCRand - Here is a great thread to get an idea of how the entire game works:

https://pinside.com/pinball/forum/topic/em-pinball-machine-complete-circuit-description-2-bally-monte-carlo

It's for a different game and manufacturer, but the logic and flow of everything is very similar to Space Mission (many of the circuits and behaviors are identical). When I get a chance I'd like to writeup a thread similar to that for Space Mission. I've charted out most of the individual pieces already, so it just needs to be written up and documented properly. I've looked at that thread many times while debugging my Space Mission to understand how things work.

For the ball drain scenario specifically, the flow should be something like the below:

1. Ball goes in the drain and closes the outhole switch, which causes the bonus relay to energize
SM_01 (resized).jpg

2. Bonus relay switch closing starts the score motor
SM_02 (resized).jpg

3. Bonus relay switch closed with the score motor turning causes one of two things to happen repeatedly until it reaches its zero point:
SM_03 (resized).jpg

a. Bonus unit reset fires up to 5 times per revolution and 1000 pts is scored each time (double bonus inactive)
SM_03a (resized).jpgSM_03a_2 (resized).jpg

b. Bonus unit reset fires up to 2 times per revolution and 1000 pts is scored twice each time (double bonus active)
SM_03b (resized).jpgSM_03b_2 (resized).jpg

4. Bonus unit reaching zero de-energizes the bonus relay, and causes the outhole relay to energize once the score motor finishes its revolution
SM_04 (resized).jpg

5. Outhole relay switch closing starts the score motor
SM_05 (resized).jpg

6. Outhole relay switch closed and score motor cam 1 switch closed fires the ball count unit step up (i.e. advancing to the next ball number)
SM_06 (resized).jpg

7. Ball count unit step up EOS closing causes the player reset relay to energize
SM_07 (resized).jpg

8. Player reset relay switch closed and score motor cam 2 switch closed fires the player unit reset coil (i.e. resetting back to player 1)
SM_08 (resized).jpg

9. Outhole relay switch closed and score motor cam 3 switch closed fires the bonus unit step up coil (resetting it back to 1000 for the next ball)
SM_09 (resized).jpg

10. Outhole relay switch open and score motor cam 3 switch open de-energizes the ball index relay (resetting it until points are scored on the next ball)
SM_12 (resized).jpg

11. Outhole relay switch closed and score motor cam 4 switch closed fires the ball release coil (kicking the ball into the shooter lane)
SM_10 (resized).jpg

To keep it simple for troubleshooting, this assumes a single player game, no extra ball active, some points have been scored (energizing the ball index relay), it's not the last ball, etc. There are also some minor things omitted that fire elsewhere in the schematics or the paths that keep these relays locked on after energizing. But hopefully this gives a general idea of the flow for troubleshooting purposes.

Feel free to ask questions or let me know if something doesn't look right, this is based on skimming the schematics quickly while I'm at work. I do admit too that there are a couple things that don't make sense after typing this up (like how exactly the long dwell cam timings work for the double bonus 1000 pt scoring).

If I’m reading the description right, it’s in a loop repeating all of the steps I posted above right (except that ball count doesn’t advance)? Do you see the bonus unit cycling from off to 1000 each time too? That is a good clue to work with.

I’ll have to stew on it, but if the entire cycle is repeating then there are only a couple switches that could kick that off - outhole switch (picture 1) and bonus relay switch (picture 3). Since fiddling with the bonus unit mechanism fixes it, it sounds more like the bonus relay switch is intermittently closing (which energizes the bonus relay since it’s not at zero, and the whole cycle repeats). Not advancing the ball count could be a side effect of the ball index relay turning off.

Do you see the ball count advance once and then never again as it repeats? Or does it never advance at all? That gives a clue whether steps 6-8 are ever happening.

One other possibility (depending on what exactly you see the bonus unit / lights doing) - if the bonus unit is at fault, then the make/break switch in step (4) could get stuck in the zero position (normally after the firing in step (9) it should toggle back so that only the outhole switch can cause the process to happen again). If that switch failed to toggle back then it would repeat everything starting at step (4) again once the score motor turned off.

In that case though you would probably not see it alternating off/1000/off/1000/ .. so if you can confirm what the bonus unit/relay/lights are doing it should help give more clues

What's curious to me about your last post is that it's cycling between off / 1000 .. but then you say the bonus relay is not energizing on each repeat. Are you certain about that? Unless something weird is going on, the bonus relay has to energize in order to reset the bonus unit back to 0 / off (since its switch is directly in the path of the bonus unit reset coil). You might doublecheck that, and also just doublecheck each step of the flow based on the photos above to see where it's getting off track.

On a side note, I don't have a lot of great tools to debug this either beyond multimeter, jumper wires, and a test light. I am spoiled by all the fancy tools I have for debugging my other hobbies (scopes, logic analyzers, emulators, microprocessor pods, etc). I wish there was a good way to probe a handful of things around the game and watch them simultaneously.

Interesting, that's one that is pretty tough to troubleshoot systematically. The stepper units being mechanically erratic can cause anything. Did you happen to figure out how that correlated to your symptoms? Atleast it works now, fingers crossed ..

On a side note, I got a new test light from Amazon and some long leads and was finally able to figure out my issue too (player number advancing beyond the number set for the game). I knew it was somewhere in the path of steps 6 - 8 above. I had already adjusted score motor switch 1-A, but apparently not enough. The light confirmed that it wasn't closing whenever it failed. Adjusted that again and so far in two days it hasn't failed yet.

Hurrah for fixing problems!

rolf_martin_062 - I still don't have a good answer for the bonus unit being in the ball index relay path (unless it's to prevent some corner case scenario, field failures, cheating, etc). But I had one theory last night about bonus unit positions 1 and 2 being tied together - if your first score of the turn was an advance (e.g. by rolling down the top/center lane), then the advance and the points will fire simultaneously. That means you don't know exactly which position the bonus unit will be on when the points fire .. so tying them together ensures that nothing gets missed.