Johnny – Cyberglove Rebuild

Somebody give this man a hand!


You just knew I was going to make that joke at some point, so we might as well get it out of the way in the subtitle, right? Johnny Mnemonic’s signature feature is the “cyberglove”. Among owners, it’s more commonly known as “the infamous hand”.  When working, it’s a ridiculously cool feature. When it isn’t working, the game is about 60% less fun.

When the player shoots a ball up the middle of the play field, it falls into a pocket and lands on a piston. A very beefy solenoid kicks the ball straight up about 8 inches, where it is caught by a strong electromagnet (hiding under a plastic glove prop from the movie). This magnet holds the ball, and the player is then given control using the flipper buttons. The glove moves on both X and Y axes, and the goal is to choose one of nine spots on the “cybermatrix” to drop the ball onto. There are various strategic gameplay reasons to choose different spots, but I won’t go into it here. Suffice it say, the player is in control of a robotic hand that catches a very heavy steel ball shot into it from a long distance. It’s insanely great. When it works.

It often doesn’t.

That lovely sound it makes while moving towards the camera is what ultimately pushed me over the edge to start this rebuild. Prior to this, the hand had been working, but was showing some signs of trouble (occasional missed catches, sagging under the weight of carrying a ball, and slow operation).


The mechanism that does all this is pretty complex, and wears out sooner or later. After just a few hours of play on my Johnny, the hand was starting to act up. Rather than messing around addressing symptoms here and there, I decided to rebuild the entire assembly. Once rebuilt, it should run smoothly for years to come. Arcade operators tended to do as little as possible to get the hand working again, and it often sat broken for long periods. That means the hand on any given Johnny is usually in need of a total rebuild like this. So let’s get started!

The general consensus is that the easiest thing to do is remove the entire backboard assembly from the play field. After doing it, I agree this is the way to go. Most of this job is done with the play field lifted and sitting on the supports. I needed to hinge it all the way vertical a couple of time to access some areas. This whole process is a bit time consuming, but there’s nothing difficult about it, and basic hand tools are all you need.

The first step is to disconnect every electrical connection to the hand assembly.

I labelled these as I went along, so it would be easy to reconnect everything later. It’s likely that every connector only fits one place anyway, but I wanted to be careful.


These two connectors can’t be reached from behind. They go to the dual relay motor driver board. This board is in kind of a silly place, but I guess that’s where they had room for it. Interestingly, this board in my game is brand new. Someone has worked on this recently.


Next, disconnect anything that is attached to the backboard. There are a couple of plastics, and the cybermatrix unit.

Check carefully for any plastics attached to the backboard- you’ll break them if you try to remove the assembly with these attached, and we all know how hard it is to replace Johnny plastics. I also removed the flasher lens and bulb to prevent damage.


The cybermatrix unit is bolted to the backboard. It looks like it is intended to be removed with the backboard. On my game, I wasn’t able to, because of that solenoid on the left. I believe it is installed backwards, because there’s a large opening in the play field that seems intended to permit extraction. However, the base of the solenoid is wedged under the play field because (I believe) it is 180° off. Maybe. Anyway, for me it was easier to unbolt the cybermatrix and leave it there.


I also found it helpful to loosen the nuts on the middle ramp, and lift it up a bit. This prevents damage when jockeying the cybermatrix out of the way of the backboard. You REALLY don’t want to damage that ramp. It’s very difficult to get a replacement.


Now we’re ready to unbolt the hand assembly itself. There are six nuts that hold it from underneath.


The nylock nuts along the bottom edge (six in total) are what we need to remove. I removed all but two of them with the play field up as shown, because it was easier. The last two were removed from behind with the play field down, so the hand assembly wouldn’t fall.


With the wires disconnected, the cybermatrix moved clear, and the bottom nuts removed, the whole assembly lifts straight out.


I put the cybermatrix on a rag to protect the plastics underneath, and taped it in place to make sure it didn’t fall down into the cabinet. If, like me, you’re doing the job over several days, you can now put the glass back on the game to protect it.


Presto! One Johnny Mnemonic cyberglove assembly, ready to be rebuilt.


Now that we have the assembly on the bench, the job is tremendously easier. Trying to do this in-situ on the machine would be a special circle of hell reserved for politicians and people who design British cars.

The main targets of our rebuild are the axis nuts, the bearing surfaces, the gearboxes, and the electromagnet. At this point, I simply took everything apart, and cleaned as I went. Some previous operator or owner had gotten a little carried away with machine oil, and there was a lot of slime and crud on things. Some Simple Green and a few shop towels go a long way. A clean mechanism is infinitely nicer to work on than a dirty one.

My strategy was to break the assembly down into major components, then work on each in turn. The wiring on mine was somewhat of a rat’s nest that couldn’t be separated cleanly. It looks like someone has repaired this harness in the past, but they routed wires in such a way that the harnesses are forever braided together. That meant I had to keep all the assemblies close together in sort of a “blob” on the bench as I went along.


Once disassembled to this point, we can get busy reconditioning things. I started with the Y axis assembly, on the front. Note that skinny rod that runs fore and aft in this photo. It’s held on with teeny tiny little spring clips that are sure to vanish forever if you attempt removal. I opted to leave it in place on that long bracket. Working around it was not difficult.


The Y-axis assembly consists of a threaded rod, a special nut that rides on that rod, a smooth rod that carries the top of the carriage, and the carriage itself which holds the electromagnet. At the back is a motor with a gear-reduction box that drives the threaded rod. The X-axis assembly is basically the same, so I won’t cover both.


Here is the Y-axis mechanism, fully disassembled. I deeply apologize for this photo. I didn’t realize how bad it was until everything was back together. Rest assured I have put 1000 needles in my eye in sympathy for how you are feeling at this moment, being forced to look at it. This was my penance, and it was harsh but fair.


On the axis assemblies, I cleaned all the old oil and grease off both rods (smooth and threaded) using Simple Green. I then reapplied a light coating of grease to the threaded rod. The ends of the threaded rod sit in bronze bushings. Those bushings where cleaned, and a light coat of machine oil applied. The smooth rods have nylon bushings that ride on them, so in theory they need no lubrication. Just in case, I put a very light coat of machine oil on them as well. If nothing else, it will prevent corrosion of the rod.

The grease I’m using is called Super Web Grease. It was originally developed for bicycle chains, but it works great on any mechanism involving gears, chains, threads, or other mated surfaces. It’s similar to white lithium grease, except it stays in place much better, and is immune to moisture. It’s great stuff, and a little goes a long way.

Check for wear on everything as you go, but likely the only part you will need to replace is the X/Y nuts. These carry the mechanism fore and aft as the threaded rod turns. They are intentionally softer metal than the rods so they will wear out first. They are a consumable part, and can in fact be replaced in situ on the machine, if needed. Most mechanical problems with the Johnny hand come down to these nuts being worn out.

Here’s the X nut out of my machine, with the new replacement on the right. It carries the entire weight of the electromagnet and Y-axis assembly, so it tends to wear out first. This one isn’t too bad, but has a slightly egg-shaped inner diameter, so it’s getting replaced. If the X-nut is egg-shaped, it causes the hand to sag downward at the front, which causes clearance issues on the cybermatrix. My Y-nut looked fine, but I replaced it anyway and kept the old as a spare. Every so often, WordPress decides to mangle a random photo. Today, it’s this one. Sigh.


Pretty much anything you might need to replace while doing this can be bought from Marco Specialties.

Once the X/Y assemblies are cleaned and regreased, it’s time to tackle the drivetrains. Each threaded rod has a motor and gear box on the end of it. This gear box drives the rod through a rubber spider coupling.

My spider couplings were both in great shape, so I didn’t bother replacing them. These can be bought online as well, if needed.


The gearboxes themselves are held together with a couple of screws.

As you can see, the gears have thrown most of the old grease off over the years, and it is pretty perished in any case. Time to replace it.


I started by disassembling and cleaning everything with Simple Green. Be careful with the small parts. For example, there are flat shims on the front and back of the shaft that sit against the bronze bushings. These appear to act as a seal, and probably help extend the life of the bushings.


With everything clean, I again applied a light coating of machine oil to the bronze bushings. The gears themselves get Super Web Grease.


When greasing, don’t forget all the surfaces that the gears will touch with the casing is closed up again. Don’t overdue it with the grease- you don’t want to gum things up too much.


I encountered a small problem at this point. In order to fully disassemble the gear train, you need to remove the spider coupling from the output shaft. The set screw in one of my spider couplings was completely stripped out by some hamfisted repairperson in the past. The coupling was secure, but it was going to very difficult to remove. I opted to leave it alone. With the coupler in place, you can still slide the gears out enough to clean and grease behind them, but you can’t do quite as fastidious a job as I did on the other gearbox (shown in the pictures above). Still, you can do what you need to. If I ever need to replace that spider coupling, I have no idea how I’ll remove that tiny stripped set screw. Grr.

While we’re in here, inspect all the electrical elements as well. Check the wiring for damage. There are a lot of moving assemblies here, and an improperly routed wire could have worn insulation. In particular, check the wires running from the magnet. This is called out in a Williams Service Bulletin:

These service bulletins are a gold mine of wisdom acquired by Williams after these machines had been in the field for a while. Heed them!


Each machine may have unique issues. In my case, the encoder boards on the back of each motor had clearly been worked on (poorly), and needed some attention. The boards sit on the back of the gear box and optically register an encoder wheel, so the game can measure the progress of the hand on each axis. On my game, someone had replaced the connectors. As I mentioned in a previous article, Williams keyed their connectors by removing a pin. In this case, the repairperson had done so poorly. Before I fall off my high horse and break something, I should note that I did basically the same thing on the power driver board recently. The difference is, I’m totally going to go back and fix that properly. Honestly, for reals, I pinky swear. Ahem. But not right now, ’cause Walking Dead is on. Later. Maybe.


That little stub was preventing the connector from seating fully. It did work this way, but didn’t inspire confidence at all. I snipped these flush with a set of quality side cutters. The connectors seat completely now.


Speaking of service bulletins, there’s another one we can attend to while we’re here. There was a bulletin issued about the connector on the back of the flasher lamp mounted in the backboard. The connector is very close to the harness that runs down the back of the cabinet from the head, and lifting the play field up and down for service can bend the pins, causing a short.


The service bulletin recommends insulating these terminals, so I unsoldered them and threw some heat shrink on there. Now is the time to do this, because it would be a real pain to do it with the assembly back in the machine.


We’re almost done! Reassembling the whole backboard is the reverse of disassembly, and installation is the reverse of removal (as we like to say in the car world). If you forget where something goes, you can refer to the diagram in the manual.


These diagrams are helpful, but take them with a grain of salt as well. This one has at least one error on it. It shows the spider coupling on the Y axis mounting to the smooth rod, not the threaded one. Weird.


There’s also a complete parts list in the manual, if you need to order anything. Most pinball suppliers’ websites will allow you to search on these old Williams part numbers to find what you need. Not everything is available, but the consumable stuff generally is.


Once the assembly is back together on the bench, it’s a good idea to test it. If something is wrong, better to find out now, rather than inside the machine. I looked up the hand motor control schematics, and it says the motors run on 12VDC:

The manuals for these machines are amazeballs.


So I set up my bench supply for 12V, disconnected the encoder boards (to eliminate any risk of damage), and powered up each motor manually to check for smooth operation.

Be careful not to crash into the limit switches when doing this. With no computer controlling it, there’s nothing preventing you from running the assemblies outside their correct range. Twist them towards the middle of their range by hand first, then apply voltage both ways for a little while to make sure everything is good to go.


Once the assembly is back in the machine, it’s a good time to check the operation of the Ball In Hand switch. This is a leaf switch that sits inside the electromagnet, and detects when a ball has been caught. The solenoid that kicks the ball up into the hand may not do so perfectly, so the electromagnet needs to be very strong to ensure the ball gets drawn into the center of the hand. Driving the magnet at this high power for long would overheat it, so once the ball is caught, the computer duty-cycles it. Less power is needed to hold the ball once it is caught and under control. The ball-in-hand switch is what triggers the lower duty-cycle of the magnet.

This is another notorious failure point on this machine, and it’s the subject of yet another Williams Service Bulletin. A lot of people remove this switch entirely, based on a rumor that a code update for the machine eliminated the need for this switch. I’m unconvinced of that, particularly in the face of Williams SB 85, which details the importance of this switch and how to calibrate it.

The procedure for calibrating it is to hook up the wiring for the magnet, but disconnect it physically from the hand carriage. You then power up the machine, hold the magnet upside down in your hand, and place a pinball in it.


While in switch test mode for the Ball In Hand switch, roll the pinball around in the magnet. The switch should stay closed at all times. If it opens at any point, just from the weight of a pinball rolling around, it is out of adjustment.


If your Ball In Hand switch needs adjustment, as mine did, you need a leaf switch adjuster tool. Resist the urge to bend it by hand. You’ll introduce weird curvatures into the leaves that you will never be able to remove, and the switch will gradually perform worse and worse.

This is one of the few specialty tools genuinely needed to work on pinball machines. That little slot holds leaf switch leaves perfectly, allowing precise adjustments without introducing undesirable bends.


Once everything was reassembled, I ran through the solenoid tests to see if everything was okay wiring-wise. The cybermatrix was no longer lifting to unload balls. Rut Roh, Shaggy!

Here’s the culprit. Those nuts on that linkage are pivot points that form a lever. The solenoid pulls down, causing the lever to lift up on the metal frame, kicking out any balls sitting on the matrix. In my previous attempt to remove the cybermatrix, I had disconnected this linkage. When I reconnected it, I foolishly overtightened it, and the solenoid wasn’t strong enough to move it anymore. It’s a nylock nut, so it only needs to be tight enough to remove slop from the pivot point. You can test it by pushing down on the solenoid, as I’m doing here with my emo-black-painted thumbnail.


That’s all she wrote! So after all that, did I actually fix it?

Like a boss. Enough shop talk. Let’s play some goddam pinball.



4 thoughts on “Johnny – Cyberglove Rebuild

  1. I know in competition they disable the hand completely, it breaks the scoring really badly. JM is such a cool machine. The Matrix conversions of JM look really cool.

    Always nice to see a pin restored to full working order!

    1. Yah, I’ve also read that the Spinner Millions mode on this machine is basically like Double Jeopardy- it renders all previous scoring and gameplay pointless. I’m not sure if it’s possible to disable that in the settings (there are SO many settings!), but it could be a problem for tournament play. For casual play, fortunately, none of that matters too much. What’s great about this game is the ability to set your own goals- go for score, go for Powerdown, go for Gigabytes, there’s a number of ways to play it.

    1. ROFL- I wish I could say that one was intentional. But I’ll take credit for it anyway. 😉

Comments are closed.

Mini Cart 0

Your cart is empty.