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Part 14: 1985 Pinstar Gamatron Project! Sockets, SCR's and Lamps Oh My!

Pinball Shenanigans·video·19m 20s·analyzed·Sep 26, 2025
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Analysis

claude-haiku-4-5-20251001 · $0.020

TL;DR

Gammatron restoration: wiring cleanup, LED work, lamp repair via SCR diagnostics

Summary

Mike Dus continues restoration of the 1985 Pinstar Gammatron pinball machine, focusing on electrical work including tidying wiring, adding general illumination LEDs, swapping ball guides between playfields, and systematically diagnosing and fixing non-working lamps by tracing circuits, testing sockets, and replacing faulty SCR transistors. The episode demonstrates detailed troubleshooting methodology using schematics and jumper testing to isolate bad components.

Key Claims

  • The Gammatron project is on episode 14 with speculation it will reach approximately 20 episodes total

    medium confidence · Opening discussion about series length with reference to Pez Johnson's over/under prediction

  • Multiple non-working lamps traced to either faulty SCR transistors on the lamp driver board or flaky lamp sockets

    high confidence · Direct observation during diagnostic work; three bulbs in a row suggested wiring issue, others individually tested

  • SCR orientation matters: metal tab side goes toward thicker silk screen printed end, and cathode/anode/ground positions are labeled on the board

    high confidence · Information provided by Andrew Spitler in pinball repair help group; verified by checking board markings

  • Ball guide removal from playfield causes minor cosmetic damage (small marks) regardless of technique used

    high confidence · Multiple removal attempts showing consistent minor damage; gentle technique reduced but did not eliminate damage

  • The workspace for lamp repair was constrained due to electrical connections through the playfield neck remaining intact

    high confidence · Host describes having only limited room to work and using a clamp to prevent playfield tilt

Notable Quotes

  • “Well, I hear my little helper. Well, hello there, Ellie. Glad you're making an appearance. Everybody loves you. They'll click on my videos just to watch you. You are the true star of the show.”

    Mike Dus @ ~11:30 — Introduces Ellie (likely a pet) as recurring channel personality; shows audience appeal beyond technical content

  • “The metal tab side goes towards the thicker silk screen printed end.”

    Andrew Spitler @ ~35:00 — Critical technical information about SCR orientation that Mike had not previously known

  • “I literally went through all that effort for one light bulb.”

    Mike Dus @ ~14:45 — Self-deprecating humor about restoration work tedium; shows realistic frustration with detail-oriented tasks

  • “These three being out in a row makes me think wiring. The rest are probably just flaky lamp sockets.”

    Mike Dus @ ~22:30 — Diagnostic reasoning: pattern recognition used to prioritize troubleshooting approach

  • “So, I don't even know if I should be using flight 2000 schematics.”

    Mike Dus @ ~29:00 — Uncertainty about schematic accuracy for different pinball machines; suggests potential confusion with multiple similar board designs

Entities

Mike DuspersonGammatronmachineElliepersonPez JohnsonpersonAndrew SpitlerpersonJay (neighbor)personCoreypersonPinball ShenanigansorganizationFlight 2000machinePinball Repair Help Grouporganization

Signals

  • ?

    community_signal: Andrew Spitler provided technical guidance in pinball repair help group, demonstrating active community knowledge-sharing around restoration techniques

    high · Direct interaction documented in episode where Spitler explained SCR orientation and pinout labeling

  • ?

    community_signal: Pinball repair community actively provides troubleshooting expertise and technical knowledge to restoration hobbyists

    high · Andrew Spitler's detailed technical guidance on SCR identification and orientation; community forum participation

  • ?

    product_concern: Non-working lamps and faulty SCR transistors on 1985 Pinstar machine suggest age-related component degradation common in vintage pinball

    high · Multiple SCRs requiring replacement; intermittent lamp flickering; socket contact issues documented

  • ?

    technology_signal: Uncertainty about schematic accuracy across different pinball machines suggests potential compatibility issues when cross-referencing technical documentation

    medium · Mike expressed doubt about whether Flight 2000 schematics were appropriate for Gammatron board diagnostics

Transcript

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0:04
I'm Mike Dus and this is Pinball Shenanigans. All right, Pez Johnson says that the overunder on this series is 20 episodes. What do you all think? I think this is episode 14 and definitely getting close. So, I was predicting over, but we shall see. All right. On this episode, I am going to tidy up this electrical tape. We want to make things look nice for these controlled lights. Why can't I add an additional one here and here and here and have two lights for each thing? I'd like to pop in the back glass and actually see what these controlled lights look like through the back glass. Here they are. See, that's too wide. That's single. That's kind of We'll see if I can pop in some additional LEDs to illuminate that even more. Uh maybe I will turn some of the unused sockets into general illumination. and possibly swap out these rails.
1:34
See if I can pull them out without breaking anything. And other just little miscellaneous things. And then actually, you know what I think I'll do is work on all these lamps. Half of them don't work and I want to get them all to work. So, kind of glad I kept this on the rotisserie cuz then I can just flip it over and gain good access to all these uh lamp sockets and not have to break my back and neck trying to work under the hood of the playfield with it installed. And we'll start with that. That should be plenty for now to keep me busy. So, all right, let's gamutron it up. Okay, just a little summary of what I have done. So, these loose old chime box wires, I've zip tied and tidied them up. And then I got rid of the electrical tape off of this connector. I removed the wire, shrink tubed it. It was soldered, so it's fine. The splice was soldered. And um repinned it. And then I did the same for these two splices here. No more electrical tape. So, that's all happy. I did just add these two red wires to turn these four guys into general illumination. And I added two bulbs. I don't need all four. I added a second bulb here, a second bulb here, and a second bulb here. And I think that is all that I've basically done. So, let's throw on the back glass and see what it all looks like. Okay. So, technically I could add more GI lighting here and then there and there. But let's pop this in and see what it looks like as is. Okay, here we go. Come on, switch. There we go. Ooh, these don't look amazing.
3:51
I'm going to have to um remove the bezels. Ooh, look at that though. Game over. Oops. Ooh, that was really looking at that. That looks nice.
4:05
All in all, I like it. But going to remove those bezels and let's hit lamp test and see the other lights here. Okay, not bad. Not bad. I like same player shoots again. That's nice. Tilt looks like kind of almost too much light. Maybe I got to remove that bezel, too. Wonder if that would look better. I'm going to mess with that for a little bit. And, you know, could possibly use some of this extra light here and even maybe there and there. So, it's a bit of a pain in the butt, but maybe I'll add a little bit more lighting. Oh, I hear my little helper. Well, hello there, Ellie. Glad you're making an appearance.
5:02
Everybody loves you. They'll click on my videos just to watch you. You are the true star of the show. Whoa. Are you going to go uh do your thing? All right. Do it. Ice. All my laundry is in your way. Get my Don't worry. Clean underwear out of the way. And um you do your thing, right, Ellie? Yeah. Well, it ain't pretty, Well, it ain't pretty, but it should look a little better. Okay, let's see if that bottom left Okay, let's see if that bottom left corner looks any better now. Way better. Still a little bright,
5:53
but not too obnoxious. Maybe I'll remove one of the bulbs. It's a lot of effort for one little freaking bulb. So, on that note, I'm probably not going to bother with any of the other ones because it's a bit of a pain in the butt. If I deem that I feel the need later, then I will. But right now, I'm pretty happy with how it all looks. Okay, I did remove one bulb and I think that looks better. So, I literally went through all that effort for one light bulb. Okay, I had success removing the one ball guide. Look how torquked that is. Why would anybody do that? I'll try and like flatten it out a little bit before I install it in the other gamutron. But here's my strategy. Oh, now you're in my way to reach around you. I know you like the reachounds. So, I'm using this plastic
6:59
so I don't dent the playfield. Just work it up nice and gently. Now it's popped out. Make sure it doesn't scratch the playfield. And well, there's a little bit of damage there. It's the same damage that caused on the other side. Just like when removing any screw, pretty much a little bit of whammo there. And you see the whammo on the other side. No. Oh, that's because I touched it up. So, you'll never notice I went even more gentle this time and it still happened. So, it's just nature of the game. So now my strategy is to just gently go back and forth. See this hole? No damage. That's cuz I was able to just slowly work it up.
8:06
Feel it coming. Just don't you don't got to rush. Less damage the better. And make sure this end is not scratching on things.
8:31
Come on now. Yay. No damage. Okay, how's this guy? Yep. Whamo. Okay, I'm going to swap now. Okay, here are the old ball guides. was actually able to straighten them out pretty good with a hammer. That's my way of finessing things into uh place. And here are the new ones from the other playfield. So, they're a little crusty. Nothing some green scrubby can't resolve. So, polish them up and install them. Okay, these lane guides are reinstalled into the old playfield much more straight and more importantly they fit in the same holes. So here are the cleaned up and nice and straight. See how that just hugs the artwork just almost perfectly. Same on this side.
9:39
So, they may potentially require some adjustment for ball hop, but uh we'll deal with that once we get to play testing. And then there's the damage. Can hardly tell. So, no worries there. But that looks good. I like it. All right, it's time to deal with the non-working lights. You know what? Oh, I was going to say there's not flicker, but I lied. There is. It's weird though. It doesn't flicker every time. Anyway, I'll get me some LED adapters. But this is the part where I can spend another 4 hours fixing 10 light bulbs. So, these three being out in a row makes me think wiring. The rest are probably just flaky lamp sockets. possibly an SCR on the lamp driver, but I'll go through everyone individually until I've got them all working. And don't forget, there's one general illumination bulb here I've got to do as well. So, I'll see you in a few hours. Well, Houston, it's a little bit of an issue here. can't rotate my playfield because of the fact that I connected it up through the neck and I don't want to disconnect everything. So, I have about this much room to work with and I had to put a clamp here to hold the playfield in place because it wants to tilt like about that. So, this is pretty precarious but slightly functional. So, that's my workspace for the next few hours. Okay, I have remedied a couple bulbs. I managed to fix two or three by just switching the wire over from the tab to the uh socket butt. I fixed that one. I tried this one. That did not resolve that, but I think that worked on one or two others. Uh but for this one, so I just I don't know if I can rely on the schematics for flight 2000, but maybe I will show you. But right now, I'm just tracing wire colors. This bulb doesn't work. So I jumper on a new socket to the wires to find out whether it lights or not. Well, it did not light. So then we know it's not the socket or the bulb. So then I trace that gray wire all the way back to this gray wire. And then I go, "Oh, that's J2 pin 1 2 3 4 5 6 7 8 9 10 11." Then I go to the schematics and find out what transistor uh J2 pin 11 uh is on and then I ground it to find out that it does f all. Then I go find that. Oh, there's another gray wire on J1. H. I don't know if you can see. This is bad videography right here. 1 2 3 4 5 6 7 8 9 J1 pin nine. Then we go over to the actually this is Bobby or schematics J1. So, I don't even know if I I should be using flight 2000 schematics. J1 pin 9 says it's 6k bonus, which
13:31
that blue light is actually the 6k bonus. So, that's handy. So, then we know that the SCR responsible for that is Q27. So then go back to the back box. I'm in switch test right now just so that playfield is alive but not all lights are going crazy. So Q27 jumper the right leg. Okay. And then look at that. Hey, wait. That's the wrong blue light. I did something wrong. Oh, I was on Q28. I got to be on Q27, I think it was. Right. And there we go. So, I guess that means my SCR is in fact bad. So, I'll mark that one as needing to be changed. But uh that's what I'm going through to resolve one bulb at a time. So fun. You should try it. Okay. I said I'd be back in a few hours. It's not that far off. It's about 2 and 1/2 hours. But Jay, the neighbor showed up with a circuit board for a uh hot tub and asked me to change a few relays for his work. And uh that was about half an hour or so. And uh it went okay except for the fact that there's some stupid coating on the back side of that board and uh made life a little more challenging. Otherwise, it would have been like half the time. But check it out.
15:25
I don't know how well this is going to show in the camera, but
15:32
Oh, I forgot the general illumination bulb. There are still three bulbs that I got to address, but those are three bad SCRs, including the one I already replaced. So, maybe I put it on backwards. But there's You can see a little piece of tape there and there and there. Those are literally the last three controlled lamps. Look how nice this looks. That's all lit up. So, for a bunch of these, I just moved that wire from the lug to the butt. And there's more just uh more time just like tracing which bulb goes to which SCR. So, I am getting close. I got to pull the board now and then finish the job. Let me do that GI first. Okay, I got the board pulled and the new SCRs just loosely in there. I don't even remember which ones they are now. And I'm learning things. I didn't know if I had installed this backwards, but I assumed I did. So, I made a post in the pinball repair help group to say which way does it go? And Andrew Spitler says the metal tab side goes towards the thicker silk screen printed end. I never even noticed that in my life. There is a thin kind of white print there and a thicker uh white side that denotes I guess the tab side. And then he says you can look at the printing near Q49 and this pin out picture. K and C are interchangeable. Sorry, it's just going back and forth like crazy. So then I noticed look C A G. So that is like your cathode, anode and ground. So you can take your STR and go. Okay. So one is cathode. All right. So that is the say front right leg C. So then you put the front right leg in the C position and voila, I in fact had it backwards. So always learning and thanks Andrew Spitler. He is a wealth of information. Okay, I got these guys installed. I just reversed my SCR on Q56 and see if that works. These connectors are really stubborn to get off. So, don't think I'm going to install this just yet or install the connectors anyway until I have my Siegecraft or generic LED adapters. And that way there's less of a chance. I mean, that way I don't have to like remove the connectors again and put them back on again. The less removing and reinstalling those stubborn connectors, the better. So, I'll see if I can maybe pick those up off Corey tomorrow. So, we're not going to see the grand finale of all the lights working just yet. I did get that general illumination bulb working. It just wasn't really in the socket. And I just had to squeeze the tabs together so it locked into place better. And I'm starting to run out of gas. It's been a long time working on light bulbs. So, I'm going to wrap it up at this point and um come back with some energy tomorrow or whenever. So, we'll see you next