# Episode 22 - 90's DMDs

**Source:** For Amusement Only EM and Bingo Pinball Podcast  
**Type:** podcast_episode  
**Published:** 2015-04-02  
**Duration:** 17m 3s  
**Beat:** Pinball

**URL:** https://foramusementonly.libsyn.com/episode-22-90s-dmds

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## Analysis

Nicholas Baldrige's episode on the For Amusement Only EM and Bingo Pinball Podcast provides a technical deep-dive into bumper (jet bumper/pop bumper) design, history, maintenance, and troubleshooting for electromechanical and early solid-state pinball machines. The episode covers bumper invention by Alvin Gottlieb in 1948, component construction, common failure modes, step-by-step rebuild procedures, and maintenance best practices. Baldrige emphasizes the importance of proper bumper tuning for gameplay quality and advises against modifications like converting AC to DC operation.

### Key Claims

- [HIGH] The bumper (jet bumper/pop bumper) was invented in 1948 by Alvin Gottlieb — _Nicholas Baldrige, episode content_
- [HIGH] Harry Williams used the term 'jet bumper' and Bally used 'thumper bumper' for essentially the same device — _Nicholas Baldrige, episode content_
- [HIGH] Passive bumpers from the 1930s had a design flaw where cracks in the skirt could trap the ball — _Nicholas Baldrige, episode content_
- [HIGH] Even the newest pinball games produced today include pop bumpers — _Nicholas Baldrige, episode content_
- [HIGH] Coil sleeve degradation is a common problem in aging bumpers that can be fixed by replacement — _Nicholas Baldrige, episode content_
- [HIGH] Games were originally designed for AC pop bumpers, and converting to DC changes the entire feel of the game — _Nicholas Baldrige, episode content, stated as design philosophy_
- [HIGH] Some machines have bumpers electrically tied together (fire simultaneously), while others have each bumper as a standalone device — _Nicholas Baldrige, episode content_
- [HIGH] Rebuilding bumpers with new springs and coil sleeves makes a significant difference in game performance across all eras — _Nicholas Baldrige, episode content_

### Notable Quotes

> "I'm sorry I can't keep up the pretense. It's my pitiful attempt at an April Fools joke."
> — **Nicholas Baldrige**, early in episode
> _Host acknowledges the episode title referencing 1990s DMDs is a joke; actual content focuses on EM-era bumpers_

> "So pop bumpers are special, they certainly stood the test of time. Even the newest games that come out have pop bumpers."
> — **Nicholas Baldrige**, mid-episode
> _Emphasizes the enduring design of bumpers as a pinball component across all eras_

> "Well tuned bumpers are essential to proper gameplay. It's very frustrating to play a game where the bumpers need to be rebuilt and the pinball just kinda goes bleh and moves slowly sadly away from the bumper."
> — **Nicholas Baldrige**, mid-episode
> _Underscores the gameplay impact of bumper maintenance and player experience_

> "I'm kind of a purist. I'm not a total purist, but there are some things which I just don't think you should mess with and this is one of them. The game was designed for AC pops. If you change them to DC, then it's going to change the entire feel of the game."
> — **Nicholas Baldrige**, near end
> _States a design philosophy against modifying original AC bumper specifications_

> "Bumpers are mechanical devices and they require some maintenance."
> — **Nicholas Baldrige**, mid-episode
> _Transition to technical maintenance section_

### Entities

| Name | Type | Context |
|------|------|---------|
| Nicholas Baldrige | person | Host and producer of For Amusement Only EM and Bingo Pinball Podcast; primary speaker and expert on EM pinball restoration and maintenance |
| Alvin Gottlieb | person | Inventor of the bumper (jet bumper/pop bumper) in 1948 according to episode |
| Harry Williams | company | Pinball manufacturer that adopted the bumper design and used the term 'jet bumper' |
| Bally | company | Pinball manufacturer that adopted the bumper design and used the term 'thumper bumper' |
| For Amusement Only EM and Bingo Pinball Podcast | organization | Podcast focused on electromechanical and bingo pinball machines; hosted by Nicholas Baldrige |
| Gottlieb | company | Pinball manufacturer; context implies Alvin Gottlieb may have been associated with or founder of Gottlieb company |

### Topics

- **Primary:** Bumper Design and History, EM-Era Pinball Maintenance, Bumper Rebuild and Repair Procedures, Electromechanical Components
- **Secondary:** Gameplay Tuning and Optimization, Wood Rail Pinball Machines, Pinball Restoration Philosophy

### Sentiment

**Positive** (0.75) — Host is educational, encouraging, and enthusiastic about the topic. Tone is informative and accessible to both beginners and experienced restorers. Minor note of caution against certain modifications, but overall supportive of maintenance and preservation.

### Signals

- **[historical_signal]** Comprehensive history of bumper design from passive bumpers (1930s) to modern active (solenoid-driven) bumpers (1948-present), including naming conventions across manufacturers (confidence: high) — Alvin Gottlieb invention in 1948, adoption by Harry Williams and Bally, and continuance in modern games
- **[restoration_signal]** Detailed step-by-step procedures for bumper disassembly, cleaning, coil sleeve replacement, and reassembly with emphasis on proper tool use and safety (confidence: high) — Multi-section technical guide covering desoldering, component removal, cleaning, and reassembly procedures
- **[restoration_signal]** Identification of bumper components including cap, lamp socket, springs, yoke pieces, rings, body, skirt, coil, and proper material compositions (confidence: high) — Detailed component breakdown: 'comprised of two springs, two yoke pieces, one metal and one fiber, the rings, two nuts which hold the yoke onto the rings, the body itself, the skirt, and the coil and the lamp socket'
- **[operational_signal]** Best practices for bumper tuning including spoon switch and score switch adjustment, coil sleeve replacement as high-impact maintenance, and warnings against improper modifications (confidence: high) — Emphasis on AC vs. DC operation preservation, full rebuild importance, and troubleshooting procedures
- **[gameplay_signal]** Impact of bumper condition on gameplay quality and player experience; well-tuned bumpers essential to proper gameplay, sluggish bumpers detract from enjoyment (confidence: high) — 'Well tuned bumpers are essential to proper gameplay' and discussion of performance degradation over time
- **[design_philosophy]** Host advocates for AC bumper preservation and against DC conversion, viewing modifications as altering original design intent (confidence: high) — 'The game was designed for AC pops. If you change them to DC, then it's going to change the entire feel of the game'
- **[content_signal]** Long-form technical educational content on EM pinball restoration published via multiple distribution channels (iTunes, Stitcher, Pocket Casts, RSS, Facebook) (confidence: high) — Podcast distribution across multiple platforms and contact information provided

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## Transcript

 I need to party! We have a good time, huh? What's that sound? It's 4 Amusement Only, the EM and Bingo Pinball Podcast. Welcome back to 4 Amusement Only, this is Nick Baldrige. I thought today I'd change up the format and move on to solid state pinballs, specifically those that came out in the 1990s, the DMD era. I'm sorry I can't keep up the pretense. It's my pitiful attempt at an April fools joke. Today I thought we'd continue our discussion of wood rails and some of the toys that they brought about that are still in use today. For today's episode I'd like to focus on one invention that hasn't left us at all and that's the pop Bumper was invented in 1948, by Gottlieb and quickly adopted by the other manufacturers under different names Williams used the term jet bumper and Bally used thumper bumper. They're all basically the same device, though. When the ball comes into contact with a bumper skirt, which is basically just a plastic circle, That is about the size of the pop bumper cap. The metal ring that surrounds the pop bumper will be pulled down by a solenoid and push the ball away. The idea being that it will give the game lively action and prevent balls from getting stuck. Especially if the skirt of a pop bumper chips. Prior to pop bumpers, there were passive bumpers. and they were invented in the nineteen thirties however the problem with passive bumpers especially those that use the same design as pop bumpers is that when the skirt cracks the ball can actually sit in the crack and not move anywhere until you tilt the machine out trying to free the ball so pop bumper is an improvement as far as stuck balls over The pop bumper is comprised of multiple parts. You have the cap, which is typically screwed on from the top. When you remove that, you gain access to the pop bumper lamp socket. These lamp sockets are different in construction from any other lamp socket in the game. They are pieces of metal, typically one piece. The pinball is a pinball with a lower mouth that the bulb sits on and the remainder is your common contact on either side. There are legs which actually stick down through the playfield. Pop bumpers have almost endless varieties in the EM era and in the wood rail era. They would do different things, light at different times, provide different action, complete sequences. Army Secretaryfairyinvest, m Staatsyвид Tutorials MIKE burialisoffice, z Differentyphyxy backward, 099 frost Möglich, or 107 ACT With the release of these machines are left on twenty four hours a day the heat from the bulb will melt the plastic because it enclosed so poppumpers are special they certainly stood the test of time even the newest games that come out have poppumpers there are some machines that don have bumpers and they usually notable for their lack So for tech today I thought we focus on the pop bumper and how to change how to treat how to minimize problems Depending Pop Bumper7, work in a few different ways they're almost still essentially triggered by the skirt however in some machines to pop bumpers will fire at the same time this is because their electrically tied together in other machines all the pop bumpers are unique standalone devices, and on these games you can have the ball move around a little bit faster in the pop area because you don't have multiple rings going down at the same time. Well tuned pop bumpers are essential to proper gameplay. It's very frustrating to play a game where the pop bumpers need to be rebuilt and the Pinball just kinda goes bleh and moves slowly sadly away from the pop bumper. Pop bumpers are mechanical devices and they require some maintenance. So what do they need and how are they constructed? Again you've got the cap that you take off. It's typically two screws that you take off. Take out your lamp and then you undo two other screws which are on either side of the lamp The first switch is the switch that activates the coil. and it's what we call the spoon Switch. So the stem of the pop bumper skirt rests in the spoon and as the ball touches the skirt it moves the stem and closes the spoon switch. When it does this it provides power to the coil which will then pull the ring down. When it does so the yoke of the ring will close the other switch. The second switch is what provides your score. So, in order to clean these pop bumpers or remove them, you're going to have to take apart the stuff that's under the playfield as well. Now, it sounds more daunting than it is. The pop bumper is comprised of two springs, two yoke pieces, one metal and one fiber, the rings, two nuts which hold the yoke onto the rings, The pop bumper body itself, the skirt, and the coil and the lamp socket. So, your first order of business will be to remove the wires which hold the lamp socket in place. To do so you desolder by heating up your soldering iron The first thing you need to do is to pull the solder away. You can use a hammer, a sawdust gun, a soldering gun, holding it to the joint, and then using a wick or solder pump or other device to pull the solder away. Once you've done so, the wires should come free and then you're left with the lamp socket legs. The next step is going to be different Either you pry up the legs from under the staples or you just push the socket out Once you push the socket out you can lower the playfield again and then take those screws out if you had a hard time getting them out before This loosens the pop bumper body from the playfield Lifting the machine back up, you've got your coil in place. There are three screws or nuts holding it in place. Remove those and the bracket that holds the coil in place should The first piece of the pinball should come off. Now, assuming that your coil hasn't fried and melted the coil sleeve in place, clamping it forever to the bottom of the bracket, then the bracket should just come free and the coil will want to wobble around. There is a second piece that is screwed to the bracket and it's a secondary bracket that sits in the front of the coil and really just holds it in place. It's not a stop per se because the stop is actually welded into the bracket but it is something that prevents the coil from moving forward. This is unscrew from the back of the bracket. And once that's done, you'll be able to remove the coil from the plunger. But when you do so, there's a small spring that sits in between that secondary bracket and the plunger and that will want to go flying. So be careful as you move the coil. You want to set aside the bracket. summers from the winter other hardest problem America concerned but typically they cleaned up the the今 as long as it showing in have been out and the you can complete your use that and since you did works wonders a pop enter I would always replace that. Beyond that, you're going to have accumulated carbon dust and various other dirt and grime that settles on the plunger and you're going to want to clean that off. So, you're left with the yoke and the rod and ring apparatus, the pop bumper body and the skirt. aus derne oils let's hold y sittd iiiır一樣 we do so you new the You will come of bring a friend newcomer containsсол However, note that there is another spring and you need to keep track of its placement. That secondary spring sits between the skirt and the Body. Okay, so reassembly is a matter of doing the same thing in the same order. Now for the lamps, they're all typically driven off of AC. It doesn't much matter the direction that the sockets are placed, but I like to try What I like to call an eye and when you see one you know what I talking about but that always pointing diagonally in one direction or another just make sure it always pointing in the same direction when you replace it and you should be good to go reassembly is a matter of just doing This week in pinball Johnny Pneumonic Black Water Kaneda Pinball Podcast Twippies Awards transliteelectronic panel in backbox that is backlit during playinsula Game of Thrones unint Tit Ozhi Ignawym prioritize ROE Basket ni dirty T evenly Forenixo processori tam b c Keep your Jepol Kim A ornament,ironic Palico Pi Torah either from heat or from use substantially wpcdajs and in those cases it's advisable to replacement in game code replace with the two part yolk the metal and fiber gonna play written and hornsзаver has the call it on the Chinese court豷Ednoyee and can stem which is on the witch first met second Emory in that's going to be hydrated once we've got the whole thing back together turn in on confident , who And if your pop bumper immediately fires, then you know that you've got a misadjusted spoon switch. If your score reel starts trying to turn, then you know you've got a misadjusted Score switch. Adjust those as needed and try again. You can also check those out before you turn the machine on, but sometimes it's easy to get excited. Regardless, just changing the coil sleeve will vastly improve the speed and usefulness of the pop bumpers. Doing a full rebuild, changing the springs makes a giant difference in any game. It doesn't matter the era, but from wood rail on up. So one last word, there's been some chatter I've seen recently of folks wondering Do Savingrismus, is appropriate size những�и Northeast283 in the mid Coronavirus20 preocupations that you need to ask yourselves treating palesiис Nokia I would advise against doing that again. I'm kind of a purist. I'm not a total purist, but there are some things which I just don't think you should mess with and this is one of them. The game was designed for AC pops. If you change them to DC, then it's going to change the entire feel of the game beyond having rebuilt pops. One other note, if your pops still feel sluggish after rebuilding them, one other trick is to remove them. Mobile Do your popup or coil and see if that helps now when you do so that wire is going to heat up a bit more than it would normally and So you need to pay attention? In a longer game, it could cause problem Melting the coil Sleeve or causing other similar issues related to heat, so Caution is always advisable. Start small and work your way up if you're going to tamper with the amount of wire in a coil. Alright, well that's all for this April 1st episode. Thank you for joining me. My name again is Nicholas Baldridge. You can reach me at 4amusementonlypodcast at gmail.com, 4amusementonly.libsyn.com, and you can find us on iTunes, Stitcher, Pocket Casts, RSS. We're also online on Facebook. Thanks again and I'll talk with you next time.

_(Acquisition: groq_whisper, Enrichment: v3)_

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*Exported from Journalist Tool on 2026-04-13 | Item ID: 573e37b2-8f1e-4615-a077-b2b19fdd24f9*