Tilting, taking turns, and winning free games: the many tricks inside old pinball machines

How do you suppose up to four players can compete with  each other on this old pinball machine

filled with nothing but wires and relays?

Well, with wacky contraptions like this one here.

This is the player unit, and with the help of two other mechanisms inside this machine

it will alter the machine’s programming to allow competing players take turns as the game progresses.

Welcome to part three of a deep dive  into this electromechanical pinball machine.

If you haven’t seen the earlier videos,  be warned parts of this might be hard to follow.

Linky-dinks are available to find part one and two, but I’ll do my best here to lightly recap important concepts where necessary.

First, though, let’s talk about something simple.

That.

This machine has several anti-cheating measures built into it.

They’re designed to detect a player moving the machine and penalize them if they do so.

Skilled players are able to physically push the game cabinet around to keep the ball from draining, a technique called nudging.

And for the record I suck at that!

But if you’re good at it you can become much more likely to get a high score and win a replay.

Operators don’t love those - they want your quarters, not your satisfaction!

So if you get too rough, the machine will register a tilt.

The tilt light comes on, the flippers shut off,

and you’re forced to lose that ball.

Now, if tilt seems like a weird word to describe this penalty,

tilting is a very old pinball term dating back to the flipperless ball-shooting machines of the 1930’s.

As those became popular, before long they started becoming used as gambling devices.

Initially this was just the players making bets on each other but later the manufacturers started leaning into it.

The written rules of the games they sold would  soon award “credits” for certain high scores,

and the proprietor of the establishment which  hosted the games would pay those credits out to winners.

As this practice spread, cheating became a serious problem.

Especially since these early games were small and light enough that you could easily pick them up and manipulate how the balls would roll around.

So they needed a way to warn the proprietor of the establishment that the game cabinet had been tilted during the game.

In the early days there were many clever ways this was done which to save time I won’t get into

but it usually involved a simple mechanism with a precariously perched object that reset with the coin slide.

At the start of the game something like a ball would find itself on top of a stick,

and if it fell off that perch, that meant the game was tilted during play and that would void the score and thus prevent any payouts.

The early and problematic relationship between gambling and pinball led to it being outlawed in some locales for many years.

And, uh, by the way - Williams?

They still exist.

They make slot machines.

And Bally?

That name’s on some casinos, isn’t it?

Though that lineage is much murkier.

The Bally name and logo also ended up on fitness centers.

And theme parks.

And sports networks.

Anyway, pinball machines with flippers were usually earnestly meant for amusement only.

Like this one!

You can tell because it says "for amusement only."

But since you can score free games

(usually - there’s a fun legal loophole I’ll cover later)

and free games hurt the operator’s bottom line, anti-cheating measures are still in-place.

And this machine has several anti-cheating devices!

This one here is the most common - pretty much every pinball machine from the 1940’s through today has a mechanism just like this,

called the tilt bob.

You might also call it a plumb bob because that’s technically what it is.

A conical weight is suspended on a rod much like a pendulum,

and the weight rests in the center of a ring  which surrounds it but doesn’t touch it.

24 volts AC is applied across the weight and that ring,

meaning together they are really just a strange pair of switch contacts.

If someone were to start shaking the machine, the weight will start to swing and get close to the ring.

Shake it too hard and they’ll touch.

And guess what that does?

It sends voltage to the tilt relay!

If the tilt relay energizes, it locks on,

illuminates the tilt indicator,

and opens this switch.

That disables practically everything in the game  so you will instantly stop scoring points,

and most importantly the flippers are disabled  so you will lose the ball.

The tilt penalty is only the ball-in-play so unless you tilted on your last ball the game isn’t over.

But you also lose any bonus points you  might have accumulated during that ball

and even an extra ball if you managed to score one.

To pour salt in the wound, the machine still executes the bonus sequence  as normal once the ball lands in the outhole,

but the tilt relay prevents it from awarding any points

so it becomes a sadistic countdown where you watch it deny every point you had previously built up.

Once that’s complete, though, the outhole relay energizes as normal which un-trips the tilt relay and the game continues.

As you may have guessed, the weight can be moved up and down on the rod to increase or decrease the sensitivity of the tilt switch.

Stingy operators would move the weight very far up so the wider diameter of the cone almost entirely filled the ring.

But those with more forgiving temperaments might  lower it so more violent shaking is needed for the machine to register a tilt.

And right above the tilt bob it is a second tilt switch in this machine.

A ball is placed in this track which, like the tilt bob, is energized at 24V.

The track is a little knackered as the original ball is missing and this second pinball is just a little too big - but it does work.

If the ball rolls forward and touches this contact,

since the ball is energized by the track, the tilt relay will trip.

This is designed to detect that someone is lifting the front of the machine to make the playfield level and keep the ball from draining.

These electromechanical games have fairly shallow playfields

so the normal tilt switch wouldn’t necessarily swing enough to trip in that case, at least if set more liberally.

Now these aren’t the only two kinds of tilt switches out there, in fact this machine has a third one hanging on the playfield.

And there were other varieties in use throughout the years.

But before I move on, if you spied the anti-cheat switch in the schematic earlier -

that’s actually something else entirely unrelated to tilting.

That switch is normally closed and in series with the coin switches.

It lives on the coin door and you’ll notice that here it’s labeled "anti-slam switch."

This switch is there because someone banging on the coin door could cause the leaf switches of the coin mechanisms to close

and start the game without actually paying for a game.

If they try that the anti-slam switch will open to prevent a false purchase.

Later machines in the solid state era would use this switch  to trigger a slam tilt - which is a much more severe penalty.

Slam tilts end the game entirely as a punishment for someone bashing on the coin door or perhaps violently kicking the machine.

This game, though, has no ability to do that.

With the cheating out of the way, let’s talk about how this machine handles multiplayer games.

As a quick refresher, this is just a huge mess of wires we’re asking to do stuff for us.

To perform specific tasks, the machine uses the score motor which is a contraption that rhythmically actuates a whole bunch of switches in stacks.

When combined with the various relays throughout the machine  which connect those switches to other devices,

the machine can execute automated sequences.

It might perform some action multiple times, which is how targets like this award 5,000 points.

Or the switches might activate several different mechanisms in a logical sequence.

You might call that a program.

Relays aren’t the only thing which determines  what all those switches in the score motor do, though.

The game is also filled with several stepper units.

These contraptions rewire the machine based on their physical position, which will change as other actions take place.

These can be used as a simple kind of memory, such as in the ball count unit and the bonus unit,

or they might alter specific steps in the machine’s program depending on their position.

And this stepper, called the coin unit, is what determines how many players can play the game.

How does it do that?

Well, when you deposit a quarter,

the coin switches trip the coin relay

which causes the machine to reset everything including the coin unit.

Once reset, its main program loop begins and it serves the first ball to you.

And now you have a choice.

You can either plunge that ball and commit to a single player game,

or you can give it another quarter to add a second player.

If you deposit another quarter, the machine doesn’t reset this time.

Since the game was powered on by the first quarter, the now latched game over relay locks out the reset relay.

That prevents the coin relay and the score motor from resetting the game a second time and instead causes it to do only one thing:

step the coin unit up.

With the coin unit now in its second position,  the backglass indicates that two can play.

These lights are controlled with this wiper arm here, with each of those contacts wired to one of the four light sockets.

But the other wipers in the coin unit are doing something more interesting.

Through their new position, they have altered the end-of-ball sequence.

That sequence occurs at the end of a ball via the outhole relay and it has four discrete steps:

First, the score motor will pulse the ball count unit step up coil to move the game from ball 1 to ball 2.

Next it pulses the player unit reset coil which resets the player unit.

Then the bonus unit step up coil gets a pulse to  put it back on 5,000 points for the next ball.

And finally the ball release coil is pulsed  to return the ball to the shooter lane.

[rapid mechanical sounds as the sequence occurs repeatedly]

That sequence works fine for single-player games  but it doesn’t work for the two-player game we have just paid for.

After the first player has played their first ball and lost it,

step one in that sequence - advancing the ball count unit - can’t happen.

The game does need to return the ball so player two can play their turn,

but the game should still be on ball one.

To accomplish this, the coin unit serves as an interrupt.

Although the end-of-ball sequence does still occur, the coin unit will not allow the ball count unit to advance in step one.

Remember this convoluted circuit path in the schematic?

In order for the ball count unit to receive the pulse of power coming from the outhole relay,

that pulse has to make it through the coin unit.

And with the coin unit in the second position for a two-player game,

this link is moved down from here to here,

thus the original circuit path is broken and the ball count unit cannot advance.

Great, that makes sense.

But the machine also has to switch from player 1 to player 2.

How’s that happen?

Well, remember how the second step in the end-of-ball sequence was to reset the player unit?

You might have wondered what that does.

The player unit is what we looked at in the opening.

It’s another stepper unit that lives in the backbox and it’s arguably the most complicated of them all.

It’s got a TON of wires attached to it, and rather than wiper arms

it’s got a fiberglass disc with 24 spring-loaded contacts sliding over a sea of brass rivets almost like snowshoes.

Those contacts on the moving disc are simply linked together in pairs

so what they actually do is bridge together a different set of wires connected to the rivet board depending on the mechanism’s position.

Despite its apparent complexity, the bulk of this unit’s job is actually pretty simple:

there are four score displays in this machine,

but only one of those displays should have points added to it as the ball hits targets.

This device is what controls that:

the player unit connects the points relays in the  backbox to only one set of score reels at a time,  

and it illuminates the player-up light to show which set of score reels is active (and thus which player is up).

Of course, then, it has four positions - one position for each player.

Its reset position is for player one and it will  always return there when the reset coil is fired.

That was step two in the end-of-ball sequence - reset the player unit.

But at the end of the first player’s first ball, we need the opposite to occur!

We need it to step up to player two.

And sure enough, that’s what happens after the first ball is lost - with a nice and distinct clack.

[bell ringing as points are added, then several distinct clacks]

Why did that happen?

If you guessed the coin unit had something to do with it, you’d be guessing correctly but only indirectly.

Let’s find the player unit step up coil on the schematic.

Here it is.

Now, it gets its pulse from the outhole relay  and switch 2-B in the score motor but looky here,

it’s gotta go through a make/break switch in the player reset relay.

There’s always another relay.

If that relay is energized, then the player unit will reset in the end-of-ball sequence.

But if it's not energized, the player unit will step up.

So it must not have been energized during the first end-of-ball sequence.

Why not? Because the ball count unit didn’t step up.

The coil for that player reset relay gets energized by an end-of-stroke switch in the ball-count unit.

That means the ball count unit has to physically move in order for the player reset relay to energize

and cause the player unit to reset.

So do you see what just happened?

Since the coin unit just prevented the ball count unit from stepping up to ball two, the ball count stayed on ball one.

And because of that, the player reset relay could not energize

and thus the next pulse coming from switch 2-B via the outhole relay stepped the player unit up instead of resetting it.

And now that the player unit has moved to its second position?

Player two is up.

The next ball that’s played will add points  to the second player’s score reels.

And that’s literally the only difference as far as how the  game operates when the ball is on the playfield.

Once the second player’s first ball is lost,

the machine will execute the end-of-ball sequence as it always does.

But now we want the machine to advance to ball 2 and go back to player 1.

How will that happen?

You might have spotted it already.

Since the player unit moved to the player 2 position, the coin unit is no longer interrupting the ball count unit.

That link which moved down from here to here?

Well, take a look at the player unit right next to it.

When player 1 was up its link was at the top so the circuit  was broken.

But with player 2 up, the link is now in the second position.

And that matches the coin unit.

So when player 2 loses their ball,

the pulse coming from the outhole relay and switch 1-C to advance the ball count unit will now make it through.

And of course, once it does, the ball count unit will advance,

so its end-of-stroke switch energizes the player reset relay, meaning the next pulse in the sequence which comes from switch 2-B

will in fact reset the player unit back to player 1.

And so, ball 2 - player 1.

So what would happen if we gave the machine three quarters at the start for a three-player game?

Well, that would step the coin unit into its third position.

And its link as shown on the schematic moves down to here.

That means the coin unit will interrupt the ball count unit until the player unit is on player 3.

So the first player loses their ball, and in the end-of-ball sequence the player unit steps up to player 2.

Then the second player loses their ball, and the same exact thing happens: the player unit steps up to player 3.

But, with the player unit in the player 3 position,

the next time a ball is lost, the coin unit’s interrupt is bypassed.

So the ball count unit can advance as normal

which then allows the player reset relay to reset the player unit back to player 1.

Put simply, the coin unit is saying “you must not advance the ball count until the player unit has reached player three.”

And once that condition is met, the ball count unit can advance which of course moves the game along but also,

through the player reset relay, puts player one back up to bat.

Now the last thing to address here is how extra balls work in multiplayer games.

If you score one, the extra ball relay locks on.

And you may recall from the previous videos that this prevents the ball count unit from advancing so you get a free ball.

But if we look at the schematic again,

you’ll see that in fact the first and second step in the end-of-ball sequence are interrupted by the extra ball relay.

The ball count pulse and the player unit pulse both go through this normally-closed switch.

So, if it’s open thanks to you scoring an extra ball, neither will happen.

So at the end of your ball the game awards the bonus points and then simply returns the ball,

and that’s why the light on the backglass says “same player shoots again.”

In a single player game it’s just a free ball,

but in a multiplayer game it interrupts the game’s progression from one player to the next.

So, if you’ve got your head around all that, I have great news:

that’s the most complex thing in this video.

From here on out, things get easier.

And now’s a good time to explain something about pinball machines from this time period.

If you haven’t noticed it before, the playfield completely resets after the ball is lost.

Every ball begins with no letters lit and the bonus at 5,000 points.

This was a compromise which made multiplayer games possible.

Single-player games of this time period often had fairly deep and complex rulesets that unfolded over the game.

But multiplayer games couldn’t do that.

Relay logic is what powers these things, and there isn’t a practical way to save the state of each player’s progress.

Some games might enable different features depending on the ball in play: Gottlieb, for instance, was very fond of doubling the bonus on the last ball.

But multiplayer capability required a fairly simple ruleset,

and in most cases these multiplayer games are better understood as one-ball games which are merely repeated a few times

in the hopes of getting a very high score.

And you might want to get a very high score in the hopes of winning a free game.

Which brings us to the credit unit.

This is another stepper unit which lives in the backbox.

It’s a step up / step down stepper like the bonus unit -

one coil moves it up by one position, and the other moves it back down by only one position.

This little window in the backglass graphics reveals what position the stepper is in and thus whether there are any credits on the machine (and how many).

If there are none, this is blank.

But you might have earned yourself a replay by getting a high score or perhaps a special.

In that case, the credit unit step up coil is fired and the window will show a 1.

And now, the game can be started again using the start button on the front.

With a credit on the machine, the start button will energize the coin relay just as if you had inserted a coin and so the game will start.

It also steps the credit unit down to remove one credit.

Now, much like the bonus unit,

to the game logic, the credit unit can only be in one of two states:

no credits, or yes credits.

The number of credits shown simply indicates how many steps away from the zero position the mechanism happens to be,

and thus how many times a credit can be removed (and a game started or a player added) before it’s back to zero.

All this thing is doing is pressing on this switch stack with this peg.

If it’s got a credit, the peg has moved away from the stack and this switch is closed.

That connects the start button to the coin relay.

And if it doesn’t have a credit,

the peg presses on the stack and this switch is open which disables the start button.

There's another peg on the same wheel which will press  the switch stack from the other direction once it hits it -

and this defines the maximum number of credits the machine will store.

Once this switch is open, the credit unit step up  coil is disconnected and it can’t add any more.

You can move that peg to a few different positions which alter that maximum number of credits the machine will allow.

Incidentally, the mere presence of this thing is what kept pinball illegal in some jurisdictions even after flipper games became common.

Some lawmakers apparently believed that if you could win a free game, you could then…

sell it? I guess? to another player and then somehow that made this a gambling machine.

Now, this sounds absurd at first but it’s a little understandable when you know that the same companies that made these pinball machines

also made bingo machines.

Those looked an awful lot like pinball machines (built into identical cabinets) but they didn’t have flippers and they were explicitly gambling machines.

Bingo machines were terribly addictive and insidious devices.

They tended to make your odds of winning slightly better by quasi-randomly enabling more features and thus making a win slightly more likely

if you gave them more money before the clock on the timed game (did I mention it's a timed game?) ran out.

I’ve linked to a very good explanation from a collector  if you’d like to learn more about them.

Those machines also awarded credits if you won

which were technically just free games.

But you might win hundreds at a time.

And the proprietor could knock them off the machine with a hidden button and pay you out their cash value.

The distinction between pinball machines and bingo machines might seem obvious enough in hindsight,

but anyone who knows how poorly Congress seems to understand the internet should be able to piece together why this confusion occurred.

The pinball manufacturers were crafty, though.

They just wanted to sell these machines to operators.

Vertical integration and strict profit-sharing agreements weren't trendy yet,

so they only made their profit when they sold the machines.

They didn't care how they got used.

So, to get around some of the stricter anti-pinball laws

they began producing altered versions of their flipper games known as add-a-ball machines.

In these games, there was no credit unit.

You couldn’t win a free game.

Law satisfied!

But you could win more balls.

These machines, rather than displaying the ball-in-play, showed balls-to-play.

The ball count unit became a step up/step down stepper,

and the game was configured to begin with a certain number of balls, lets say 5.

Then, when you lost that ball, it would step down to 4 remaining.

The game would end when you reached zero balls remaining of course

but you could fairly easily add a ball through scoring enough points or hitting a certain target sequence.

And you could often end up with more balls to play than you started with!

Ah, loopholes.

Oh, that’s also partly why the outlanes on this machine say “special” when lit, rather than “replay” when lit.

The operator could configure this  to award an extra ball rather than a credit,

which would be enough to satisfy at least some of the weird legal prudes out there.

I think that also might be why the credit unit doesn’t show a zero:

disable replays and make the special an extra ball and then there’s plausible deniability that this machine can even store credits.

Then again, it was also just an option given to operators

and would enable the same playfield design to be used in both add-a-ball and replay machines

so I’m not sure how much the legal issue influenced the term “special” but the use of it to imply “replay” was nearly universal

unless you lived where it was illegal.

But of course I’ve skipped the most important thing - what adds credits in the first place?

Well, first of course there’s the outlanes when lit for a special.

When it’s lit and the ball hits the switch, the credit unit steps up.

The lane is only lit if the bonus unit is at the maximum position AND you’ve lit every letter in AZTEC so it’s pretty hard to score a special.

Plus which outlane is lit flips back and forth as you hit 10 point targets

so it’s pretty rare to earn one this way.

But you can also win replays by getting a high enough score.

How’s that work?

Well, until now I’ve been deliberately ignoring  all these wires going to some of the score reels.

Three of the five reels in every player position  have a circuit board attached to it.

That board has 11 wires coming from it: a common connection and 10 wires for each of the 10 digits on that reel.

A wiper on that circuit board connects  the common connection to one of the 10 wires.

That wiper is attached to the drum, so as it rotates, the single wire connected to the common wire changes

with the specific wire connected corresponding to the number shown on the drum.

How does that give you free games?

Well, here in the backbox you’ll find a rather strange adjustment jack.

This connector has 10 positions, and next to it are 9 differently-colored wires with their own plugs.

Those loose wires are connected to the drums at the 100,000 position.

And the connector you plug them into has each hole wired to the drums of the 10,000 position.

This guide here shows how to use them -  if you want to award a replay at 350,000 points,

then you need to plug the yellow wire, for scores between 310,000 and 400,000,

into the bottom-left hole of the connector, the 50,000 position.

Now, what that actually did was link the 3 in the 100,000s score reel to the 4 in the 10,000s score reel.

Betcha thought I was gonna say five.

But see, the machine has to add that credit at the moment the display first reads 3, 5, something something something points.

And the action which takes place before that happens is the rolling of this digit from 4 to 5.

What actually moves that score reel forward in the game is the 10,000 point relay.

So what these plugs do is connect this switch in the 10,000 point relay to the credit unit step up coil,

but that connection goes through the first two score reels.

If and when they are in the correct position, in this case 3 and 4,

then the next pulse of the 10,000 point relay will of course roll the 4 up to a 5 but it will also award a credit.

And here’s that mess of wiring drawn in the schematic.

On the left are the 10,000 point score reels and on the right are the 100,000 point reels.

The adjustment jack is in the middle.

Like the player unit, these arrows represent the link the score reels are making based on their position,

and since the schematic is drawn with the game reset, the top position is zero, then 1 through 9 follow.

The yellow wire is connected to the 3 in the 100,000 point score reels and when it’s plugged into this position on the adjustment jack,

then when the displays reads 3,4 something something points,

there’s a link through all this mess and up to this switch here.

The next time the 10,000 point relay energizes, as it will when rolling the 4 to a 5,

it sends a pulse through the credit or extra ball adjustment and finally through to the credit unit step up coil.

And so you won a replay!

[knock]

Which brings us to knockers.

When this machine awards credits, it also energizes the knocker.

This is a solenoid attached to the cabinet which simply whacks its bracket to make a knocking sound.

[knock]

Why?

The exact reason is likely lost to history,

but the sound is unique and lets both players  and operators know that a free game was won.

On these electromechanical games the knocker is fairly subtle,

but into the solid state era, the manufacturers started having fun making them startlingly loud.

In machines from the early '90s, the sound level is similar to a balloon popping in your face.

♫ fanfare ♫

[KNOCK]

That is until they got too cheap to put in an actual knocker coil and started playing a sound effect through the loudspeakers.

Williams started it but they at least tried to emulate the old sound with their games.

Meanwhile, over at Stern?

Well, if you know you know.

Put it back, guys. That noise is hideous.

Also,

fun knocker fact,

while video games really did a number on the pinball manufacturers,

some notable early arcade games were made by the likes of Bally, Williams, and Gottlieb.

Gottlieb produced Q*Bert,

and for fun they installed one of their knocker coils into the game cabinet

so it made an actual thud shortly after Q*Bert fell off the board.

Also, Haunted Mansion fans?

That wrap on a table is probably coming from a pinball knocker, or at least something quite similar.

Now did you notice something when we were looking at this mess?

The player unit was also involved.

If you’re wondering why, well what would happen if, say,

player 2 lost their ball and then, once they were awarded their bonus points, they ended up with 345,720 points?

Player 2’s score reels would then display 3 and 4, so the 10,000 point relay would be set up to award a replay.

But when any other player is up, that connection must be broken.

Otherwise the next player to score enough points to bump their 10,000 point relay will win Player 2's replay undeservedly.

So the player unit only connects the score reels of the player that’s currently up to the credit unit.

But there’s one more way you might score a replay, and that’s with the number match feature.

At the end of the game (if that feature is enabled), a number appears on the backglass.

That number will either be double-zeros,

10,

20,

30,

40,

50,

60,

70,

80, or -

and this might shock you

- 90.

If that number matches the last two digits in your score, you win a replay.

[knock]

Now you probably already have a good sense of how that might work.

The 10s score reels also have the circuit board attached to them, so their position is “known” to the game.

It would seem that the number that appears  on the backglass must be determined by some other mechanism,

and if it and the last digit in your score match, then you win a replay.

This is that mechanism.

It’s called the number match unit and it’s a very simple device.

This is just another stepper unit and like the score reels it merely spins in circles.

The match unit receives a pulse to advance with the 10 point relay, so every time a 10-point target is hit, this moves to its next position.

The match feature is only one part of its job, though -

this little switch is what’s been causing some of the targets  to change as the ball moves around.

A cam in the center of the match unit alternately opens then  closes this switch which energizes a relay called the change relay.

That relay is what’s flipping which of the bumpers are lit for 1,000 points,

which of these two targets will award bonus points when hit,

and it also flips the lane that's lit for special.

I’d go over how it does that but the answer, as I’m sure you know by now,

is wires.

The number match feature is done by the circuit boards on either side of the match unit,

and both of them have a pair of wipers bridging a common wire with 10 other wires, just like the score reels.

One circuit board illuminates the lights on the backglass which indicate the number this is on (though that’s hidden until the end of the game),

and the other board links to the 10s score reels of every player.

If the score reel’s position matches this mechanism's position at the end of the game, the machine awards a replay.

In fact, one for every player that matches.

[knock knock]

This works more or less identically to how the high score credit award worked, at least as far as the linking between the score reels and the match unit,

but it’s the game over relay which actually awards those credits.

Look here on the schematic.

Switches 2-C, 3-C, 4-C, and 5-B are always sending pulses through the 10s score reels, then through the number match unit, and to the credit unit throughout the game.

But this switch in the game over relay prevents those pulses from going anywhere when the game is switched on.

When the game switches off, which happens when switch 1-B advances the ball count unit and trips the game over relay,

those pulses can make it through.

So if the score reel’s position matches the match unit’s position, a pulse will make its way to the credit unit step up coil and you win a game.

The number match is the very last thing the  machine does before it shuts off.

Since the score motor was pushed out of its home position by the outhole relay, even though the game over relay is about to trip

it will still complete the cycle.

And actually, take a look - if I move the last digit of player 1 to match the number that's lit,

then every time I push the score motor forward, it awards a replay.

Wait, why didn’t that work?

Oh, the player reset relay also has to be pulled in.

So if I hold it in and then turn the score motor - there we have it.

The knock tells me it added a credit.

[kachunkaKNOCKkachunkahunkaclack]

Now, you might wonder - if it’s the 10 point relay which moves the match unit,

that means the match unit and the 10 reel are always moving at the same time.

Wouldn’t that mean the machine could get stuck in a loop  where it’s always awarding a match?

Well, not really.

Remember that the scores are reset to zero between games, and the number match unit doesn’t move during that process.

So it will desynchronize unless the game ends with the score reel on zero.

And to fix that potential issue, the numbers the match unit picks aren’t in order.

You’ll notice that as I advance it manually,  the numbers move around quite frantically.

Actually - probability people.

I have a question about this.

Intuitively, since the match unit has 10 positions and the score reels have 10 positions

then it should award a replay 10% of the time.

But, and I’ll admit I haven’t kept track over hundreds of games to confirm this,

it sure feels as though it happens much less frequently.

Is that possible?

It feels like it shouldn’t be, but since the two mechanisms are running in different sequences,

there are scenarios where it’s not possible  to get a match if they stay synchronized.

Say the match unit starts on 6 and the game starts with the score reel on zero.

If the two mechanisms always move together then it’s  impossible during that game to win a replay.

It will just be repeating these 10 pairs, none of which match.

So unless the mechanism is faulty, the only possible way for a match to occur if the match unit starts on 60

is if a second player is added so their ten-point scoring desynchronizes the match unit and player 1.

Now, there’s a confounding issue, here, which is  that the match unit in this game isn’t working quite right -

many times the mechanism doesn’t advance when it should.

It’s kind of sticky.

But even if it were working perfectly, I suspect given how the game works and the sloppiness of the real world

there will be occasions where the 10 point score reel moves but the match unit doesn’t, or vice versa.

But I am really curious to the probabilities here if it were working perfectly.

Wait a minute, I can just do a matrix can’t I?

OK, of the 100 possible ending combinations assuming the two mechanisms stay synchronized throughout a single-player game,

10 result in a match.

So it does seem as though the likelihood is 1 in 10 overall,

but the odds of getting a match in the next game are heavily influenced by where the match unit ends in the previous game.

If it ends on 60, 40, 30, or 20, then you cannot win a match in the next game  (assuming, again, the mechanisms stay synced).

But your odds of getting a match are great  if the previous game ended with the match unit on 70 or 50.

But how multiplayer games mess with this, where each player up jumbles the sequencing up,

is well over my head.

I have tried to give it some thought but it hurts too much so I’m throwing it out to you!

I fully expect it to still be 1 in 10 overall but this bunching of possibilities combined with how the sequences might synchronize then desynchronize feels fishy.

Now if you didn’t spot it before, the coin unit makes itself known one more time at the end of the game.

Remember, it determines how many players can play.

And what if the number match unit landed on zero in a single-player game?

Three score displays would match because they’re all zeroes, but you only paid for one game.

Since it’s in the reset position, the coin unit prevents the number match feature from working on players 2 through 4.

But, in a two player game, these three arrows all move down

so now switch 3-C will pulse the 2nd player player and award a replay if it matches.

Three players? Then 4-C gets hooked up, too.

And in a four player game, every score display gets checked against the match unit,  and any time one of them matches, you score a replay.

And with that - we’ve reached the end.

As in, I think I’ve gone over pretty much everything this game does.

But this won’t be the last video - at least two more videos on Aztec will be put out on Connextras.

The first will be an unscripted one where I go over some frequently asked questions - so, uh, ask your questions in the comments below!

And the second will be a sights-and-sounds video where I  make audio recordings of it going through its various sequences

and explain what’s on the screen for those who can’t see it.

Oh, but I will address one thing which kept coming up:

many of you have presumed that these electromechanical games must be horribly unreliable and a pain to take care of.

Well, as someone who has had this machine for over 10 years and even -

and here comes a surprise -

had it on location in revenue service at a restaurant for a couple of years...

I'm that weird.

I can tell you from first-hand experience this isn’t the case!

This machine has only had one thing break in all this time - and that was a flipper.

One of them just broke on the shaft.

The only other issue I had to take care of over several thousand games was the slingshots -

on occasion the kicker would slip out from behind the rubber ring

and then this would happen. [rapid, painful chattering]

Luckily my friends who ran the restaurant would shut it off right away and put it out of order,

and all I needed was to slide out the glass and put the kicker back.

In contrast, this Theatre of Magic machine from 1995,

which lives in my home and doesn’t have the general public giving it quarters and beating it up,

oh and also is run by a computer rather than all this crap,

has had at least a dozen things go wrong with it which required repair in the last couple of years.

I’m talking potentiometer adjustments,

mechanical realignments,

wire-reattachment and repair,

parts replacements, switch adjustments,

and even driver board repair.

And still! It has a problem with the trunk motor where it  sometimes gets stuck for no apparent reason,

there’s a light socket I need to repair,

and now the right flipper is sticking in the up position.

Pinball machines from the '80s and '90s are an endless battle of weird little issues (especially as capacitors decay)

but these electromechanical games are shockingly resilient!

Aside from catastrophic mechanical failures like a flipper breaking off,

the only truly troublesome thing in these electromechanical games are the stepper units.

They are rather delicate devices and their proper operation relies on smooth movement,

properly-tensioned springs, and clean contacts.

If they get gummed up or the springs start to fail,

the game logic breaks down or sometimes it just doesn’t do what it should -

for instance I did have to reimburse my friends at the restaurant for several games when the coin unit didn’t step up properly for a second player.

Other than that, though, these machines usually just require cleaning dirty switches and adjusting them if need be.

And, if they’re adjusted properly, they should mostly clean themselves.

Their rounded shape and over-extension as they’re actuated produces a rubbing action which grinds off any deposits.

What is truly difficult with these old games is troubleshooting problems.

If a single switch is out of adjustment, it can wreck a whole lotta stuff.

And since all these switches look the same, with some normally open yet others normally closed,

finding the problem switch can be a nightmare.

But if you can learn to read their schematics and you understand what the game should do when,

you’ll usually be able to find it pretty quickly.

And I hope through these videos that you’ll have some idea of how to do that for yourself.

But I must warn you:

if you decide to get a pinball machine of your own,

before long you’re going to discover why they put a power outlet inside the cabinet.

That’s for your soldering iron.

And you will need it.

Sometimes annoyingly frequently.

Sure is worth it, though.

♫ salaciously smooth jazz ♫

...between gambling and pinball led to it being outlawed in some locales -

locales.

In some locales.

In some locales.

In some locales.

I am really struggling with saying those words!

With the coin unit now in its second position - ah!

I should start it, huh?

[ka-chunk and all the lovely noises]

[another ka-chunk as he finally remembers to add a second player]

I think I said relay funny.

The pulse coming from the outhole relay and switch 1-C to advaooohhh [tiny burp] god that line is too long!

Meaning the next pulse in the sequench whits comes from swi - ah crap.

...until the player unit is on player 3.

And I lost my place.

So, ya think a video on Theatre of Magic and what these games started to look like in the solid state era might be worth it?

There is some cool stuff in there: clever sensors, magnets, matrixed lamps and switches.

Plus it's kind enough to keep track of things and tell you when there are problems!

Well, usually.

Self-diagnostics only go so far...