# 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

Nick Baldridge of the For Amusement Only podcast delivers a deep technical dive into pop bumpers—a foundational pinball mechanic invented by Gottlieb in 1948 and adopted across manufacturers (jet bumpers at Williams, thumper bumpers at Bally). The episode covers pop bumper history, mechanical construction, maintenance procedures, and common repair mistakes, emphasizing that well-tuned bumpers are essential to proper gameplay and that coil rebuilds and spring replacements significantly improve performance.

### Key Claims

- [HIGH] Pop bumpers were invented in 1948 by Gottlieb — _Nick Baldridge stated this as a foundational historical fact early in the episode._
- [HIGH] Williams called them 'jet bumpers' and Bally called them 'thumper bumpers,' but they are all essentially the same device — _Nick Baldridge explained the manufacturer naming conventions directly._
- [HIGH] Passive bumpers preceded pop bumpers (invented in the 1930s) but had a critical design flaw: when the skirt cracked, the ball could become stuck in the crack — _Nick Baldridge described the historical evolution and the practical problem passive bumpers solved._
- [HIGH] Pop bumper coil rebuilds and spring replacements make a significant difference in game performance across all eras — _Nick Baldridge stated: '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.'_
- [HIGH] Converting pop bumpers from AC to DC changes the entire feel of the game and should be avoided — _Nick Baldridge advised: '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.'_
- [HIGH] Some machines electrically tie multiple pop bumpers together so they fire simultaneously, while others have standalone pop bumpers that fire independently — _Nick Baldridge explained the electrical design variation: '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.'_
- [HIGH] Pop bumpers remain present in the newest games that come out today — _Nick Baldridge stated: 'Even the newest games that come out have pop bumpers.'_

### Notable Quotes

> "Pop bumper is an improvement as far as stuck balls over passive bumpers."
> — **Nick Baldridge**, early section
> _Explains the functional advantage that made pop bumpers the industry standard._

> "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."
> — **Nick Baldridge**, mid-section
> _Emphasizes the critical importance of pop bumper maintenance to player experience._

> "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."
> — **Nick Baldridge**, near end
> _Clear guidance against a common modification that would alter game design intent._

> "Just changing the coil sleeve will vastly improve the speed and usefulness of the pop bumpers."
> — **Nick Baldridge**, late section
> _Simple maintenance recommendation with measurable impact._

> "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."
> — **Nick Baldridge**, late section
> _Reveals his philosophy on restoration and authenticity._

### Entities

| Name | Type | Context |
|------|------|---------|
| Nick Baldridge | person | Host of the For Amusement Only EM and Bingo Pinball Podcast; technical expert on electromechanical and early solid-state pinball machines. |
| Gottlieb | company | Historic pinball manufacturer credited with inventing the pop bumper in 1948. |
| Williams | company | Historic pinball manufacturer that adopted pop bumpers under the name 'jet bumpers.' |
| Bally | company | Historic pinball manufacturer that adopted pop bumpers under the name 'thumper bumpers.' |
| For Amusement Only | organization | EM and Bingo Pinball Podcast hosted by Nick Baldridge, focused on classic electromechanical and early solid-state pinball machines. |

### Signals

- **[historical_signal]** Pop bumper invention (1948, Gottlieb) and adoption by Williams and Bally under different names; evolution from passive bumpers (1930s) to active solenoid-driven bumpers, addressing stuck ball problems. (confidence: high) — Nick Baldridge's detailed historical timeline of pop bumper development and the problem passive bumpers solved.
- **[design_innovation]** Pop bumper mechanical architecture consists of coil, yoke (metal and fiber), springs, ring, skirt, cap, lamp socket, and dual-switch activation system (spoon switch for activation, score switch for points). (confidence: high) — Comprehensive technical breakdown of component construction and assembly sequence throughout the episode.
- **[operational_signal]** Detailed pop bumper maintenance and rebuilding workflow: desolder lamp socket wires, remove socket, access coil via underplayfield screws, remove coil bracket and secondary bracket, clean plunger and remove carbon buildup, replace coil sleeve and springs for maximum performance improvement. (confidence: high) — Step-by-step maintenance procedure described with technical specificity and warnings about potential hazards (heat, spring tension, coil melting).
- **[restoration_signal]** Host advocates against AC-to-DC conversion of pop bumpers as it fundamentally alters game feel and design intent; identifies himself as a 'purist' on certain restoration questions. (confidence: high) — Direct statement: '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.'
- **[product_concern]** Melted or degraded coil sleeves are a common failure mode in older pop bumpers, reducing ball ejection speed and playfield liveliness; coil sleeve replacement identified as critical maintenance. (confidence: high) — Nick Baldridge emphasized: 'Just changing the coil sleeve will vastly improve the speed and usefulness of the pop bumpers.'
- **[gameplay_signal]** Pop bumper condition directly affects gameplay feel and machine design intent; sluggish or weak pop bumpers reduce lively action and can indicate need for rebuild, coil upgrade, or wire adjustment. (confidence: high) — Multiple references to sluggish performance after long use and the importance of well-tuned bumpers to proper gameplay experience.
- **[content_signal]** Educational podcast episode providing hands-on technical guidance for pinball hobbyists, operators, and collectors on a foundational game mechanic; part of broader content strategy focused on EM/early solid-state preservation. (confidence: high) — Episode structured as detailed how-to guide with safety warnings, tool recommendations, and troubleshooting tips; published in series focused on EM era mechanics.

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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 2026-08-04 | Item ID: 573e37b2-8f1e-4615-a077-b2b19fdd24f9*