# Episode 6 – Beginner Series – EM Pinball Terminology Part 2

**Source:** EM Pinball Journeys  
**Type:** podcast_episode  
**Published:** 2025-02-09  
**Duration:** 16m 26s  
**Beat:** Pinball

**URL:** Buzzsprout-16566472

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## Analysis

David Rick Morgan delivers the second installment of his beginner series on EM pinball terminology, diving into the electrical and mechanical systems beneath the playfield. The episode covers transformers, fuses, relays, solenoids, steppers, score motors, and other core components that enable EM machines to function, with emphasis on safety and proper maintenance practices.

### Key Claims

- [HIGH] EM pinball machines of the 1970s are much more complex than machines from the 1930s and 1940s due to innovation and competition driving feature expansion — _David Rick Morgan, opening discussion of EM evolution_
- [HIGH] An Alvin Gottlieb pinball machine from 1973 uses a 6 volt circuit for lights and a 25 volt circuit for other components, stepped down from 120 volts via transformer — _David Rick Morgan, describing specific machine example_
- [HIGH] Fuses in EM machines range from as small as a quarter amp to as high as 15 amps, and should never be replaced with higher amperage due to fire and damage risks — _David Rick Morgan, fuse specifications_
- [HIGH] Three-chime units were commonplace by the 1960s, with each chime tone representing different score values (10, 100, 1,000 points) — _David Rick Morgan, historical account of chime implementation_
- [HIGH] By the early 1980s, chimes were rarely used in pinball machines as digital sound took over — _David Rick Morgan, transition from analog to digital sound_
- [HIGH] The score motor is often referred to as the 'heart of an EM' and uses cams and switch stacks to manage complex game operations — _David Rick Morgan, explaining score motor function_
- [HIGH] Jones plugs were named after their manufacturer, Howard Jones, and are multi-pin connectors used to disconnect sections of wiring harness — _David Rick Morgan, explaining Jones plug origins and function_
- [HIGH] It is strongly recommended to work on a pinball machine with the power off and unplugged, as dangerous electricity remains even when the machine is off but plugged in — _David Rick Morgan, safety warning_

### Notable Quotes

> "When I looked inside an EM for the first time, I was surprised at how many wires and mechanisms it takes to make a pinball machine operate."
> — **David Rick Morgan**, ~2:30
> _Establishes the complexity theme of the episode and relatable entry point for beginners_

> "The transformer is the center of the electrical system... it lowers the amount of electricity to provide the appropriate voltage needed in the different circuits throughout the machine."
> — **David Rick Morgan**, ~3:45
> _Core explanation of transformer function in EM architecture_

> "Safety is very important. It is strongly recommended to work on a pinball machine with the power off and unplugged. Even when the machine is off and plugged in, there is still a dangerous amount of electricity going into the machine."
> — **David Rick Morgan**, ~5:00
> _Critical safety message for hobbyists and new owners_

> "You can think of the relays as the hardwired programming and with the help of the score motor, relays make decisions, so to speak, as they activate and deactivate things throughout the game."
> — **David Rick Morgan**, ~7:30
> _Explains the logic/decision-making function of relays in EM machines_

> "People often refer to the score motor as the heart of an EM. It has many functions, but it helps communicate how many points the score reels need to add to the score after points are earned."
> — **David Rick Morgan**, ~28:00
> _Defines the central role of score motor in EM game logic_

### Entities

| Name | Type | Context |
|------|------|---------|
| David Rick Morgan | person | Host and narrator of EM Pinball Journeys Podcast; provides educational content on EM pinball terminology and history |
| EM Pinball Journeys Podcast | organization | Educational podcast focused on electromechanical pinball machines and their history, hosted by David Rick Morgan |
| Howard Jones | person | Historical manufacturer of Jones plugs, multi-pin connectors used in EM pinball machines; distinct from the 1980s singer |
| Alvin Gottlieb | company | Pinball manufacturer; David Rick Morgan referenced an Alvin Gottlieb machine from 1973 as an example of EM architecture |

### Topics

- **Primary:** EM pinball electrical systems (transformers, fuses, circuits), Relay logic and switch mechanics in EMs, Solenoid-driven mechanical systems (flippers, bumpers, slingshots, kickers), Score motors and stepper units
- **Secondary:** Audio systems in EMs (bells, chimes, knockers), Safety practices for EM pinball machine ownership and maintenance, EM pinball history and technological evolution (1930s-1980s)
- **Mentioned:** Tilt mechanisms and coin mechanics

### Sentiment

**Neutral** (0.5) — Content is educational and informative with no emotional valence. Host maintains professional, instructional tone throughout. No controversy, criticism, or celebratory language present.

### Signals

- **[community_signal]** EM Pinball Journeys Podcast providing structured educational content on EM pinball terminology and maintenance to newcomers and casual players (confidence: high) — Multi-part beginner series designed specifically for those new to EM pinball; episode builds foundational knowledge with detailed explanations of electrical and mechanical systems
- **[technology_signal]** Historical transition from analog audio systems (bells/chimes) to digital sound in pinball machines by early 1980s (confidence: high) — Three-chime units commonplace by 1960s; digital sound took over, and by early 1980s chimes were rarely used at all

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## Transcript

 This is the EM Journeys Pinball Podcast. Hello and welcome back to the EM Pinball Journeys Podcast. I'm David Morgan, and I'm glad you're joining me for another episode. This is the third episode in the beginner series designed for those who are new to EM pinball or pinball in general. Today we're going deeper into EM pinball terminology, exploring the inner workings and anatomy of these amazing machines. In the last episode, we focused on the player facing elements like the playfield, cabinet and backbox. This time we'll venture beneath the playfield and behind the back glass to uncover what makes an EM tick. Even if you're just a casual player with no intention of owning or repairing a machine, I think you'll still find today's episode fascinating. Let's get started. When I looked inside an EM for the first time, I was surprised at how many wires and mechanisms it takes to make a pinball machine operate. The EM pinball machines of the 1970s are much more complex than the earlier machines in the 1930s and 1940s. Innovation and competition drove the designers and manufacturers to continually create more features to attract more nickels, dimes, and quarters. First up, the transformer. Inside the cabinet, you'll find the transformer, which is the center of the electrical system. The transformer is a metal-cased component that steps down the voltage coming in from the power cord, known as the line cord. In other words, the transformer lowers the amount of electricity to provide the appropriate voltage needed in the different circuits throughout the machine. Components that move in a pinball machine need more power than, say, the lights. Because of that, the lights are on a separate circuit. I'm looking at a Gottlieb pinball machine from 1973 and coming from the transformer, there's a 6 volt circuit to the lights and a 25 volt circuit to everything else basically. This is a lot less power than the 120 volts coming in from the power cord. I'd like to add here that safety is very important. It is strongly recommended to work on a pinball machine with the power off and unplugged. Even when the machine is off and plugged in, there is still a dangerous amount of electricity going into the machine. The wires that come out of the transformer are connected to fuse blocks. The fuse blocks protect circuits from an unsafe amount of electrical current. Each fuse block is connected to two or more wires and holds a fuse. The fuses found in EM pinball machines are small cylindrical components that resemble a glass or ceramic tube. Fuses have metal caps at both ends which are used to connect the fuse into its holder, the fuse block. If there is an overload or short circuit, the fuse inside the fuse block will blow which breaks the circuit. The idea is to prevent damage to the wiring and components. Fuses are typically transparent and fuses made of glass allow you to see the filament inside which is designed to melt and break if the current exceeds the limit for that fuse. In an EM, a fuse might be as small as a quarter amp or as high as 15 amps. I'll cover fuses in more detail in the future, but they should never be replaced with a higher amperage. Otherwise, there is a risk of overheating and fire, as well as potential damage to components. In EMs, fuse blocks are typically located inside the cabinet. Typically, many of them are together near the coin door. Often, they are also in separate locations, such as underneath the playfield. I mentioned the on-off switch in the last episode. The on-off switch is typically on a circuit wired between the transformer and a fuse block that connects to the power cord. EMs have no integrated circuits and relays control the functions of the machines You can think of the relays as the hardwired programming and with the help of the score motor, relays make decisions, so to speak, as they activate and deactivate things throughout the game. There are a lot of electromagnets inside an EM. Each relay has a coil of wire that, when electricity flows through, it magnetically pulls an armature, which is a metal plate connected to a plastic tray with slits holding switches with contacts. As the armature is pulled in, the bottom blade from one of each set of switches moves and changes the state of the switch. A switch is typically two blades, and sometimes more than two blades, of metal connected to wires that are used to temporarily complete a circuit. There are tiny round contacts on each switch blade and when the contacts on the switch touch, an electrical connection is made, and current flows through the switch and its connected wires. Closer to where the wires connect to the switch is an insulator that helps keep the blades separated so that only the contacts touch together. This type of switch is used in various parts of every pinball machine and is commonly called a leaf switch. Some switches are normally open, and when the state of the switch moves to closed, a circuit is completed or is considered closed. The contacts on the two switch blades were pulled together. Other switches are normally closed, and when the relay pulls the armature in, the switch blades and the contacts separate, and that circuit is now open, and there is no connection. For example, if you hit a target, a light might come on, or a light might come off. The switch on the target sends a signal to the relay that either turns on the light by closing a switch or turns off a light by opening a switch. There is a third type of switch. So far I talked about a normally open and a normally closed switch, which typically have two metal blades. The third type is called a make-break switch, or sometimes called a break-make switch. This switch is typically three blades, and when the switch state changes, the middle blade with contacts on both sides is moved back and forth. At rest, a make-break switch has two of the three blades making contact. When the switch changes state, the middle blade moves away from the blade it was just touching and toward the opposite third blade, and then the contacts are touching only on the middle blade and the opposite third blade. If you hold up your middle three fingers and move only your middle finger between the other two, that will give you a sense of how a make-break switch moves. Switch blades sometimes need to be adjusted with a switch adjuster tool that helps bend the blades without damaging them. Setting the proper amount of space between switches is called gapping. If the contacts are too far apart, they may not make a proper connection, and if they are too close, the gap may cause an unintended short circuit. Relays can have as few as one switch, or they may have many switches and control several operations simultaneously. A grouping of switches that are stacked on top of each other are called a switch stack. Depending on the function, a relay may be activated only briefly or it may hold on for a long period of time. When the electricity is cut, the armature is no longer being pulled in toward the coil, and a spring assists in returning the armature and the switches back to their deactivated state. Another type of relay is called an interlock relay. An interlock relay has two coils that activate a set of switches back and forth. This is used when switches are used in one state or another for a longer period of time. When one of the coils is activated, we also say when one coil fires, the armature is moved to the corresponding position. The coils only need to have enough electricity to move the switches back and forth so the state of the switches can be maintained without electricity until a change is needed again Some Pimdall machines have a bank of relays that can be reset together This is called a trip relay bank Trip relays are typically a few relays up to a dozen that are together A trip relay changes the state of switches with an armature by the trip coil being activated. Each relay has its own trip coil. The trip relay can hold the state of the switches without power until reset. There's typically a reset coil that resets the relay bank to its preset state. The reset coil is typically a solenoid coil. A solenoid coil is larger than a relay coil, but also is a coil of wires. A solenoid coil is hollow in the center so that a metal plunger pulls into the hollow part when the coil is activated. A solenoid coil is used in many parts of a pinball machine. Almost everywhere there is movement within a device, a solenoid coil or two are involved. In the above example, when the plunger pulls into the trip bank solenoid, the relays are all reset together. The most commonly used solenoid is in the flippers. Each flipper is activated by pressing a button, and underneath the playfield the corresponding solenoid fires, pulling the metal plunger into the coil, which is linked to a mechanism that lifts the flipper in the upward position. Pop bumpers, slingshots, and kickers all use solenoids. Stepper units also use solenoids. Stepper units are also called steppers, step-up units, or step units. Stepper units are mechanisms that advance or reset functions such as the ball count, game credits, or bonus ladders. A solenoid coil is used to advance the stepper mechanism up one position at a time. Another coil might be used to step down one position at a time, or in some cases, instead of step down, the second coil is used to only reset the unit. Some steppers are only continuous, meaning that they only move in one direction. Stepper units typically also use a ratchet and pawl mechanism, which remind me of old clocks, especially because springs are also used. Some steppers use contact boards that have a series of contacts that form into circles or partial circles around the contact board. These types of steppers have wipers that look like spiders rotating around the circle. Others are wipers called snowshoe wipers. The wipers make electrical connections at different positions on the contact board. Score rails are an example of a continuous stepper unit. Score rails are sometimes called a drum unit. Each solenoid step causes the score reel to advance one step. The score reels have numbers 0 through 9 printed on them, and they go around and around. On reset, the score reels have to make it back to 0 one step at a time. It happens very quickly, though. Even in older machines before score reels were used, a stepper unit was used to count the score and highlight the score on the back glass. Bells and chimes also use solenoid coils. The solenoid simply fires an extension of the plunger into the bell or chime bar. Bells were first implemented very early on in the EM era and were used to reward the player. Bells were commonly used to audibly signal to the player that points were being awarded. Three-chime units were commonplace by the 1960s, and the tones of each chime represents a score value. For example, one chime tone might represent a 10-point score. the second one is for the 100 point score, and the third is for the 1,000 point score. Some games have chimes and bells in the same game. The use of chimes extended briefly into the solid state era. Digital sound soon took over, and by the early 1980s, the chimes were rarely used at all. A knocker provides a loud knocking sound, letting the player know that they have been awarded a free game either by earning a replay award or a match award the knock feature is still used in pinball machines today The knocker mechanism uses a solenoid coil that when energized pulls a plunger striking the inside of the pinball machine or a metal plate The score motor is used to help connect more complex operations. A score motor is a rotating motor with cams and switch stacks. A cam is a rotating part of the score motor that helps cause the switches to open and close in sequence. People often refer to the score motor as the heart of an EM. It has many functions, but it helps communicate how many points the score reels need to add to the score after points are earned. The score motor and the score motor frame are basically the same from game to game by manufacturer, but the switch stack configurations and their functions are specific to each game. The score motor is also used to help with the game reset sequence. The tilt mechanism includes a pendulum known as a tilt bob Also slam switches and a roll tilt switch that is activated by a ball and is separate from the ball in play Next, Jones plugs You can take apart a pinball machine for transport or repairs You can remove the backbox from the cabinet And in the backbox there are wires connected to the cabinet that can be disconnected using what are called Jones plugs Jones plugs got their name because they were manufactured by a man called Howard Jones. No, not that singer who famously sang, things can only get better in the 80s. The plugs are multi-pin connectors that are used to connect separate parts of the wiring harness. In most games, the number of pins per connector is different so as to not plug the wrong connector into the wrong place. Sadly, this is not always the case. operators and owners need to simply match the wire colors from the pins to the connectors to be sure coin mech or coin mechs is a term that you'll hear often coin mech is shorthand for coin mechanism and refers to the component that accepts or rejects coins that are inserted into the coin slot the proper coin and the proper amount of coins trigger is a switch to start a game or add a credit. I'm going to wrap it up here. Hopefully these terms make for a helpful start as you learn more about EMs. This episode and the previous episode are meant to give you a foundation upon which to build. We'll keep building in future episodes. There are many more terms that I've not covered here, especially when you consider all the various parts that are used in a pinball machine. The best way to learn about the parts and their names is to get copies of parts catalogs, which I covered back in episode two, EM Pinball Resources. If you haven't already listened to that episode, please listen, and you will learn how to acquire parts catalogs. And that concludes today's episode. I want to thank you for joining me today on the EM Pinball Journeys podcast. I hope that you enjoyed this episode. Please look out for more beginner series episodes. If you want to contact me, I can be reached at empinballjourneyspodcast at gmail.com. You can also follow me on Facebook or Instagram at Adirondack Pinball, and that's spelled A-D-I-R-O-N-D-A-C-K. Please let me know if you have any questions, comments, corrections, or suggestions of future EM pinball topics. I'd love to hear about your journey so far. Thanks for listening. I'll be back again in two weeks. Thank you. you

_(Acquisition: groq_whisper, Enrichment: v3)_

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*Exported from Journalist Tool on 2026-04-13 | Item ID: 048ccbb1-b72f-4f38-844f-f0eb23980226*