Grand Prix: L+R Bonus Advance always pulse simultaneously

Change Relay Switch C is for the lights. This is related to the No. Match unit, which is used to alternate sides. So if I turn the match unit, let's say the "odd" numbers select the Left Side, and the "even" numbers select the Right Side (match unit is used since it rotates continuously and perfectly alternates between L & R). So depending on the Match Unit number, the change relay moves and closes Switch C to illuminate the corresponding Side Lights. Also if I touch Switch C, I can manually move the lights left or right. So it appears to be working as intended.

Thanks for the response though!

#4 6 years ago

MarkG

OP
Quoted from goingincirclez:
If I touch the L Adv relay, the R Adv works too and vice versa. Same if I touch the 500 relay. Same if I turn the spinner units.

I want to check that I've understood what you're seeing. So the Left Advance relay should advance the Left Bonus stepper, and the Right Advance relay should advance the Right Bonus stepper and they should operate independently. What you're seeing is that when you manually activate either the Left Advance or Right Advance relays, both Left and Right Bonus steppers advance. Is that right?

I don't follow the bit about the 500 pt relay or the spinner units. If you manually activate the 500 point relay both Bonus steppers advance? And if you turn the spinner units manually you can get both Bonus steppers to advance?
Grand Prix LR Advance relays (resized).jpg
The spinner units should advance their corresponding Advance relay occasionally, not for every step. Is that what you're seeing?

Looking at the schematic above I agree with your suspicion of the Change relay A Make/Break switch (the switch closest to the metal relay frame). I wonder if you temporarily desolder one of the outer tabs of that switch (maybe the green-orange wire closest to the frame that goes to the Right Advance relay) if the Left and Right Advance relays still fire together. It sure sounds as if the blue-orange wire to the Left Advance relay and the green-orange wire to the Right Advance relay are shorted together somewhere. Desoldering one of them temporarily might give another clue as to what's going on.

/Mark

#5 6 years ago

GIC

goingincirclez

Mark, you've got it exactly as I intended. Any action that should cause just one of the Bonus Advance relays to fire, instead causes both to fire. It doesn't matter if it "should" be L or R... both will go. Yes, pressing either the L, or the R, or the 500 relay, causes both to work. And the spinner does only trigger advance occasionally (every 3rd or 5th or whatever spin) as it should - while the orange spinner lites stay in their lane, both advance relays will fire when triggered. The side lights switch sides as they should.

I didn't want to muck about with soldering back there yesterday so I shimmed the gaps with cardstock... but I see your point that maybe there is some other short source, frayed wire against the frame or something. The Change Relay passes visual and "observed operating" inspection so I tend to leave well enough alone... but I guess I could unscrew it and look closer. I really want to make sure I've read things correctly and eliminated all other possibilities first.

#6 6 years ago

HDF

HD_Fatboy

Pinside member

Wilcox, PA

6y 36,550 531 4

I had my right bonus counting down and then my left bonus counting down. I do not fully understand if your problem is similar or related. But mine was two wire tabs touching on the left bonus stepper. that got bent because if you raise the playfield, and slide it out some, then lower playfield this stepper unit can rest on the cabinet where the lockdown bar goes.

With that being said, I would check the left and right bonus stepper unit for shorts, or other things that don't look correct.

#7 6 years ago

MarkG

Hmm. That 500 point relay may be worth a closer look too. I don't see how they should be at all related. Do either of the L or R Advance relays when fired manually also fire the 500 point relay? Or is it just the 500 point relay that can fire the L and R advance relays? Can you block out the three NO switches on the 500 pt relay with your index card one at a time to see which one fires the Advance relays?

This sure feels like a short...

#8 6 years ago

GIC

goingincirclez

I think the 500/L-R relationship goes both ways. 500 relay has to do with scoring, and as I understand it any switch that would advance the bonus is worth some amount of points on its own, so it didn't strike me as odd.... other than how it's not really connected in that L/R Advance schematic loops.

Yes, I agree it almost has to be a short somewhere, but dang. I can trace every playfield advance switch in that schematic to its associated relay... but the only electric path to the coil on "the other side" is through that M/B switch C on the Change Relay. Even if there was a short somewhere else, how would it get back to that coil...

#9 6 years ago

HOW

HowardR

Pinside member

Boulder, CO

7y 78,050 6,246

OP
Quoted from goingincirclez:
Yes, I agree it almost has to be a short somewhere, but dang. I can trace every playfield advance switch in that schematic to its associated relay... but the only electric path to the coil on "the other side" is through that M/B switch C on the Change Relay. Even if there was a short somewhere else, how would it get back to that coil...

If the Left Advance relay and Right Advance relay activate together when they shouldn't, look at the "A" switch on the Change relay. Check the contact points and the solder lugs.

Pinball (resized).png

#10 6 years ago

GIC

goingincirclez

Shoot, I typo-ed that in my previous reply... I *meant* Switch A. Someone else mentioned C before and we discussed that. Yes, "A" is the one that diverts coil power between the L and R sides.

It appears to be working... see my previous troubleshooting tests... but since the consensus thus far is there isn't "some other place or path" besides that switch, where the coil power could bridge... I guess I have more digging to do with it. I'll take it apart tonight.

#11 6 years ago

HOW

HowardR

Pinside member

Boulder, CO

7y 78,050 6,246

OP
Quoted from goingincirclez:
I guess I have more digging to do with it. I'll take it apart tonight.

It might be easier to first try putting slips of paper between the switch contacts or unsolder the Blue&Orange or Green&Orange wire and see how that affects things.

#12 6 years ago

GIC

goingincirclez

OK. I've just spent two hours chasing my tail on this because something isn't making sense and now I'm not sure how this ever could have worked at all...?!

As promised, I inspected the Change Relay: Removed it, removed the switches, everything looked fine! But when I toned out the M/B Switch A - specifically, the L side to the R side (ignoring the middle leaf which completes either circuit) - BZZZZZT short. WTF?

I then disassembled the switch, separated the leaves, and clipped the tone probes to them. Blue wire is left side.... green wire is right side...

ChangeRelayShort (resized).jpg

Continuous tone = permanent short somewhere... OK, so now I know why both advance relays fire at once. But where is the short?

Look at the schematic posted earlier above: the Blue+Orange (Left), and Green+Orange (Right) wires ONLY connect switches in series: the respective Outlane and Standup switches on the playfield, and the Spinner, Bonus, and Advance relays in the block under the playfield. That's it. Sure enough, touching any of those elements to any other on the opposite side confirmed a short. But not a single terminal / leaf / wire was obviously touching or shorted!

I (eventually) unplugged the pf harnesses and confirmed the short existed only in the playfield itself (not in the backbox or bottom panel).

Eventually I probed a middle leaf in one of the pf switches by accident and still registered a short... on say, one of the yellow (power) lines. WHAT? How is that possible?

So now, look at the following photo:

LRAdvance (resized).jpg

The Advance Relays are the pair on the far right. So. Look at the Left Advance, with the blue wire on the left switch... which shares a yellow wire... which connects to the relay coil... and flows through the coil, coming out the other lug... which is connected to the Right Advance coil, flowing through that to its other lug... through its own yellow wire, and to the switch with the green wire for the Right side. Pow. Permanent short. From the factory?

Indeed... if I remove either the blue or the green wire from either relay, the short goes away.

Clearly I am not understanding something here.

#13 6 years ago

MarkG

OP
Quoted from goingincirclez:
The Advance Relays are the pair on the far right. So. Look at the Left Advance, with the blue wire on the left switch... which shares a yellow wire... which connects to the relay coil... and flows through the coil, coming out the other lug... which is connected to the Right Advance coil, flowing through that to its other lug... through its own yellow wire, and to the switch with the green wire for the Right side. Pow. Permanent short. From the factory?

I don't think that's your short. That's exactly what the schematic shows:
Grand Prix LR Advance relays 2 (resized).jpg
There is a path from the blue-orange wire through the L Advance relay and R Advance relay to the green-orange wire, but it's not a short. Each of those M-29-1100 coils should measure about 16 ohms so normally you should see 30+ ohms between the blue-orange wire and the green-orange wire.

I suspect if you switch your meter from the continuity setting to the lowest resistance setting you'll see something much less than 30 ohms which would indicate a short. Coils can have resistance as low as 5-6 ohms and some meters will register paths through coils as shorts. But it's really only a short circuit if you can measure the resistance between two points as no more than an ohm or two.

So I still think you have a short (of an ohm or two) but I don't think it's through the coils (30+ ohms). If you desolder one of those yellow jumpers on the coil lugs I suspect you'd still see a short.

Key post

#14 6 years ago

MarkG

Let me clarify. If you were to desolder the yellow jumper on either of the Advance relay coils you should be able to measure about 30 ohms across the two coils (which would be normal), and just an ohm or two between the dangling yellow jumper and the other yellow jumper (which would represent your short).

#15 6 years ago

GIC

goingincirclez

Ha ha Mark... after I typed all that out last night, and before you replied, it dawned on me: "Hmm... actually what I am seeing is exactly as the schematic shows after all..." just as you pointed out. Which begs back to my other question: "How does it ever work at all?!?!"... so thanks for explaining the resistance values being "conductive" but not necessarily "shorted".

Sigh. So in the end I wasted a bunch of time with that. BUT I FIXED IT LAST NIGHT and hoo boy, I'm not sure I ever would have found it WITHOUT wasting all that time. The symptom / causes were a perfect coincidence storm, overlooked due to a quirk of how GP is designed compared to every other game (over a dozen now!) I have worked on.

SO COME ALONG FOR THE ADVENTURE and answer this question: "What happens when you have a stuck-closed standup switch?"

Your instant clue is something continuously scores / rings / fires / locks / etc etc right???? So if nothing is happening there are no stuck switches right?

Well.

The L and R standup switches seemed fine because nothing happened unless I (or the ball) touched them. So they're not stuck closed.

BUT!

I finally fully realized that each of those standup switches - unlike most any other standup switch I've messed with in any other game - have THREE leads... wait what?

Sure enough, each one is like a make-make switch... and one make was stuck closed... on EACH side.

Apparently when I replaced the rubbers, the new tighter tension was just enough to close the first two leaves on EACH standup. But the tension wasn't enough to push all three leaves together. Now I did not realize this, because "nothing happens" when those first two leaves are closed. No buzzing, no scoring, no locking, nothing. But push them further to close the third leaf and POW you get an Advance pulse as you would expect... so there was nothing to suspect.

Where are these other leaves?

GPstandShort (resized).png

Orphaned on the bottom left of the schematic down by the high-powered stuff. But lookie there: the 500 relay.

Apparently those switches put the 500 relay on standby to pulse when the other half of the switch is closed. But if they are stuck closed, they create a silent short!

Anyway, once I noticed the standup switch config, I fix the Right side standup first and... sure enough, that side would finally only advance the Right bonus. If I touched the Left standup (still partially closed at this point)... BOTH sides advanced. I fixed the Left standup and... both sides finally worked properly!

Now if only either/or standup had been messed up... OR if the closed halves had actually locked something on... OR if they had been fully closed all the way... OR if the short didn't follow its own natural path in spite... OR if the 500 relay wasn't "silent standby" and still used during the apparent score trigger... OR if I'd ever seen an implemented 2-way standup switch before... I would have found this so much sooner!

Oh well. Glad I figured this out, regardless. Feels like an accomplishment. Thanks to all for the help!

Key post

#16 6 years ago

???

currieddog

Pinside member

Springfield, MA

7y 63,550 3,312 6

Thanks for some very well-written descriptions all.

#17 6 years ago

MarkG

Wow, great catch. I don't recall encountering make/make targets before.

I don't completely follow the final solution though. The schematic seems to show that if one half of the make/make standup target switch was stuck closed either the 500 pt relay or one of the Advance relays should have been constantly active as well. And if it was the 500 pt relay, the score motor should have been turning. I thought that none of the three relays (500 pt, L & R Advance) were active. Am I misunderstanding the symptoms?

#18 6 years ago

AXE

YeOldPinPlayer

Inactive member

Unknown

8y 111K 6,454 4 12

Thank you to everyone, OP & helpers, for an excellent troubleshooting thread. It's very informative and I'm sure it will help others in the future.

Edit: A photo of the offending switches on the top side of the playfield might be helpful.

In post one the words "grand prix" auto-link to the 2005 Stern game. Grand Prix links to the one you're working on.

Edit2: I've marked some key posts, will mark more/modify descriptions as needed to address points raised by Mark & Rolf.

#19 6 years ago

rolf_martin_062

Inactive member

Aarau

9y 59,550 4,150 14 8

Hi goingincirclez +
great - You found and fixed an tricky fault. As (probably others and) MarkG I am (also) not that happy with the theory in post-15 --- specifically the "silent standby of 500-Relay". I put together the stuff from the ipdb-schematics (have mirrowed some part) --- the big question is : WHAT color (wire then blade then blade then wire) had permanent-faulty connection . Also very interesting an answer to the question: A ball rolls to the target - target is moved - blade of which colour ? starts moving - moves and gets in contact with blade / wire color ? --- the both (blades / wires) move and finally get in contact with blade / wire of color ?.
This topic is very interesting - please write about. Greetings Rolf

0Grand-Prix-Work-36 (resized).jpg

#20 6 years ago

GIC

goingincirclez

Mark & Rolf,

Yes, I agree my "explanation" is probably not the most technically elegant or accurate... but I really don't know how else to summarize what happens, much less the "why". But I confirmed the behavior again tonight. If you close the "500 relay half" of either standup, that side will advance even when the *other* side is the one triggered!

Here are pictures of the mechs:

Standups (resized).jpg

You'll note there's not much room for all three blades in the hole, so this is actually pretty easy to mess up I guess. I had to bend them quite a bit after changing the rubber, once I realized what was happening. Though in fairness three blades are so OBVIOUS when you look at them... it didn't register to me at first because hey, "the switch is working like every other standup in every other game".

And speaking of confirmation: yes, if you close those first two blades, NOTHING HAPPENS!!! No relays (not even the 500!) close, pulse, buzz, fire, or click. No lights. No actions. NOTHING. It's completely silent!

So here is a consolidated schematic:

GPStandConsolSchemLabeled (resized).jpg

Best I can figure is once the yellow power side is completed through the 500 portion of the standups, the respective advance can get power from there "in addition to and/or instead of the Change Relay". The 500 Relay is engaged with the Score Motor, so it runs any time the Advance Standup (proper) is triggered. I still don't understand how this happens without the Advance Half of the respective "untriggered" standup being closed... but as I said, I've tested this a few times now. And yes, I made sure the outlane rollovers aren't closed either.

Very tricky indeed... or at least I'm going to tell myself so!!!

#21 6 years ago

MarkG

OP
Quoted from goingincirclez:
yes, if you close those first two blades, NOTHING HAPPENS!!! No relays (not even the 500!) close, pulse, buzz, fire, or click. No lights. No actions. NOTHING. It's completely silent!

According to the schematic that's not possible. Closing either switch of the make/make pair should fire either the 500 pt relay or one of the Advance relays.

BUT, I have a theory. Your photos show both switches with brown-black wired to the middle (short) blade and the right side photo shows yellow on the outside (short) blade. I'll assume the left side switches have yellow wired to the outside (short) blade too via the orange jumper. I'm going to suggest that the switches are wired wrong.

According to the schematic, the main supply or yellow wire should be on the middle (short) blade so that if either of the two switches in a make/make set closes yellow gets connected to something and a relay fires. In your game, with yellow on the outside (short) blade, it will only be connected if both switches close. In your case, on the right side for example, it looks like brown-black (500 pt relay) can connect to green-orange (R Advance relay) without either touching yellow which shouldn't happen. But if it did happen neither relay would fire, which is what you see.

If yellow were wired to the outside (long) blade moved by the rubber, then the game would probably behave the same as if yellow were wired to the middle (short) blade of the switch. But with it wired to the outside (short) blade furthest from the rubber, the game wanders into the weeds as you have spent a few days observing.

/Mark

#22 6 years ago

AXE

YeOldPinPlayer

Inactive member

Unknown

8y 111K 6,454 4 12

Quoted from MarkG:
Closing either switch of the make/make pair should fire either the 500 pt relay or one of the Advance relays.

What is the point of a make/make pair rather than a two wire, normally open switch? A make/make should activate feature X on a soft hit that only makes the first pair and activate feature X & feature Y on a harder hit that makes both. If closing either one fires both Williams should have used a two wire normally open switch.

#23 6 years ago

MarkG

I too was wondering why a make/make switch. The 2nd switch could have been added to the switch stack on the relay closed by the 1st switch. (In this case the L and R Advance relays could have fired the 500 pt relay). When wired properly a make/make could be used to award different things for soft and hard hits as you point out, but in this case a soft hit did nothing and a hard hit did the wrong thing.

#24 6 years ago

HOW

HowardR

Pinside member

Boulder, CO

7y 78,050 6,246

Williams saved the cost of 2 relays by using these make/make switches. And re. having the L and R relays fire the 500 point relay, not so good for the spinners or top eject hole.

Pinball (resized).png

#25 6 years ago

GIC

goingincirclez

AAARRRRGGGGH MY GOD AM I AN IDIOT!

(Well I already knew that, but sheez... now the rest of you know too).

I had the wire ID's on the standup switches wrong. Gad Zeus it just hit me... DUH: the green and/or blue wires... that are connected to the advance relays... are connected to the **FIRST** switch leafs...! AKA the ones pressed by the rubber...!

....so OF COURSE nothing happens when those are connected to the middle leaf, being the leaf for the 500 relay...

...because nothing is powered until they both touch that last leaf - the POWER wire - and then boom!

Meanwhile... if those "first two" leafs are touching one one side, then yeah... power flows shorted to the untriggered side. And if the leafs are shorted on both sides, well...

My god I feel so stupid... but the Make-Make switch in this case kept confusing me because I've never had to pay attention to one and kept thinking "well all this is supposed to do is advance a bonus, and that happens when the last two switches touch, just like a normal standup" and in my head that's what was going on.

But no - it's all right there in the photos and schematic. Ugh. Suddenly everything about this makes sense.

It's 1:30 am here and now I can go to sleep. Sorry for spreading confusion... but maybe we all learned something, a little but, maybe....?

#26 6 years ago

GIC

goingincirclez

But in my defense.... ugh... the way the schematic is drawn, and as we tend to follow them, it reinforces a set of false assumptions. Such as which blades are which, because of course the Advance Relay leaf and the Power leaf on a switch would be next to each other as shown... because that's how every other switch works right?

And the 500 leaf and the power leaf would be next to each other the same way, right?

And because a shared Make-Make gives you just 3 leaves and not 4, you might think the power leaf (yellow wire) is the middle one... indeed, just as it's drawn.

But it isn't!

So here is the "Corrected Incident Schematic" showing how this all went wrong on a short. Remember the yellow wire for power is actually on the LAST leaf in the stack. So neither relay fires until all 3 leaves touch. The first two leaves touching create the short shown below. And now you can see how such a short would bridge a connection to the triggered L or R side, bypassing the Change Relay M/B swtich.

GPStandConsolSchemLabeledCorrect (resized).jpg

Turns out my original observed theory / explanation wasn't really so wrong after all - there IS an "alternate path of sorts through the 500 relay" (to be fair though, it's not through the *relay* as much as its associated switch) - but I couldn't fully understand or conclusively explain how or why until now.

Lesson from all this: sometimes schematics... lie...? (Pay attention to wire color location, and think outside the lines)

#27 6 years ago

rolf_martin_062

Inactive member

Aarau

9y 59,550 4,150 14 8

Hi goingincirclez
I was working on my JPG (I show here in this post) --- in the meantime You made post-26 - I do not like to do drawings and then not posting --- so I do post.

There is no reason to blame Yourself --- it was a tricky fault. As far as faults can be beautyful: This is extra-ordinary beautiful. In my fake drawing I left-out the stuff "Spinner / Change-Relay". Greetings Rolf

0Grand-Prix-Work-37 (resized).jpg

#28 6 years ago

MarkG

Quoted from rolf_martin_062:
There is no reason to blame Yourself --- it was a tricky fault.

I agree with @rolf_martin_062. This was really tricky. It took multiple sets of eyes and multiple clues to suss out. I didn't see it until you posted your schematic and photos in reply #20 when this jumped out at me:
Grand Prix make make switch (resized).jpg
This is what screamed out to me, "yellow is in the middle".

Quoted from rolf_martin_062:
As far as faults can be beautyful: This is extra-ordinary beautiful.

I agree with this too. Very cool bug.

#29 6 years ago

MarkG

Quoted from HowardR:
Williams saved the cost of 2 relays by using these make/make switches. And re. having the L and R relays fire the 500 point relay, not so good for the spinners or top eject hole.

You're right of course. Having one relay close the second relay only works in the simple case where all events that advance the bonus are worth the same number of points. That solution falls down when you add events worth different numbers of points, or spinners that allow no time for something like 500 points to be added. In that light it's a pretty elegant solution. I should have expected nothing less from a Steve Kordek design.

#30 6 years ago

rolf_martin_062

Inactive member

Aarau

9y 59,550 4,150 14 8

Hi goingincirclez +
maybe a true story - maybe a fairytale ?

Back in the old days - in 1976 when Williams designed the "Grand Prix". They made a prototype - played it and said: Oh - poor us --- the left and right Stand-up-Switches both advance both (left and right) bonus. We mounted simple two-blades standup-switches - the feature we want does not work with these two-bladed switches.
Hey --- didn't we invent on "Space Mission" an UNIQUE Tilt-rollover-feature*** --- there we had to mount an three-bladed Make-and-Make-Switch --- common-wire-yellow on the first - the first-moved blade. Then on second blade the UNIQUE Tilt-rollover-feature*** (secured / put out of order through an switch opening on Ball-Index-Relay - when Ball-Index-Relay pulls-in) - then third blade to make an bonus.
Hey - lets mount on Grand-Prix also three-bladed Make-and-Make-Switches on the left and on the right. O.K. - they mounted - played the pin and the feature "left and right separately" worked --- but grumble - a grace shot closing only blade-1 and blade-2 (but not both also closing to blade-3) the player gets half of the feature - depending on how we wire blade-2 and blade-3 (blade-1 has / had wire-common-yellow): The player gets on a grace shot either "making 500 points" or then "advancing on the bonus".
We want "all or nothing" we want "BOTH subfeatures or NONE" --- lets move the common wire yellow to third blade and the two feature wires on blade-1 and blade-2 --- and we have the "all or nothing, both or none".
And to veil / obscure / conceal what we did: We draw on both sides in the schematics two two-blades switches - nobody will realize - nobody will ever complain.
And then came goingincirclez and bought new rubbers. End of story / fairytale.

I show the situation in Space Mission --- (rightbound) first blade must have wire-common-yellow. Wire-color-w-b-7 must come second for to eventually activate the UNIQUE Tilt-rollover-feature*** and then third comes the wire-color-blu-w to actuate (in normal play) the Bonus-Advance.

About two months ago I said: My Space Mission plays nice --- I want it perfect / tuned. I always had the idea: When the ball rolls up on the left lane - not completely up - but up enough to actuate the rollover - grumble, I sometimes do not get my bonus advance.
I opened the pin, had a look at - learned about the threebladed switch and the two features --- decided "I do not want the UNIQUE Tilt-rollover-feature*** - I change the setting - I only use it as an twobladed switch for the bonus advance. Shame on me --- reading and writing here in the topic: I did not remember "my Space Mission three-bladed switch" ...

Today I looked up on my Big Deal --- there is NO UNIQUE Tilt-rollover-feature*** implemented - a simple two-bladed switch is mounted - for the Bonus-Feature.

"Aztec" is the same as "Space Mission" - ALSO an threebladed switch for UNIQUE Tilt-rollover-feature*** plus "regular bonus advance".

UNIQUE Tilt-rollover-feature*** --- on Grand Prix http://www.ipdb.org/machine.cgi?id=1072 ipdb has some text on this UNIQUE Tilt-rollover-feature*** - we can click onto and we land here http://www.ipdb.org/glossary.php#Tilt_Rollover some text and a link to http://www.ipdb.org/search.pl?ft=tilt.rollover&sortby=date&searchtype=advanced - two SS pins and the Grand Prix and the Liberty Bell and the Hot Tip.
In the ipdb-list missing are Space Mission and Aztec --- maybe because the UNIQUE Tilt-rollover-feature*** is hidden / covered by the "Add bonus feature" ?
Greetings Rolf

0Sp-Mi-Work-20 (resized).jpg

#31 6 years ago

GIC

goingincirclez

Rolf,

You know it's funny: I was ruminating much the same as you, wondering if the game was designed and built in one straightforward way... and then certain play conditions were discovered, or modification desired, and then they decided to modify it (make-make standup) but didn't really change the schematic comprehensively. The interesting thing to me is the GP plays 100% fine with the "silent standby short" and for some players, maybe advancing both bonuses would be desired.... but it's obviously more challenging with them separated. And it's interesting to see how relatively easy it was to separate them after all.

The more I dig into EM's, the more I love them. Having to deep-dive and figure things out like this gives me new appreciation for the engineering genius that went into them. I told a friend it's fun to break the "mechanical computer" metaphor down further into subroutines. Each component is a mechanical code block: a Match Unit becomes a Spinner Unit becomes a Side Alternator; a Coin Unit becomes a Player Count unit... and so on. The mech labels themselves aren't as important as what they're actually doing.

Oh, and THANK YOU for explaining what that "mystery rollover" in the top left arch is! "Tilt-Rollover": I never heard of the feature, and I never would have guessed its need, much less ever have tried to test it in that specific condition. Glad it's nothing I need to be too worried about.

Again, the guys that designed these things were geniuses...

2 months later

#32 5 years ago

MarkG