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    👨‍⚕️ Repair log: Doctor Who (Bally, 1992)

    1992 Bally Doctor Who Repair log

    Repair logs are quick summaries of workshop and on-site repairs. If your machine needs a service, 📬 Contact Us to discuss how we can help!


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    Plenty of fun repairs to get this Doctor Who running at full speed. First problem was an easy one. No action from the right flipper at all. Cabinet switch worked fine, but the coil would not fire. Took a look under the playfield and saw that the BLU/YEL wire had broken off the coil, as well as the power and hold coil windings. This wire is the 50 volt supply from the flipper board, and without it you'll never get any flipper action. This coil had a hard life as the lugs had all broken off at some point, but you can use the eyelets as a convenient solder point as well. Once the wire and windings were reattached, the flipper came back to life.


    Error reports indicated failures of some of the opto switches on the mini playfield opto bank. First step is to raise the mini playfield so you can activate the switches in test mode. And this was the first roadblock. The mini playfield would not move up or down at all! We will deal with that a bit later... but to get around this, you can unbolt the gearbox and cam assembly from underneath the mini playfield. Remove them, and you can now move the mini playfield by hand. Just don't drop it on your fingers!


    With the switches accessible, I found three out of five were unresponsive. Taking the target bank assembly off the mini playfield gives you access to the opto boards for inspection. The problem with one switch was obvious right away. Broken ORG/GRN wire on the receiver board. Soldered it back on and that switch started working again. Two more to go. These turned out to be dead transmitter optos. You can check these with your phone camera; a glow indicates they are working, no glow indicates they are not. These two were replaced, and all five switches were back in action.


    Back to the mini playfield movement issues. The gearbox was rooted. I could move the cam freely by hand, which is a bad sign. I cracked the gearbox open to get a better look. The problem was the gear attached to the main arbour. It was freewheeling on the shaft. A pretty common failure, particularly on Doctor Who. Off to my mate Darren who is a great welder. He silver soldered the gear and spline back onto the shaft. Greased the gears and rebuilt the gearbox. Back in the game, the mini playfield moves up and down really well now.


    Last issue (for now!). No sound effects or music at all. Game booted up and made two "bong" sounds. The sound board has its own processor, so the tones tell you its status. Two bongs means the 6264 RAM at U9 has failed. I've seen plenty of cases where a failed RAM will not trigger any unusual messages and will appear to boot normally. However U9 is usually the problem. I removed the chip, installed a socket, and plugged in a new one. Replaced the electrolytic caps at the same time for good measure. Sounds are all playing again!


    That's enough excitement for now! Hopefully that keeps this machine going for a very long... time!


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    ✈️ Repair log: Supersonic (Bally, 1979)

    1979 Bally Repair log Supersonic
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    ✈️ Always loved the backglass on this machine. Perfectly captures "the magic of flight" at a time when the Concorde had just entered service and the world still seemed like a big place...


    Anyway. Where were we? Few things to fix on this Supersonic. Game booted up and played OK... except for the total lack of playfield solenoids. Sure enough, playfield fuse was blown. Replaced it and powered up again. Fuse held until the very end of the boot sequence and blew again. I could tell that it was blowing the instant the drop target reset coil was firing. The coil was very crispy, and measured only 2 ohms. It should be about 10. Clearly this one was fried. Hard to find a replacement for these big drop target reset coils (24-1400). However, most of the large size coils will work. I found a 26-1900 which fit, and worked a treat. 


    A few displays were wonky. Two were missing some digits, one was flickering. Reflowing the header pins on these and replacing the six 100k ohm resistors solved these issues. But still couldn't get the last display to light a hundreds digit. No problem... here's a sneaky trick. The ball in play and credit display don't need a hundreds unit, so whack the display into that slot and nobody will ever know! 🤫


    During testing I realised some of the switches weren't registering nicely. Cleaned their contacts which certainly helped, but some were still hard to register. Took a closer look and realised that someone had cut the capacitor off every single switch on the playfield. Sigh. These are needed for the CPU to read switch closures properly, so don't cut them. Soldered them all back on and switches were all good. Someone had also cut the playfield tilt switch out of circuit too. Savages!


    Lots of lamps needed replacement/adjustment. Playfield got a good clean. Checked the backbox and noted a bit of corrosion on the CPU board, but we will deal with that another time. Sound board also needs a rebuild as some of the sounds are a bit scratchy and out of tune, so we'll do that at some point, too. But for now it plays nice and fast like it should!


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    Repair log: Scared Stiff (Bally, 1996)

    1996 Bally Repair log Scared Stiff

    Repair logs are quick summaries of workshop and on-site repairs. If your machine needs a service, 📬 Contact Us to discuss how we can help!


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    Scared Stiff was in for a general service after a few years of storage. After an initial check-over and first boot, the game came to life with a factory settings restored message. Lovely! This means memory is no longer being kept by the CPU board. Sure enough, the batteries had leaked. 🔋 Last replaced in 2011! Thankfully, only minor damage to the battery holder, which was replaced with a button cell.


    Now we could start a game and give things a bit more of a test. Gameplay was a bit wonky. Sometimes a switch would register in gameplay that shouldn't have. Sometimes the game would display errors about switch ground shorts. Didn't seem to be much of a pattern, until I realised that all of the affected switches were optos. Jiggling connectors on the MPU board didn't have any effect. So next port of call was the opto board under the playfield. Scared Stiff uses a lot of optos, so this is a 16 opto board. This board was RAGGED ☢️ The 470 uf capacitor had spilled it guts everywhere. First time I've actually seen electrolyte bubbling out of the capacitor when it is under load. Cool! 😎 These boards are available to buy but I was impatient and wanted it done today, so I just rebuilt it. About half of the board components removed, chemical treatment, sanding, and new components installed. All optos working as intended now!


    There were some odd display artefacts and sound effects that played when they shouldn't. Sometimes lines would appear on the display. Sometimes the display fonts would change. Totally whacky behaviour. 🤪 Since there were issues with the sound and the display, first suspect was the audio/visual board. Things checked out OK here visually, and the ROMs were good. Fiddling around with the ribbon cables revealed the problem was at the I/O connector between the CPU and the audio/visual board. Jiggling around got the display to do all kinds of weird stuff. New ribbon cable and reflowed solder on the header pins. All displaying and sounding normal now.


    Finished off with the basics. Playfield cleaned. New rubber rings. Globes replaced. Switches adjusted. Coil assemblies checked. Ready to scare again! 😱


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    Repair log: Twilight Zone (Bally, 1993)

    1993 Bally Repair log Twilight Zone

    Repair logs are quick summaries of workshop and on-site repairs. If your machine needs a service, 📬 Contact Us to discuss how we can help!

    

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    🛠️ Basic service for a Twilight Zone that had been sitting unused for a number of years. First port of call was the CPU board. Batteries weren't retaining any memory. No wonder, they expired in 2016! Other than the battery pack, there was only minor damage to one connector and header pin which was causing one column of switches to fail. All replaced, and a coin cell battery added.


    Now onto the playfield. Rubbers were perished, so new rubber rings installed throughout, including the mini playfield. Several lamps not working. New lamps and sockets were necessary. Of course two of the pop bumper lamp sockets were broken, so they had to be desoldered, unstapled, pulled out and replaced. Very fiddly! Highly recommend the lamp sockets with centering brackets for this.


    The trough release coil was jamming, stopping from balls moving in the trough. Pivot point was gummed up with dirt and debris. Cleaned and re-sleeved.


    Lockdown bar had a bit of surface rust on it as well. Treated and polished. Nice and smooth now. Playfield also got a clean to finish off.


    📺 Reminds me I need to watch the original Twilight Zone series!


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    Repair log: Centaur II (Bally, 1983)

    1983 Bally Centaur Repair log

    Repair logs are quick summaries of workshop and on-site repairs. If your machine needs a service, 📬 Contact Us to discuss how we can help!


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    Time to get a Centaur II up and running again! First problem? Start a game, and the balls are nowhere to be seen. Turns out they were all hiding in the multiball trough. But they weren't getting kicked out because the ball launcher was gummed up with grease that had solidified, rendering it immobile. Cleaned and re-sleeved and the ball issue was fixed.


    The left flipper had also given up the ghost. Broken wire between the flipper coil and the end of strike switch. An easy fix!


    ...then a hard fix. A sound issue. Absolutely criminal on Centaur, because the best thing about the game is hearing it say "Destroy Centaur"! One of the wires on a sound board connector had come loose. New crimp pins and a new connector housing solved the problem temporarily, but it returned soon after. One clue was that some of the backbox lamps would go out when the sound went out. Weird. Somebody had cut the backbox GI lamp braid, and simply tied some wire around it to reconnect it; a poor connection. Once this was soldered back together, the sound (and backbox lamps) returned.


    Plenty of lamps out on this playfield, which were replaced as needed. The "B" in "ORBS" was a little less cooperative. The SCR driving this lamp had failed. New rectifier installed and it was lighting up again.


    The rubbers on this machine were long gone, so a new rubber kit went in too.


    Finally, the ground braid connecting the lower cabinet to the backbox was... not connected together. Didn't seem to be causing any issues, but it certainly could do, so they were reconnected.


    🔊 "Destroy Centaur!"


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    Repair log: Judge Dredd (Bally, 1993)

    1993 Bally Judge Dredd Repair log

    Repair logs are quick summaries of workshop and on-site repairs. If your machine needs a service, 📬 Contact Us to discuss how we can help!


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    Lots of work involved in preparing this machine for sale! First, a thorough clean. This necessitated taking all of the ramps off the playfield so you can access all ball areas at the top of the playfield. There was some Mylar lifting in this area so that had to be removed.


    Next, the drop targets. The "J" target was not staying up. The targets are meant to rest on a plastic shelf which keeps them in the "up" position. Somebody had installed a homemade version of this part which had cracked. Correct part installed and assembly rebuilt.


    Next, the subway entrance. There were some lamps missing here which were reinstalled. There are also two small wire ball guides on either side of the hole which guide the ball into the subway. They had fallen out at some point and were in the base of the cabinet. They were re-tensioned and glued back into place. New rubbers installed while I had this bit apart.


    Next, the lamps. Plenty not working, particularly those on the lamp boards. Cracked solder is common on these, particularly the lamps in sockets which are parallel to the playfield. Most of these needed resoldering.


    Next, the Deadworld. It kept spinning and wouldn't stop to allow the magnet to pick up the balls. One of the optos under the playfield which reports the Deadworld position was not working. It was fouled up with dust and dirt which were keeping it "closed". Cleaned and back in action.


    Finally, the flippers. Upper right flipper to be exact. This one was intermittently weak. A quick rebuild did not help. Test mode revealed the flipper switch was flaky. This switch is on an opto board. Rebuilt the connector and reflowed solder on the board but this didn't fix it. Turns out, the opto itself was on the way out. Replaced it and all was good again in Mega City One.