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Electro-mechanical, commonly referred to as EM, pinball machines were manufactured from the 1930's until the mid 1970's, when the transition to solid state machines was made. From that span of 40 plus years, literally hundreds of companies manufactured EM pinball machines.
This guide focuses on machines primarily made from the 1950's until 1977 made by four of the largest pinball manufacturers at the time. Manufacturers included in this guide are:
- D. G. Gottlieb & Co.®
- Chicago Coin
Although the amount of companies discussed here is somewhat limited, EM repair transcends beyond these four companies. The operation of a relay, stepper unit, and score motor is essentially the same, regardless of the manufacturer.
Pinball machines operate off line voltage (120V in U.S.) so care must be taken when working on your machine. If you are not comfortable with the risk you should only attempt repairs that can be done with the machine unplugged.
Most EM machines primarily operate with 6.3VAC and 25VAC, which is somewhat safe. However, line voltage will be present from the line-in cord to the primary side of the transformer and the service outlet. Also, some machines have coils which operate on 120VAC, so some relay switches, score motor switches, and anti-cheat / kick off switches have 120VAC present on them. Finally, some older machines have 120VAC going to the start switch and the weighted slam switch located on the coin door. On these games you should check to make sure the fish paper insulation is still in good condition. The fish paper is used to isolate switch voltages from other current conducting items, like the coin door. If the fish paper is torn, misaligned, or missing, there is the potential to receive a shock. This shock can occur while either playing the game, or by touching the suspect game and another, properly grounded game simultaneously.
By all means if you decide to work on a game, do not perform any repairs in socks or bare feet. Don't laugh people have done and do this.
The "Big Three" manufacturers were Gottlieb®, Williams, and Bally. The "best of the rest" would probably include Chicago Coin and Midway, as well as some popular foreign brands, such as Sonic, Segasa, Recel, Rally, Zaccaria, and Playmatic. Some of the foreign manufacturers used American pinball manufacturer parts in part or in whole. For example, Sonic is mainly based on Williams EM architecture, while Recel is mainly based on Gottlieb®.
A quick search of the Internet Pinball Database, shows that between all the manufacturers, there are over 3403 electro-mechanical games within this very broad category. There were many companies which only produced a few games, especially early on.
4 Technical Info
4.1 Recommended Documentation
Probably the single most important documentation to have while attempting to work on an EM pinball machine is the schematics. Schematics are analogous to the roadmap of a state - they are the electrical roadmap of a game. It is always highly recommended to have a copy of the schematics for a particular game on hand. Second to schematics is the game's manual, if one was printed. Game manuals for EM pinball machines were not available until 1967 for Williams, 1971 for Gottlieb®, approximately 1971 for Bally, and approximately 1972 for Chicago Coin. The game manual is an excellent, complimentary documentation to the schematics. If a game manual is available for a particular game, it is recommended to acquire it too.
A guide to reading schematics is available here:
Key to Schematic Symbols
Relays are small coils that when energized complete one or more circuits. They are usually high resistance so they can be activated for a long time without burning up or blowing a fuse. They are the workhorse of the EM world; without the relay, the proper circuits do not get energized and nothing happens. The relays set up the conditions that the score motor then completes the work on. Similar to how a mechanical cash register works; you punch in the functions, and pull down the handle which is that machinery's "score motor."
For example, a 500 point relay will pull in, causing a circuit path to the 100 point relay (which adds 100 points directly to the active score reel set) to be made, and also starting the score motor. The score motor will turn and additional switches will pulse 5 times, causing the 100 point relay to pulse 5 times, adding 500 points to the score. A 5000 point relay operates the same way - except it's completing a circuit to the 1000 point relay. The same 5 pulses from the score motor "do the work" of adding the score.
It is the interconnection of relays and their circuits that comprise the "programming" of an electro-mechanical machine. You can change the way a game plays by adding and changing circuits, to either fix errors in the original programming, or to create new and exciting rules.
4.2.1 Relay Types and Their Functions
A relay is a electrically operated device that when activated, has a moving armature that has the ability to operate various switches affixed to it. One function of a relay is to operate several switches in various discrete circuits at the same time. Step switches, due to their physical construction, need a certain amount of time to complete a step. A relay can trigger a switch or series of switches, in a very brief power pulse. For instance, a ball hitting a pop bumper might not close a switch long enough to enable a stepper unit to advance to the next contact. A relay can “lock in” and complete a circuit for a period of time that would enable a stepper unit to advance or reset properly.
188.8.131.52 Magnetic Relay
There are four basic types of relays used in EM machines. The first type that we shall reference here is known as a magnetic relay. Please refer to the schematic and diagram to the right for this section. Referring to the schematic, take as an example a N.O. switch (type A, by GTB) labeled “bumper” that is closed by a pinball striking the pop bumper. The coil indicated as a L RELAY, is a magnetic coil that is energized by the bumper switch. The result is that the coil becomes an electromagnet and attracts the armature which pulls down to the coil core and closes the 2 N.O. switches marked L 1 & L 2. The closed switch L 1 keeps the L relay energized, even though the pinball has bounced away from the bumper and its contact has opened.
Current still flows through the circuit via the closed L 1 switch, then through the N.C. switch labeled “on step switch”, to the electromagnetic coil on the L relay. This “on step switch” is mounted on the stepper unit so that it only opens when the step up arm of the stepper unit has completed a full stroke. After the step up arm has completed its stroke, the switch opens the circuit, cutting off the current to the L relay. Since the circuit to the L relay coil is now open, the coil no longer attracts the armature to its core. Helped by a spring attached to the armature, the armature returns to its original position and opens the 2 switches L 1 & L 2. With the switch at L 2 open again, the coil on the stepper unit is no longer energized, and so the drive arm returns to its original position, re-closes the N.C. switch and the stepper unit is ready for another cycle.
184.108.40.206 AG Type Relay
The second type of relay is similar to the above electromagnetic type, but is a high speed type with short switch blades and a short stroke, and is known as an “AG” relay. Please refer to the diagram on the right. An AG relay may have several switches in one or two stacks, in any kind of switch formation, N.O., N.C., Make-Break, or Make-Make. A plastic or nylon ”ladder” is riveted on the armature to operate the switches in unison.
220.127.116.11 Interlock Relay
The third type of relay is known as an Interlock relay, and it consists of two electromagnetic relays that are constructed in such a way, that when one relay pulls in (is energized), the armature of that relay operates the switches mounted on it, and the armature of the OTHER relay slides over and locks the first armature in its closed position. This holds the switches in the activated state, even as the power is cut off from the first coil. The switches cannot return to their normal state until the SECOND relay is energized, pulling the second relay’s armature back, thereby unlocking the first relay’s armature, permitting the first relay’s switches to return to normal.
18.104.22.168 Trip relay
The fourth type of relay is a TRIP relay, usually ganged together is what is called a TRIP or RELAY BANK. There may be only a few relays in the bank, or up to a dozen. A trip relay, when energized, releases an armature which trips a latch that operates a series of switches. Even after power is removed from the trip coil, the latch, its spring and switches are held in the activated position. The only way the armature and its associated switches can be reset to normal, is mechanically by a large bank coil(or coils) which operates a bank reset arm. This coil is often 120 volts AC due to the large amount of physical power needed to reset a large bank of relays. When the reset coil is energized, the reset arm is pushed against all the latches of all the coils in its bank returning all the switches to their normal positions and releasing all the armatures which snap open due to the armature spring. The open armatures hold the latches in the open position when the reset coil is de-energized, and the pull of the reset spring draws the reset arm away from the latches.
22.214.171.124 Armature Switch and Series Latch
The trip relay bank may have an armature switch held open by the trip relay armature when in its reset state. The armature switch is wired in series with the reset bank coil, and its function is to ensure that the current flows to the reset coil until the bank is fully reset to its normal at rest position. In addition, there may be a SERIES LATCH, which does NOT have a coil to hold it open, but instead has a bar that rests on two or more latches in the relay bank. When ALL the latches in that series are tripped (activated) the SERIES LATCH drops also to operate its own group of switches.
4.2.2 Series Relay Explained
The series relay is, as implied by the name, a relay in series with another set of relays. This was done to allow a group of target switches to have both an individual action and a common, or shared, action.
For example, Gottlieb® used a series relay in it’s 1975 “Spirit of 76” game. A portion of the circuit diagram showing the series relay, labeled A, is shown in the figure below. A-1119 = 2.2 ohms, A-9746 = 1.8 ohms. The A-E star rollovers energize one of the 1B-5B bank relays while simultaneously energizing the series relay. The bank relay trips to control the rollover lights. The series relay controls the scoring. [ED: It would be good to identify the earliest game this was used on.]
Coil resistance is very important to correct operation of the series relay circuit. It is important to use the correct replacement coils in this circuit. The coil voltage will be divided across the coils in series, so each will only see a portion of the coil voltage. Typically, coils in series will be about the same resistance, so each will see one-half of the available voltage.
Game design is also critical to correct operation of the series relay. The relays in the circuit with the series relay must be controlled such that only one is energized at a time. This requires that the playfield switches in the circuit be physically separated so the ball has no way of actuating more than one switch at a time.
Use of the series relay was a design choice driven by cost. There are other ways to achieve the same game operation, but they involve using more switches and more relays.
4.2.3 Reset Completed Relay
4.2.4 Delay Relay
Bally used a special relay in the 1970s to provide a time delay circuit. The delay relay uses a #455 flasher lamp in the lock-in circuit to generate the time delay. The lamp is in series with the normally open lock-in switch. When the relay is energized, the lock-in switch closes and the lamp lights. When the lamp filament heats up and the lamp flashes off for the first time, the open circuit releases the relay.
The flasher lamp is required for correct operation of the delay relay. Using a standard lamp will result in the relay locking on once it is energized. If the lamp is missing or burned out the relay will fail to lock-in, resulting in the relay energizing momentarily and no time delay. Note that the 6.5V lamp is powered by the 50V coil voltage in this circuit, so the delay is shorter than the normal flash delay. If the delay is too short or too long, the Bally game manual recommends experimenting with different #455 lamps until the desired delay time is achieved.
The picture to the right shows the delay relay from the "Over The Top" buzzer circuit on a 1976 Bally "Hokus Pokus" game. The #455 lamp is pointed out in red.
The following circuit diagram shows the control for the delay relay as used in the "Hokus Pokus" Over-The-Top circuit. The right two circuit legs are the enable circuits for player 1 and player 2 respectively. The relay is energized when the "9th position" switch on the player's 10,000 point score reel is closed and the end-of-stroke switch closes. That is, when the score rolls over from 90,000 to zero. The left circuit leg is then enabled by the normally open switch on the delay relay itself, lighting the time delay lamp.
Leaf switches in pinball games come in 4 formats: Normally Open (N.O.), Normally Closed (N.C.), Break-Make, & Make-Make, the last 2 of which are really combinations of a N.O. and/or a N.C. switch. Regardless of their function, all switches are in fact, a N.O. or N.C. type.
Leaf switches in EM games are of 2 compositions,at least 2 bronze blades each holding a Silver Contact or a Tungsten Contact(occasionally 2 contacts per blade). Since silver is a very high conductor of electricity, it is used on most EM switches, with the exception of the flipper cabinet and End of Stroke (EOS) contacts, which are tungsten. Silver tarnishes and turns black, but this does not effect its conductivity. Silver contacts may be cleaned with a flex-file or sandpaper, in order to redress the switch for adequate surface contact. Tungsten flipper contacts must be redressed with an ignition-type flat file as used in automotive repair, as the contacts are too hard to be smoothed by sandpaper or flex file abrasive. Gold flashed contacts, are not normally used in EM games, and must NEVER be cleaned with a file or sandpaper. A business card, or thin cardboard, is all that is necessary to clean electronic gold flashed contacts.
4.3.1 Normally Open (N.O.) Switch aka Form A Switch
This is a leaf switch that has 2 (rarely 4) contacts that complete a circuit when pushed closed by some mechanical device. The switch re-opens when the device moves away from the moveable contact, and the springiness of the blade opens the circuit. Gottlieb® calls this type of switch, a “Form A” switch, and this term is sometimes used in its schematics.
4.3.2 Normally Closed (N.C.) aka Form B Switch
This type of switch, called a “Form B” switch by Gottlieb®, opens a circuit when a mechanical device pushes against the blade. A typical use of a N.C. switch is the bottom cabinet tilt or game off switch GTB uses on early EM games. When the bottom of the cabinet is struck intentionally or by a disgruntled player, the weight on the end of the blade moves the contacts apart and turns the game off.
4.3.3 Break-Make aka Form C switch
This switch is really a composite of a N.O. and a N.C. switch with just three blades instead of four. The moveable center blade has contacts on BOTH sides. Proper adjustment insures that when a device moves the center blade towards the open contact, the CLOSED switch OPENS BEFORE the center contact touches the open switch’s contact. When the pressure is released, the center blade returns to its N.C. side and re-makes contact. This type of switch is often used on relays. A Make-Break switch is really the same, just upside-down, or in reverse, of the order of actions of a Break-Make switch. Special care should be taken with a Make-Break switch that the three blades are at not time shorted together. This can happen often when the blade stiffener is maladjusted, and contacts the other blade of the pair.
4.3.4 Make-Make aka Form AA switch
A make-make switch is a composite switch consisting of two N.O. switches using only 3 blades. When mechanical pressure is applied to the blade, the switch “makes” or closes the circuit, and continues to move until a second switch contact is closed, tying all 3 blades together.
Additional information & photos about leaf switches can be found here.
4.4 Score Motor
The Score motor of an EM machine is the heart of an electro-mechanical computer. Through a combination of a motor, cogs and switch stacks, the score motor controls the game reset, scoring and features for the pinball machine. Like a computer program which has a fatal error, if a function controlled by the score motor cannot be executed the score motor will run on and on in a runaway fashion.
The score motor switches take a lot of abuse, and are often the target for an inexperienced repair person, when in fact, the reason the score motor will not stop rotating, is because a switch elsewhere is not operating correctly. The score reels are a notorious example of this, and will be discussed further below. Correct gap on the score motor switches is critical for proper game operation.
4.4.1 Gottlieb® Score Motor
Most of the following will concern Gottlieb® score motors, but the general concepts will apply to all other motors as well. The score motor consists of a frame, gear motor, cam assembly and various switch stacks. The motor operates at 26 RPM, with a vertical shaft which has a cam assembly attached that operates the switch stacks.
126.96.36.199 Gottlieb® Score Motor Physical Description & Function
The cam assembly consists of 2 circular notched cams that rotate, driven by the motor. The cams in turn, actuate the switch stacks by two methods. Switch “dogs” ride along the edge of the cams, and pins protruding vertically from the face of the cams, above and below the score motor assembly, actuate switch stacks additionally. This arrangement creates 5 vertical levels of switch stack positions.
The top cam is divided into three equally spaced notches, while the lower cam has 3 notches which are further divided into 5 equally spaced teeth. When the score motor makes one complete revolution, this results in 3 complete operational cycles.
188.8.131.52 Understanding The Location of Score Motor Switch Stacks
There are little paper labels that are numbered 1 through 3 ½ and 4 stuck to the base plate of the score motor to identify which position you are looking at. Feel fortunate if yours are still there and legible. If just one of them is remaining, you can count clockwise from that one to determine which stack is which number. Sometimes ALL of the stickers are gone, but you still can determine the switch stack. Number 3 ½ is a wireless switch blade all by itself attached to the frame. Just identify # 3 ½ and count clockwise to 4, then 1, 2, & 3. It may help you to make little labels and attach them to understand what you are looking at quickly, and for future reference.
Not all switch positions have switch stacks at every level. It may help to un-pin the score motor and pivot it up to look at levels A and B, or to adjust them. Of course, you will do this with the power off, unless you have no fear of the consequences of finger grinding gears, merciless sharp edged cams and electrical sparks.
184.108.40.206 Gottlieb® Switch Level Nomenclature
Gottlieb® names the switch stacks by level and orientation around the circumference of the top cam. At a casual glance, some of the switch stacks cannot be seen, because they are located below another switch stack. Each of the 5 positions around the circumference does NOT have the same number of switches or switch levels as the others.
Level A- Located at the bottom of the score motor assembly and actuated by the edge of the bottom cam.
Level B- Positioned just above the “A” level and operated by studs mounted vertically to the bottom of the top cam.
Level C- Switches actuated by the edge of the Top Cam.
Level D- Switches operated by vertical studs mounted to the top of the Top Cam.
Level E- A switch operated by a very long vertical stud mounted to the Top Cam.
Switches are further identified by the position they occupy around the circumference of the score motor cams. The positions are labeled in a clockwise direction. 1,2,3,3 ½, & 4. A switch may be designated by the schematic by the label 1C, which tells the repairman that the switch in question occupies the switch stack at position 1 (NOT 1 o’clock), riding on Level C, which is operated by the edge of the Top Cam. There may be several switches all occupying the same location, or it may be unique. The numbers and letters have no bearing on the order in which any of the switches control any operation of the machine. Please see the diagrams and photos for a visual reference that may make this clear.
220.127.116.11 At Rest Machine Position
In a normal at rest condition, the score motor will be in a position where a “dog” will be resting in one of the 3 notches in the Top Cam, at Level C, Position 1. This switch will be a N.O. or Form “A” switch (as GTB calls it) whose function it is to lock-in the score motor for a 1/3 revolution when a power pulse is applied to the motor, coming from another circuit in the machine. The switch dog that rides along the edge of the cam, “climbs” out of the notch, closing the gap and making an electrical connection through switch 1 C. When the motor finishes rotating 1/3 of a revolution, the switch dog drops into the cam slot again, opening the circuit at 1C, thereby stopping the motor. Helping to keep the motor from over-running its desired position, is a single formed switch blade without any wires connected to it, that acts as a motor brake, located at position 3 ½ B. It sometimes happens that this switch is broken, and the game will act erratically. In proper operation, the switch at 3 ½ B contacts a cam stud, just after the switch at 1 C drops into its notch, stopping the motor.
In function, the score motor acts like a relay, but unlike a relay, the score motor can operate many switches from 1 to 5 times per power pulse. A further benefit of the score motor is that, the score motor supplies sufficient time for the stepper units to complete a step, ensuring proper game scoring and features.
Most of the switch stacks operate the same for each 1/3 of a revolution of the score motor, but the addition of the studs on the faces of the cams make it possible for a switch to operate only once for each complete revolution, or, if 2 studs are fixed at that level, two times for each revolution.
Each of the switch dogs have 2 slots in them, making it possible for the manufacturer to vary the timing of the operations that these switches control. These switch dog positions MUST NOT BE CHANGED. If you suspect that the position of a switch in the slot has been altered, in some schematics the proper location for the switch is indicated.
18.104.22.168 Detailed Operation and Identification of Score Motor Switch Positions
Below is a detailed explanation of the operation of each set of switches in a generic fashion, which may or may not be identical to your machine. Keep in mind that each motor number and letter position may refer to one or several individual switches. Although position 1 has switches that are first in operation, not all the switches at that position follow that sequence of operation.
Motor 1 A: This switch opens and closes 5 times for each 1/3 revolution of the score motor. The switch at 1A may control a scoring unit directly or in series with other motor switches through a controlling relay. It can also furnish impulses to reset continuous stepper units, to flash lights, or any other purpose where a short duration pulse is needed and timed through another motor switch.
Motor 1 B: Operates 4th in operational sequence and generally is used to time a scoring function. It can be used in series with other switches to eliminate or carry over the fourth pulse that would occur with motor 1 A.
Motor 1 C: As discussed above, this is the normal at rest position for the score motor. It functions as the motor override switch, and always operates the motor until 1C opens. This switch insures that the motor always stops at the same relative place, regardless when an external switch opens that triggered it. Additionally, motor 1C opens the replay button, keeping the player from energizing the start circuit until the motor is back to normal. Motor 1C cuts off power to the playfield switches while the motor is “off normal”, to keep scoring from the playfield from interfering with scoring coming through the motor. I may also control lights associated with scoring conditions active only when the motor is off normal.
This switch will often show a blue spark, especially noticeable in a darkened cabinet, that is a normal consequence of the motor’s EM field collapse when it turns off. Although normal, it causes pits and shortens the life of the contacts of 1C, which may need to be cleaned with a flexstone file or sandpaper, and its gap re-adjusted (if necessary), for reliable operation. This switch is the first thing that should be investigated when a score motor will not stop running.
Motor 1 D: Switches at 1D are actuated by studs attached to the top cam. If the 1D switches operate time with the 1st position of 1A, the switch is used to control scoring, or close a circuit to any unit such as a relay, that requires a pulse from motor1A. Motor 1D should be checked and adjusted if necessary, that it closes before motor 1A, and opens after motor 1A is opened.
If 1D is time coordinated with the 1C at rest position, it is usually used to turn on or off lights related to contacts on the playfield, or change score values of same.
Motor 1 E: Turns on or off lights for scoring and is not timed with motor 1A.
Motor 2 A: NOT USED.
Motor 2 B: Actuated by studs between the two cams and timed to operate between motor 4C and Motor 1C. Often used to hold in scoring, start, or extra ball relays, until they have completed their function. Drop out of these relays then occurs after 4C
Motor 2 C: This position is timed to the 2nd pulse from motor 1A, & is used to eliminate or carry over this pulse to other scoring circuits. The function of 2C may be to subtract the replay, step the total plays meter, reset a bank of relays, match (replay), or some other purpose that must time with motor 1A. This switch stack operates in the long position of the switch dog, while all the others are usually operated in the short dog position.
Motor 3 A: NOT USED
Motor 3 B: This motor position is timed with the 3rd pulse of 1A, and eliminates or carries the pulse to other scoring circuits in the machine. This switch stack may operate kickers, reset banks of relays, etc.
Motor 3 C: NOT USED
Motor 3 D: Operates with the motor at rest to turn on or off lights & control scoring, and may be used as an anti-cycle switch for a roto unit. Is not timed with Motor 1A.
Motor 3 E: May be used instead of, or in addition to 3D, and serves the same function.
Motor 4 A: This position is used as an alternative to 1A, and is timed to alternate with 1A. By operating this way, it reduces electrical load at any one time, due to this intentional staggering of operation with 1A. It may also flash lights when the motor is running, or in coordination with other relays.
Motor 4 B:This motor position is timed with the 3rd pulse from 1A and is used together with motor 3B. It is often used in the extra count circuit.
Motor 4 C: This position is timed with 1A in the final 5th pulse. It controls match, scoring, extra chute count, bank reset and other functions.
Motor 4 D: Operates in the rest position and therefore not timed to 1A. It controls lights, changes scoring, etc.
Games will always have exceptions and additional uses for the score motor at the above positions, and this section is meant to give an idea of the order of switch operation on the score motor. Ordinarily, no adjustment is needed in these switch positions, but attention should be paid to proper gaps for each leaf switch.
4.4.2 Williams Score Motor
The Williams EM score motor is very similar to the Bally EM score motor. Each motor has an "index" cam, located next to the actual motor. Adjacent to the index cam are 6 timing cams. The first 5 of these cams "drop out" at different points during a score motor revolution. The 6th cam drops out at the same time as the 5th cam. Adjacent to the 6th cam, the last two cams are "impulse" cams, used to carry out game functions requiring 5 pulses during a half revolution of the score motor, like bonus countdown, 50/500/5000 points, and score reel resets. The two impulse cams share the same timing, but typically the switch stack over the 7th cam is mounted forward of the switch stack over the 8th cam, causing the timing of these two cams to be exactly out of phase.
4.4.3 Bally Score Motor
stub (describe switch positions and general make up like GTB score motor section)
Bally score motor switches have a number and letter, for example 4C. They are indicated on the schematics with a circle around the switch. The number indicates the cam number. The letter indicates the position in the switch stack, with A being the bottom, or closest to the cam. Switch 4C will be on the fourth cam, third switch in the stack. Cam #1 is the cam closest to the motor.
The schematics contain a timing diagram for the score motor. The cam position are shown in the rows, numbered along the left side. The columns indicate the rotational position of the cams. Zero is the "at rest", or home position. The black squares indicate the position that the switches on the cam operate.
Bally score motors from 1965 to 1977 operate for 180 degrees for each score motor cycle. The timing diagram depicts one full rotation of the score motor which is two score motor cycles. Both cycles provide the same switch operation.
Not all, but the vast majority of Bally score motors used in pinball machines use a vertical cam system. Switch stacks are then placed on the cams closest to the score motor outward. Below is an example of switch stack 1 on a Bally score motor in both at rest and motor running positions. This will give a general idea how normally open, normally closed, and make-break switches react while riding on a score motor cam.
22.214.171.124 Bally Motor Switch Level Nomenclature
Bally score motor switch levels are identical to Williams. Starting with the switch level located closest to the motor cams, the first level is referred to as "A". Any switches added above "A", are B, C, D, E, and so on.
4.4.4 Chicago Coin Score Motor
stub (describe switch positions and general make up like GTB score motor section)
4.5 Stepper Units
There are 3 basic types of steppers used in EM machines.
- Step up / reset stepper
- Step up / step down stepper
- Continuous stepper
Additionally, Williams made a three-mode stepper -- Step Up / Step Down / Reset. The Reset mode is enabled by a rod connected to a relay plate. When the relay is enabled, the rod holds the step-down lever away from the gear, allowing it to sweep all the way back to its origin.
One thing that all steppers have in common is that then need to work well for you to be happy with the way your game functions. In fact, most of the functions are so integral to the game that your game will be "broken" if the steppers do not work. Most games cannot get through a reset sequence unless the score reels reset. Additionally, they might not advance to the next ball if the bonus is not counted down correctly. In order for a stepper to work correctly, it must be relatively clean and free of sticky grease and oil. The electrical contacts must be clean and should be coated with some sort of dielectric grease. The coil and plunger need to function smoothly. Finally, it needs to step once and only once per actuation. There are often adjustments to stops and coil locations that can be made to ensure this. When you actuate a stepper by hand, it needs to move smartly from by one step to the next. If this doesn't happen, it is time to rebuild your stepper.
4.5.1 Step Up / Reset Stepper
The step up/reset stepper is generally used when you only need to count up, not down. An example of the might be on a ball count unit that is used on a replay machine. For this application, you count up to 3 or 5 balls played, depending on the setting, then reset to 0 or 1 ball as part of the start up sequence. Step up/reset steppers are also used for the 100K unit on a Gottlieb® Woodrail. They are also occasionally used for bonus counters with the "scan style" bonus used on some later Gottlieb® games, like Target Alpha or Solar City and certainly in other places as well.
126.96.36.199 Gottlieb® Ball Count Unit Wiper and Switch States Explained
In the following image gallery, a Gottlieb® ball count unit is shown in the various different states. This applies to Gottlieb® single player replay games, where an automatic ball lift is used [King of Diamonds (1/67) to T.K.O. (3/79)].
- Upon the game resetting, the ball count unit's reset coil is pulsed, and the stepper wiper travels to the position one less than the first rivet of the upper rivet pairs. On the switch side, the zero position ball count unit switches open, and the 6th position ball count unit switch is closed. While the game is in this state, there is no power to the playfield coils, except possibly kick out holes (confirm ko hole statement).
- Once the ball passes over the trough switch for the 1st time, the ball count unit step up coil pulses once. This advances the wiper one step clockwise. At this point, the zero position ball count unit switches close. Likewise, the 6th position ball count unit switch remains closed. Each time the ball passes over the trough switch, the wiper advances one position. The switch states of the zero position and 6th position ball count unit switches are all closed during the course of gameplay.
- When the last ball being played drains to the outhole, the wiper moves to the 6th rivet pair position. For 3-ball settings, the ball count unit step-up coil pulses 3 additional times from the 3rd rivet pair position. For 5-ball settings, the ball count unit step-up coil pulses only once from the 5th rivet pair position. Once the wiper reaches the 6th rivet pair position, the 6th position ball count unit switch on the back side opens. When both these instances occur, the power is shut off to the playfield, the game over light is illuminated, signalling the end of the game.
4.5.2 Step Up / Step Down Stepper
A step up/step down stepper is possibly a little more common than the step up/reset style. A typical application would be as the ball count unit on an Add-A-Ball game. Here, it would step up the ball count to 5 (or 9), then step down one at a time as balls are used and step up one at a time as balls are earned. Another common application would be to count bonus points, where it steps up as bonus points are earned, and steps down at the end of the ball or whenever the bonus is collected. The most common application of all is to count the credits on a machine.
188.8.131.52 Gottlieb® Credit Unit (Drum type) Switch States Explained
In the following image gallery, a Gottlieb® credit unit is shown in the various different states. This applies to Gottlieb® replay games, where a drum style credit unit is used. This unit is used on all games from 1950-1979. The exceptions are games starting with Super Soccer (1/75) until Sure Shot (3/76), which use the "half-moon" style of credit unit.
- Details to be added
184.108.40.206 Williams Credit Unit Examples
As mentioned previously, the credit unit is a common example of a step up/step down stepper. Since the various states of the credit unit are not adequately illustrated in Williams schematics or manuals, a few examples are provided below. In general these credit units work by causing a cog or pin on the stepper wheel to move clockwise when credits are added (the step up coil pulses once per credit) and counter-clockwise when credits are decremented (the step down coil pulses once per credit). This cog then actuates a M/B "zero position switch" to indicate whether there are or are not credits on the machine. Williams credit units also have a "max credit" switch which is opened by a second cog that turns clockwise. This switch opens the circuit and prevents additional credits from being added to the machine. The max credit cog is adjustable by the owner/operator. Machines which use a credit light located on the lower ball apron (pitch & bat games included) will have an additional NC switch that is actuated in tandem with the M/B switch. The light is used as a quick visual identifier when credits remain on the game. As long as one or more credits remain, the light is on. When this switch on the credit opens (zero credits on the machine) the lamp on the apron is no longer illuminated.
4.5.3 Continuous Stepper
By far the most common stepper is the continuous stepper. They come large and small. The small unit is the infamous, often cursed and never loved AS stepper on later Gottlieb® games. This is used most often for the match feature and occasionally as part of the circuit for spinner scoring. The AS unit can often be removed from the game by unplugging a pair of Jones plugs. In theory this was done so that the AS match unit could be removed from areas where matches for free games were not allowed. As a practical matter, it is probably a good thing as these miserable little Rube Goldbergian contraptions will cause you grief at some point and will need to be rebuilt, preferably in a good light. Good lighting is required because when the AS relay malfunctions and needs to be rebuilt, it will get its last lick in by flinging a part of itself across the floor in a desperate suicidal mission to permanently bring your game down.
Luckily, full size continuous steppers are much more common than their diminutive and cantankerous smaller brothers. The full size stepper are often found in the match feature of earlier Gottlieb® and Williams games, often ringing the bell while also stepping along merrily with the smallest score increment (1 or 10 points). They are also used in Gottlieb® woodrails to track the 10K points and send a signal over to the 100K stepper when it steps past 90K and needs to carry the decade over. Another common application is in the "player unit" on multi-player Gottlieb® games.
[It is worth noting that on later Bally games (1974 onward), the 0-9 unit and the spinner score units are, by and large, score reel units without the score reel.]
220.127.116.11 Score Reels
By far the most common use of the continuous stepper is in the score reels. In fact, it is so common that score reel rebuilding was given its own section in the Pinwiki. A continuous stepper often is used very heavily, which means they are subject to wear out – possibly more than other failure modes such as getting gunked up.
4.6.1 Different Styles of Flipper Assemblies
4.7 Roto Target
4.9 The Start Up Sequence Explained
Regardless of a particular machine's manufacturer, every EM pinball machine has a start up sequence. When a coin is inserted (if the coin switch is set for one game per coin) or a credit button pushed, an EM pinball machine has to successfully complete the start up sequence before a game can properly begin. Analogous to an EM's start up sequence is a computer booting up, and loading an operating system successfully.
The primary events which occur during the start up sequence are:
- Resetting all the score reels to zero, or resetting lamp scoring values or lamp projected scoring values (games from the 1930's and 1940's in some cases) to zero on machines manufactured prior to the use of score reels.
- Resetting the ball count to ball 1, player 1 or ball 1 minus 1, player 1 on multi-player games; resetting the ball count to ball 1 or ball 1 minus 1 (ball count unit does not reset to 1; it advances to 1, once ball has closed switch on ball trough in most cases) on single player games, where the ball count unit increments throughout a game; or setting the ball count to the maximum balls allowed per game on games where the ball count unit decrements throughout a game. In the case of older machines where a manual ball lift assembly was used, advancing when releasing the ball in multi-player games or balls in single player games.
- Resetting game progressive sequences and features for machines which do not have game-to-game, progressive, carry over game features / sequences.
- Resetting game specific mechanical assemblies such as single drop targets, drop target banks, vari-target, ball lane gates, etc.
- Allowing power to pass to the playfield mechanisms
Although some of the above events may not occur, a game can still start and play. These types of issues can usually be overcome rather easily. The more difficult problems are when a particular event or events do not occur or halt the process during start up and the score motor continues to run. It is up to the repair tech to determine at what point the start up sequence has stalled or failed.
Below are some game specific start up sequences. These start up sequences can be applied to similar machines from the same manufacturer and era. In most cases, the start up sequence is explained in the machine's manual, if a manual was created for it.
4.10 Gottlieb® Solenoid Coil & Sleeve Chart
|A-4893||A-5064||1 21/32" (note B)|
|A-5141||A-5064||1 21/32" (note B)|
|A-5143||A-5142||2 3/4" w/collar*|
|A-5193||A-5171||1 19/32" (note B)|
|A-5194||A-5064||1 21/32" (note B)|
|A-5195||A-5064||1 21/32" (note B)|
|????||A-6087||1 1/4" w/collar*|
Where noted with an asterisk*, sleeve has a collar 1/4" from end.
Note B: Original GTB specs are 1 19/32" & 1 21/32" but SUBSTITUTE 1 5/8" instead. Also, SUBSTITUTE 2" for 1 31/32" w/sleeve.
Older Gottlieb® and Williams, et al; may use a brass sleeve. If it can be removed, a nylon one can be used, but some brass sleeves are still available.
Additional information on Gottlieb® coils & sleeves can be found here.
4.11 Williams Solenoid Coil & Sleeve Chart
4.11.1 24 Volt Coils
|Coil Number||WMS P/N||Length|
|A 21-550||3 A-7066||1 3/4"|
|A 22-550||3 A-7066||1 3/4"|
|A 23-600||3 A-7066||1 3/4"|
|A 23-650||3 A-7066||1 3/4"|
|A 26-1350||3 A-7066||1 3/4"|
|A1 23-750||3 A-7067||1 5/8- 2"|
|A2 23-750||3 A 7067-1||2 1/2-2 5/8"|
|A6 22-550||3 A-7067-4||???|
|A 5 26-1350||3 A 7067-3||1 9/16- 1 13/16"|
|B 26-800||3 A 7066-1||1 1/4"|
|C2 26-800||3 A 7067-2||???|
|DU 23-740||3 A 7066-2||???|
|FL 21-28||3 A 7066||1 3/4"|
|G 22-550||3 A 7066||1 3/4"|
|G 23-600||3 A 7066||1 3/4"|
|G 23-650||3 A 7066||1 3/4"|
|G 23-750||3 A 7066||1 3/4"|
|G 24-750||3 A 7066||1 3/4"|
|G 24-850||3 A 7066||1 3/4"|
4.11.2 50 Volt Coils
|Coil Number||WMS P/N||Length|
|A 24-975||2 A-2167-4||1 5/8" Aluminum*|
|A 25-900||3 A-7066||1 3/4"|
|A 25-1000||2 A-2167-4||1 5/8" Aluminum*|
|A 26-1100||3 A-7066||1 3/4"|
|A 26-1200||3 A-7066||1 3/4"|
|A1 26-1100||3 A-7067-1||2 ½- 2 5/8"|
|A2 26-1100||3 A-7067-1||2 ½- 2 5/8"|
|A2 26-1350||3 A-7067-1||2 ½- 2 5/8"|
|A3-25-950||3 A-7067-1||2 ½- 2 5/8"|
|A 30-2700||3 A-7066||1 3/4"|
|B 27-1100||3 A-7066-1||1 1/4"|
|B 28-1450||3 A-7066-1||1 1/4"|
|B 29-1600||3 A-7066-1||1 1/4"|
|C 27-1300||3 A-7067-2||1 3/8" w/collar*|
|C 30-2400||3 A-7067-2||1 3/8" w/collar*|
|D 22-1150||2 A-2168||2 1/4" Aluminum*|
|D 24-1150||2 A-2168||2 1/4" Aluminum*|
|D 24-1400||2 A-2168||2 1/4" Aluminum*|
|D 24-1600||2 A-2168||2 1/4" Aluminum*|
|DU 26-1350||3 A-7066-2||1 13/16"|
|FL 25-31||3 A-7066||1 3/4"|
|FL 26-950/250||2 A-2167-4||1 5/8" Aluminum*|
|G 25-1100||3 A-7066||1 3/4"|
|G1 25-1100||3 A-7066||1 3/4"|
|G 26-1400||3 A-7066||1 3/4"|
The asterisk(*) denotes a best guess.
4.12 Setting your EM Machine to "High Tap"
EM machines provide a second transformer output for coil voltages called "High Tap." This voltage is intended for locations that have low line voltage, usually due to having a string of machines connected to the same electrical circuit. A location with modern wiring should not have low line voltage. By moving the power wire for the coils from the normal (25V) output to the high tap output, coil voltage is increased by about two volts.
In some cases, owners or operators may have switched a machine to "high tap" to overcome weak flippers or pop bumbers. This is not recommended. The root cause of the problem should be addressed by rebuilding the flippers and/or pop bumpers.
In other cases the machine may have been "high tapped" to increase the speed of the game play. It's your game, so set it however you like. It can always be changed back. Be advised that ball speeds over and above those intended by the original designers increase the possibility of breaking targets, drop targets and playfield plastics. This is also true when "juiced up" flipper coils are used such as the Gottlieb A-5141 "yellow dot" or "orange dot" coils made by the Pinball Resource.
5 EM Concepts of Operation
5.1 Basic Relay Logic
The diagram at left shows several key concepts to help understand how an EM game operates.
A simple example of how a game can score 5000 points (5, 50, or 500 too) begins with the #1 rollover switch, shown as "normally open" (NO), and with a "Start" arrow pointing to it.
When the rollover switch closes, the circuit to the coil on relay "A" is completed, and A energizes. From the relay information table, we see that relay A has three normally open (i.e. "3A", or 3 form A) switches, all of which are shown in the diagram. All of these switches close when A energizes.
The top switch is the "seal in" switch for the A relay. Via the "normally closed" (NC) switch at motor 2B, and the now closed seal in switch on A, the A relay will remain energized.
The middle switch on A, shown in the diagram, closes too. It will complete the circuit to energize L each time that the switch at motor 1A closes.
The bottom switch on A shown in the diagram closes and causes the score motor to begin running. The score motor will continue to run through a complete cycle via the switch at motor 1C. The switch at motor 1C closes when the score motor begins to turn, by virtue of a cam that raises, thereby closing the switch. Gottlieb motors revolve 1/3 of a revolution to complete a typical action. Bally and Williams score motors revolve 1/2 of a revolution to complete a typical action. The switch at motor 1C is called the "motor runout switch" because it guarantees that the motor will complete the full 1/3 revolution.
Gottlieb score motors pulse switches at level A on the score motor 5 times per 1/3 revolution. Bally and Williams score motors pulse switches on the "impulse" cam 5 times per 1/2 revolution. These switches are used to score more than a single 1, 10, 100, or 1000...typically 5, 50, 500, or 5000.
As the score motor turns, the switch at motor 1A will close 5 times in succession. When the switch closes, it completes the circuit to L, the 1000 point relay. Subsequent circuitry associated with the 1000 point relay causes the score reels to increment, the 1000 point chime to ring, and perhaps increment the 10000 point score reel (via a 9th position switch).
This basic kind of operation can be extended to include much more complex game actions. You will find that this circuit implementation is reused many times.
5.2 Start Up Sequences
The following is the start-up sequence for a Gottlieb® Southern Belle. The Southern Belle is a woodrail from 1955 with lightbox scoring. In other words, it has no score reels. Other Gottlieb® woodrails from this era will be similar, but not exactly the same. You will need to consult your schematic and figure out the exact sequence if it differs slightly from the one below:
Southern Belle Start Sequence:
1. Push start button, pulls in start S relay
2. Start relay resets 100K unit, closing switch at -1 position on 100K unit
3. Closed switch at -1 position pulls in Z relay
4. Z relay pulls in ball release coil which is held on by 2 ball hole switches and a switch on the ball release unit
5. The balls move off the two switches, opening the two switches, so now the ball release coil is retained by Z only.
6. Switch on Z relay closes and allows pulsing of 10K unit through Motor 1A
7. 10 K unit continues to pulse until it hits position 9 or 19 or 29 on the 10K unit, then the "bridge" there, in series with the NO switch (which closes once/pulse) on the 10 K unit pulls in the M relay.
8. The M relay steps the 100K drive coil up and stays pulled in until the 100K NC switch is opened (upon stepping once)
9. The 100K step moves the 100K stepper off the -1 position, opening the switch on that keeps the Z relay pulled in.
10. The Z relay releases – the 10K unit can no longer be pulsed though the switch on the Z relay.
11. Z relay opening also releasing the ball release coil.
12. The N flip/flop switch seems somewhat redundant in this setup.
The following is the start-up sequence for a Gottlieb® Roto Pool from 1958. You can see it is similar, but not exactly the same as the Southern Belle sequence.
Roto Pool Start Sequence:
1. Push start button, pulls in start S relay
2. Start relay resets 100K unit, through NC switch on motor 1C closing switch at -1 position on 100K unit
3. Closed switch at -1 position pulls in U relay
4. U relay pulls in ball release coil, which remains on by the U relay, a switch on the unit itself and a flip/flop on the N relay
5. Switch on the U relay is closed, allowing pulsing of the 10K unit though switch on motor 1A
6. 10 K unit continues to pulse until it hits position 9 or 19 or 29 on the 10K unit, then the "bridge" there, in series with the NO switch (which closes once/pulse) on the 10K unit pulls in the 0-9 coil relay
7. The M relay pulls in and is held in by it's own switch and a NC switch on the 10K unit and remains on until the 10K unit steps. The 100K step moves the 100K stepper off the -1 position, opening the switch on that keeps the U relay pulled in.
8. The U relay releases – the 10K unit can no longer be pulsed though the switch on the U relay.
9. The N flip/flop switch activates at some point, releasing the ball release coil (IMO, this is a poor design, leading to a burnt coil for any number of reasons (no FMEAs at Gottlieb®?)
1960s Gottlieb® Add-A-Ball Start-Up Sequence (Flipper Clown)
- COIN CHUTE energizes START (S) relay. If HOLD (R) relay is not energized it will energize and hold on through it's own switch.
- S relay switch starts the SCORE MOTOR
- Score reels reset through S switch and SCORE MOTOR 1A
- RELAY BANK resets through S and SCORE MOTOR switches 2C and 1B
- BALLS TO PLAY steps down (SUBTRACT coil) through switches on S and D and SCORE MOTOR 1A.
- RESET (D) relay energizes when all score reels and BALLS TO PLAY unit are at zero. It holds through a switch on itself for one score motor cycle, dropping out at SCORE MOTOR 1C.
- While D is energized the BALLS TO PLAY unit steps up five times through a switch on D and SCORE MOTOR 1A.
Gottlieb® Start-up Sequences from the 1970s
There is a great repository of Gottlieb® startup sequences gleaned from numerous game manuals.
70s Williams Start Up Sequence (4 player)
- When the start (credit) button is pressed, the credit unit is decremented. This is done through the CREDIT UNIT zero position switch and a set of parallel switches that ensure the game is in "game over" or still on player 1, ball 1, and not at the maximum number of players (COIN UNIT last position switch).
- The end of stroke (EOS) switch on the CREDIT UNIT decrement coil energizes the COIN relay.
- The COIN relay:
- Trips the GAME OVER latch/trip relay once the PLAYER UNIT and BALL COUNT unit reach zero.
- Energizes the RESET relay.
- Runs the SCORE MOTOR.
- The RESET relay:
- Energizes the BALL COUNT unit reset through the SCORE MOTOR.
- Energizes the GAME OVER relay latch coil.
- Energizes the COIN UNIT reset coil.
- Energizes the NO.1 and NO.2 (score) RESET relays, through the score motor.
- Runs the SCORE MOTOR.
- The score reset relays pulse and zero the score reels, through a switch on the score reel that opens in the zero position to stop the reset for that reel.
- The SCORE MOTOR runs until all score reels and the BONUS UNIT reach the zero position.
- The RESET relay decrements the BONUS UNIT until it reaches the zero position.
- When the BONUS RELAY drops out it energizes the OUTHOLE relay through a different BONUS UNIT zero switch and through the SCORE MOTOR.
- The OUTHOLE relay:
- Runs the SCORE MOTOR and increments the BONUS UNIT once.
- Energizes the BALL RELEASE coil which kicks the ball into the shooter lane.
Bally start sequence:
1. When the coin is inserted into the game the coin relay energizes. It stays energized through its own hold on switch and a score motor switch. Once the start button is pressed the credit relay is energized which in turn energizes the coin relay if there are sufficient credits.
2. The lock relay is then energized by the coin relay at which time the game illuminates. The lock relay stays energized through its own hold on switch and a delay relay switch.
3. The coin relay then energizes the reset relay through a switch on the game over relay.
4. As the score motor runs, it energizes any score reset relays. The score reset relay will now resets the score reels to zero.
5. The total play meter is advanced by the coin relay via the score motor.
6. The ball count and player units are then reset by the reset relay via the score motor.
7. The credit unit is stepped down by the coin relay via the score motor.
8. The game over relay latch coil is now energized by the coin relay via the score motor.
9. The 100,000 relay latch coil (if equipped) is energized by the coin relay via the score motor.
10. The ball is now introduced into the shooter lane by the outhole relay via the score motor (assuming the outhole switch is closed).
11. If multiple players are added by the start button, the coin relay advances the coin unit,advances the total play meter, and steps down the credit unit.
5.3 Score Reel Switch States
Most score reels have three switch pairs, although the highest most score reel denomination typically has only two switch pairs. Regardless of the total amount of switch pairs, the switch states are actuated dependent upon the value displayed via the score window. The most important score values are when the score reel is either displaying a zero or nine.
Any given game needs to know when the score reel position is zero in order to successfully complete the start up sequence. If all of the score reels are not returned to zero at start up, the score motor will continue to run, and the start up / reset sequence will not finish.
The importance of the ninth position of the score reel is rather simple. When a score reel reaches a value of 9, it must send a signal to the next highest value score reel in order to advance that reel at the same time. Here's an example. While playing a Williams Gulfstream, the score is currently at 480 points. A 10 pt. switch is closed, and the score becomes 490 points. At this given point, the ninth position switch on the 10's reel is now closed. Shortly after, a second 10 pt. switch is closed, and the total score becomes 500 points. If the ninth position switch was not closed on the 10's reel, during the 10's reel advancing to zero, the score would "appear" to loop back around to 400 points. However, since the 10's reel ninth position switch was closed, an additional signal was sent to the 100's reel, telling it to advance one position, at the same time the 10's reel advanced. On a properly functioning machine, this event happens when any given reel reaches the ninth position. The exception is the highest denomination score reel, which typically does not have a ninth position switch.
For values other than 0 and 9, the game determines these values (including 0 and 9) via a bakelite circuit board attached to the score reel assembly. See the next section for details regarding these circuit boards.
NOTE: Although the pics below are from specific eras and reels, the switch states are not all inclusive to all games with these types of reels. The pics shown are just a sampling, and it is noted what specific game the pics came from. The game you are working on may not be the same as shown in the pics.
5.4 Score Reel Bakelite Circuit Boards
In some cases, it is important for a game to know exactly what value any given score reel is. The two most common events where a game uses this information is the free game scoring thresholds and the match sequence at the end of the game.
Unfortunately, the score reel switch stacks are limited to conveying when a score reel is only at either the 0 or 9 position. If switch stacks were used to determine every value, the assembly would be large, cumbersome, and costly. To overcome these issues, a bakelite circuit board is attached to the score reel assembly. The compliment part to the circuit board is a small, two contact wiper secured to the score reel drum. As the score reel advances, the wiper makes contact with two, isolated circuit board traces. In turn, the wiper completes a specific circuit on the board.
Most all score reels have bakelite circuit boards attached to them. The exception is typically the next to lowest score reel value. In other words, if a game uses 4 reels total to achieve a maximum point value of 99,990 (the ones position is a non-existent dummy reel), the 100's reel assembly would not use a circuit board. The reason is it is not necessary. The 10's reel has a circuit board, because of the match feature (match numbers would be from 00-90 in this example). The 1K and 10K score reels have circuit boards too, because the free game scoring thresholds are in the range of 10,000 to 99,000. However, the game never needs to know the exact state of the 100's reel.
++++add more info and pics++++
6 Problems and Fixes
Over-lubrication causes far more trouble in coin operated equipment than under lubrication. Practically all cases of poor contact on switches and wiper disks are due to oil or grease, or oil vapor, which forms a film or residue on the contacts and will not allow current to pass through. Excess lubricant may also seep into clutches causing them to slip.
IMPORTANT: NEVER USE VASELINE FOR LUBRICATION ON ANY PART OF THE MACHINE! Vaseline is not a true lubricant. It leaves a dirty and gummy residue and becomes very thick when cold.
Step-up levers, ratchets, cams, shafts and other sliding or oscillating parts should be very lightly greased with special coin machine lubricant. The bakelite disks (biscuits) on the motor units and step-up units will require lubrication with the special coin machine lubricant only after the grease is completely evaporated or when the film of the grease becomes dirty (machines with bakelite disks only). In either event, clean the parts thoroughly with a solvent, then apply an extremely thin coat of the special grease.
Solenoid plungers should not have a lubricant of any kind. Should there be a sluggish tendency or if plungers are sticking, the parts should be cleaned with a solvent and flaked graphite if anything, applied on reassembly.
The general rule is "when in doubt, don't". There are very few places on a pinball machine that need lubrication and they're only in spots that have metal-to-metal contact. When needed, a good choice is "Super Lube Teflon Grease", a clear synthetic grease with Teflon. It can be found at local hardware stores or online, for example: http://www.pinrestore.com/Supplies.html
6.2.1 Adjusting Switch Gaps
Proper switch clearance gaps are crucial for correct operation of any pinball game. Very many problems in EM games come down to a problem with incorrect operation of a switch. The switch blades are made up of phosphor bronze, which has high conductivity, resilience to form and excellent soldering characteristics, but has the drawback of being brittle compared to copper. Switch blades therefore, are commonly broken by the game, or careless actions by the repair person. A switch adjusting tool, purchased or homemade, is a necessity. Pliers or screwdrivers might be used in special circumstances, or in extremis, but are not best practice.
Switches in EM games are designed to have a degree of over-travel, which creates a wiping motion that helps clean the switch. The contacts must meet, stay together and slide across the face of the contact slightly, to be perfectly adjusted. They also must be gapped wide enough that they do not bounce, causing multiple switch closures. This problem is more often seen in electronic games, due to the rapid nature of the switch closures being too fast to effect an EM game. Electrical sparking can often be seen in dim light between the contacts, and this is not necessarily a cause for concern.
Before adjusting switches, make certain the screws holding the switch stacks are tight. Bakelite spacers in the switch stacks due to excessive moisture have occasionally shrunk by drying out, causing poor adjustment. Failing to tighten a switch stack prior to adjustment can cause newly adjusted switches to become maladjusted in short notice. When tightening a switch stack, tighten the screw closest to the switch blade contact first. The screw closest to the soldering tabs can then be tightened. Tightening switch stacks in this manner will keep the switches from "fanning" out, if the screws are tightened in the opposing manner. Some switches have a hex nut on the backside which will require holding it as you turn. After tightening a switch stack, be sure to recheck the gap of each switch, because it can change.
If you clean a set of points and find yourself having to do it again soon, check the switch contact. Switch contacts can become loose and swivel or spin. In turn, the contact will arc, and will not function effectively. Firm placement of the contact on the switch blade is necessary. The contact can be repeened, or soldered to the backside of the switch blade.
Using your switch adjusting tool put twisting pressure on the shorter switch blade as close to the switch stack as possible and include the blade stiffener (if present) in the adjuster slot. Except on rare occasion, never adjust the longer switch leaf which is actuated by the relay's armature. The exception to this rule is when when an inexperienced tech has mistakenly adjusted it previously and it needs attention. Try to use as little force and change of gap as possible to incrementally reach your gap goal. Using too much force and a back and forth gap readjustment tends to bend and weaken the switch blade which can make a deformed switch blade difficult to set for correct operation. This is often seen in games that have been “hacked”; sometimes the only way to remedy the situation is to replace the entire switch or disassemble it entirely. Cycle and recycle the mechanical device that activates the switch and observe the switch for proper gap, wiping action and release.
6.2.2 Recommended Gap Specifications
Gottlieb® recommends a gap of .019" on a normally open switch on the AG relay, with overtravel of .015". The lock-in switch should have only .010 gap in a de-energized state. Absolute precision in these measurements is not critical, but should give you an idea of what amount of gap you should look for. A automotive feeler gauge set could be used to help with this setting, but after some experience, “eyeballing” it will suffice.
Magnet type and interlock relays have longer switch blades, so the gap is wider at .031" or 1/32" with a similar overtravel. Rollover switches that are N.O. have some tolerance to their gap at .031" to .062" or 1/32" to 1/16" with a very small overtravel of 1/64". If the rollover is N.C., only a 1/64" gap is necessary.
Kicking rubber, or slingshot switches usually have a generous gap, at least 1/16", due to the rubber ring pushing back against the switch, and a bit of trial and error will be necessary to find the ideal gap setting. Pop bumper switches and scoring “dead” bumper switches, should have a gap of 1/64" for the actuating switch under the spoon, and a 1/32" gap for the score switch when open. All other types of switches will probably function well with a 1/32" gap, and this would be a starting point, modifying the gap on a case by case basis.
6.2.3 How to Fabricate Leaf Switches
Very often the need to rebuild or fabricate leaf blade switches presents itself to the EM repair person.
Sometimes the silver contact is worn out or missing, or the blade is bent or broken, to the point that a
satisfactory repair cannot be done without replacing the switch. It can happen that the switch is missing
entirely. When doing a repair on location, the exact parts may not be available. Fortunately, most switches for
EM games can be replicated, and at a cost that may be cheaper than a new assembly. The mechanical procedure is described below, but first a general discussion of individual components (which I hope will be helpful to the novice) will ensue.
Switch blades come in 3 thicknesses depending on the intended use. The light gauge .008" blade may be used in
relay banks where a small coil may have to draw down several switches, and perhaps in a spinner switch. The
medium gauge .010 blade is used generally throughout the pinball game for any switch that is not a relay or
flipper cabinet or EOS switch. The heaviest gauge .016" is used in EOS and flipper cabinet switches. They can be
purchased from PBR, and it is advised to buy several of the medium and a few
of the light & heavy blades for emergency and general repairs. These blades are of a single length, which may be
cut to a suitable size, and are pre-drilled with 7 contact positions.
Switch blades are brittle, and cannot be bent or formed apreciably without cracking or breaking the blade. This
makes it easy to score the blade with some side cutter pliers, then break off the unneeded section by bending it
back and forth with a pair of pliers and a vise or some other hold down method. If a formed bend as used in drop
target switches is required, an old blade from a scavenged switch must be utilized, or special ordered from a
supplier (if available).
New switch contacts are no longer available in silver (that I am aware), but a gold flashed pair of contacts can
substitute wherever the voltage and current handling is low. Tungsten contacts must be used for the End-of-stroke
(EOS) switches and the flipper cabinet blades due to the higher voltage (35v or greater) and greater current
these contacts must supply.
Fish paper spacers may be required for some EOS switches and usually for the coin door credit switch, and perhaps
in other instances. The old fish paper if undamaged, can be used, and new pre-cut fish paper blades are
available. A substitute can also be hand cut, if the need arises. Next, some switches require a blade lifter or spacer to push upon another switch or mechanism, such as in double EOS switch assemblies and score motor stacks. Many times these can be scavanged from the old blade, or a new one of a suitable length can be used. The height ranges from 3/32" to 11/32" by increments of 1/32", but usually the exact height is not critical. Again, having a small variety of blade lifters on hand for spares, is strongly
urged. Some switch assemblies use a metal cover plate and a rectangular speed nut for the anchor for the screws,
and new ones are available, but the old ones are usually fine.
Switch stack separators, usually made of bakelite or some other non-conducting material, come in 2 thicknesses,
1/16" & 1/32" and will be combined in various combinations to achieve the desired spacing the operating mechanism
required. Old ones are fine to use, but are very brittle and prone to breaking if levered off too strongly or at
an angle. A little care in separating the old switch stacks is indicated here. You may purchase new copies from
the usual suppliers if necessary, or just scavange the necessary bits from previous repairs or your parts bin.
If a machine screw is used to hold the switch assembly in place, it is a 4-40 screw (varying lengths) and
corresponding nut, or a #4 pan head screw, if secured to the cabinet or playfield, or by a speednut.
6.2.4 Procedure to Fabricate a Leaf Switch
If the original switch is present, it is an easy task to replicate a new one, or renew the bad parts, using the
old switch as a model. Experimentation will be the only source for a missing or incorrect switch. For a
complicated, multi bladed assembly, it is advised to take careful notes of how many spacers were used between
each pair of switches,the presence of a "dead" lug (if any) and its location, and which blade had the blade
lifter or blade stiffener, etc. Use a Stanley or other utility knife to separate the switch stack, levering each
end of the stack a 1/64" or so, taking care not to crack the fragile bakelite spacer. You may also have success using a pin punch to press the tubing out. The tube switch insulators can be re-used or new ones put to service.
Each contact must be peened to the blade tightly for good electrical conductivity. A craftsman may also solder
the peened nub to the blade to ensure its faultless operation. Use a hard wood scrap block (maple or similar), to
back up the contact, while striking the nub with a punch and hammer. Don't backup the contact with a metal
surface like a vise or anvil, as it will likely be marred or cracked. Clip off the long end of the blade if it is
too long for the application by scoring the blade with a pair of side cutter pliers, and then bending it back
and forth along the score line with suitable means. A bit of attention with a metal file to the ensuing sharp
edge may save you a nasty scratch at some point. As an alternative, use a pair of diagonal cutters you don't really care about and just snap right through the blade directly. The nylon blade lifter, if required, may be peened by squeezing it with pliers, since it is rather soft.
Re-assembly is straightforward, esp. if you took good notes.
In place of re-creating the entire switch assembly, it may be that the only thing necessary to do is adapt an
existing switch to an unavailable assembly by a slight modification of an existing readily available part. The
blades are soft and easily drilled for a new spacer or contact, so I have found that an EOS switch like the
Williams #03-7811, works quite well with a bit of modification for other EOS switch applications that are
unavailable, involve double switches, or are just expensive. If a longer blade is needed, the top blade can be
swapped out, or a second switch pair can be sandwiched in for a double flipper setup. Likewise, the
Williams/Bally #SW-1A-120 assembly can sub for many playfield applications with just an addition of a spacer or
two or a blade lifter. Your ingenuity can compensate for a lack of parts from available sources.
6.4 Stepper Unit Issues
6.4.1 Gottlieb® Stepper Unit Repairs
What follows is a step by step process for completely rebuilding a Gottlieb® step up/step down type stepper motor. This will be remarkably similar to a step-up/reset stepper or a continuous stepper. It will be close enough to a Williams that you can apply the procedure and figure out the few differences For instance, there are no snowshoes on a Williams, but there is a nasty looking brass spider that does the same thing.
This procedure is fairly comprehensive and if you want to just “fix what’s broke” you can pick and choose what to do within the procedure. The most common issue is probably that the unit requires a general degreasing and cleanup to step properly. After 40+ years, the original grease gets dirty, hard and sticky and the stepper will not function optimally in this condition.
The first thing you should do is to familiarize yourself with the function of the stepper you are rebuilding. Actuate the plungers by hand. Try to mimic an electrical response with your fingers – fast on and fast off. Observe the rotation of the stepper on the rivets. The stepper should advance one set of rivets with each actuation. It should move quickly, with no hesitation. The contacts should line up exactly with the rivets. Step the stepper up and down and establish it’s zero and maximum position. See if it binds under any of these conditions.
Assess the cleanliness of the rivet board, the springs (both on the snowshoes and the return spring), the plungers, the levers and the switches. Play with any levers and see that they rotate freely about their pivot points. Try to hold the levers out of the drive gear and assess the sluggishness of the gear when free of these encumbrances.
Look for any other obvious issues. Do you notice bent, or worn snowshoes? Is the plastic piece on the lever broken or missing? Do you notice rivets with large grooves or is the Bakelite disk burned next to some of the rivets? Are there any broken wires etc.?
The quickest, dirtiest method of fixing a gunked up stepper is to just clean up the rivets that you can get to with 600 grit sandpaper using alcohol as a lubricant/wetting agent. Then step the unit a bit and clean up the rest of the rivets. Wipe off the Bakelite disk with some alcohol and lubricate it with some Teflon gel and you are done. This may or may not fix your sluggish stepper, but there is a high probability it will get you at least marginally functional. If you are just starting out, you may want to leave it go at that. If you want to go further or this didn’t fix your issue, read on. Again, you can pick and choose what you do, but don’t do anything you are not comfortable with.
The following example is from a Gottlieb® Subway, 1966. This is the ball count unit. Since Subway is an Add-a-Ball, this is a step up/step down unit. The unit was actually functioning more or less fine when I got it, but I like to assess everything and check the coil stops etc. Additionally, I really like my mechanisms to be clean. Finally, I needed to write this pinwiki article, so I just scattered the whole thing and took lots of pictures. Also, was rebuilding the entire head, so I had the board out of the box and lying flat. So if it appears to defy gravity, or some angles seem odd, that is why.
Remove the Main Mechanism:
This is usually held in place with one hairpin on top and two on the bottom. If you remove the top one, it will allow the mechanism to flop down for some inspection and minor repairs or adjustments. If you remove the bottom two hairpins as well, you will have better access to do a complete overhaul.
Mark for reassembly
Mark your moving and stationary disks in some way that you will be able to reestablish the correct relative position of the stepping disk, the stationary disk and the gear/actuating mechanism upon reassembly. This is very important, so don’t skip this step. I like to do the following:
- Step the mechanism to it’s “home” position. Usually there is a hard stop of some sort on the back of the gear.
- Now use a paint pen or sharpie to mark at least one rivet and it’s corresponding snowshoe. I like to mark on the edge of the Bakelite, so it doesn’t get sanded off in later steps.
- Take a picture, just to be sure.
Remove the active, snowshoe disk and spider
- Remove the 3 screws that hold the active disk on the spider
- Remove the spider by loosening or removing the set screws. I like to remove them, just to be sure they are out of the way. Note: On some machines, these screws run in a recess on the shaft, on others they run on a flat and on others they run on a finished, round portion of the shaft. Regardless, you need to make sure they are out of the way.
- Work the spider off. Depending on the design (see above) and how bad the shaft is chewed up, this is anything from a 2 second job to 10 minutes of pain and hate.
- At this point, your shaft is free on this side and held in place by the mechanism on the other side. You can stop here if you don’t want to completely remove the entire mechanism from the back box. You will have great access for cleaning up the rivets etc.
- –Optional- Remove the rivet board from the stepper by removing the two screws that hold it to the frame. I like to do this to get the stepper free and to better manipulate it to strip the back side.
Inspect the snowshoes, and rivets
Again, this one wasn’t too bad. I replaced a couple of rivets for the “photo shoot”, but they probably didn’t need it. Here are some horror stories from another machine I recently worked on:
Note the burned out rivets and erosion on the disk. This was fixed by replacing the rivets and filling the grooves with JB Weld. In the second picture, the disk was warped and wouldn’t track properly. The snowshoes were stuck and bent. Ultimately, this part was replaced with a new one.
Remove the Coils, Coil Stops and Plungers
I like to do this regardless. As long as I am back there, I want to at least inspect the coil stops and sleeves. The only way to do that is to take them off. It isn’t too hard:
- Remove the coil stops, this will be done by removing either a screw and nut or a socket head screw with an allen head wrench.
- Slide the coil off the plunger.
- Remove the plunger by either sliding it off the lever or removing the E clip, depending on the design.
- Remove the coil sleeve.
- Inspect and clean the plunger.
- Face off the plunger end if it is mushroomed or excessively peened. You can also just replace the plunger if it is rusty or too far gone.
- Replace or clean the coil sleeve (I always just replace it)
- Inspect the coil stop. Replace if required.
- Clean parts as required. Pay attention to any joints, such is the Bakelight/plunger joint.
6.4.2 Gottlieb® Replay Unit (Credit Unit) Issues
This applies to the step up / step down replay unit, commonly referred to as the credit unit, which uses a metal drum wheel. This does not apply to the "half moon" replay unit used in the mid-70's. Pictures are from 1970s and 1960s Gottlieb® credit units. Construction and function of these two different era units is the same.
A common issue with a Gottlieb® credit unit is the decrement of more than one credit at a time. A properly functioning credit unit should only decrement one credit. This issue is more prevalent with credit units from the mid to late 70's, however, any other like Gottlieb® credit unit applies here. The cause of this issue is typically due to a sticky subtract pawl (A-2484), which is secured by a shoulder screw (A-1058). The shoulder screw is lubricated by the factory, but due to contaminants and age in general, the lubrication becomes gummy. When the step down coil pulses, the subtract pawl will successfully be lifted from the ratcheting gear. However, the pawl will only slowly return to its proper resting position versus quickly springing back. A prime symptom of this issue is when 2 - 15 credits are showing via the credit window. Once the game's start button has been pressed once for a single game, the credit window now shows 0 credits available.
To resolve the issue, the shoulder screw must be removed, cleaned, and lubricated. To remove the screw, the backing nut on the drum side of the unit must be removed. The shoulder screw can now be loosened and removed. Take special care in removing the screw, as the chance of shearing the screw is high. The odds of shearing the screw, while attempting to remove the shoulder screw without loosening the backing nut first, are even higher.
Once the screw is removed, thoroughly clean it, along with the holes used to secure the subtract pawl and reset lever (A-1279). Use rubbing alcohol as a cleaner, and make certain all of the old lubricant is successfully removed.
The old lubricant will sometimes have to gently be scraped away with a small flat blade screwdriver or similar instrument from the frame of the credit unit. After all of the pieces are cleaned, apply a conservative amount of Teflon gel or similar lubricant to any of the metal-on-metal areas. Assemble the unit. Note that the shoulder screw should not be tightened completely down. If this is done, the unit will function improperly as if the shoulder screw was still gummy. Find an acceptable adjustment for the shoulder screw, and then while steadying the screw with a screwdriver, tighten the backing nut. The credit unit should now decrement only one credit at a time.
6.4.3 Williams Stepper Unit Repairs
This shows a basic rebuild of a Williams Player Unit, This was necessary as someone thought it was a good idea to spray paint the unit blue.
In addition to removing the paint from the bakelite boards so that electricity might flow, a rebuild was needed as the levers were gummed up and sticky.
For reference this unit came from a 1973 Jubilee
The basic procedure is as follows
- Remove the coils and coil stops.
- Remove the switch stack
- Remove the center nut on the bakelite board side
- Mark the bakelite board in the reset position so that it can be reinstalled in the correct position
- Remove the board from the shaft
- Mark the gear on the front in the reset position so that you know where to put it back
- Remove the gear from the front
- Pull the metal stepper unit out of the machine
- Disassemble the parts needing to be cleaned
- Clean parts, I prefer an ultrasonic cleaner and some sandpaper
- Reassemble the unit and reinstall.
- Verify coil moves correctly and freely.
This repair references the Player Unit stepper.
Someone had spray-painted blue paint all over the unit.
Note: It does not work better when blue.
In addition the levers and coil sleeves were gummed up and the plungers would not move freely.
This facilitated a full rebuild of the stepper unit.
First remove the springs, both coils and switch stack.
This is a good time to look at the coil sleeves and replace them if necessary.
To remove the wiper disc first mark the position of the disc while in reset position and then remove the big nut in the middle.
You can then pull the wiper disc off easily from the assembly
The rivets were totally covered in paint this required a sanding at the minimum.
I used Melamine foam and 92% alcohol to remove the paint.
When reassembling use a thin layer of Teflon lube on the rivets to reduce wear and allow the fingers to move freely across the rivets.
Note the winds of the center spring and mark the position of the unit in reset position. Then remove the gear and it should come out freely.
The stepper unit pulled out of the machine and ready for disassembly. All that was needed was a screwdriver, 11/32 socket and a wrench.
Here is a closeup of why the lever wouldn’t move freely. Notice the large buildup of old grease on the far post.
Remove the levers and spacers and then you should be able to unscrew the posts
All the parts laid out and ready to get cleaned
First I soaked the parts in Mean Green.
I then used an ultrasonic cleaner and sand paper when needed.
All finished, reassembled and ready for reinstall
6.5 Score Reels
There are many types of score reels. Score reels are essentially 10 unit continuous steppers. In fact, many of the parts catalogs refer to them as such. Each manufacturer has their own individual design. Within each manufacturer, there may be several designs and even variations within each design. For instance, Gottlieb® introduced "rat trap" metal score reels in late 1954 with the multi-player game, Super Jumbo, and in 1959 the first single player game to use them was Miss Annabelle. Starting with Dancing Lady in late 1966, Gottlieb® moved away from the rat trap score reels to a newer, less complex design, plastic 10-sided reel, called a "Decagon" unit. However, the Decagon unit itself has several iterations, with 10-sided reels, round reels, and plastic mechanical parts replacing metal parts. In early 1975, Super Soccer was the first game to use the new style Decagon unit. Gottlieb® did a major redesign of the unit, which was cheaper, and considerably easier to service than prior versions. Even though the unit went through a complete redesign, it was still called a "Decagon" unit.
The point of all this is that there are many designs and iterations of these designs, and you will need to figure out your particular unit for yourself. It is unlikely that every iteration will ever be covered in this guide with a step by step procedure.
Score units generally provide the following functions:
- Step once and only once per signal.
- Provide a signal used by the startup sequence that the score reel is at zero. The majority of the time the switch is closed at zero, but sometimes it is open. It is best to refer to the game's schematic, or inspect other score reels in the machine if uncertain.
- Provide a signal that the score reel did move. This is often a switch that is normally closed call the end of stroke (EOS) switch. Some form of an actuator is attached to the score reel's plunger, which opens the EOS switch each time the plunger is pulled in. This can be a cause of locked on coils, so be certain the EOS opens properly. Some people advocate keeping them permanently open on Gottlieb® Decagon units, however, this is not considered a good practice.
- A signal when the unit is at position nine. This is used to "carry over the decade" upon the next advance of the reel. Of course the highest score unit will not (usually) have one of these, since there is no higher score reel to carry the decade over (though there may be an auxiliary "over the top" or other overflow score indicator light on the back glass).
- Provide a signal to the high score and match features of a game as to exactly where the score reel is. This is typically done via a circuit board attached to the side of the reel unit, and a wiper on the reel, which rides on the circuit board.
Generally, you will need to do the following to service/rebuild one of these units. At a minimum, clean the circuit board, clean the score reels themselves, and de-gunk the unit so it steps smartly. You can go deeper as required or desired either due to the necessity of the repair, or your level of comfort taking it apart.
- Pull the score unit from the game and let it hang.
- Remove the retention on the circuit board
- Remove the score reel
- Clean up any gunked up, sticky moving parts with Mean Green or a similar degreaser
- Clean up the score reel with Novus. BE CAREFUL, do not clean the numbers off the wheel.
- Degrease the circuit board
- Sand the face of the circuit board with 600 grit wet or dry sandpaper, using rubbing alcohol as the lubricant.
- Clean any remaining grit or residue on circuit board with rubbing alcohol
- Apply a Teflon based lubricant to the circuit board, like Superlube or a similar product.
- Clean all the contact points.
- Re-assemble and verify the unit steps correctly and the contacts open and close correctly
6.5.1 Gottlieb® Decagon (Early Design) Score Reel Overhaul
A Youtube Video of the process on a Gottlieb® Decagon is here:
Teardown – (Note, I have since found out that it is a lot easier to do this if you de-solder the coils): http://www.youtube.com/watch?v=XVdUp5kVkjk
Epilogue - Fixing a problem: http://www.youtube.com/user/newmantjn#p/u/5/zQUHiT7BJB8
6.5.2 Gottlieb® Rat Trap Score Reel Overhaul
According to the IPDB, the first appearance of a Rat Trap metal score reel was on the four player "Super Jumbo" game in 1954. It is probably not pure coincidence that this was also Gottlieb's® first 4 player game. Gottlieb® had made a few 2 player games with lightbox scoring, but no four player games. It is likely that the Rat Trap reel was developed to allow for four player games, as the real estate required for lightbox scoring on a four player game would have been excessive. The single player games didn't catch up until 1959 with Miss Annabelle.
The mechanism itself is fairly robust and a beautiful piece of engineering. It suffers from having a lot of parts, which probably meant that it was a little expensive to produce and difficult to assemble. Additionally, there were some adjustments within the mechanism that needed to be made, which always adds to assembly cost. The score reels themselves are gorgeous and feature black letters on a white reel, with a distinctive, yet familiar font. The Wedgeheads of the 1960's that had these score reels just ooze nostalgia and class in a way that can never be approached with a DMD display. The drawbacks, most likely the cost of the unit, lead to its eventual replacement in 1966 with the "Decagon" unit. Subway was the last game to use this classic score reel.
As you read the following procedure, please note a few things.
- Only do what you are comfortable doing. 9 times out of 10, you will only need to clean up the circuit board, file the points and inspect the coil stops and sleeves.
- Many of these procedures would apply nicely to a Decagon, Bally or Williams score reel. It's all the same – Take it apart, clean it, lube the circuit board, replace broken parts.
- Take more pictures than you will need. You still will not have enough.
- The letter/number combinations ( i.e. A-3131) are part numbers straight out of the 1962 parts list. The names are generally correct per the parts list as well (although "Rat Trap" is a term of endearment, not an official Gottlieb® name).
- Remove the score reel assembly from the backbox. This is done by removing the two hairpin style cotter pins. It is OK to let the score reel assembly dangle
- Next, remove the three screws holding the score reel on. Note that the score reel and the grounding wheel beneath incorporate a "poka-yoke" design. Poka-yoke is Japanese for "idiot proof", but here in the States we can come up with some pretty good idiots, so you may want to mark the score reel for orientation as well. The Poka-yoke feature on the score reel is that one of the plastic buttons is larger than the other three, so in theory it can only go together one way. The top button in the picture is the largest of the three. It can be jammed together if you are not careful, so be sure to familiarize yourself with this feature, or mark it (or both).
- Next remove the score reel and the grounding wiper beneath it. Note in the picture of the grounding wheel that the top hole is much larger.
Stop here. Ask yourself: "Do I need to take this apart further?" Or "Can I get away with just cleaning up the circuit board and maybe replacing the coil stop or coil sleeve?" This is your machine, so do whatever you are comfortable with. The directions that follow will get you through a complete overhaul. This allows for inspection and cleaning of all parts. It also may result in lost parts and misassembly.
- Remove the E clip that retains the cam and ratchet hub assembly. E clips are known to go flying, often resulting in cuss words and trips to the hardware store. Ease the E clip out and keep your finger over it.
- Remove the bottom two screws from the circuit board. Slide it out from the retaining post on top.
- Desolder the lead from the circuit board. While it is possible to work around this 10 second job, you will spend an extra half hour trying to reach things that you can't reach without a tweezers. You will also spend an extra hour hunting the pieces that go flying and two hours on diagnosing the poor switch cleaning and misassembly that will inevitably result in not having adequate access to the parts. Spend the 10 minutes desoldering and soldering. It is time well spent.
- Swing the circuit board out of the way and there you have it! Access to a mechanical engineering marvel. Take a moment to enjoy that.
- Next, remove the coil stop, coil, plunger, insulating fish paper and coil sleeve. Unscrew the two screws holding the coil stop on and remove the coil stop. Slide out the coil and lift the plunger off the pin on the Step Up Pawl. Note any worn parts for replacement. Set aside the plunger, coil stop assembly, and coil sleeve for cleaning, unless any of these parts will be replaced.
- Remove the Cam and Ratchet hub from the score reel assembly. You may need to rotate this while pulling it up. You may also need to move some of the spring loaded parts out of the way with a small screwdriver. (no picture)
- Remove the E clip that holds Step Up Pawl A-3131 on. Remove the step up pawl and spring. Set aside for cleaning and/or replacement. (they should not need replacement) You can further disassemble this part to facilitate cleaning and drying if desired.
- Remove the E clip retaining the A-5177 Drive Index Pawl Assembly on. Remove the spring and finally, the pawl.
At this point, your Rat Trap score reel is completely disassembled and ready for clean up. It should look like this.
Cleaning and Refurbishing the Parts
- The circuit board will almost always need to be cleaned up. It will likely have a coating of old, dry, sticky grease on it. This coating causes sluggish score reel response, in turn preventing the machine from scoring correctly or maybe preventing it from resetting properly, resulting in the dreaded "score motor just runs" syndrome.
- Clean/degrease the circuit board with synthetic steel wool (a "scrubbie") and Mean Green. DO NOT use real steel wool. I prefer to clean up the circuit board in two steps. A general degreasing and a contact cleaning using Mean Green and a scrubbie followed by sandpaper with alcohol. This two step process will save you sandpaper and yield better results than a clean up with sandpaper alone – but it is your machine, if you want to skip the Mean Green step, feel free. After the intitial clean up, it should look pretty good, but we can do better.
- Next use alcohol and 600 grit wet or dry sandpaper to resurface the copper circuit board surface. You can use rubbing alcohol or denatured alcohol.
- Finally, coat the circuit board with a very light coating of Teflon grease. Very light.
- Lightly touch up the point on the Grounding Wheel.
Rotating and Actuating Parts
- Take all the parts you set aside, including the ratchet parts, springs etc. and douse them with Mean Green.
- Run a bottle brush through the holes if they are dirty.
- Chuck everything into an ultrasonic cleaner if you have one. Scrub the parts with a toothbrush if you don't have a cleaner. Be CAREFUL! Don't lose those small parts!
- Pull all the parts out and blow off with compressed air. You might want to put the smaller parts in a sock for this step so you don't blow them across the floor.
- Clean the number surface with Novus 2 and a VERY gentle hand. Don't clean off the numbers. (Test on an inconspicuous part of a number if you can find one - some score reels will lose ink if you look at them funny with cleaner in your hand.)
- Coat the number surface with a coat of pure carnauba wax. Wipe off when dry.
- Clean the inside surface with Novus or Mean Green (or leave it alone if you don't mind the dirt).
Coil/Coil stop/Coil Sleeve/Plunger
- The coil stop and coil sleeve are often borderline for replacement. Generally, I figure that if they show any wear, they get replaced. The plunger itself is usually OK, or maybe could stand to have the end that hits the coil stop re-faced with a grinder. The coil is generally either perfectly fine, or completely failed. This score reel got a new coil stop and coil sleeve. Both of these parts were marginal, but once it is apart, you may as well replace marginal parts.
- Replace the coil stop by holding it tightly in a vice and unscrewing the nut. Install the new one the same way.
- Slip the new coil sleeve into the coil.
- Tighten all switch stacks.
- Clean all switches with a flex stone, small file or folded 400 grit sandpaper. Blow out, or better yet, run a piece of paper through the switches to get rid of any grit left in the switch.
- Install the Step Up Pawl A-3131, spring and E clip. I find it easier to hook both ends of the spring on and drop the assembly over the post. Take care not to overstretch the spring if you do it this way.
- Install the A-5177 Drive Index Pawl Assembly, spring and E clip. You will likely need a dental pick, or needle nose pliers to install the spring.
- Install the Cam and Ratchet Hub. This is trickier than it looks. I will get hung up on the spring loaded parts you just installed. Rotate it, use a small screwdriver to move the parts out of the way and gently push on it while rotating to get it to "drop" a level at a time. The first time you do it, you will have to keep looking to see what it is hung up on, but soon you will be a pro at it.
- Reinstall the E clip that holds the Cam and Ratchet hub on
- Drop the plunder in over the post on the Step Up Pawl.
- Slip the coil with the new sleeve into the plunger.
- Put the fishpaper insulator over the coil stop assembly and install both pieces onto the score reel frame. Don't forget the insulator. This can result in additional swearing.
- Slip the circuit board onto the post and install the two screws/nuts that retain it. There is some slop in the holes, so center the circuit board hole on the Cam and Ratchet hub.
- Solder the wire lead back on.
- Hold the Grounding Wheel in place, being mindful of the proper orientation – the large hold and possibly the mark you put on it.
- Put the numbered score reel in place, again being mindful of the orientation.
- Put the spider washer, A-6362 over the score reel in any orientation.
- Install the three self tapping screws to retain the score reel.
- Put the score reel back in the backbox and retain it with the two cotter pins.
6.5.3 Chicago Coin Machine (CCM) 3" Score Reels
CCM Score reels are different than many of the major manufacturers. Instead of having a switch for the decade rollover, the connections are performed by the wiper fingers on the circuit board. The switches are only for EOS on this unit.
For reference the following pictures are from a 1974 Hi Flyer.
6.5.4 Score Reel Related Reset Problems
For EM score reels to reset properly, two things must happen.
- The score motor must run to pulse the score reels until ALL off the reels have reached the zero position.
- Each reel must advance until it reaches zero and then stop advancing.
The different manufacturers had slightly different ways of implementing these functions.
1970s Gottlieb with PLAYER UNIT (e.g. Spirit of '76)
- Each score reel reset (zero position) switch must close when its score reel is at zero. The reset switches are all connected in series and will advance the PLAYER UNIT when they are all zero. The Z1 & Z2 relays open alternately to reset players 1 & 2 separately from players 3 & 4.
- Each score reel RUNOUT switch must open when its score reel is at zero. Pulses from SCORE MOTOR switch 1A advance the score reel until the reel is at zero and the RUNOUT switch opens. The Z1 relay enables players 1 & 2 for reset. The Z2 relay enables players 3 & 4 for reset.
1970s Williams (e.g. OXO) and 1970s Bally (e.g. Wizard!)
- The DRUM UNIT ZERO switches are all wired in parallel. They are in the lock-in circuit for the RESET relay. All DRUM UNIT ZERO switches must open for the RESET relay to release, which stops the reset sequence.
- A second DRUM UNIT ZERO switch opens when its score reel is at zero. Pulses from the #1 or #2 SCORE RESET relay advance the score reel until the reel is at zero and the DRUM UNIT ZERO switch opens. The #1 and #2 SCORE RESET relays are energized by score motor switches whenever the RESET relay is energized.
There are several problems that can occur during score reel reset. Since there are many switches involved in the score reel reset, especially on four-player games, it is a common cause of reset problems. It is important to note that the zero position switches, when out of adjustment, can indicate zero when the score reel is not on zero and visa-versa. Three common problems are described in the following sections.
- If a single reel doesn't reset properly, the first thing to check is its RUNOUT switch. If it is stuck open the score reel won't advance for reset. If it is stuck closed, the score reel will keep advancing past zero.
- If the reels all advance to zero and the the score motor keeps running (that is, reset doesn't complete becuase the PLAYER UNIT didn't advance (Gottlieb) or the RESET relay didn't release (Williams/Bally)), there is likely a zero postion switch stuck open (Gottlieb) or closed (Williams/Bally).
- The last problem is tricky to diagnose. If a score reel zero position switch is stuck, the reset sequence can terminate prematurely, leaving some of the reels partially reset. This will show up on score reels that have low, non-zero scores. Since they need the most pulses to reset (e.g. 9 pulses for a '1') they may only get to 8 or 9 before the reset stops. Setting some score reels to '1' before starting a reset can help to isolate the problem, but it may be a problem with any of the zero postion switches.
6.6 Drop Targets
Complete Teardown and Rebuild of a Gottlieb® Drop Target Bank
This procedure was developed a few years ago while working on a Volley. The Volley has three, 5 target banks. Sometime after rebuilding the first one, I decided that there must be a better way. No way would David Gottlieb® have put up with dental picks and the like on his assembly line. So my goal was to develop a procedure that would require only fingers, or maybe a little "help" from a screwdriver. Note that this is for a complete overhaul. You might have to adapt if you just want to change a target or two. Generally, I like completely overhauling something and not worrying about it again, ever.
One other thing to note is that Gottlieb® made three or four variations on this target bank. Some have series bars, some don't. Some have bent reset bars, some are straight etc. If you generally follow these directions and take a lot of pictures, you will be fine.
One thing I have discovered over time is that a common mistake is to spend a lot of time trying to save a little time. This comes up in auto repair a lot. People will try real hard to not pull off a part which is held on by 4 bolts. So, in order to save the 3 minutes of time removing the 4 bolts, they will add an hour to the repair time trying to work around the part they should just have removed. The procedure really takes everything apart. It took about 45 minutes to completely disassemble the bank, clean every part and re-assemble. By contrast, the when I did a Big Brave bank a few years prior to this, it took me hours to get it done, since I tried to not take it apart all the way.
One more thing – you can leave some of the sub assemblies together if you don't plan on running the parts through a cleaner. For instance, you could leave the brackets attached to the back of the target bank. It's your machine, you decide how far you want to take it down.
Drop Target Bank Rebuild Procedure:
Remove Drop Target Bank from game
- Put the playfield up in the full service position, with the playfield resting against the backbox. Use a towel to protect the playfield and backbox.
- Unscrew all the switch stacks one by one. Wrap each switch stack in low tack masking tape or thread a 5-40 nut onto each screw to hold the switch stack together.
- Undo the coil from the target bank. Don't let it just hang by the wires, tie it up with a piece of wire, string, tie wrap or old rubber ring.
- Remove the screws that hold the target bank to the bottom of the playfield and pull out the target bank.
Teardown – NOTE take more pictures than you will ever need. You will still not have enough.
Rebuilt bank on the left, dirty bank on the right. Note, I helped myself out a little here, in that this was the third bank I did (so I had practice) and I had an exact target bank to reference. Not even a mirror image, which can make you stop and think for a bit.
The bank was completely off, some of the mounting brackets were loose from pulling it from the machine. The "front" and "back" of the target bank assume the bank is situated as shown, with the targets furthest from you. The side closest to you is the "front" and the side furthest away from you (closest to the targets) is the "back".
Drop Target Bank Teardown Procedure:
- Remove the E clips on both sides of the rod
- Remove the two plastic bushings that guide the rod
- Remove the mounting bracket for the coil and rod
- Remove the mounting bracket for the other end of the rod Note, you may need to slide the rod back and forth ¼ to ½ inch to accomplish this.
- Remove the trigger arm return spring.
- Remove the rod that runs through all the triggers.
- Remove the front of the target bank.
At this point, you will have a sub-assembly like the one shown below. It should be fairly obvious that it is easy to pull off and reattach all those springs on the drop targets and triggers with the sub assembly as shown. One word of caution: Do not mix up the springs. The lighter weight springs attach to the plastic target. If you mix them up, the drop targets won't drop.
- Remove all the springs from the drop targets and triggers.
- Pull out the drop targets.
- Disassemble the rest of the steel box (if desired for cleaning)
I feel that mechanical mechanisms work best when they are clean. They were not designed to work with a layer of grunge, oil and dirt on them, so I like to clean them up prior to re-assembly. If it is your first shot at this, you might want to minimize some of the disassembly and cleaning in favor of making sure you can get it back together. That said, I like to clean the face of the drop targets with Novus, then put a generous layer of carnauba wax over the hot stamped face for protection. Next, scrub out the nooks and crannies in all the parts with Mean Green and a toothbrush. Then, into the ultrasonic cleaner, if you have one, otherwise rinse off and blow the parts dry with compressed air. BE CAREFUL not to blow you parts all over the garage. You can put the little parts in an old sock or something when you blow them off. Wipe off the wax when dry. For the very small parts, like screws, you are probably better off not washing them at all, unless you have a lot of spare parts around.
Target Bank Assembly Procedure:
- Attach the "heavy" springs to the bottom plate.
- Attach the "back" (the side closest to the targets) to the top and bottom. Be careful and consult your pictures as it is easy to put the top on upside down, or mix up the top and the bottom. This is why you may be better off leaving these three sides of the steel box in place the first time you do this. ATTACH ALL THE SCREWS LOOSELY.
- Drop the targets in through the holes. No, you can't put the springs on first, they won't fit through the holes.
- Stick the triggers in through the targets. Make sure you have them right side up.
- Attach the springs from the bottom plate to the trigger.
- Attach the springs from the target to the trigger.
Note: You can do the prior two steps in either order. You shouldn't need any tools to do it, but a needle nose pliers, a hemostat or even a small screwdriver may help you if you have sausage sized fingers. Once this sub assembly is together, the springs will hold the triggers in place.
- Feed in the reset arm. Make sure you have it oriented correctly. Notes: You cannot feed it in after you attach the back plate. Also, on a very long bank, you may need to feed it in prior to attaching the springs from the bottom plate to the triggers. Take care on how you position the reset arm - make sure it is on the correct side of the stop screws in the bottom plate. With this method of assembly, it is fairly obvious though.
- Attach the front plate. You may have to move the triggers around a little to get them to go though the proper slots in the front plate. This is fairly easy though.
- If there is a series arm, now is a good time to feed that in from one side or the other.
- Now, feed in the arm through the guides in the front plate and all the triggers, the reset arm and the series arm. Leave the E clips off of both sides of the rod for now. You may have to wiggle the trigger arms a bit to get the rod to feed through.
- Install the reset arm return spring.
- Install rod support on one end of the assembly and the coil bracket/rod support on the other end. Install the plastic bushings on the end of the rods.
- Tighten up all the loose screws.
- NOW – finally- install those E clips!
Put the entire assembly back into the game. Clean up the backside of the switches that the trigger arms actuate when the targets drop. Gunk on those is a major reason what targets only go down half way. I like alcohol for this. Verify that all targets score. Verify that when all targets are down, the series bar pulls away from the NO switch (if you have one) and the switch scores.<br.
Sit back, have a beer or other tasty cold beverage, and congratulate yourself on a job well done, secure in the knowledge that you will not have to do it again for 20 years.
6.7 Pop Bumpers
Over time, pop bumpers will need to be removed. If removal is necessary, rebuilding / refurbishing the pop bumper is recommended. Below are several reasons why removal of a pop bumper assembly is necessary.
- The coil has melted from locking on and shorting its windings. Or, possibly the assembly has been gunked up by some unknowing repairman, who kept spraying the assembly to lubricate it. The assembly has become covered with years of built up gunk from the use of this unnecessary lubricant. The pop bumper now needs to be overhauled. Even though Williams recommends in their EM operational manuals to lubricate the coil plungers with graphite, pop bumpers should really never be lubricated.
- Another reason is due to the pop bumper body becoming broken or cracked. Pop bumper bodies are made of plastic, and deteriorate over time. In most instances, a cracked or broken pop bumper body does not impede the proper function of a pop bumper, but they can look unsightly.
- The final reason is related to appearance, but preservation comes into play. On the top side of the playfield, most pop bumpers have a Mylar shield or "free-floating" platter, which gets worn and looks ugly. If dirt and / or grit are present underneath the platter, (this is extremely common), the platter starts to act like sandpaper. The end result is that the platter wears away the clearcoat and paint versus protecting the playfield like it was intended to do. The only resolution is removal and / or replacement of this platter.
Gottlieb®, and in the case of this narrative, Chicago Coin use "free-floating" Mylar platters. Some manufacturers such as Williams and Bally use self-adhering Mylar rings around the perimeter of the pop bumper skirt. The self-adhering style of protection may only need replacement if the Mylar ring is losing adhesion, and starting to lift away from the playfield.
For this narrative, refurbishing a pop bumper from a 1966 Chicago Coin Kicker machine will be discussed. Nearly all pop bumpers are constructed the same, so this rebuild will apply to many machines. Several solid state machines are similar, and equally apply.
|This is the pop bumper that we will be restoring. As you can see the platter next to the playfield is well worn. This pop bumpers brother to the right will also need to be updated eventually.|
| The first step in working on the bumper is to remove the pop bumper cap. This is a game manufacturer / game era dependent step. In this case, we have two screws that need to be removed to access the interior.|
For Gottlieb® games, starting with Surf Side in 1967, gently compress the sides of the cap at 3 o'clock and 9 o'clock. In doing this, the tabs which hold the cap in place come free, and removal of the cap from the pop bumper body can be done.
| Once we have gained access to the internals, remove the bulb from the lamp socket, and set it aside. A good tip is to place related parts from a section into an old peanut can or similar container to keep them together. At this point, do not remove the screws which secure the pop bumper body to the playfield. Instead, turn the playfield over to access the pop bumper "guts" on the underside.|
Removing the playfield from the cabinet and placing it horizontally can make it much easier to work on. However, take special precautions not to crack or break plastics and other assemblies which are elevated higher than the playfield rails. The playfield should not be resting on these types of assemblies if it is turned over. Otherwise, these assemblies can and probably will break.
|Here is a look at the underside of the playfield with the pop bumper with parts identified (click on image to enlarge).|
| Remove the mounting bracket for the bumper. This is done by removing the two screws which hold the pop bumper plunger and yoke assembly to the mounting bracket. Next, remove the four screws which hold the mounting bracket to the playfield. In the case of this unit, removal of the pop bumper coil stop at the top is not necessary. On this game, one of the coil stop mounting screws has been removed, and not replaced. Probably by someone who removed it, and did not place it in a peanut can to keep the parts together, but I digress.|
It is worth mentioning that most other manufacturers employ a pop bumper coil stop which is integral to the pop bumper mounting bracket, and not removable. Chicago Coin, "classic" Stern, Data East, Sega, and "new" Stern are the exceptions.
| Now remove the rod and ring by choosing an appropriate socket and unscrewing the nut cap from the rods. A 5/16" nutdriver is typically used.|
|Once the rods are removed, the plunger assembly can be lifted from the rods. Take note how it is assembled to restore the assembly to its original configuration.|
|Unsolder the lamp socket from the wires which feed it power.|
| The playfield now has to be turned over again. Remove the two screws inside the pop bumper body which secure it to the playfield, and safely put them aside. Always take care not to lose any parts.
| The remaining portion of the pop bumper assembly on the top side of the playfield can now be removed. Just look at that mess around the Mylar protector.|
Once the body has been removed, and at some point prior to reinstalling it, clean the pop bumper spoon switch with rag or towel dipped in rubbing alcohol. The spoon switch collects dirt, especially if any lubricants have been applied to it.
| Removal of the excess remaining solder from the lamp socket leads is necessary, if the lamp socket is to be reused. The leads will need to be clean to fit through the holes in the pop bumper base and body. If the lamp socket is not going to be reused, clip the socket leads just above the location where they were soldered.|
Please note that the yellow piece on the tip of the skirt finger is not typically used with manufacturers other than this era of Chicago Coin.
It is also worth mentioning that Bally used metal skirt assemblies for a period during the mid-1960's.
| This is not a playfield restoration narrative to be sure. However, clean the area thoroughly under the old platter. After a good cleaning place down a new shield. A new platter can be purchased from the various pinball parts suppliers.
|| These shields come in two flavors, self-adhering and free-floating. The recommended version is self-adhering, because once it is applied to the playfield surface, dirt and grime cannot get under it. The free-floating platters can be subject to the same wear as the originals, if not kept constantly clean. Ultimately, it is all a matter of personal preference which style to use. It may be necessary to cut the new replacement platter to fit. Use the removed platter as a guide for cutting the new replacement.
| Now, it's time to clean all of the pop bumper parts. This includes the skirt, base, and body. Note how all of the pieces go together to reassemble. The base is press fit into the pop bumper body and can be difficult to remove. Take your time and gently pry the pieces apart with a small screw driver, if required. Inside the base is a small spring which allows the skirt to retract to its centered, "home" position, after a pinball comes in contact with it.|
Take extra care with any plastic pieces which are hot ink stamped. Even the most gentle cleaners like soap and water can possibly remove the ink. Test a cleaning agent on a very, very small portion of an inked area first, before cleaning the whole inked area.
The best way to clean the plastic parts is with a mild liquid soap and and warm water in the sink. On old toothbrush can be used to clean particularly dirty or hard to reach areas. Another method is to place the parts in the dishwasher. If using a dishwasher, do not put it on a heat dry cycle. Do not put plastics which are hot ink stamped in the dishwasher!
Clean the rod and rings with chrome polish from any auto parts store to make them shine again. Replacement parts can be purchased from most of the recommended pinball parts suppliers.
| Reassembly is essentially the reversal of removal.|
First, assemble the pop bumper body and associated parts which are located on the top of the playfield. The order in which the parts go together is the pop bumper body, the rod and ring, the skirt, the small skirt spring, and then the base. Next, insert the lamp socket leads into the top side of the pop bumper body. Make certain to use the two openings in the body, which are not intended for securing the body to the playfield.
Please note that some of the pop bumper skirts will have a small pointed tip on them. This pointed tip should point to the top of the playfield when installed. Our example does not have this little skirt tip. Next, place the pop bumper body onto the playfield, and using the two screws, secure the body to the playfield. Once the pop bumper body is secured, turn the playfield over to expose the underside again.
| You will notice there is a sleeve inside of the solenoid, and the plunger moves back and forth inside of it. This is commonly referred to as a coil sleeve. It is recommended to replace this sleeve, again available from most any of the recommended pinball parts suppliers. In this example, the original brass metal sleeve is on the right, and a new nylon replacement is on the left. Each style of sleeve has a small flange on one side. When installing a new sleeve in a solenoid, make certain the flanged side is facing towards the coil stop, and away from the pop bumper spring.|
Some manufacturers did not use replaceable coil sleeves prior to the 1960's. In these cases, the coil sleeve is actually an integral part of the coil's windings. If the coil sleeve is brass, and there appears to be great difficulty in trying to remove it, don't remove it. Just clean it as best as possible. If the sleeve is worn through, replacement of the coil is the only solution.
| Next, solder the lamp socket leads to the wires which feed power to the lamp. Then, place the plunger yokes over the rods, and secure the nuts to the rods. Do not over tighten these; Hercules need not apply here. Make them snug and secure. Along each step of the way, make sure the rod and ring moves freely, and that the skirt acts as if it is floating on the base. If things are not moving freely or feel restricted, go back and double check your work.|
See how that plunger is shining in the picture, it was cleaned and polished too.
|Now it is time to remount the bracket. Secure the plunger bracket to the mount with the two screws. These two screws will typically have captive lock washers on them. Next, place the solenoid over the plunger. Pay special attention to the orientation of the solenoid lugs. Make certain the solenoid wires are facing the proper direction. Otherwise, they may get in the way when the pop bumper activates. Finally, secure the bracket to the underside of the playfield with the 4 screws.|
| Now it is time to inspect the switches. The switch stack was not removed, so adjusting may not be needed. However, due to age and general wear, it may need some adjustment. Equally, contacts which are slightly pitted should be burnished.|
It is a good practice to make certain that the skirt finger is centered within the spoon switch. Gently push on the center of the backside of the spoon switch. If the skirt finger moves at all, adjustment is necessary. Loosen the screws that mount the stack to the playfield, and adjust accordingly. Once the spoon switch is properly adjusted, push down on the skirt from the top side of the playfield. Push down at all points where a pinball can roll onto the skirt. Doing this will ensure the spoon switch contacts properly make at all possible positions.
| Manually actuate the solenoid plunger with you finger by pushing down on the edge of the yoke. If this case, make certain the normally closed EOS switch opens when the plunger is pulled in. In other cases, the switch activated by the yoke may be normally open. Everything should be moving freely with no binds. Check the rod and ring too for any bindings.|
|All done, she's lookin' 'more better'.|
6.7.2 Lamp Sockets
Pop bumper sockets used by almost all manufacturers are almost always problematic. A pop bumper lamp has a tough life. The vibration environment inside the pop bumper body is pretty severe. The lamp filament is subject to a lot of abuse. Better electrical connection and (somewhat) reduced vibration can be achieved by gently and gradually squeezing the lamp socket with a sturdy pair of needle-nose pliers. You want to squeeze the socket together just enough so that the lamp fits snugly. Using a "lamp cleaning stick" to burnish the socket base also helps. Even if you decide to use a 6.3V AC powered LED in the pop bumper, improving the electrical connection will help.
6.8 Score Motors
6.8.1 Gottlieb® Score Motor
18.104.22.168 Gottlieb® Score Motor will Not Stop Running: Frequent Cause
Besides investigating Motor Switch 1C (as above), a frequent cause of a score motor that will not stop running is located in the score reels (when equipped). Each score reel has a ZERO POSITION switch, and EVERY switch must be open for the game to complete its startup routine. If the switch is maladjusted or bent closed, the score motor will run on and not stop. The score reels may continue to cycle the reel with the bad switch, so that could be a clue as to where to investigate first. The wiring of the switch should also be inspected, since even if the switch operates correctly, the reel will not complete the circuit to the score motor. There may be other causes for a score motor that will not stop rotating, but the zero position switch is very common and deserves a special mention.
22.214.171.124 Servicing and Lubrication of the Gottlieb® Score Motor
The score motor should have two kinds of lubrication when being serviced. A thin smear of a gel type grease like TEFLON GEL or similar should go on the edge of the top and bottom cams, and the studs which protrude from each. Excess lube that can get on the switch contacts must be avoided. In NO case, should you lube or oil the brass gears, and if someone has done so, remove the substance with a degreaser. The score motor itself takes a few drops of light oil like 3-in-1 oil, through a small hole in the base on the underside. To access the oil well of the score motor, most units were hinged, and held in place by a single hairpin opposite the hinged side. Pull the hairpin out with some needle nose pliers, and the motor can now be pivoted upward. Make sure to replace the clip when done. Pivoting the unit upward is also helpful when trying to view or adjust motor switches located in levels A or B.
Unfortunately, Gottlieb® score motor units from the 1950's and early 1960's were physically screwed to the wood "motor board" from the underside of the board. To access the motor's oil well, the large wood "motor board" has to be removed, turned on its side or upside down, and the screws holding the score motor assembly must be removed. When removing the wood motor board, take precautions not to twist on contort wiring harnesses.
6.8.2 Williams Score Motor
6.8.3 Bally Score Motor
6.8.4 Chicago Coin Score Motor
6.8.5 General: Score Motor Keeps Running
A common problem in EM games is the continuous running of the score motor. The score motor controls the relay logic whenever a sequence of events is required, for example, during reset or when a target score requires multiple steps of a score reel. Score motor problems can be difficult to isolate because there are usually many different functions in the machine that run the score motor.
It’s important to note that the score motor running is a symptom of the problem and it’s unlikely that the actual problem is the score motor or a switch on the score motor. To find the relay switches that enable the score motor, find the score motor on the schematics and trace the wire. You’ll find a group of relay switches in parallel, each of which can energize the score motor. Normally, those relays should not be energized, so a first check is to see if any are energized. It’s also possible that a switch is bent and stuck closed. Sliding a strip of business card between the switch contacts is a good way to make sure the switch is open. Also check the switch solder tabs to make sure they didn’t get bent and shorted together.
If the score motor starts running when you power-on the game, a common problem is stuck coin switches on the coin door.
If the score motor continues to run after you start a new game, then the machine has not properly completed it’s reset sequence. Problems here are often in the score reel zero position switches or the bonus unit zero position switch. There are often multiple switches that indicate the zero position, so even though the mechanism appears to have reset correctly, the switch used to indicate completion (zero-position) to the reset circuitry may be malfunctioning.
EM game design often included triangular "slingshots" near the bottom of the playfield. Operation of slingshots is pretty simple. As pictured left, most slings have 2 standup switch pairs. When the ball impacts the rubber ring, one or both of these switches will close, routing coil power to the slingshot coil. The coil pulls a plunger in, which is attached to the kicker arm via a pivot joint. The kicker then kicks the entire sling rubber forward.
Adjustment for optimum performance of slingshots is important. Solid "Kick" factors include:
- Proper sized rubber ring.
- Tension of rubber ring.
- Gap between standup switch contacts
- Cleanliness of standup switch contacts. These contacts tend to build up carbon. Filing lightly will improve performance.
- Distance of the kicker arm from where the ball impacts the rubber.
- Overall length of the playfield facing sling kicker dimension. Shorter kickers impart a greater percentage of the kicker arm energy.
- Friction at Plunger/Link/Kicker arm pivot points.
- Alignment of plunger with coil sleeve.
- Cleanliness of coil sleeve.
- Condition of built-in coil stop on kicker coil bracket.
- "Mushrooming" of kicker coil plunger.
- Electrical current provided to the kicker coil.
- And there may be others...
6.10 Chime Units
Chimes in electro-mechanical games evolved from discrete bells (or chimes) to "chime boxes" where all (or most) of the games chimes were collocated. Except for the occasional fried coil due to a scoring relay locking on, or a broken/missing nylon plunger tip, they are generally trouble free.
One exception is the Gottlieb chime box of the 1970s. Gottlieb used "beer tape" under each chime plunger to cushion the plunger's fall after chiming. Over time, this beer tape disintegrates into a sticky "goo", acts like contact cement, and prevents the chime plungers from being pulled up through the coil sleeve.
Correction is easy...
- Disassemble the unit.
- Scrape the beer tape residue off.
- Use naphtha or isopropyl alcohol to clean down to the metal.
- Replace the beer tape with your choice of cushioning material, as shown below. Ensure that the material is roughly the same thickness as the original pad. If the material is too thin, the chime plunger may not pull up into the coil sleeve.
6.11.1 Noisy/Buzzing Flippers
When a flipper is held in the up position, some buzzing is not uncommon, especially in machines with AC voltage coils. The buzzing can be minimized by ensuring that the plunger and coil stop are flat and that the coil and all parts of the flipper mechanism are tight. The plunger and coil stop may need to be filed flat if they have mushroomed out. A spring (wave) washer that keeps tension on the coil can also help.
Flipper return springs that are too tight can also cause buzzing flippers. With the playfield up, the springs should just barely return the flippers to their resting position.
Excessive buzzing can indicate that the flipper coil is not switching to the hold coil at the end-of-stroke. You can read about flipper coils in PinWiki section Flippers. In a typical EM flipper circuit, the low-resistance (~2-8 ohms) power winding is in series with the high-resistance (~10-20 ohms) hold winding. The flipper end-of-stroke (EOS) switch shorts out the hold coil when the flipper is at rest. When the flipper button is pressed and power is applied to the flipper coil, the power coil flips the flipper. Near the end-of-stroke, the EOS switch opens which switches the hold coil into the circuit. The combined high resistance coil is enough to hold the flipper up. If a fast-moving ball should knock the flipper down, the EOS switch closes and the power coil keeps the flipper up.
There are alternative flipper wiring in some machines, so check your schematics to see how your flippers are wired.
If the EOS switch isn’t working, the power coil will be active while the flipper is up. This typically causes a very loud buzz from the flipper. Also, the flipper coil will rapidly overheat if the flipper is held up. The power winding of the flipper coil is only designed for low duty-cycle operation.
6.11.2 Weak Flippers
If the EOS switch is not making good contact, the hold winding will not be properly shorted out when the flipper is at rest. This will result in a weak flipper.
6.12 Power Issues
Williams silicon bridge rectifier:
The function of the rectifier and capacitor is to convert the alternating current (AC) to direct current (DC), supplying DC to the bumpers, kickers, etc. The bridge rectifier would typically never need replacing as it is rated well over the voltage and current requirements of the components it supplies. If, however, the 15 amp 24 volt fuse on the mechanism panel opens, it could be due to a faulty rectifier. Disconnect the AC input to the rectifier, replace fuse, and recheck. If the 10 amp fuse located next to the rectifier opens, check all DC components I.E. bumpers, kickers etc. for shorts.
Bally silicon bridge rectifier:
Bally also used a bridge to convert AC to DC for various coils (usually flippers) in some of their games. The wiring is similar to Williams' and the diagnosis of a bad bridge/fuse blown is the same - check the end of stroke switches on the flippers, and for any stuck contacts on pop bumpers, sling kickers, etc.
6.13 Replacing a Power Cord
After many years, it is likely that your power cord on your old EM will need to be replaced. This could be for a number of reasons. Sometimes they get old and brittle, sometime they get cut and spliced with electrical tape or whatever. Replacing the cord is not too difficult.
The first thing you need to decide is if you are going to upgrade your existing setup or merely just replace like for like. EMs come with both grounded and ungrounded plugs. If you are replacing a grounded 3 prong plug with another one, your best bet it to just buy a 3 prong cord from Pinball resource, de-solder the old one and solder in the new one exactly how the old one was. Be careful not to switch the hot and neutral wires as that would make the game less safe.
If you are doing a straight swap of a two prong plug for a two prong plug, the easiest and cheapest solution is to buy a 12 foot or longer brown extension from a big box home improvement store, a mom and pop hardware store or even a dollar store. Cut off the female end, split and strip the wires. But which wire goes where? The new plug will be polarized, in other words, it can only go into the outlet in one direction. The old plug likely was not polarized and can go in either way. This is actually a good thing, because by carefully hooking up your new cord, you will make your game safer.
The reason a cord is polarized is so that you will know where the hot wire is. The hot wire is the one that should always be switched and fused. Why is this? If you check for voltage at a plug with a multimeter, you will see that you get about 120v from the hot (small) slot to either the neutral (large) slot or the round (ground) hole. Within your household wiring, the ground is actually tied back to the neutral at the breaker. Furthermore, the ground is tied back to the earth at some point. If you switch off the neutral, rather than the hot wire, YOU could supply the ground, even if the game is turned off or there is a blown fuse. Current could flow through YOU to the earth. This would be a bad day. By switching off the hot wire, you minimize this risk. Further discussion on household wiring convention is here, if you are interested: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/hsehld.html
So, which wire is hot and which is neutral? You can follow from the male end of your plug and see that the smaller (hot) side of your cord is SMOOTH. This is what gets hooked up to your fuse block. The ribbed (neutral) side gets hooked up to your transformer.
6.14 Adding an On/Off Switch to an EM
Many EMs from the mid-sixties and earlier had a “kick-off” switch. While this was the on/off mechanism for these machines, it really wasn’t a great set up. The way the circuit worked was that it was always “at the ready” to come to life if you dropped a coin in, even after you kicked it off. The line (110v) voltage went through the fuse and several normally closed switched (often including a slam switch in the METAL door). When you dropped a coin in this would complete the circuit to the 110v side of the transformer, which would, in turn, pull in the hold relay on the 25v side of the transformer. The hold relay had 110 volts going though it’s switch which supplied the line voltage to the transformer for the duration of the time that the game was on. When the bottom of the machine was kicked in the area of the kick-off switch, it momentarily cut primary voltage to the transformer and everything would go dead, including the hold relay, so now the machine was “off”, waiting for somebody to drop a coin in and wake it up again.
This is a less than ideal setup for a number of reasons. First, I just don’t like to kick the bottom of my 50 year old machines. Second, the 110v to the coin door is just asking for trouble. Third, the hold relay is bad news, often getting quite crispy from being on all the time. Finally, I never feel comfortable with all that voltage “at the ready” within my machine. I want to know it is switched off in a positive manner. The following modification will make an early machine close to a seventies style on/off setup. You can choose to bypass as many of the NC switches as you want to improve the safety and reliability of the game. I personally choose to bypass all of them, get the 110v out of the coin door and disable the hold relay. You really don’t need all those slam and cheat switches in a home use environment and all they do is decrease the reliability of your game.
My preferred method is to disconnect the line wire from the downstream end of the fuse block. This is not the brown plug wire, but the wiring that is part of the harness. From here, run a length of wire up to the “traditional” switch area on to the right of the coin box. Now, find the hold relay switch pair with the 110v and de-solder those from the relay. Solder those two wires together, along with a new wire that also runs up to the switch area of the cabinet. Install a switch between the two added wires, shrink tube the splice and you are good to go. A good installation will also have the switch sitting in a recess in the bottom of the cabinet, so it does not get broken off. See a stock game with a switch for how that should look.
The smaller black and red wires, just to the left of the shrink tubing were pulled off the hold relay and soldered together and also to the single black wire coming out of the splice to the right. The lower, larger, light red/pink wire is the new wire installed at the fuse block. This is downstream of the fuse.
Another way is to simply de-solder the kick-off switch and run those wires over to your new switch. I have also seen the switch simply added with a wire going from the fuse block to the switch and back to the “downstream” wire that used to be on the fuse block. All these methods will “work”, but you will still be running 110v through all the normally closed slam switches and into the coin door if you choose to add the switch this way.
Regardless of how you wire it, the switch should go into a wooden recessed switch block, similar to those used on later machines. The following describes how to modify your cabinet to add a recessed switch. You may actually want to do the cabinet modifications prior to the wiring modifications.
First, get some birch plywood, cut to 3"x5" and find the center by connecting the corners. Now, drill out the center and coat the plywood with a heavy coat of Tightbond or similar grade wood glue. DON'T use gorilla glue. Next, use a big wood screw or deck screw and screw the block all the way through the bottom. Let it dry overnight. Remove the screw and use a hole saw to cut out the hole for the switch. Note how the hole left by the screw will be gone after the large hole is cut. Only saw about half way through. Now go from the bottom up to minimize splintering. The cabinet is now ready for your switch.
In order to mount your switch above the hole, you will need to attach it to a plate of some sort. Some people use hardboard (similar to peg board) and some people use a metal plate from the hardware store. I feel the cleanest installation is to use a plate that is made for this purpose and scavenged off another machine. Note that most machines have two of these plates mounted back to back. This was to not allow access to the threaded ring from the outside of the game, presumably to cut down on vandalism. In a home use environment, you really don’t need two plates on each machine, so you can easily scavenge one off a later machine that has two plates and use the “extra” one here. If you really want to finish it off nice, add an original switch cover. This will be tougher to find, as you will need something from a parts machine. To finish up and make it look nice, either zip tie or lace the new wires together and use a cable strap to tie them down so they will not get in the way. You can reference another machine to make it look “factory”.
6.15 Roto Targets
6.16 Vari Targets
6.17 Wax Lacing for EM wire bundles
<add a picture of a laced bundle here>
An excellent resource for learning how to tie wax lacing around wire bundles can be found here. Of course, wax lacing is for the purist. It's much easier to use "zip ties" these days.
7 Test Procedures
7.1 Testing with a Jumper Wire
7.2 Testing with a Test Light
How to build your own test light: http://www.planetimming.com/Pinball/Pinball_EM_test_light.html
7.2.1 Electrical short troubleshooting Fuse helper
As an aid to finding the cause for an electrical short, you can make a circuit breaker tool to eliminate the need to constantly replace a fuse, while you investigate the cause. This could save you money in the long run. It is better to under-fuse the connection by a small amount, then to use the rated fuse rating, so a 3 amp circuit breaker could be used on a 5 amp fuse holder, or a 10 amp breaker for a 20 amp G.I. fuse holder. The very small GMA fuses (5x20mm) will probably need some kind of jumper wire setup.
- a burned out fuse of any amperage or voltage (you were saving them just for such a thing!)
- a circuit breaker of 1, 3, 5, or 10 amps, whatever amperage you require for the circuit you are troubleshooting. Buy ones like P/N 691-CMB10311C3NBA (CARLING) OR 655-W57-XB7A4A10-10 (Tyco)
Solder the burned out fuse to the spade terminals of the circuit breaker as shown in the photo. Alternatively, make a two wire female spade mini harness, and solder the bare wires to each end of the bad fuse and attach the circuit breaker that way.
Online help is available by posting a request to the rec.games.pinball newsgroup. If you're new to newsgroups, Google Groups provides an easy-to-use interface: http://groups.google.com/group/rec.games.pinball/ Create a post with "Tech EM: " in the heading and provide as much information as possible about the problem.
There is also an "empinbalmachines" group on Yahoo! Groups. http://games.groups.yahoo.com/group/empinbalmachines/
Team-EM provides help via e-mail. From the Team-EM site at http://www.team-em.com/ you can send an e-mail to the team (the link is at the bottom of the page).
Here is a handy file showing what fits what and the dimensions for coils and sleeves.
9 Game Specific Problems and Fixes
Example would be servo controller on Independence Day pinball
10 Repair Logs
Did you do a repair? Log it here as a possible solution for others.