The bottom panel of a 1976 Williams Space Mission. Note all the metal filings! These come from the metal coil sleeves installed in this game from the factory, which wear as their metal plunger strokes inside the metal sleeve. Metal coil sleeves should be replaced on all commonly used coils (flipper, slingshots, chime bells, pop bumpers, etc.) with new *nylon* coil sleeves. If the original metal coil sleeve won't come out of the coil, the whole coil needs to be replaced (nearly all new coils use nylon coil sleeves, with the exception of some really large coils like Baseball bat coils which could have an aluminum or brass coil sleeve). New nylon coil sleeves will also "dry lubricate" the coil plunger, and make the coil have more "snap" and better playing action.

Here's a picture of a worn out aluminum coil sleeve! Note the red circle showing where the coil plunger wore right through the sleeve. I have never seen this happen to a nylon coil sleeve. This sleeve came out of a 1 point bell coil. This was replaced with a new nylon "double flanged" coil sleeve.

Another high-wear part on 1970s Williams EM games (Space Mission). This is the chime "box", which uses three aluminum bars of different lengths for different chime tones. There is a coils for each bar with a nylon tipped metal plunger that hits the bar. With time, the hole in the aluminum bar retaining post that the retaining pin goes through will enlongate and eventually break (as seen in the bent over post below). If the nylon tip breaks off the metal coil plunger (common), this problem will happen even faster. Also note the groove worn in the used retaining pin. A new chime box and retaining pins will need to be installed, or the old posts and pins replaced with new metal posts and pop riveted in place (as seen here). Also note the rubber spacer for the chime has been replaced. If this is not done, the chime will sound frail and harsh. An old rubbon playfield post sleeve (as used on 1990s pinball games) was cut to replace the old rubber spacers (two used on each post, one under and on top of the chime bar).

A 1954 Genco 2 Player Basketball which has been converted from using the original Selenium rectifier, to a new silicon bridge rectifier. Note the 10 amp fuse installed too, on one AC lead going to the silicon bridge.

Lamps.

All games use lamps. The most commonly used lamps are 6 volt AC with bayonet bases (#44, #47 or #55). Many arcade games use 120 volt florescent lamps too. But other lamps are sometimes also used, especially on Genco games (#1458 lamps, 20 volts). Number 67 lamps are also used on some arcade games, which are a larger 6 volt version of a #44. And flashing lamps (#455) are often seen behind pinball backglasses. These 6 volt lamps have a thermal switch that when it heats up after a second, the metal expands and opens a contact, turning the lamp off. After cooling for a second, the metal contracts and closes the contact, and the lamp lights again. This process repeats over and over.

Switches.

EM games use lots of leaf switches. These switches have two or three contacts attached to metal blades (the "leaf"). Between the switch blades are bakelite insulators. Switches come basically three ways: Normally Open, Normally Closed, or Make/Break. The schematics show if a switch is normally open or closed. (Pinball schematics identify all the switches when the game is turned on, reset, and ready to play with the first ball in the shooter lane. Other arcade games like pitch & bat and bowlers are pretty much the same, with the game reset and ready to play the first ball).

Note the four Normally Closed (top 4 pairs) and one Normally Open (bottom most pair) leaf switches in this switch stack. All are quite dirty with black dust.

Normally Open means the two contacts are open, and not connected. Activating this switch closes the two contacts, and turns on the circuit. Gottlieb identifies these types of switches as "A" contacts.

Normally Closed means the two contacts are closed (touching), and are connected. Activating this switch opens the two contacts, and turns off the circuit. Gottlieb identifies these types of switches as "B" contacts.

Make/Break means there are three contacts on the switch. A middle or common contact, a normally open contact, and a normally closed contact. When this type of switch is activated, it closes the normally open contact, and opens the normall closed contact. Gottlieb identifies these types of switches as "C" contacts.

Bakelite Insulators are the small brown fiber-looking plates between the switch contacts. These insulate the switch blades from each other in the switch stack.

Fish Paper is an insulating gray paper used between switches, mostly in switch stacks. It prevents one set of switch contacts from shorting against another. Often this paper gets worn and damaged. This can cause adjacent switches to short. Inspect the paper, and replace where necessary.

Relays.
A relay is a small coil that pulls in, and activates (or deactivates) a number of switches. One switch turns on the relay coil, which in turn activates a number of other (normally open or normally closed) switches. This amounts to the action of one circuit controling many more circuits, without an electrical connection to them! An example of this would be a feature relay that is activated by a pinball playfield switch. This can turn on a relay, which will then turns on (or turns off) many other switches, which can score points and turn on numerous playfield lights.

A Gottlieb pop bumper relay. The playfield switch turns this relay on, which in turn energizes the pop bumper and triggers the 10 point relay to score the points.

AC voltage relays have a copper "slug" center surrounded by an iron center. AC coils have a coil stop made with these same materials. This material creates a small magnet. This holds the magnetic field of the coil as the AC (alternating current) moves through zero volts (remember, AC volatage alternates from a positive voltage, to zero volts, to a negative voltage, and back to zero, then to positive voltage, and so on). An AC relay or AC coil stop will work in a DC circuit, but a DC relay or DC coil stop won't work in an AC circuit.

A Gottlieb Hold relay. This hold relay is the style used in games prior to 1968 (Sing Alone/Melody and before). Once the game is on and play is started, this relay is energized until the game is turned off. Hence the toasty brown paper wrapper from this relay's constant use.

Relay coils usually have a resistance of 100 ohms or greater. The higher the resistance, the less magnetic pull the relay will have, but also the less chance the relay coil will heat up and burn if it is energized for a long time. Because of this, most relays are generally designed so they may stay on for long periods of time. These hold relays are designed to stay on sometimes the entire time the game is turned on. Hold relays are often used for the game power hold and coin mechanism lock outs.

Latch-Trip Relays: a latch-trip relay is used as a hold relay. The top Bally latch-trip relay is used for the "game over" switches. This particular game-over latch-trip relay is the source of many Bally problems. The bottom Gottlieb latch-trip relays are particularly nasty as the switch travel is small, so the switches must be very accurately adjusted.

A subset of the hold relay family is the Latch-Trip relay. Basically it's two relay coils that control one set of switches. The pull-in (latch) relay coil activates the switches, and a metal armature plate locks the switches mechanically (even when the pull-in latch coil is not energized). When the second release relay coil activates, it un-latches (trips) the lock and releases the metal armature plate. A latch-trip relay can retain its state without being constantly energized (unlike a hold relay). A latch-trip relay can even retain its state if the game is turned off.

Latch-trip relays are a common source of problems. For example, if a Bally or Williams pinball won't light up after turning it on (and pressing the left flipper button!), often this can be traced to the switches in the game-over latch-trip relay. Gottlieb latch-trip relays used during the 1970s are even more troublesome. The switches in Gottlieb latch-trip relays have a very small amount of travel. This means they must be adjusted perfectly to function correctly.

A Gottlieb relay bank. This relay bank houses a mere five relays. The reset solenoid can clearly be seen at the bottom.

The last type of relay configuration is the relay bank. This consists of a number of relays (generally four to twenty) mounted on a common frame. Each relay can be "tripped" individually, much like the trip relay in a latch-trip system. When a relay coil is energized in the relay bank, it releases an armiture plate which opens or closes the relay's associated switches. When the relay is de-energized, the switches stay in their new tripped position. The beauty behind the relay bank is the reset. With a single solenoid connected to a moving bar on the relay bank, the bank can reset all of its relays to their untripped position. Some early pre-1954 pinball games have a manual reset bar for the relay bank, which the player unknowingly resets when they insert a coin into the front door coin slide mechanism!

New Hi-Power Gottlieb Flipper coils, with new fiber flipper links attached to the plungers. New links will make your old flippers work like new, as does a new coil sleeve. The hi-power coils are about 10% stronger than the originals. Note the EOS (end of stroke) switches for each flipper.

Solenoids (Coils).

Solenoids are bigger versions of relay coils. They are much larger, and usually have much lower resistance. Most coils have a resistance of 3 to 120 ohms (less than 3 ohms and the coil is becoming a direct short, and will blow a fuse!) The lower the resistance of the coil, the more powerful it is (for example, pop bumper coils tend to be about 3 ohms). High resistance coils are made to stay turned on. This includes the ball release coil (on pre-1967 Gottliebs), and the hold side of a flipper coil (more on that below). But for the most part, coils can only be on for very short periods of time (otherwise they will smoke and burn). Solenoids have a center hole through which a plunger travels until it hits a "coil stop". When a solenoid is switched on, it sucks this plunger down inside the solenoid coil.

Flipper Coils are a unique type of solenoid. This coil is actually two coils in one package. One part of the coil is the high-powered side, and is usually about 3 ohms. This uses large diameter wire, with a limited number of turns (low resistance). Since there is low resistance, the power can travel quickly and easily through these windings. This part of the coil gives the flipper its initial power to kick the ball.

The second part of the flipper coil is the hold side, and is usually about 100 to 150 ohms. This acts much like a hold relay; lots of turns of thin wire with high resistance. This part of the flipper coil is normally shorted out and bypassed by a normally closed end of stroke (EOS) switch.

It works like this: When the player presses the flipper button, the high-powered side of the flipper coil is activated, and the low-powered side of the coil is bypassed. The high-powered side of the coil moves the flipper plunger through it's stroke. As the flipper reaches it's end-of-stoke (EOS), the flipper pawl opens the normally closed EOS switch (which has shorted out the low-power side of the flipper coil). When this switch is opened at the end of the flipper's travel, the electricity passes through both the high powered and low-powered sides of the flipper coil in series (one after the other). The combination of these two coils together (with a combined resistance of the two coils) allows the player to hold in the flipper button without burning the flipper coil. If the high-powered side of the coil was activated alone for more than a few seconds by itself, the coil would get hot, smoke, smell, and burn, and probably blow the game's solenoid fuse.

Score Motor.


Almost all post-WW2 EM games have a score motor (except Genco EMs). The score motor comprised a small electric AC motor (about 25 RPM) that is speed reduced through some gears. Attached to the motor shaft are several disks (also called cams) with indentations around the outside. Stacks of multiple switches surround the cams, which have a lever. The switch levers either rides around the outside of the rotating cams, or they come in contact with pins that perturd perpendicturly to the cams. As the cams turn, the switches open and close, as dictated by the indentations or pins in the cam (via the switch levers).

Score motors also have a "Home" or "Motor Run" switch. The purpose of this switch is to keep the motor in motion (after some external circuit started the motor) until it finishes turning through a "cycle", ultimately resting at a "home" position. Most score motors have two to four cycles per cam revolution.

This is all fine and dandy, but what purpose does the score motor serve? Its job is to make a certain feature repeat a desired number of times. For example, say in a pinball machine the player hits a 50 point target. To score 50 points, the 10 point relay must be engaged five times. This repeated usage of the 10 point relay is done using a 50 point relay and the score motor. The 50 point relay engergizes, which turns the score motor on for just a moment. Once the score motor is on, it will continue to turn one cycle, and then shut off (thanks to the home switch). As the score motor turns through its one cycle, a score motor switch is opened and closed (pulsed) five times which turns on and off the 10 point relay, through a closed switch on the 50 point relay (which is still energized thanks to yet another score motor switch). This registers the required 50 points on the score reels. After the five pulses of the score motor switch and the completed cycle, the score motor stops and the 50 point relay de-energizes (because of yet another score motor switch opens turning the 50 point relay off). This whole process takes about one second, and involves a number of switches. It's computer logic without the computer!

Another usage of the score motor is for reseting the score reels to zero when a new game is started. Each score reel (discussed more in detail below) has a zero position switch that opens when a the score reel is at zero. Using a reset relay and a score motor switch, a circuit to the score motor is used that pulses the score reels until they all reset back to zero. Once all the score reels' zero position switches are open, the score motor circuit opens, and the motor stops turning. Again, as with the 50 point example above, the score motor is used to do a task (pulsing the score reels) multiple times.

A Gottlieb score motor, top view. The blue circles indicate two of the switch stack numbers (from 1 to 4).

Because the score motor has several different levels (cams), and many switches associated with each cam, a numbering system was created to identify the switch stacks. This number format is usually shown on the game's schematics. On Gottlieb score motors, numbers are used to identify the switch mounting brackets (usually from one to four). Letters are used to identify the switch stack's level (cam), with "A" being the level closest to the bottom board, and "E" closest to the playfield. If the schematic referred to switch "4C", this meant the switch was located in the switch stack mounted on bracket number four, and was the "C" (middle) level. Note there could be as many as five or six individual switches on the switch stack 4C! In order to find the exact switch in question, the schematic also identifies the switch's wire colors (and hopefully the game's wire colors have not faded!)

A Gottlieb score motor, side view. Here the "A" and "C" switch levels can be clearly seen ("A" is closest to the bottom of the picture).

Stepper Units.


If relays are the most common device in an EM game, steppers are the second most common (and largest). Most steppers consists of a metal frame with a brown insulting material containing lots of small metal contacts, grouped in circles. There is a ratchet mechanism to advance "contact fingers" or "wiper blades", which touch the small metal contacts on the brown insulator (as many as 50 wires can be soldered to the contacts on a single stepper unit). Wipers are a type of switch on the stepper unit that rotate with the unit. As the stepper unit moves, the wiper blades make contact with a different set of copper contacts. This is used to change features or scoring on a game. In addition there is one or two solenoids that energize to move the contact fingers.

A common type of stepper unit is called the reset stepper, which uses two solenoids. One solenoid is known as the "step up coil", which advances the unit one position via a ratchet mechanism. This moves the wipers to the next set of contacts on the stepper. As the stepper increments, it winds a clock style spring tighter. Eventually the unit will come to some mechanical end, where it can no longer advance. There is also a second "reset coil" which releases the ratchet and resets the unit back to the "zero" position, regardless of its current position. Reset steppers are often used for scoring on games with no score reels (pre-1961). They are also used on newer style games as ball and bonus counters.

Yet another type of stepper unit is called a continuous stepper. These have just one solenoid, known as the "step up" coil. The only difference between the above reset stepper and the continuous stepper is the lack of a reset and there is no clock spring. To bring a continuous stepper back to the "zero" position means stepping through all its position to get back to zero. Continuous steppers are used where resets are not required, like in a "match unit". They were also used from pre-1961 as the low-score unit (the unit that kept track of the lowest score numbers in the game, like the 1000s or 10,000s). Another type of continuous stepper is the score reel (see the score reel section below for more information).

The last type of stepper is the increment/decrement unit. There are two coils on this unit, a "step up" coil and a "step down" coil. The step up coil works just like the other two steppers, using a ratchet mechanism to advance the stepper one position. But the step down coil also has a ratchet mechanism that decrements the stepper one position. A good example of the increment/decrement stepper is the credit unit.

Most stepper units also use at least one End Of Stroke (EOS) switch for the stepper coils. When a stepper unit's solenoid energizes, this switch closes (or opens) as the coil plunger moves. Also most stepper units have some sort of zero position switch.

Schematic Symbols.


At some point the schematics will need to be referenced when fixing a game. The graphic below shows the most commonly used symbols on EM schematics, as discussed above.

The most common schematic symbols used in EM games.

Left: a Bally fuse block with cracked fuse holders. The stress cracks can be seen. Right: a new replacement fuse block.

Fuse Holders.
Often the fuse holders on EM games are tired and have lost their "spring". This will cause a bad power connection. Symptoms include missing all lights on the playfield or backbox, all coils don't work, or a game that just won't power on. This is very common on Bally games. Often the fuse holder's tabs can be bent for a better connection, though sometimes the tabs will break doing this. Keep a stock of new fuse holders around and replace when needed. Also clean the fuse holder. These can be so dirty, the fuse won't make contact to the holder. Dirty fuse holders can also cause resistance, and the heat generated can cause the fuse to open (blow).

What Causes a Fuse to Blow?
The first thing to figure out is what does the blown fuse control? Is it the 6 volt lighting fuse? (Note sometimes there are two 6 volt fuses, one for the backbox, and one for the playfield.) Is it the solenoid fuse? (usually 30 or 50 volts.) Or is it the 120 volt line fuse? Also on some EM games there is a selenium or bridge rectifier or diode(s) and an associated fuse for that (this is common on 1970s Williams and Bally pinball games and 1950s Genco games).

The first thing to do is to vacuum all the crap out of the inside of the game. It amazes me what you will find inside an old game, and often when the game was moved, this junk can lay across some wires or contact points and cause a blown fuse. So vacuum the bottom of the game (but save all the parts you find, including loose nuts and bolts).

If the 120 volt line fuse is blowing, look for a shorted power cord or a shorted transformer (rare, but it does happen).

If the game is blowing a 6 volt lighting fuse, that is often caused by a shorted light bulb or light bulb socket. The best way to find that is by visually inspecting each lamp socket. Remove all the light bulbs too (you were going to replace them all with new #47 bulbs anyway, right?) If the fuse stops blowing with all the bulbs removed, then there was a shorted bulb. Replace the bulbs one at a time with the game turned on to find the culprit (or just install new bulbs). Sometimes flashing #455 bulbs can short too. If the light fuse still blows with all the bulbs removed, there is either a shorted socket, or maybe a short at a connector (see the section below on connectors).

If the 30 or 50 volts solenoid fuse is blowing, this can happen from a low resistance EM coil (please see that link for more information). Also on pinball games, if the flipper coil's EOS (End of Stroke) switch is not adjusted correctly, this can cause the solenoid fuse to blow. See the flipper coil explaination section above for a description of how the flipper coil and EOS switch work together (but basically the flipper EOS switch should open when the flipper is fully energized; if it doesn't open, a burned flipper coil and/or blown fuse will result).

Also on (primarily 1970s Williams and Bally) games with selenium or bridge rectifier or diode(s), these can short and blow its accompanying fuse. Starting in 1972, Williams changed their pop bumper and slingshot kickers to operate on DC voltage. Bally also made this change in 1976. To do this, Williams and Bally used a silicon Bridge Rectifier. Unfortunately, sometimes the bridge shorts internally, and will blow the solenoid fuse when a game is started or when a pop bumper/slingshot coil fires. Please see When things go wrong for more information on fixing this.

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2b. Before Turning the Game On: Check the Plug Connectors and Lamp Sockets

A Gottlieb pin style connector after a quick cleaning. This pin style connector is the most common EM connector.

Before plugging the connector in, take your 600 grit wet/dry sandpaper and sand the circumference of the male side of each pin of the plug. This is the area that the female plug bites in to. Wrap your sand paper around each pin, and rotate a few times. They don't have to shine like a new penny; just get the major crud off.

Alternatively, use a small wire brush and clean the connector pins. This works really well too.

This flat style of connector is usually just seen on some Williams games. These are real easy to clean, but generally this is not as robust of a connector as the pin style.

Examine the Male Connector.
Often the insulation on the wires going to the male connector pins has shrunk or is pushed back. This can cause the bare wire to short against an adjacent connector pin or wire. If this happens, a blown fuse is the likely result (in addition to some function of the game not working). To fix this, the tip of the connector pin will need to be heated with a soldering iron, and the wire pushed further inside the pin (add some solder to the wire end of the connector pin too). Also check for broken wires on the male plug. And finally look at the bakelite material that holds the pins. Sometimes these crack and break. If this happens, there isn't much that can be done except for replacement (though sometimes the bakelit can be reglued with Super Glue).

Bally Connectors.
Bally connectors are particularly troublesome. For some reason, Bally decided to make their own connectors, instead of buying them from an established connector company. Hence Bally connectors are low quality in comparison. This causes particular problems, as the female portion of the connector can metal fatique, not providing proper tension to the mating male pins (or worse yet, the female pins can break). the male portion of the Bally connector is fine, it's just the female part that breaks.

Top: a Bally female pin connector. Bottom: a Gottlieb/Williams female pin connector.

The only way to repair a broken female Bally connector is to replace it. Since these connectors are not available new, an old Gottlieb or Williams parts game can be used as a donor, and the female Bally part replaced.

Gottlieb Coin Door Connector.
It's also a good idea to clean the connectors that attach to the bottom panel of the game, and the coin door connector. Gottlieb coin door connectors are especially important: if this connector is not making good contact, the game will refuse to work!

"Fixing" a playfield lamp socket. The wire that powers the tip of the bulb is moved directly to the tip of the socket. The base of the socket is then soldered together so it can not rotate. Be sure to sand the parts before soldering, and to use some Rosin flux on the socket.

Lamp Sockets.
Though bad lamp sockets aren't going to make a game not work, they are really annoying. Lamp sockets are made of metal and a fiber insulator. They are pressed together to form an air tight seal against the parts. But as time marches on, the fiber insulator shrinks, and air gets between the parts. Corrosion comes, and the socket becomes intermittent or doesn't work at all. Often playfield lamp sockets can be repaired, but really the best solution is to replace faulty sockets. Backbox sockets (the lamps behind the score glass) can almost never be repaired, and must be replaced.

Left: Bally lamp socket. Right: Conventional lamp socket. Bottom: A #47 light bulb.

The worst offender in sockets is Bally. Nearly all the other EM game companies bought sockets from established lamp socket companies. Bally made their own, and hence Bally sockets are bad quality. Also Bally backbox sockets are a completely different design than the other companies, and always need to be replaced.

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2c. Before Turning the Game On: Switch Contacts

A Word of Wisdom and Caution...
When I first started getting into EM games, a well experienced repair friend stated, "if every switch contact in the machine is clean and properely adjusted, your game will work perfectly". I thought to myself, "I can clean and adjust contacts and get this Nip-It working myself!" (Nip-It was my first EM fixit project). Unfortunately, this statement is an over-simplification of the truth.

I did clean and check (and often adjusted) every contact on that Nip-It game. And in reality, his advice did NOT work. I ended up with a game that worked far worse than when I started. I created problems that weren't there in the first place. This was mostly because I didn't have the experience to tell when a switch really needed adjustment.

There is a moral to this story: "if you're new to EM games, don't fix or adjust what isn't broken".

If you are experienced in EM fixing, then fine, check and/or clean every contact and adjust only as absolutely necessary. I do this now that I have the experience, and it works quite well. Before I even turn the game on, I clean and check all switch contacts. BUT if you aren't experienced, please be careful! Potentially problems could only become worse. Just follow along and do the bare minimum amount of contact adjusting, and only when you are absolutely sure the switch needs adjusting.

Newbies can clean all the switches, but don't go nuts. Again, it could make things worse. Newbies should definately give all switches an "examination" though. Look at the switches, and check for obvious flaws. Broken wires (vibration will often break wires from their switches, especially on score reels), crud fallen between switches, hacked up and over bent switches, etc. If a switch clearly looks out of adjustment, then compare it to a neighboring switch of the same style. If an examination of five similar switches shows the suspect switch as "different", that's a fair indication the suspect switch may need adjustment. But remember; think before acting, and be aware of the consequences if an improper adjustment is made!

For the most part, even a newbie can clean switches, and the game will be "better off" for it. This assumes the newbie does not file the switch's contact to nothing, and does not change the adjustment of the switch. If the newbie just can't leave well enough alone, tighten the screws on the switch stack only, and don't adjust the switch!

Why Do Switch Contacts Get Dirty?
Whenever an EM switch contact opens or closes, a small arc of electricity occurs. On high current solenoid circuits like flippers and kicking rubber, this blue arc is quite large and can easily be seen. This arc burns the switch contacts slightly, and produces some black soot (Silver Sulfide). Over time, the switch contacts can increase in resistance from the contacts burning and from the black soot (though the black Silver Sulfide is actually a conductor, it can cause problems if there is an abundance of it).

Self Cleaning Switches?
Switches can be adjusted so they are "self cleaning"! If switch contacts are adjusted with a "wiping motion", this self-cleans the contacts as they operate. But if a game is in storage for a period of time, burnt contacts can oxidize. If a switch is mis-adjusted and doesn't clean itself with a wiping motion, it too can fail. This is why switch contacts need checked and cleaned, and perhaps adjusted.

Cleaning the Contacts.
Dirty and mis-adjusted switch contacts are the major cause of all EM game problems. Fixing an EM will require some switch cleaning and perhaps adjusting.

(Left) Filing a relay switch in tight quarters. (Right) Filing the flipper EOS switch on a Gottlieb.

To clean switch contacts, use a Flexstone file, 400 grit sandpaper folded into strips, or a small metal point file. Just put the file between the two contacts to clean, and file them. The two switch contacts will need to be held together with fingers or needle nose pliers to get ample pressure to clean them. Don't hold them too tight or the switch blades could distort and bend. The metal contact pads should be shiny and clean after cleaning. Don't over file the contacts, because this will change the adjustment of the switch (because the contacts are now thinner). Obviously the game should be powered off when doing this!

Using needle nose pliers to hold two contacts together while filing with a flexstone on a Gottlieb reset bank.

Often, especially on relay switches, the adjacent leaf blades will be so close together that you can't get ample pressure against the file to clean the contacts (fingers won't fit!). In this case, use a small screw driver to put presure on one of the contacts. Sometimes manually activating the relay by hand helps apply pressure to the contacts for filing.

Other times using fingers or a screwdriver to get pressure on the contacts for filing won't work. For example, on Gottlieb game feature and reset banks, there just isn't enough room. Instead use needle nose pliers. Just gently hold the two contact together with the pliers and the flexstone between them.

Silver Contacts versus Tungsten Contacts.
Most switch contacts are made of silver. These contacts file fine with a flexstone. But the contacts on the flipper button switches and flipper EOS (End of Stroke) switches have tungsten contacts. These contacts will have to be filed with a small metal file, or removed from the game and filed with a standard metal file. Tungsten contacts will wear out a flexstone in short order; the flexstone just can't cut them. Note that during the 1970's, Williams and Bally started using tungsten contacts on pop bumper and kicking rubber switches too.

Self-Cleaning Contacts and Types of Switches.
All EM leaf switches have a "wiping" action to them: the short blade contact is stationary, the long blade moves and makes contact with the stationary contact. As it makes contact, the switch will continue through it's stroke and wipe itself on the stationary contact. This is known as a "self cleaning" switch. For the self cleaning to work, as the contact come together, the stationary blade must be moved a bit by the other moving blade as it touches. Of course this doesn't happen all the time, but it should.

Shiny clean and smooth EOS contacts after filing.

With this in mind, adjust any switch so it has this wiping motion. Normally Open (NO) switches should have about a 1/16" distance between the contacts. And as the two contacts touch, they should continue to touch and "wipe" as the switch continues through its stroke.

Normally Closed (NC) switches should be adjusted the same way: make sure as the switch opens and closes, there is some wiping action. A 1/16" contact distance when open is desirable in most cases.

Make/Break (M/B) switches are the toughest to adjust. They have about the same amount of travel as the normally open and normally closed switches, but have two contacts to make and break and wipe clean. Adjusting these is difficult.

The best method of switch adjustment is this: adjust the switch blades so that the contacts either open or close at the half way point of their operation. This will give the most reliable, self-cleaning action. This holds true for relays and playfield switches.

Damping (Pre-Tensioner) Switch Blade.
On playfield switches, there is a third, shorter switch blade sandwiched between the two contact blades. This damping or pre-tensioner blade provides support to one of the contact blade, so the switch doesn't "bounce", and so more spring tension is provided. But sometimes these damping blades get bent and short out to the other adjacent blade. Be aware of this. When you adjust a switch with a damping blade, you must adjust both the short contact blade and the damping blade together.

Note the Damping Blade: this playfield switch has a third shorter blade between the contact blades to provide support. Make sure these damping blades don't short out against the adjacent blade. And remember, don't adjust the long blade. Adjust only just the short blade, and the damping blade (if the switch has one).

Accessing the General Health of your Switches
(why do switches get out of adjustment?)
Every EM switch stack consists of metal blades, and bakelite insulating spacers. With time and changes in humidity and temperature, the bakelite spaces can expand or contract. When this happens, the spacing on the switch blades will change.

When I am working on an EM game for the first time, I like to access the general health of the switches. This is easy to do; just try tightening a couple different switch stack screws. If the screws are generally tight, the health of the switches is probably good! If the switch stack screws are loose, this means you will no doubt be doing a far amount of switch adjustments (the bakelite has shrunk with time, changing the gap in the switch blades). This is good information to know, BEFORE you start adjusting any switches!

Also, if the switch stack is not tight, the bakelite insulators can become damaged with humidity (because moisture has greater access to the bakelite spacers). So keeping the switch stack tight is a good idea.

Note the adjustments made to the switch stack will not be forever consistent. At some point (could be many years!), the stacks could "loosen" again, and switches will probably need re-adjustment. Tightening a few different switch stack screws in the game will give you a general idea of the game's switch health. If you found a few loose, keep this in mind. Since your sample is loose, the whole game will probably need more switch attention.

Using a contact adjuster to adjust the short blade of a switch.

Tighten the Stack BEFORE you Adjust!
If a switch needs adjusting, tighten the switch stack before starting. Since tightening the switch stack will change the spacing of the switch blades, don't forget to tighten the switch stack BEFORE adjusting the switch blades!

When tightening a switch stack, it is best to tighten the screw closest to the switch contacts first. Though this is not a big deal, this is what Gottlieb recommends. If the switch stack is really loose (or the switch stack was disassembled to replace a blade), alternate the tightening of the screws. That is, tighten one screws a turn or two, then change to the other screw. Be careful not to kink the metal switch blade, and not to crush a bakelite spacer.

Adjusting Switches.
The best method of switch adjustment is this: adjust the switch blades so that the contacts either open or close at the half way point of their operation. This will give the most reliable, self-cleaning action. This holds true for relays and playfield switches.

Adjust the short (stationary) blade contact only (and the damping blade if the switch has one). Put your contact adjuster on the short blade (and the damping blade), and slide it down to the bakelite insulator stack. Bend the blade (gently!) here. A small adjustment of just a few thousands of an inch is all that is required. If you are making large adjustments, you are probably doing something wrong! (or someone else previously mis-adjusted the switch; large gross adjustments at the switch stack could break the switch blade).

Usually the only time the long (moving) blade of a switch will ever be adjusted is if someone before mistakenly did this. Otherwise the moving blade of any switch should not be adjusted. There are some exceptions to this. For example, make sure the moving blade is pressed against its activator (a wire form for rollover switches, or armature for relays). If it is not against its activator, then the moving blade will need to be adjusted. Having the moving blade against its activator can make a big difference, especially on Gottlieb relays that have a very short switch throw. On relays, look at the blade where it is inside the armature slot. If the blade is at the "bottom" of the slot, the blade will have *less* travel (and hence the switch will be less reliable and harder to adjust). Those blades at the "top" of the slot will move the most when the relay is activated, and all moving blades should be adjusted to have the most travel. Note this is not for the faint of heart. If there are any doubts, don't adjust the moving blade!

It is important to adjust EM switches at the switch stack (that is, where the switch blade touches the bakelite spacers). This is how Gottlieb (and some very well-known EM game mechanics) recommend EM switches be adjusted. Do not adjust switches on the length of the blade (unless a previous adjustment mistake needs to be corrected, where the switch was grossly mis-adjusted!).

The reason for this is simple; adjusting the switch anywhere but at the switch stack will compromise the "temper" of the switch. Every switch has a certain "temper" or "springiness", depending on the length and thickness of the switch blade. If adjusting the switch anywhere but at the switch stack, the temper can be compromised. Remember, only small adjustments to a switch blade is being made. If someone before really mis-adjusted the switch, and very large switch adjustments are required, this may have to be done over the entire length of the blade. But for normal switch adjustments, adjust the switch blade (gently and slightly) closest to the switch stack.

It should be noted that Williams recommends switches be adjusted across the length of the switch blade. This is contrary to what Gottlieb recommends. My feeling is unless correcting someone else's adjustment mistakes, adjust the switch at the switch stack only. The "temper" of the switch is important; this determines how much "spring pressure" the switch puts on its associated parts. If adjusting the switch blade along the length of the blade, this can change the temper. On relays, this can cause a relay to not work properely (if the spring pressure is reduced), or to "buzz" loudly (if the spring pressure is increased). For this reason, only adjust switches at the switch stack.

A Mis-Adjusted Playfield Switch: Notice the damping blade in the middle (which dampens the upper contact) is shorting to the lower contact. Yet the contact pads are adjusted correctly. This is visually deceiving.

Fish Paper.
Fish paper is the insulating gray paper seen between switches, mostly in switch stacks. It prevents one set of switch contacts from shorting against another. Often this paper gets worn and damaged. This can cause adjacent switches to short. Inspect the paper, and replace where necessary.

A Good Reason to Inspect/Clean Every Switch.
One of the reasons I tell people to clean every switch is that things you would not normally see become obvious. Stuff like missing switch contacts, broken switch blades, broken switch wires. All these things are very obvious if you have cleaned every switch. This is a systematic and proactive way of repairing these games. And if you don't understand EM schematics very well, this can be an incredible time savings. Because if you found an obviously broken switch while cleaning, finding the same broken switch because the game doesn't work tends to be A LOT tougher, and a lot more frustrating!

Can you see the missing switch contact on the switch blade? This one easily found problem during switch cleaning could have been the only thing preventing the whole game from working. Yet if every switch was not cleaned and inspected, this would have been over looked. Then a process of tracing the game's schematics is the only repair method (which proves to be a lot more frustrating for an EM newbie). This problem can be easily repaired by sanding the switch blade, and soldering in a new switch contact (the tension of the switch blades against each other can hold the new contact in place while soldering).

Think BEFORE Adjusting!
Let's repeat that: Think BEFORE Adjusting!
If adjusting more than about 5% of all switches on an EM game, you are probably doing something wrong! Stop now before troubles become worse. Unless the game has been mangled, adjusting more than 5 switches out of 100 is very unlikely. See the above "Word of Caution"...

A "Quick Fix" Idea - Working in the "Dark".


There is an old trick that can be used to find problem switch(es) in an EM game. For example, one reader explained this problem: "My Williams Spanish Eyes machine had an interesting problem when I first got it. Just before the first replay value of 50,000 points (at 40,000) the replay knocker would begin to rapidly fire for several seconds...It sounded like a machine gun firing! It did this every time at 40,000 points. It seemed like a switch could be out of adjustment and oscillating, causing the knocker to 'machine gun'."

At this point, most people would get out the schematics, and hunt down the problem. But wait a minute! Why not turn out the lights and look for the infamous "blue sparks" to find the trouble switch(es). In this example, the reader ran the game up to 39,000 points with the playfield up and the back box opened up, then turned out the lights. Only then was the last 1,000 points scored manually with the playfield glass off. The knocker started to 'machine gun' again, and right in tune with it was a display of blue sparks coming from a switch controlling the thousands scoring. In this example the switch blades were adjusted too close together. Two minutes later the problem was fixed. The schematics weren't even needed.

This technique can be used to find direct shorts too. Just a warning though: this "dark room" technique certainly won't help fix every problem. And on games that are completely dead, it won't help at all.

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2d. Before Turning the Game On: Score Reels

The Biggest Problem in EM Games.

Think about it: what's the most used (abused!) device on any EM game? The score reels! (Note: if a 1950's game without score reels, skip to the Stepper Units section.) The score reels move for every point scored, hundreds of times per game.

If the score reel contact points are mis-adjusted, the game will never complete its start-up sequence! This is definately the most common problem in EM games. It's pretty easy to identify this problem too: press the "start" button on the coin door, and the score motor in the bottom of the cabinet "runs". It never stops, and the game never starts.

The reason the score motor is running is the game doesn't think the score reels are reset to the zero position. This happens for a bunch of reasons, but usually it's because the zero position switch(es) are out of adjustment or dirty (though sometimes it can be as simple as a wire broke off the score reel solenoid or score reel edge card, or the solenoid is dirty and sticking).

All Score Reels are Very Similar.
During the 1950s and 1960s, all the game manufacturers seemed to use the same score reel "guts" (exception: 1965 to 1975 Midway games used motor driven score reels instead of a solenoid driven - see the next section for information on those.) The only major difference between the other various game makers was the rotating reel itself. The rotating reel on Gottlieb and Williams games was aluminum with the numbers screen printed right on the the reel. Genco used an aluminum reel also, but the numbers were printed on a paper reel cover. Chicago Coin uses plastic reels. (Which by the way are *very* easily damaged if cleaned. Only use Novus2 to careful clean the plastic reels. A water solution will remove the numbers!)

The other difference in score reels between manufactures is the sometimes used "circuit board" on the score reels. This circuit board is used for the match and high score sensing (so not all reels or even all games will have these).

The point I'm trying to make is score reels are basically all the same. Here is what they all have in common:

• A stepper solenoid to advance the reel.
• A zero position switch which opens when the reel is at "zero". This is used in the game's reset process to set all the score reels at zero.
• A nine position switch which closes when the reel is at "nine" (not all reels will have this, as this switch is used to advance the adjacent reel).
• An EOS (End of Stroke) switch which closes when the score reel solenoid energizes (again not all score reels have that switch).
• A circuit board with a rotating "finger" to sense where the score reel is currently set (used for Match and high score circuits). This is not on every score reel or every game.

Sometimes there will be other switches or components on the score reels too, but above are the most common.

Removing a Score Reel.
Each score reel will have some easy mechanism to remove it from the backbox. On most Gottlieb, Williams and Genco games up to 1967, the "rat trap" reels have a small "hairpin" that must be removed. Chicago Coin used two screws to secure each reel. On 1967 and later Gottlieb "decagon" score reels, there's a nylon release tab. 1970's Bally and Williams have small levers that are held to remove the score reel. Whatever the game, there will be some mechanism that allows easy removal of the score reels for service.

Checking for Mechanical Problems.
With a reel removed, manually press the coil plunger in and let go quickly to release it (do this quickly; if the plunger is let out slowly, there may not be enough momentum to move the score reel to the next digit). Does the reel move easily to the next digit? If not, disassemble the mechanism and clean the moving parts with alcohol. Typically the plunger inside the coil is gummed up. Note: do not lubricate the coil plunger! It's a dry system, no lubrication (which just attracts dirt) needed! If someone before lubricated the coil plunger, this may be the problem! Clean it.

Also check the return spring tension. The return spring pulls the coil plunger mech arm back after the plunger pulls in. It has to do this with enough spring strength to move the score reel to the next digit. Sometimes these springs are old and tired, and need to be replaced (in the short run you can cut 1/4" cut off to temporarily rejuvenate the tension). This doesn't happen often, but it does happen. But before doing that, make sure the mechanism is clean (see previous paragraph). Increasing the spring tension on a dirty, sluggish mechanism doesn't help anything!

Manually Moving the Score Reel.
A score reel can be manually moved by pressing in the score reel coil plunger by hand. Use fast concise movements to emulate a coil pulling-in the plunger. Do not wrench on the score reel itself. This will damage the mechanism.

For a test, turn the game on and try to start a game. Do the the score reels move to zero? If not, try manually moving all the score reels to the zero position. Now try starting a game; does the score motor stop running? It may or may not, depending on what is wrong. If the switches are out of adjustment or dirty, the score motor may still run. If the game starts after manually moving the reels to zero, just cleaning the score reel mechanism so they could turn easily may fix the game!

1970's Williams Score Reel (Space Mission): note the zero and nine position switches at the lower left. The 1970s Williams and Bally score reels are very similar.

1960's Bally Score Reel: note the zero and nine position switches at the left on this Bally unit.

1970's Bally Score Reel: note the zero and nine position switches at the lower left on this Bally unit.

A Gottlieb "rat trap" score reel with no printed circuit board (easy switch cleaning and adjustment; no dis-assembly required).

1960s Chicago Coin score reel. Notice the plastic reel which is easily damaged during cleaning. Also not the different style of score reel circuit board.

1950s Genco and Chicago Coin score reel. Essentially the same mech as a Gottlieb/Williams rat trap reel, but with a different paper covered numbered aluminum reel (Genco 2 Player Basketball).

Score Reel Switches.
If the game still won't start, it's a good idea to examine the score reel switches. Clean and maybe adjust the zero position or nine position switches. All score reels will have some sort of cam that opens and closes a set of switches as the score reel moves to the nine and zero positions.

On 1970's games, this is real easy to find. These switches are on the outside of the reel, and easily seen. On early "rat trap" Gottlieb score reels this is a bit more difficult. Score reels with printed circuit boards on the outside will need to be disassembled to get at the switches (see pictures). Starting in 1967, Gottlieb switched to the "decagon" score reels (the reels themselves are a decagon shape, and are not round). The switches on these units are much easier to access.

A Gottlieb "rat trap" score reel with printed circuit board (dis-assembly required to clean and adjusts the switches, which live under the board).

A Gottlieb "decagon" score reel, as used from 1967 and later. Note the switches are much easier to access, even with the printed circuit board in place.

Once there is access to the zero and nine position switches, manually move the score reel solenoid. Note how the switches operate, especially when the reel is at the nine and zero position. If it's not obvious what is happening, compare to a functional score reel to figure it out (this is a very handy trick, assuming at least one of the game's score reels is working and resetting!)

There is also a nine position switch on all the score reels (except for sometimes the last, largest number reel). When the score reel is in the nine position, it closes one or two switches which tell the next score reel in line to move up one when the current score reel advances to zero.

Gottlieb Decagon Nine, Zero Position Switches: The decagon score reels provide easy access to these switches for cleaning.

The zero position switch(es) tell the score motor when the score reel is at the zero (reset) position. There is usually two sets of zero position switches: one for the score motor, and one which enables the score reel's solenoid.

Clean all the nine and zero position switch with a flexstone. And make sure they operate with a good wiping motion, and adjust accordingly. But be careful in adjusting the zero and nine position switches. There is a balance between switch blade tension and the amount of "horsepower" available to turn the score reel. If the switch blades have too much tension, the score reel may "hang" and not move past the nine or zero positions. This is a common problem, and some (incorrectly) change the return spring tension to try and compensate for it.

Lastly, many score reels have a score reel solenoid EOS (End Of Stroke) switch. Make sure this switch opens when the score reel solenoid is fully engaged. Also clean this switch. See below for more details on this switch.

Gottlieb "Rat Trap" Reel: Remove the three screws so the metal score reel can be removed from it's cam. Do not remove the retaining clip from the cam shaft! With the reel removed, use some 600 grit sandpaper and clean the printed circuit board traces so they are shiny. Note the one larger alignment pin (blue circle) on the nylon hub. This lines up the score reel's larger hole (blue circle) when replaced. But don't get the alignment holes mixed up with the three (like sized) screw holes!

Gottlieb "Rat Trap" Reel: After removing the two screws from the printed circuit board, you can slide it out to get at the nine, zero position and EOS switches.

Cracked Solder Joints On Williams Score Reel Switches.
Williams games have a particular problem with cracked solder joints on the wires soldered to the score reel switches (zero, nine and EOS switches). This happened because of an inferior manufacturing technique William's used to attach wires to the solder lugs. This can cause game reset problems. It's a good idea to pull on each wire going to these switches to check for cracked solder joints. It's almost a guarentee to find at least one wire with a cracked joint on any Williams games. To properely fix this, cut the wire(s) clean and twist together. Heat them with your soldering iron, and apply some solder. Now heat the solder lug on the score reel and flow the tinted wires into this joint. A smooth joint will not break.

Clean the Score Relay Switches.
Each of the score reels is driven by an associated relay. Since the score reels get considerable use, you can also assume the relays that drive them do too! Because of this, clean ALL the contacts on each score relay. There will be about five switches (more or less) per relay. At least two switches will activate the score reel itself (and maybe the next reel in the line for when the current reel's score moves from "9" to "0"). One of the switches will probably go to the bell solenoid for that score reels. Clean all the switches with a flexstone. Also check that the switches are adjusted correctly with a good wiping motion (as described in the switch contact section).

Williams Score Relays: shown are the three relays in the lightbox that control the four score reels. Note the absence of a fourth score relay (for the 10,000 score reel); that score reel only gets advanced when the 1000's relay hits "9", and hence doesn't need its own relay.

The Score Reel EOS Switch.
Each score reel will have an end-of-stroke (EOS) switch for its coil. This normally closed switch will open as the coil plunger reaches its end of stroke when advancing the score reel.

The EOS switch's purpose in life is to break the power going to the score relay. If this switch never opens, a score relay can get stuck on. This can lock on the score reel coil and any feature (such as a bell or chime) wired to the score relay. This EOS switch needs to be cleaned and adjusted properely.

What about a missing or broken score reel EOS switch? In reality this is usually Ok, and very common. Often one of the blades on the EOS switch breaks off (from constant use). This leaves the circuit permanently open. Again, this is Ok in most cases. The only problem that can occur is if the EOS switch becomes permanently closed, not open! If there is a broken score reel EOS switch, just forget it. Don't replace it (unless you are comfortable with this repair and insist your game works just like the factory intended). Having a broken normally closed EOS switch blade only makes the pulse slightly shorter for the score reel to move to the next position. The exception to this is if the EOS switch is a 3 blade make/break switch or a normally open switch. In this case it is performing a carry function and is critical.

Testing the Score Relays.
Once the score relay switches are filed clean and adjusted, test them. (Even if the game is a 1950's EM with no score reels, it still has score relays that connect to the score stepper units instead of score reels.)

On Gottlieb games, the score reel relays can only be tested during a game. On Williams and Bally games, just turn the game on. Manually push each one of the score relays in by hand. The score reel it controls should advance. Note: when doing this in "game over" mode, if "0" is reached on the score reel, it will NOT advance the next score reel. But if you do this test in the middle of a game, when a "9" is reach, manually pressing the score relay again will advance the next reel one step too.

Gottlieb "Rat Trap" Score Reels and Relays (Buckaroo): notice the three relays to the right which control the three score reels. Since this game has a lighted fourth "one thousand" score, there is one relay for each score reel (unlike the picture of the above williams relays where one of the four score reels doesn't have a corresponding relay).

When starting a game and manually testing the score relays, check the "9" position of each reel. That is, advance a score reel to the "9" position. Now activate the score relay again. Does the next score reel advance with the current reel? If not, the "9" position switch on the current score reel may be dirty or out of adjustment (or the highest score reel in the numeric set is being tested!)

Remember, on Gottlieb games, the score relays can only be tested during a game. So if a game can not be started at this point, the score relays can not be tested. This is unfortunate, but there isn't any alternative.

the "Art" of Manually Activating Relays.
As dumb as this may sound, there is actually an "art" to activating a relay by hand. If done incorrectly, the relay can be mis-aligned, and seemingly make a working relay into a temporary mess.

Each relay has the coil itself, a pivot point, and a metal activating lever plate with a plastic or bakelite piece that the switch ends ride in. To activate a relay, press the metal plate in towards the coil. But be careful, if pressed with a sideways motion or pressed too hard, t he metal lever plate can be knocked off its pivot point. This will mis-align the switches and cause chaos. It's easy to fix, but the mis-alignment may not be noticed, and all the switches in this relay will look like they need adjustment (when in fact they do not)!

Score Relay Stuck On?
This is a common problem. One of the score relays is stuck on as a game is started. A lot of times people don't notice this till they smell the score reel solenoid burning! A sure sign of this is a score reel doesn't register points. This happens because the score reel solenoid and the score relay are both pulled in and won't release.

Check all the playfield switches; one is probably "on", thus locking it's corresponding score relay on. If a closed playfield switch can not be found, it could also be a feature relay switch that is stuck on. For example, the Fifty point relay has a stuck switch which connects to the score relay.

Some other things that cause a score reel to stick "on":

• Score Reel EOS Switch is dirty or permanently closed (see above).
• Two solder lugs of a switch are bent and shorting together.
• A single loose strand of the multi-strand wire is broken and bent, shorting to another solder lug.
• The vibration damping blade is shorting against the other adjacent switch blade.
• Pitted or mis-adjusted contacts driving the score reel. Until the score reel takes its step, it won't release the score relay.

A Mis-Adjusted Playfield Switch: Notice the damping blade in the middle (which dampens the upper contact) is shorting to the lower contact. Yet the contact pads are adjusted correctly. This is visually deceiving.

Of the above listed problems, the last one is the most common! A lot of times you just don't noticed it. But if you look at a playfield leaf switch, you'll notice it consists of two leaf blades with contacts. BUT there is a third, shorter blade. This blade is the vibration damping blade. It provides support to ONE of the blades. Yet sometimes this damping blade is bent and shorts against the other blade. This will lock a score relay and/or feature relay on.

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2e. Before Turning the Game On: Midway Motorized Score Reels (1965-1975)

Starting around Mystery Score (August 1965) to about 1975 (when Midway largely converted to solidstate score displays), most (if not all) Midway pinball and arcade games used motorized score reels. I don't really understand why they did this, but it must have been some attempt at "making a better mousetrap". Unfortunately Midway did not succeed (at least in my opinion). The conventional solenoid driven score reels as used by all other game manufacturers were easy to work on and well understood by any decent game repairman. Midway's system was unique and not easy to understand or work on. They didn't really use less moving parts, and they weren't more reliable. And when the motors overheated and burned it wasn't as simple as replacing an inexpensive solenoid to fix it. For these reasons there are some people that avoid 1965 and later Midway games because of the motorized score reels. Myself, I find the unique game play of the 1965 to 1975 Midway games irresistable. For this reason, I have a love/hate relationship with these motorized score reels.

How They Work.
The score reels move using two motors (or "score motors" as Midway calls them, just to confuse people with the bottom panel score motor used by other makers - I call them "score reel motors" to avoid confusion). There are two motors that controls all three (or more) score reels for one or two players. The two score motors are placed right next to each other in the horizontal center of the backbox, but act independently (though they appear to be a single motor). One motor spins the reels forward, and the other motor spins the reels backwards.

The system works like this: There is a relay latch mounted towards at the back of the score reels. The relay latch work on the "ones" (or lowest denominator) score reel. The other score reels (tens, hundreds, etc) also have a latch plate just like the ones reel, but no relay to control it. Each score reel also has a simple clutch, so that the reel can stop spinning while the score reel motor continues to spin. When the game is reset, the *reverse* rotating score reel motor turns due to a switch that closes on the start relay. All the score reels move to zero and then lock in place because of a groove in each score reel, which stops the score reel from spinning on its latch plate. The score motor continues to turn in reverse for a pre-determined length of time (determined by the game's "feature motor", which is the same thing as any other maker's score motor). If any score reel hits zero before the score reel motor stops turning, the score reel stops spinning on the score motor's rotating shaft because of the reel's clutch.

Now that all the score reels are reset to zero, whenever points are scored, it is done by turning on the *forward* rotating score motor. This will move the lowest denominator (one's) score reel. Timing is used based on the score reel motor and feature motor's known RPM speed to achieve a particular score, in conjunction with the score reels latch relay (which pulls in, and allows the score reel to turn) and the score reels stepper-unit-like fingers on a bakelit disk. The tens, hundreds, thousands reels only move as the previous reel hits nine and advances back to zero.

A set of Midway motorized score reels. Note the slip joint that mates the motor shaft to the score reel shaft. Also not the latch plates for each score reel. Game: 1965 Midway Mystery Score.

Working on the Motorized Score Reels.
At first it seems like an ingenious system, until you have to work on one! Usually each score reels has a pair of "fingers" which move across a bakelite disk, like a stepper unit. Often these bakelite disks and fingers need to be cleaned. Or the score reels do not have the proper "shaft slip" (clutch) for them to reset to zero. Or worse, the score reel motor burns. If any of these happen, the score reels need to be taken apart.

This is where things get tricky, and I must warn you. DO NOT DISASSEMBLE THE SCORE REELS UNLESS YOU ARE SURE THEY NEED TO BE TAKEN APART. It is really easy to mess up the whole clutch system, so don't take them apart unless you must.

The first trick is removing the reels from the backbox. To do this, tilt the backbox insert panel back. This will allow easier access to the difficult-to-access four machine screws that hold the set of score reels to the mounting base plate in the backbox. After the four screws are out, the whole set of score reels can be slide up and back. This happens because of a slip joint between the score reel motor and the score reels.

At this point, STOP AND THINK. Any disassembly of the score reels is VERY risky. If not put back together correctly, the whole set of score reels will not work. And it is *very* easy to make a mistake! DO NOT take the score reels apart unless you have a darn good reason. Chances are excellent you will only make things worse.

At this point, just examine the set of score reels. Are any wires cut or broken off the relay or bakelite plates? Does the latch relay look to be in good condition? Do the reels seem to move without binding when the latch plate is engaged or disengaged, in either direction? Usually any of these problems can be fixed without any disassembly of the score reels. The only thing that really can't be worked on is the cleaning of the score reel "fingers" and the bakelite plates the fingers ride.

If the score reels must be taken apart, take good notes! This is very important. Also start on the side of the score reels *with* the locking "E" clip. Remove the clip and the two screws that secure the end plate. Then remove each notched washer, spacer, score reels, and bakelite plate. Make notes of how and where each part was removed. Stack the parts in order, making it easier to reassemble. Clean the score reel fingers and backlite plates with 600 grit sandpaper. Reassemble it all, making sure not to mess up the order of the parts. Pray that you did it right.

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2f. Before Turning the Game On: Stepper Units

The SECOND Biggest Problem in EM Games.

The other common failure in EM games are the stepper units. Steppers have at least one coil that "steps up" the mechanism, and often another coil that "steps down" (or fully resets) the mechanism. Often these units bind.

Stepper units are used for a variety of uses. If you have a 1950's EM game, they are used for the lightbox scoring. There's a stepper for each scoring range (thousands, ten thousands, etc.). Each stepper will have a step up coil, and maybe a reset coil (to reset the points to zero). Usually the lowest scoring stepper (like the zero to 10,000 point stepper) won't have a reset but will just rotate around to the zero position. Stepper units are also used extensively in score reel era games too. Uses for steppers include counting bonus points, keeping track of the current ball number, matching (at the end of a game), keeping track of number of credits, and keeping track of the player number (for two and four player games).

(Left) Bally Stepper Unit with no step-down or reset coil. This unit is known as a "00 to 90" unit, and is used for the match. (Right) Bally Stepper Unit used for ball number with both step-up and reset coils.

Each and every stepper unit in any EM game needs to be examined, cleaned and manually tested for proper operation. Common problems associated with stepper units are:
• Game can not be started.
• Score motor continues to run when a new game is attempted.
• Game credits not added or taken off.
• Current ball number in play never changes (always stuck on ball 3).
• Can't change number of players on multi-player games (only 1 player allowed or won't reset back to 1 player).
• Bonus points don't work properly.
• Match number always the same.
• Score won't reset to zero (1950's games with lightbox scoring).

(Left) Williams Stepper Unit showing the wiper fingers and printed circuit board. (Right) Williams Stepper Unit with a step-up and step-down coil.

Note the metal wiper "fingers" on each stepper unit. These wiper fingers determine the path the electricity takes for each step of a stepper unit. The wiper fingers move across a series of brass rivets or across a printed circuit board. These rivets or circuit board must be clean for good contact.

To clean a stepper unit, follow this procedure:

• Turn the power off to the game!
• Un-bolt the stepper from the board it is attached to. Not always necessary, use your judgement.
• Set the unit to the reset position. This is only necessary on steppers that have two coils (a step-up coil, and a step-down or reset coil). Using a "Sharpie" pen and mark the zero position on one of the wiper fingers and on the board it runs across (for future reference, otherwise you could assemble the unit 180 degrees in reverse!).
• Remove the SPRING that winds the unit. Again, this is only necessary on steppers have have two coils. when releasing the spring, COUNT the spring winding as the spring is un-turned. Write the number of spring turns on the stepper unit itself with a Sharpie pen.
• Remove the one or two coils that step-up or down the unit. Clean the plunger(s) with alcohol, and if rough sand the plungers smooth with 600 grit sandpaper or a scotchbrite green pad (do NOT use steel wool!). Put in a new coil sleeve (if possible). Do NOT reassemble the plunger(s) at this time.
• Remove the NUT at the end of the turning wiper shaft. This will remove the wiper fingers from the shaft. Usually the shaft will pull out from the other side. Clean everything with alcohol (or Mean Green), and if rough, sand the shaft smooth with 1000 grit sandpaper or green pad. You may have to remove a mechanism spring or two to get the shaft out. Make notes and drawings as to where the springs and levers go.
• On Gottlieb stepper units, sometimes the three screws on the other side of the stepper will need to be removed to get at the brass rivets that the fingers touch. Mark the disk orientation with a Sharpie pen before removing the disk! See picture below. Also some fine adjustment of the wiper/rivets alignment may be required. And while the wiper/bakelite disk is removed, use an allen wrench and tighten up the three prong holder the disk bolts to.
• Sand the bakelite disk with the brass rivets or the printed circuit board that the wiper fingers glide over. Use 1000 grit sandpaper or a green pad. Green pads work really well, except on Bally units. Those clean up best with sand paper because of rivets don't have round heads. Almost need to block sand Bally flat heads to clean properely. Make the brass or cooper shine.
• Re-assemble the shaft and wiper parts. Use CoinOp oil, light 3-in-1 oil, or Radio Shack teflon grease on the shaft. Don't use much! VERY LIGHTLY lube the brass rivets or the printed circuit board on which the wiper fingers glide.
• Put the nut back on the wiper shaft, and make sure the wiper finger Sharpie lines match up when the stepper unit is reset.
• Wind the spring back to the same number of turns.
• Re-assemble the plungers and coils (DO NOT lube!).

Now manually test the unit. It should step up nicely, and step down (or reset) nicely. If there isn't enough spring tension to reset or step down the unit, wind the spring one more turn.

A 1960s Chicago Coin stepper unit. This unit uses a motor to move the stepper, and a lock relay (right) is used as a "brake" to quickly stop the stepper at a precise location.