EM Pinball Scoring without Chips with Mark Gibson

Pintastic Pinball & Game Room Expo·video·51m 41s·analyzed·Feb 7, 2025

Analysis

claude-haiku-4-5-20251001 · $0.024

TL;DR

EM pinball scoring explained: electromagnets, relays, and circuits without chips.

Summary

Mark Gibson delivers an educational technical presentation on electromechanical (EM) pinball scoring mechanisms at Pintastic Expo, walking through the physics of electromagnets, relay circuits, score reel mechanics, and the lockin circuit logic that enables games to track and award points without digital chips. The presentation layers complexity from basic electromagnetic principles to practical circuit examples demonstrating how EM games calculate bonuses, handle carries, and reset scores.

Key Claims

EM devices rely on motion to perform computation—they open and close switches and evaluate circuits through mechanical motion, unlike solid-state games where motion is primarily for ball control and toy activation.
high confidence · Speaker explicitly contrasts EM computation methods with solid-state architecture early in presentation
Score reels advance one step per pulse from the circuit; to score 50 points requires five pulses, which are generated by the score motor's multi-nib cams firing in sequence.
high confidence · Detailed circuit walkthrough and animation demonstration of 50-point scoring mechanism
The score reel only advances when the solenoid coil power is cut and the spring relaxes—holding the switch closed does not advance the reel.
high confidence · Live working model demonstration where speaker holds button and reel does not advance until button is released
Lockin circuits use a second switch path to keep a relay active indefinitely after an initial pulse, allowing the game to 'remember' that points are owed until a release switch opens the circuit.
high confidence · Detailed lockin circuit explanation with specific example of earning extra ball and remembering it until claimed
Every score reel has at least one, usually two, zero-position switches that identify when the reel reaches zero, enabling the reset circuit to know when to stop advancing each digit.
high confidence · Reset circuit walkthrough explaining how multiple digits require different numbers of pulses to return to zero

Notable Quotes

“Electromechanical devices require motion right—they rely on motion to actually do the computation, to open and close switches, to make things and to evaluate circuits in the game.”
Mark Gibson @ ~1:00 — Core foundational principle distinguishing EM from solid-state pinball architecture
“Once a magnet has stuck, there's no elegant way to pull that apart—you get to do it once and you're done, game over. So we need a way to control the magnetism so we can actually do it more than one time.”
Mark Gibson @ ~3:30 — Explains the necessity of electromagnets over permanent magnets in EM pinball
“The score reel doesn't actually rotate until the plunger is allowed to relax—until the coil relaxes and the spring pulls that plunger back, and that's what walks the score reel forward.”
Mark Gibson @ ~14:20 — Critical mechanical principle for understanding score reel operation
“It doesn't advance until I let go of that button—if I hold it, the score wheel doesn't go anywhere, and it's not until I let go that it advances.”
Mark Gibson @ ~16:30 — Demonstrates the release requirement for score reel advancement with live working model
“This is electrically how you carry the one and get the next column to advance—when you add numbers on paper in school and carry the one, this is the electrical equivalent.”
Mark Gibson @ ~21:00 — Explains the carry mechanism that allows score column overflow
“The lockin circuit is a fundamental circuit that's used over and over and over again in EM games—it's important to understand how this works to get past the simple circuits into more interesting circuits.”
Mark Gibson @ ~28:15 — Identifies lockin as essential building block for EM game logic
“The score motor always steps through 180 degrees to what's called the home index position and stops whenever it gets to that position—some cams fire once every 180 degrees, others fire five times in 180 degrees.”
Mark Gibson — Explains the score motor's variable pulse generation mechanism

Entities

Mark GibsonpersonPintastic Pinball & Game Room ExpoeventWilliamscompanyValleycompany

Signals

?
community_signal: Stern Pinball / pinball community is actively preserving and sharing EM technical knowledge through educational presentations and hands-on learning opportunities at major expos
high · Educational presentation at Pintastic Expo with working models, booth inspection opportunities, and website resources for continued learning
?
community_signal: Educational tech and historical knowledge sharing is valued in the pinball community as a way to deepen understanding of the hobby's technical foundations
high · Full technical presentation dedicated to understanding EM mechanisms without digital computation; audience engagement and invitation for hands-on learning

Topics

Electromechanical pinball scoring mechanismsprimaryElectromagnet theory and designprimaryScore reel mechanics and advancementprimaryRelay circuits and lockin circuitsprimaryScore motor operation and pulse generationprimaryBoolean logic in EM circuitssecondaryPinball history and design heritagesecondaryEducational outreach and technical knowledge sharingsecondary

Sentiment

positive(0.85)— Speaker is enthusiastic, patient, and encouraging. Positive engagement with audience; invites hands-on learning and interaction. No critical or negative sentiment; purely educational and constructive tone.

Transcript

youtube_auto_sub · $0.000

uh well thanks for coming I appreciate you're taking the time on the morning um I want to just walk through um some background to get you to the point where you might understand some of the circuits that drive the score reels and um we'll start with the very Basics and I hope to pick um add complexity in layers and at the end we will understand how this game scores how it resets how it adds multiple points things like that uh and this device will be available for your inspection uh for the rest of the weekend out on in my booth along with a lot of other gadgets that I brought with me um so with that let's Jump Right In um I want to point out um so electromechanical devices or games require motion right we talk a lot of uh solid state games you have motion but that's primarily to kick the ball around and to activate the toys and things they don't require motion to do comp computation electromechanical devices uh rely on motion to actually do the computation to open and close switches um to make things uh to to evaluate circuits in the game so we have to understand how that motion is created to get to the root of how these things are working um so the question is how do we create motion um in in electromechanical device um so uh we could use magnets right maybe you've seen this picture in a former life and when middle school or something this is just a bar magnet and this is showing you the magnetic field lines that surround the magnet uh this is just a cross-section right those field lines surround that magnet kind of like a a donut would and uh if you were to slice through that doughnut this would be a picture you would get if you ever took a a magnet and sprinkled iron filings over it you might end up with something to look like that uh the way to read this is It's like a topographical map right the strength of magnetic field that's created by this magnet is is stronger where these lines are close together so on a topographic map when the lines are closer together you you on a steeper pitch uh and where they spread out on the sides and above and below this thing there it's a very weak very gradual magnetic field uh so when you attract something to a magnet you're attracted to the poles because of this density the fact that these lines are closer together and if you're ever uh to take a a a compass and get it anywhere near this magnet the compass would align itself with the nearest line so uh that's how compasses work when you're hiking right Earth is magnetic and it's picked up on one of these lines and it's just aligning itself and pointing towards the North Pole um but the problem with using magnets to create motion right once something has stuck once a magnet has stuck on an Armature or or or plunger or something there's no elegant way to pull that apart you get to do it once and you're done game over right so we need a way to control that magnetism so that we can actually do it more than one time have thing repeat so what about electromagnets um electromagnets uh are the final answer that's what we're going to get to but how do they work how do we control the magnetism that's coming out of device um and so I'd like to show a couple videos here to try to explain how that works so what I I'll show you here is uh an animation that looks like a just it's a piece of solid copper wire and I will put electric current through that wire and what you'll see is that as the current flows through that wire an invisible magnetic field forms around that wire along the entire length of the wire and it has a direction just like the mag the poles on your your bar magnet the problem with this is that as cool as it is it's there's no way to control this it's it's uniform across the length of that wire so there's no way to attract a plunger or an Armature to one section over another section it's it's uh it's consistent across the length of that wire and it's also very weak there's not enough magnetic field here to really work with so but it's a first step right it's a way that I can create a magnetic field by um and and have it under my control if I stop that current the magnetic field dis disappears if I would take that same piece of wire and I build a loop with the wire and send the current through it the same magnetic field forms but inside that Loop suddenly these magnetic field lines get a little bit closer together they're kind of concentrated sort of like a lens concentrates light a loop like this concentrates these magnetic field lines so now suddenly I've got a place where you know it's pretty uniform along the length of the wire but right inside that Loop the magnetic field has gotten a little bit stronger because I focused it in there all those lines sort of combine together inside so that's the next step it's not we're not quite there yet this is still pretty weak and and there's not much I can do with just that but the next step would be what if I were to take this Loop and stack up several Loops above it right I can add add all of the magnetic field lines from each Loop and they combine so as current goes through this thing the magnetic field lines are focused on the inside right does that make sense um so now this starts to look like the bargain magnet I showed you a minute ago right this is the magnetic field um and I can control it now by sending current through that or not sending current through that um and this is the basis of all of the electromechanics IAL devices all the solenoids the relay coils anything that creates motion is created by this electromagnet uh and which has a magnetic field that I can create or make go away or create go go away as I as I want to so if I have this ability now to fabricate a magnetic field out of thin air right how do I control it well I can take that mag that electromagnet and and give it a power source and a switch and that now allows me to uh control the current that's going through that device um when I I want right now this is uh the switch here at the bottom is shown it's open so there's no current flowing through here but when I close that switch um I create that magnetic field which looks just like the one on on the magnet so now I can have that magnet activate and deactivate activate and deactivate as that switch opens and closes okay does that make sense so all right so now I've got a a way to create a magnetic field but now I've got to figure out when to actually activate this thing and when to let it let go uh and that's done with switches obviously right we're going to open and close circuits to allow current to flow through that thing uh and there are several varieties of switches that are used but these are the most common ones they're normally open switches and normally closed switches uh on the left are the schematic symbol for them and the arrows are meant to show you how that switch is activated either by a relay or by a stepper or some other device the out hole perhaps um activates this is the direction that the switch would be activated in and now I can control the current that's going to go through that that coil most of these devices uh that use coils are going to use the magnetic field to pull something in One Direction um but it's going to be a spring that actually pulls that device back to reset it in the other direction so the the uh the magnetic field only works one way and then I rely on a spring so as as that M magnetic field pulls a plunger or a relay or something it's actually stretching out a spring and putting energy in that spring so when I cut power to that coil uh that spring is what's going to pull it back to its steady or reset position but just having a single switch and a coil isn't terribly interesting what gets interesting is when I start to combine these switches in various patterns and that's what determines the behavior of your game or the behavior of the the devices you're trying to control um so here is a a contrived example where I have a bunch of light bulbs and I have a power supply this is a Transformer at the bottom um and I just have different kinds of switches in different kinds of configurations uh and all these lights are going to turn on at different times based on the combinations of switches that I've used uh at the bottom of this picture uh there are they could be targets they could be relays they could be steppers it's just a device so I have an a device and a b device and when that device activates it will flip all of the switches on that device so if I um can I get over there can I get the whole slide please yeah there we go right so if I activate a down here then all of these switches are going to change from whatever state they're in to the opposite state right switches only have two positions same thing with B if I activate B it will change all of these switches together all right so maybe they're all in this maybe this is a relay and all these switches are stacked up in the same relay well if I just apply power to the circuit the way it's shown right now only some of these bulbs are going to turn on and these are these bulbs kind of represent what's called Boolean logic right they they are the the basis of of computation so the first one for example that bulb would only light if both A and B devices are active okay and I can walk down through that table and get the different uh functions um and I can make these arbitrary arbitrarily complex so if I apply power to the Circuit um I only get two of these bulbs on right because those are the only switches that provide a complete path for the current to flow through right so I get the A and B and the a nor a n b and a nor B because the neither a or nor B are active at the moment they're both false essentially but now if I activate the a device all these a switches are going to flip and I'll get a different set of bulbs coming on I now I get a or b lights up because a is true right uh B is still false so I'm getting a different combinations of functions if I turn B on I get still a different set of of Lights coming on at the very top now I've got a and b is on because I've got both a and be active at the moment um and then if I turn a off and leave bit on I get still different combinations of switch uh different combinations of light bulbs that are active based on those switches so this is just meant to give you a flavor I can build arbitrarily complex behaviors and functions just by combining more and more switches in different configurations uh and build up an arbitrary bonus count or an arbitrary reward system on a game um so let's look for a minute uh what what is controlling these switches all right we uh let's have a good look at a relay so this is a B relay um and the relay is built of a coil and and a set of switches uh and an Armature so the coil that we talked about earlier the electromagnet is the the the coil in red here um is is what's going to make this thing happen right what's going to make the relay activate and the switch is maybe open or close we don't really know we don't really care but the point is when that coil activates all of the switches are going to flip to their other state they're e they will either open or they will close when that relay activates so when I put current through that coil I'm going to get this magnetic field I talked about a minute ago right so the maget magnetic field forms going through the coil like that um because that's the byproduct of putting current through that coil so now that I've got this magnetic field magnetism attracts Iron and Steel right so it's going to want to pull down on that um Armature piece which is can I reach I don't know where my mouse is well the top plate there at at the top of the coil is going to move down and that's just enough motion that it's going to activate all of those switches right so if I just put this in motion every time that coil fires you put current through that coil the magnetic field appears and grabs that Armature and pulls it down that's what's changing all the switches in that relay um and when the co when the current is cut through the coil the spring is what pulls it back up and allows all those switches to relax okay and if you worked on any Em games you you've probably seen what a switch what a relay looks like when it's activated right it's just open open and closing as I'm putting current through that coil so far so good all right let's look at something that's a little bit more complicated all right let's this is a score reel and the way the score Reel Works is it's you know there's a big frame and there's a a wheel that turns with numbers on it um let's see there it is okay so there's a tooth gear that lives underneath this the the score reel disc uh and there's a sort of a rack and pinion Arrangement here that slides in and out of this coil and every time that thing pulls in um it stretches this spring here and arms that score reel and it's not until the the solenoid or the score reel relaxes that the spring pulls forward and that's what rotates your score reel okay so I have the same coil again the coil is a bit stronger there are more Loops going through it it there's more power going through it it's it can pull more than just a little Armature it's pulling an entire plunger and everything that's tied to it so when I put current through that coil I get my magnetic field again just like the relay and what's going to happen is it's going to pull that plunger right into the coil that's going to stretch the spring and drive that uh rre and pinion forward and when I cut power that is when the score reel will advance and and this is what it looks like in animation right that that rack and pinion is moving back and forth every time you want to get another Point added and this will only take a single step every time this thing fires right so if I want one point I fire it one time if I want five points I have to do this five times I have to repeat it again and again okay and this is what this looks like in real life if you pay attention you can see that the plunger pulls in but the score reel doesn't actually rotate until the plunger is allowed to relax right until the coil relaxes and the spring pulls that plunger back and that's what walks my score reel forward okay so let's go back to the Circuit side of the house uh this is a trivial example I've got um let me walk through this a little bit so this is a Transformer here um this is a relay coil okay um and this is a a Target um a switch that might live behind a 10-point Target okay so and this is just representing the target itself so when the ball hits the target this switch closes it completes the circuit I fire up that relay the relay is going to send power over to my score reel and this this is the schematic symbol for a step unit which is basically what score reel is um and it will activate the the uh the coil on the score reel and then when the circuit uh when the switch opens the ball rolls away the switch opens that's when the magnetic field disappears the spring does the work of pulling it forward so if I walk this forward now you can see every time I hit the the target the target turns green the switch closes sends power through the whole Co the whole circuit but it's not until the power goes away that the digit actually rotates to the next position any questions no good all right oh and so now I should point this out so this is the working model of what you're looking at right so I have a Target here that's represented by a button okay it's just a single button there's a switch underneath it when I close the switch the score reel advances um and it's doing exactly what you're looking at the animation here I should have given you a heads up do you want us and you'll notice that it doesn't advance until I let go of that button right if I hold it the score wheel doesn't go anywhere and it's not until I let go that it advances okay I'm going to do two or three of these here in a minute one after the other all right so that's this is what that circuit looks like when it's running that make sense okay good good good so that's one way I can advance a score reel okay that's interesting um but there's another way right that uh maybe I don't have a target maybe I'm a 10-point score reel and my neighbor in the onepoint score reel has walked up to nine well something has to happen to carry from the nine to the 10 so there has to be another circuit that behaves slightly differently that's going to allow that carry to happen when you add numbers on a piece of paper right in school you were doing it on paper da and carry the one well this is electrically how you carry the one and get the next column to advance okay so at the very top up here uh this is the same switch we were just looking at right I've got a Target that's worth one point every time I hit it I I complete the circuit through the one point relay um the onepoint relay now is going to close the switch down here in the circuit to the 10-point relay okay so every time I get one point this switch is going to close uh but there's a second switch here that's only going to allow that circuit to take effect if my onepoint score reel is at position nine so so the first time I hit that Target right I get a path through the top coil and that notice the switch in that second circuit is also closed it's trying to let current through but because that 9po this switch hasn't closed yet because I'm only at seven and when I kill uh when this top switch opens up everybody relaxes and I roll forward to eight and I can do it again and I activate the circuit I'm going from 8 to nine uh it's just like the previous one I end up at nine okay the next time I hit that Target um I'm going to close both uh complete both circuits now so you can see that not only the onepoint circuit but also the 10-point circuit is complete so now both score reels are primed and ready to walk forward and when the when the T the switch finally opens up both score reels walk forward one position good and I'll show you how that works um so there's a ninth position switch that's back here and when I walk forward uh eight and when I get to nine one of these switches is going to change and that will allow my carry and I encourage you to come back by afterwards and do this for yourself it's way better in person okay so that's how those two circuits are working together and step away from score reels for a minute and talk about a lockin circuit uh this is a fundamental circuit that's used over and over and over again in um Em games uh and it's important to understand how this works to get past um the simple circuits into more interesting circuits and the way this works is that there are two paths um here we go so I have one relay coil just like before and I have a Transformer just like before um I have one switch which I'm just calling activate it can be anything it can be a Target it can be re another relay uh but this top circuit is the one that's going to make this relay fire the bottom circuit is what's going to keep that relay fire uh active after this switch disappears so what happens is that this switch closes fires this relay um this relay is now going to close this switch and this switch is already closed right so as soon as I apply power I'm getting uh both circuits are active keeping that coil going right but now this might be a uh uh um the activate Target might just be like a onepoint Target on your play field well that just closes momentarily and the ball rolls away and that switch opens up again okay but in if you're using a lockin circuit like this as soon as that ball rolls away the switch opens on the top path but I still have the bottom path that's going to keep that relay active and it will keep it active indefinitely right until something else comes along and opens up this second switch and I just represented that here with another Target so maybe there's another Target on the other side of the Playfield maybe extra ball right maybe the the upper path is you've earned extra Ball but I have now the game has to remember that indefinitely uh until you use that extra ball and that's when this thing would open up and allow um the circuit to relax okay so that could be seconds or minutes right and then when that release switch relaxes then everything is back to normal and waiting for the next activation yeah okay so lock in is going to be become important here in a minute let's talk briefly about a score motor uh so a score motor this is a picture of a uh a valley uh score motor um Williams used a very similar design uh these cams rotate um towards you in this drawing um these little nibs Will Roll by and and bounce the switch Stacks that are mounted to the top of the score wheel uh to the top of the score motor right but notice that the the little nibs are all in slightly different positions so these are firing a little bit like the Pistons in an engine in a very spec specific sequence uh and a very specific timing relative to each other um and notice at the back end here there are some cams that have multiple nibs on them so when the motor turns um some of these will fire once every 180 degrees some of these switches are going to fire five times in 180 degrees okay and for those who haven't seen it this is a William motor operating um and it always steps through 180 degrees to What's called the hmer index position and it stops whenever it gets to that position but if you look at the cams on the left they're activating their switches one at a time and just once per half rotation uh the two cams on the right side to the right end uh those are activating multiple times every time this motor runs so that's going to be the key to how I get from uh uh one event to multiple events I have to engage the score motor so the a classic example of of how all these pieces work now is how do I score 50 points okay I have a Target that's worth 50 points the ball closes a switch very briefly so I have one little pulse that I can work with and now I have to get five pulses into my score reel because I only get it to advance One Step per pulse so I have to go from one pulse to five pulses right how is that done um so let's work down from the top this is the uh the 10-point relay we were looking at before and there's a Target here uh that gives me 10 points terrific so that's for the scenario where I just you know one pulse gives me 10 points one and done right but there's a second path now into this 10-point relay that uses a switch on the 50-point relay and it's using another switch over here which is tied to one of those cams on the score motor that's why there's a circle around it so this switch is going to close uh five times uh every time the motor turns and if you look this this chart here on on the left this is showing you the pulses that the score motor is throwing out as it's rotating it's like a if if you were to if you've ever seen a player piano roll right those the holes tell the notes when the fire uh that's kind of what this is showing you or if you took that score motor and and Inked it up and rolled it out over paper you might get a pattern that looks a little bit like this it's showing you exactly when those pulses are in time so the top cams are all firing just once per the 180 degrees but the last cam or two those are Ro those are rotating through 180 degrees but firing five pulses 1 two 3 four five if you've ever listened to an em game reset right d da da do dot dot do dot dot dot do do dot do dot those are the five pulses that come in Chains like that all right it's endemic to all the Em games they all do it so uh the way this works is uh so the top path here gives me one point or or 10 points the second path is what's going to give me 50 points the five pulses are going to walk through there um down here I have a Target that's behind a switch that's behind a 50 point target that will close this uh switch here this is my lock in circuit right I uh I've got one target that's going to fire this 50 Point relay and then I've got a second path that's going to keep that thing on for some time until there until this switch opens so this second piece here is a lock in circuit that's going to remember I owe you 50 points and I can't let go until I've given you those 50 points and the bottom down here is the the score motor so it starts up whenever the game recognizes that it has to deliver 50 points so I can put this in motion now and we can see what's going to happen is that you're going to get a little uh sort of a radar display walking across that chart which represents time as it's going by it's going to show you what switches are opening and closing um so let's do that so it starts off um and you can see down here the 10-point relay fires every time I'm going over one of these bumps okay because my 50o relay this is awarding me 50 points it remembers it has to remember the whole time and that's that's what's keeping my score motor running so the motor runs through an entire 180 degree cycle U and it's throwing out these five pulses that are ending up in my 10-point score reel they're taking five discrete steps right and the motor runs until the very end which uh this switch that lets the motor stop is way at here on the right side it's it's after those five pulses had gone through I say okay I've given you my the 50 points I owe you I'm done I can let the motor stop um and this just Loops through showing you the same thing again and again does that make sense basically how that works so there's there's basically you know I owe you 50 points and I have to remember and the score motor is going to send pulses um and it's the key is this uh this switch here that says um let these pulses through right so it's not every time that the score motor runs I mean the score motor can run for other reasons uh and these pulses are going to come through this switch but it's only if I actually owe you 50 points that it gets through both switches right so um another interesting thing the score reel has to do is at the beginning of the game you have to get back to zero right I've shown you circuits that Advance the score re right oh and let me show you the 50 point um how the 50 point works right there's an extra relay here there's a something here the 50 point relays here and it stays on for the entire duration to keep that score motor running in fact I'll just let you hit that button and you can frame frame it any way you want so one of these is chattering one of these relays is firing my 10o relay and the other one is staying on right and it's staying off for the duration until it knows that the the 50 points have been awarded okay all right thank you resetting back to zero um so there's a little bit more complexity here uh we're kind of sneaking up on it so at the beginning of the game all the score Wheels need to come back to zero so I can't just keep throwing arbitrary pulses at my score reel because it it would just keep rolling forward so there has to be another piece of intelligence in there another switch somewhere that says how far to roll forward uh and it turns out that every score reel has uh at least one usually two switches on it to identify when it gets to zero um and if we walk through this circuit um again the Transformer up here uh this is the score motor that will start running uh when the reset relay f so when you start your game with a replay button or you drop a coin the first thing that happens is that the reset relay fires and resets your score reels and your bonus count and and uh trip relays and all sorts of other things so the reset relay is the is the cop who says I need to keep going still not done with reset um and this is the circuit here for the reset relay down here and it starts with a start button and then this whole business down here this is the lockin part of the lockin circuit and that will keep this reset really active uh until all the work is done uh notice here that there are two switches um that say that that are um closed when the score reel reaches zero um no they're open I'm sorry they're open when the score reel reaches zero they're closed otherwise um so when I anim this uh we'll see that there there's two different values on my score reels right so they're going to want to take different numbers of steps to get back to zero the the ones digit here is going to stop it only gets three pulses before its um zero position switch opens up and it and it won't walk past that and it's the second score reel that requires the motor to go through a second cycle it's keeping the reset relay active and it's going to make the motor go through a second uh 180 degree cycle here to get the last couple of pulses to get it back to zero and maybe what I'll do is I'll play that again if that helps and these animations and a lot like them are all on my website um along with a lot of devices that look a lot like this one um with much better and more thorough explanations of how they work but what my motivation here is that I want you to come back to the booth and pick up a score reel and figure out you know where the ninth ninth position switch is where the zero position switches are things like that see if you can if you're not familiar with them already figure out what switches are doing what and how they're are used in these circuits uh because they're common to all of your score reels um and then I the last thing I'll do is demonstrate that here the last button is the reset button and it will walk through however many digits it needs so that the middle score reel here is showing a nine let's put one here uh so this only needs to take one step forward um this one only needs to take nine steps forward and this one will need to take uh six steps forward right so there their zero position switches are all going to change at different times as this motor is running and they will stop independently question and that is because you shut off the carryover circuit so you don't have to worry about if you gave extra pulses to the T because of the carryover for yes the carryover I I sort of simplified that circuit a little bit there is the carryover circuit is smart enough to recognize that I shouldn't be doing this if we're resetting so it it there's another switch that I did not demonstrate that will keep that makes these circuits exclusive okay so I go ahead and hit that last button okay and we can do that a couple times try that again so all the circuits we've talked about are represented here on this board and again I invite you to come out and try them for yourself see if you can identify which is which which is uh the reset relay which is the 50 point relay Etc uh and please come come by and ask any questions you have that's what I've got okay uh there there always questions online about why is my score reel doing this and I think you've got the whole chart here of you know the Reel keeps turning around when I'm resetting or uh the points don't I can hear a relay clicking but the score reel doesn't step and each of these switches explains each of those different problems yeah so when you have an issue when your score wheel or your motor isn't behaving as it should it helps tremendously to understand how it should work and then try to imagine a scenario where it would you know maybe my my score never carries over right well you might remember well there's a switch in there that that has to happen has to close to make that carryover happen right I know my score reels work independently so the coils must be good but there's something broken in the communication between the two of them and so that might help you narrow down uh to one or two switches uh once you get a handle on looking at your schematics and understand you know same thing with reset you know trying to understand what parts of the uh um you know what what is the mechanism that gets those pulses into my score reel um and what how does it know when to stop things like that and that will help you zero in on on a schematic and then you can just go and find those switches in the game and try to see if they're working properly question how does m stop how does a motor know when to stop turning excellent question so um let me back up and um maybe I have a picture of that yeah so look carefully at this drawing uh this is right out of a parts catalog thank you um notice how most of these drums or most of these cams have nibs on them right so the nib goes under the switch stack and bumps up the switch the first one actually has a gap instead of a bump so that's kind of working it's letting its switches drop um instead of raising them up well this first cam is used among other things to keep the motor running to the next Gap in that cam so once I start this motor um I can actually even just push this coil forward uh usually it's a circuit that electrically gets the motor to start but I can walk this forward enough to activate this first cam or this first switch here um and the motor knows that it has to run forward to the next home position the motor can't just stop arbitrarily it has to be ready for the next computation the next bit of math uh you may notice for example um a lot of em games have uh targets that say you know blah blah blah when lit and that light will often go off when the motor is running that's because the motor is committed to doing some calculation and it can't start a second calculation until it has finished the first one so it disables some of the more elaborate things on the game while it's doing the math to figure out what it owes you and when it gets back to the next position it's ready to start the next thing whatever that is how about since people always ask about the uh I'm resetting and it doesn't stop resetting whe keeps turning I think you the score wheel or the motor score and the motor so the motor score right so the motor you know it common complaint my score motor won't stop turning and there are a lot of reasons that the score motor turns right it'll turn for 50 points it'll turn to count of bonus it'll do all sorts of things uh is used for all sorts of things but during reset right um I mentioned that there's zero position switch uh there actually two of them one of them i' I showed um blocks uh one of them I mentioned blocks any more Pulses from walking the score reel forward right um so if I'm using the reset circuit it's going to go through a switch that says well don't take any more pulses once I reach zero okay that's one zero switch it turns out there's another zero switch that talks to my reset relay and the reset relay needs to hear back from all the individual score reels and it will uh until it hears back from each one it says well somebody out there still hasn't reset so I'm going to try again and send it through one more cycle here and send it another five pulses see if that'll get it to zero well if the motor keeps running it might be that one of these score reels has not reported home again right um you and you might think that's a bug you might think well why doesn't it just send out 10 pulses and stop right uh and that would work on a new game but an older game that has some wear or some dirt maybe you have trouble getting past nine into zero and maybe it takes three or four tries well that's why the motor keeps running it says well okay I'll give him a second chance I'll give him a third chance and eventually you know for a while it will walk to zero eventually if you give it enough pulses uh so I think that was done by Design uh to keep the motor running until it has seen from each individual score reel that they're all back at zero what else what else do we often hear well I don't know if we of here I was asking about the the score motor chart that you posted that's on the schematic is that are those uh position indexes on the schematic as well is that or is that something you created no that's lifted right off the drawing that's right well I I recreated it but that most schematics will have a score motor chart they don't all but most of them do and they represent the uh the pulses that are coming off whatever motor you're using the the charts will look different across manufacturers this is what a Williams uh chart would look like um but they're all they all have similar information and the key is that you know when does this thing happen in relation to that thing right and they will never swap their order so you know something that's controlled by an early switch will always always happen before something controlled by a later switch and you can sort of tell based on these uh blocks and that doesn't tell me when the switch closes or when it opens it just tells me that it changes right because some switches are normally closed some switches are normally open right this just tells me when it changes right when it changes position we can see there that the the 50 relay itself has to be done before you get near that index switch otherwise yes the 50 point relay would still be on at the and you go around again yes let me see if I some timing at end of so these are the five pulses that are awarding my 50 points right and they correlate to these they'll even turn green right when when it's activating something that block turns green and then the last one here is going to turn green all right and then it's this pulse that's later that's going to finally let my 50 point relay relax okay so I I know based on the profile of these cams that those five pulses have done their thing before I allow that 50 point relay to let go and there is no feedback me mechanism there you don't get a second third bite at the Apple to try to make sure you got the 50 points it's it's this is just one and done and it they're counting on it working properly and that's all called Boolean logic that's a latter logic that yeah so the Boolean logic is way back here right it's the the beginning it's it is used to describe the combinations of open and closed switches that you're working with right and the beauty of Boolean logic is that you can describe it in English right um that first circuit at the very top that bulb only turns on when a is true and B is true right um and the second one down is the bulb comes on when a is true or B is true they're very different things right and just by changing the configuration of the switch I can change the behavior of that bulb or that that can be a relay that can be a step unit that could be any electrical device that needs current through it right just by manipulating and changing the configuration of the switches that go into that device I can affect when it when it happens right and this can be arbitrarily complex this is this this among the simplest examples of combining switches right but if you look at a real schematic most circuits will have three four five switches um and and multiple branches right and it's the combination of those things that you have to learn to unw mind uh to figure out what makes that device happen in a big schematic you often see that they're trying to economize like there'll be a on a goly it would be a motor 1A for five pulses and there's just a whole bunch of stuff coming off one motor one a switch M so that's the branching like John Youssi on a or b is a great big Branch so that they economize on the number of switches on motor 1A and you know if you're unfamiliar with schematics they can be pretty intimidating you know it's a big a lot of wires and whatnot but I I use the analogy of you know the schematic think of it as you know you you you're on vacation you've traveled to New City and you're looking at the subway map right nobody memorizes the subway map nobody stands every stop and subway map right you care about getting from point A to point B you find them on the map and you figure out what connects those two right and 98% of the subway system you couldn't care less about you just care about getting from A to B well this reading a schematic is kind of the same way when you're troubleshooting right I I've identified something that's misbehaving I think I've identified you know the the coil or the relay that makes that misbehave so I'm just looking at how what circuit you know what are the three or four switches that make that device fire and I'm looking at a circuit that looks like any one of these lines right start there and the rest of it you can ignore for the short term right you don't have to be intimidated by the whole the whole newspaper schematic that that reminds me another thing that on P side is often U someone will say the 10 point switch is not scoring and one of us will come on and say what if you push in the 10-point relay yourself does the 10-point relay do the right thing so therefore it's not activating the 10-point relay or is it that you hit the 10-point relay and downam right so to get 10 points right there's a switch behind a Target and that fires a relay and the relay fires a score reel well initial observation is I don't get 10 points right well there's at a high level there are two circuits there so just by knowing which relay is supposed to fire I can observe without touching anything I can just observe you know hit a 10-point Target and see does that relay fire right if it doesn't fire the problem is not my score reel the problem is my relay right if my relay does fire well I know that the target can talk to the relay so I can eliminate half of my problem and now Focus why don't I get from the relay to the score reel right you divide the problem in two and see if you can isolate one from the other and and keep dividing by two until you figure out you know what what what the issue is yeah when you're troubleshooting is there like a tool uh you can use to like send send current through a part of the circuit like you just touch it yeah absolutely so if you have a a jumper wire which is a piece of wire with alligator clips on either end I can jump in there if I suspect that this switch isn't closing I could jump in there with a jumper wire and jump to either side of that switch and provide a bypass around that suspected switch well if the circuit starts to behave or behaves differently when I clip in there that tells me that my problem is between what I clipped into right so if I bypast one switch the problem is likely to be with that switch because once I remove that switch from the circuit things start to flow and that proves to me that all the other switches in the circuit are working right so that would be the simplest debug pluging tool troubleshooting tool differences between the manufacturers score are there noteworthy differences between the manufacturers of the score reels some are a lot easier to take apart and put back together than the others functionally they're all essentially the same uh they will have zero position switches ninth position switches Etc they will all have the same basic stuff but the the the the engineering and the way it was put together um got better and better I'll put it that way uh so the more modern ones tend to be easier to take apart and clean and whatnot which is going to be important to all of you at some point um but yeah there's there's certainly subtle variations and I have back at at my desk I've got a box full of loose score reels of three or four different manufacturers and I encourage you to take two of them and compare and see if you can figure out how it's done on each one yeah like a little Charter gift different like valy does Z to n one there is a chart that floats around um I've never I don't use it I tend to come at the problem a different way but um that certainly seems to help some people I don't want to have to have that with me if I'm on a job trck repairing a game and I don't want to commit it to memory either right uh because it's not just a matter of the three manufacturers but it's also different eras changed what those switches do so you might have two or three different flavors of B based on what year the game came out that's way more than I want to carry around up here I'll just look at the schematic and figure out what I'm supposed to do gotl kept it proving the mechanics of this score reel even in the mid 7s when they already knew solid state is coming and they just kept you know making the nylon thing a little better smoother acting less likely to jam up and uh the ratchets would have less we on them and so they wear out as quickly end of stroke switch I guess you know they had those real short end of stroke switches that broke off because they're just getting so much flexation on a short blade U what else the end of stroke switches is really trouble spot for a long time I I I I think of the getting the coil out and cleaning the coil sleeve or replacing the co coil sleeve some of them getting it back together is is a it's like those puzzles with blocks that only go together one way you know some of those score reels are kind of like that there's a secret way to get them back together and I don't have that committed to memory either I have to figure it out every time some of them go a lot faster than others um but it's good practice right you know um that's something you you will have to learn to do and just do it take it apart slowly and carefully and take pictures uh and then retrace your steps after you've cleaned everything uh and you'll get through it you know it it builds character right I mean if it's if it's if it's hard any other okay good thanks Mark thank you everybody [Applause]