Category Archives: Pinball

Flip Flop, Bally Pinball Machine (1976)

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Symptom: Not resetting, only adds players with start button.
Location: Littleton, CO

I’m always very happy when I solve a problem with a pinball machine that its had since it left the factory. This pinball machine would not reset when the start button was pressed. Instead it would add players. I was able to trace the problem to the #8 Cam-stack of switches on the score motor (the 8E normally closed contact to the reset relay coil).  There I found two wires on two leaf switch terminals that had never been soldered.  The wires were folded over the terminal, ready for soldering, but someone on the Bally production line must have gotten distracted. The wires were making a good enough connection for the machine to pass testing and shipped out to the first customer.  It’s unknown how many owners this machine has had over the past 40+ years, but I bet it was having this intermittent problem throughout its life.

I’ve probably come across a half dozen machines that have left the factory with issues. So far the machines have been in above average physical shape because they got pulled out of public service earlier due to their intermittent issues and sold to private individuals.  A few years ago I worked on a Gottlieb Circus that left the factory with a bad crimp pin connection in one of the connectors. The machine was immaculate.

Intermittent issues are very difficult to find, especially if the machine starts working correctly the moment I start tracing the problem. In this case I was lucky and the machine stayed dead until I found the problem.

Transformers, The Pin (Stern, 2012)

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Symptom: Would not power up
Location: Firestone, CO

This is a home model pinball machine.  There is currently very little (none?) technical information about this pinball machine. It uses the Stern Spike system, which is used in some other professional machines and one other home machine (Avengers). I was unable to find any schematics for this machine or the individual boards. (I’ve read that Stern will be releasing some documentation in the near future.)

The machine would not power up. There is a 48 VDC power supply mounted inside the cabinet (you have to remove the bottom of the pinball machine to gain access to it). The 48 volts was working.

On the Spike MPU/Sound board (which is in the backbox), there are 4 LEDs to indicate the status of +48V, +24V, +8V, and +5V.  In this case the 5V LED was not lit. I found that D12 was shorted. Once D12 was removed from the board, I checked that D12 was truly shorted and it was. I also checked the pads where D12 was located, and it was still shorted there as well. This meant that the A8498 regulator chip (U30) was also bad. Once both components were replaced, I bench tested the board and all of the power status LEDs came on.

(Note: if the 5V is working, the +24V and +8V LEDs will only come on once the microprocessor has booted.  If the 5V is not working, then they will light regardless of the microprocessor.)

Stern Spike MPU board, 520-5318-01, from Transformers

The following is a more detailed look at the power section for other repair people who have the expertise to repair surface mount boards.This only covers the power sections and not any other functions such as sound, the microprocessor, or the interface circuitry.

The 48 volts from the cabinet feeds the 24 volt, 8 volt, and the 5 volt regulator sections. Each of the regulator sections utilize an Allegro A8498 chip, which is a 3 amp switching step down regulator. The enable pin (pin 2) for the 24 volt and the 8 volt sections are connected elsewhere on the board.  If the enable pin is not 0 volts, the regulator will be disabled (turned off). The enable pin for the 5 volt section appears to be grounded so that it’s always enabled.

Each regulator section consists of the A8498 (Allegro A8498SLJTR-T), a 68uH inductor, a 60V, 5 amp Schottky diode (Comchip CDBC560-G), and some input and output filtering capacitors (470uF at various voltages).  Near each regulator is a test pad where the voltage can be checked.  The 5 volt test pad is near the reset button. Note that the A8498 has a thermal pad underneath the chip which is soldered to the board. Only a hot air rework station will remove this chip.

Each regulator section consists of the following components. Refer to the A8498 data sheet for details on how things are connected together.

5 volt section: U30, D12, L8, C132, C135, C133, C134, R106, R107, R108.

8 volt section: U10, D4, L6, C55, C56, C59, C60, R24, R23, R25

24 volt section: U6, D1, L5, C47, C48, C49, C50, R125, R16, R18

The output of the 5 volt regulator goes on to power three other regulators: 3.3V (U9), 1.8V (U31) and 1.0V (U32). These regulators are Rohm BD18KA5W, BD18KA5W and BD10KA5W respectively. There are no LED status indicators associated with these regulators, however there are test pads near each one to check voltages.

Transporter the Rescue, Pinball Machine (Bally, 1989)

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Symptom: Machine is not working at all
Location: Greenwood Village, Colorado

The first problem the machine had were the batteries had been forgotten about. So the battery holder was replaced and new batteries were installed. All too common a problem.

While replacing the batteries, I noticed some burned circuitry.

Burned circuit in one of the pop bumper driver circuits

The burned driver circuitry was related to the lower pop bumper. Whenever I see this kind of damage, I always check the fuses.  Sure enough someone installed a 7 amp fuse where it should only be a 2 amp fuse.

Some of the fuses in an Williams System 11 pinball machine.

Out of the 6 fuses shown above, 3 were incorrect values, all higher than what they should have been.

The fuses are meant to protect against this kind of damage. Often in the history of a pinball machine, someone will replace a fuse with a higher rated fuse to keep it from blowing again without every investigating why the fuse blew in the first place. I’m not really sure why people do this. So instead of just simply having a blown transistor, the circuit board got damage and the pre-driver transistor, 7402 chip, and the coil were all damaged and had to be replaced. The 7 amp fuse never blew to protect the circuits.  Instead the transistor caught fire and burned until it acted as its own fuse and the circuit eventually opened.

The actual cause was the switch contacts on the pop bumper being adjusted too close together. Causing the pop bumper to energize continuously.

This wasn’t my customer’s fault. The blame probably goes to the operator who first purchased the pinball machine and placed in a public location to make money. A fuse or two probably blew and to keep the machine making money, installed larger fuses. Then eventually the pinball machine ends up in a home environment with the wrong fuses installed.

 

The Lost World Jurassic Park Pinball Machine (Sega,1997)

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Symptom: Snagger releasing ball too early, or not lowering enough to grab ball.
Location: Lakewood, Colorado

The snagger mechanism on a Lost World pinball machine uses both optos and microswitches to determine the ends of travel.  Or more accurately, the microswitches are wired in series with the motor to cut-off the power when at one end or the other. The game MPU has no knowledge that this has occurred. The MPU instead uses the optos to determine when it is at one end or the other. So the microswitches are acting as safety switches to stop the motor if the optos fail or are unplugged, etc. The game code also has a timer to flag an error and disable the snagger if it doesn’t reach one end or the other in the allotted time.  When using the special test function in the Diag->Lost menu, the display will show the status of the optos, but relies on the switches to stop the motor at one end or the other. But during game play, the optos are used. So adjusting the switch levers had no effect.

Over time, the gears and belts develop mechanical play or slop. The original designer never accounted for this. The only adjustment is the center of travel, basically the flag that interrupt the optos. This can be loosened, rotated, and re-tightened on the motor shaft.  One could also loosen one of the pulley screws and accomplish the same thing. But this only adjusts the center of travel. If I adjusted it so that the ball would release and fall into the Jeep properly, the snagger wouldn’t lower far enough at the other end to grab the ball. If I adjusted it to grab the ball properly, it wouldn’t raise far enough and the ball would release on the edge of the Jeep and just sit there.

The largest source of play is the cam on the left side of the last hinge of the snagger.  As of this writing, Marco Specialties sells the shaft and the end housing of the snagger.  I wasn’t able to remove the last pulley due to damage of the set screw, so replacing it wasn’t an option.

What is really needed is a way to move one of the optos so that the motor runs a little bit longer to account for the slack in the mechanics.

I removed one of the optos and with a very small Dremel bit, created slightly curved slots for the opto leads in the circuit board. This would allow for the opto to be adjusted.

Showing new position of opto before final adjustment in the machine.

Added wires to leads to allow for movement

After determining the ideal position for the opto and adjusting the center travel (as mentioned above), I put a little drop of hot-glue on the top side of the board at the end of the opto to hold it in place.

The snagger now works perfectly.  Not the prettiest solution, but sometimes things need a slight design tweak. If there were more Lost World machines out there, I’d design an aftermarket board that would make this a lot easier.

Wizard of Oz Pinball Machine, Jersey Jack (2014)

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Symptom: Version 2.0 LED Board replacement project
Location: Parker, CO and Highlands Ranch, CO

[This post has been updated to reflect the 2.0 Light Upgrade Kit shipping in the Fall of 2019.  The kit contains improved instructions along with a check-off sheet to make sure your kit is not missing anything.]

The Wizard of Oz (WOZ) pinball machine was state of the art back in 2013/2014.  There were many things about it I admired, and the biggest standout was RGB LEDs used everywhere, including the lowly general illumination. Previously pinball machines had fixed colors for their lights.  On this machine every LED can be individually controlled to be any color.

However, with time, the lighting system has proven to be problematic and there were several attempts during production at making it more reliable. It’s a situation that didn’t become apparent until machines were built and out in the real world. Many people suspect the problem is static electricity building up and damaging the LED driver chips. All of the LED boards are in a serial chain, and if one of the boards in the chain fails, every LED downstream will no longer work correctly.  Often when the lights are malfunctioning, it can be traced to a single board that has failed. The bad board can be bypassed by moving cables and updating the settings to let the software know a board has been bypassed. If a replacement board is available, the bad board can be replaced. If a replacement is not available, you’d have to wait until JJP decides to make more, or upgrade to the 2.0 system.

There are now 4 generations or versions of light systems for this pinball machine. The first three are all controlled with the serially connected signals as mentioned above.

  • The original system used in machines built prior to September, 2014, is often referred to as “5 volt unbuffered”.  This is the least reliable system.
  • There is a later system referred to as “5 volt buffered”, where the serial control signals are buffered with a driver chip.  I was told by a person who works at Jersey Jack Pinball that this is the most reliable of the serial systems.
  • There is another referred to as “7.5 volt”, which uses a 7.5 volt power supply rather than 5 volt. The serial control signals are also buffered.
  • And finally there is the “Version 2.0” system, which uses an entirely different LED control scheme and is the system used on newly-built Wizard of Oz machines, as well as The Hobbit and Dialed-In.

What follows are some tips to anyone who is upgrading to the 2.0 system.

It’s not a trivial task to do the upgrade. In a nutshell, you’re replacing every LED board (there are 48) and the associated wiring. Most of the boards will need new mounting holes drilled and use different screws than the original boards. This includes removing the two mini-playfields and replacing the boards used on them. Depending on your experience, mechanical aptitude and patience, you should be able to do the upgrade in 8-12 hours.

There were 29 pages of printed instructions provided with the kit. This includes a listing of all parts in the kit and a photo of each part, which is a great improvement over the earlier kits. It’s very important to inventory the contents of the kit.  It will familiarize you with the parts and you can take care of any shortages before starting the project.

Unfortunately, as of this writing, they still don’t provide L brackets for mounting the new power supply to the cabinet and you will have to go to a hardware store to purchase them.  You’ll also need some M4 x 6 machine screws to mount the L brackets to the power supply. In the past I’ve used 1″ brackets and it’s possible 3/4″ brackets will work.

Personally, I like to do steps 9 (installing brackets onto light boards), 15 (installing BAG controller to bracket) and the first part of 17 (attaching cables to the power supply) beforehand.  Hold off on the last part of step 17 (mounting the power supply) until you get to it because you’ll be using screws leftover from earlier steps.

Diagram of positions of light boards next to playfield.

Another personal preference I have is to print two copies of the light board placement from page E20 of the WOZ manual on 11×17 sheets of paper and tape them up on both sides of the backbox.  It is important when installing the new smaller boards, to put them in the orientation as shown or else the cables may not be long enough to reach them. Plus it is handy because each light board is referenced by a number in the blue circle.

The most time-consuming aspect of this project is each GI or single RGB LED board has different mounting holes than the original boards.  There are about 38 of these total, which translates into positioning, marking and drilling pilot holes for the new mounting screws on all three playfields.

This is optional for the user who is only doing this upgrade one time: I used two mini rechargeable drills; one to drill holes, the other to drive the screws.  This is easier than constantly changing bits.  I used an extender for drilling due to having to drill around wiring harnesses and playfield support rails. For the screws you will need a #1 Phillips bit, which are not as commonly available as the number #2. Also when driving screws, set the clutch to the lowest setting to avoid damaging the screw heads or stripping the hole.

Drill with bit extension to reach tight areas.

In step 4, place a piece of tape on the end of the cable and label it with “Step 26”.  It will need to be re-routed over to the W7 board in the lower left. By placing a label on it, you’ll be able to find it later and not to forget it.

Another personal preference is to do the mini-playfields (steps 24 and 25) before step 17, and get all of the light boards installed before diving into the cabinet and routing all of the new cabling.  Just be sure to check off each step so that you don’t leave anything out.

Other than the tips above, just follow the steps provided with the upgrade kit and eventually you’ll be finished.

 

Revenge From Mars Pinball Machine (Williams, 1999)

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Symptom: Would not boot up.  Machine appeared dead.
Location: Littleton, Colorado.

Revenge From Mars is one of two pinball machines using the Pinball 2000 platform, which combines pinball and video. A video image is projected down onto a special playfield glass which merges video action with pinball.

The pinball machine is controlled by a customized personal computer platform. The machine uses a CRT for the video projection. Both the PC and CRT have many failure points.  Parts to repair the PC are scarce, as are people who can repair CRT monitors.

This particular pinball machine had been upgraded to an LCD monitor and a modern PC.  The PC was running software provided by Nucore, which allows the custom Pinball 2000 system to be emulated on commonly available PC hardware.

Pinball 2000 Nucore system

After checking some voltages, it appeared power was going into the PC, but nothing was happening beyond that point. So I ordered a new power supply and installed it, and it was still dead. I was expecting to have to replace the PC motherboard.  As a last ditch effort, I decided to check the CMOS memory battery. The battery was dead, but I had never encountered a PC that wouldn’t power up due to a dead battery.  I replaced the battery and surprisingly it powered up.  Most PCs will still power-up with a dead battery, but you get a message from the BIOS saying there is a problem with the CMOS (or NVRAM), and it often hangs before booting the operating system.

Coin battery for CMOS RAM

The motherboard is a Foxconn A6VMX series.

Once the PC was powered up, I had to go through several settings in the BIOS and change their default values:

Power State: Power ON
Halt On: All Errors But…
Keyboard: Enabled
Mouse: Enabled
Floppy: Enabled

Under Peripherals:
The parallel port mode should be EPP
Address: 378

The above settings will allow the system to start as soon as power is applied, and will skip checking if the keyboard, mouse and floppy are present.

Once the system was booting up, I discovered a number of switches and lights not working.  I replaced a couple of switches that were broken and adjusted the ones that weren’t working. For the lights, every one of the light boards had cracked solder joints at the input connector, which often resulted in the entire board not working. This is a common problem on most late model Williams machines using circuit board mounted 555 bulbs.

Footnote

There has been some legal drama surrounding Pinball 2000 emulation systems.  Nucore developed the system, but were found violating the GPL open source license. At around the same time someone removed the copy protection and distributed the Nucore software for free as Pinbox.  Nucore and Pinbox are the same thing. Nucore is back with an updated version, but currently without the licensing to make copies of the original pinball 2000 ROMS, which are required to run the emulation.

Moving a Pinball Machine?

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One of the questions I get asked the most is how to pack up a pinball machine for moving. There are several different approaches, depending on whether the head (backbox) folds down with a hinge or not. Generally, pinball machines made after the mid-1980’s have a hinged backbox.

Hinged Backbox (machines newer than mid-1980s)

  1. Remove all loose items from inside the machine such as the ball(s), coin box, manuals, everything!  Some machines have an option in the test menu to eject all balls from the machine.
  2. Open up the backbox and remove any large bolts holding the backbox to the neck of the cabinet.  Some of these bolts might look like a large wing-nut.
  3. Close up the backbox.  Make sure the inner door is closed and latched tightly, so it doesn’t rub on the backglass.
  4. Unlatch the backbox.  On a Bally/Williams machine, this might look like a suitcase latch.  On Data East/Sega/Stern, you will need to insert a large Allen wrench into the hole on the back and rotate it.
  5. Carefully pull the backbox towards the front of the game, while ensuring the cabling between the lower cabinet and the backbox is not getting hung up on anything.  There should be enough slack in the cables to allow the backbox to rest on top of the playfield portion of the lower cabinet.
  6. Note where the backbox is being supported by the lower cabinet. Place some cardboard, Styrofoam, towels, or other padding material in between to keep both the lower cabinet and the backbox from damaging each other.  This is usually at the very top of the backbox and the edges of the lower cabinet. Do not lay any packing material that would put pressure on the backglass.
  7. With straps, rope, or plastic stretch-wrap, tie or wrap the backbox to the lower cabinet so that the backbox can’t be lifted off of the cabinet.
  8. Place a chair or your knee under the rear of the lower cabinet and remove the rear legs, by removing both bolts in each leg.
  9. Lower the rear of the cabinet to the floor and then stand the pinball up on end so the coin door is facing up.
  10. Remove the front legs by removing both bolts in each leg.
  11. Keeps all of the bolts, balls, etc., in a safe place so they don’t get lost.
  12. With the machine on end, a dolly/hand-truck can be used to move the machine.

To reassemble the pinball machine, just reverse the process.

If you are shipping the pinball machine to another location, Contact NAVL (North American Van Lines) as they seem to have quite a bit of experience shipping pinball machines.

Detachable Backbox (machines older than mid-1980s)

  1. Remove all loose items from inside the machine such as the ball(s), coin box, manuals, everything!
  2. Open up the backbox. Label and disconnect the electrical connectors between the backbox and the rest of the machine.  On an EM machine there will be 2 or 3 large connectors.  On a solid state machine, you will either have to disconnect the plugs from the circuit boards (Bally), or there may be in-line connectors in the neck of the cabinet (Williams and some Gottlieb) that will need to be pulled apart.  You may leave connections that just go from one part of the backbox to another.
  3. Remove the 2-4 large bolts holding the backbox to the neck of the cabinet.
  4. Close up the backbox.  If you have a solid state machine, make sure the inner door is closed and latched tightly so it doesn’t rub on the backglass.
  5. Lift backbox from the lower cabinet.
  6. The power cord can be carefully stuffed down into the neck of the machine.
  7. Place a chair or your knee under the rear of the lower cabinet and remove the rear legs, by removing both bolts in each leg.
  8. Lower the rear of the cabinet to the floor and then stand the pinball up on end so the coin door is facing up.
  9. Remove the front legs by removing both bolts in each leg.
  10. Keeps all of the bolts, balls, etc., in a safe place so they don’t get lost.
  11. With the machine on end, a dolly/hand-truck can be used to move the machine.

To reassemble, simply reverse the procedure.  Take care to put the power cord back into the notch (this varies from machine to machine) before setting the backbox back onto the cabinet. Also take care in reconnecting the connectors to their original locations.

Note: Some people like to treat detachable backbox machines as they would a hinged backbox, by leaving everything connected, laying the backbox facedown on the lower cabinet, and securely wrapping or tying the backbox to the lower cabinet, as if it had a hinge.  But you need to make sure the backbox doesn’t move at all, so that it doesn’t pull on the wires (plastic stretch wrap would be best for this). This might be desirable if you are shipping a machine. But if you are moving a machine, it might be easier to move it as two pieces.

 

F-14 Tomcat Pinball Machine (Williams, 1987)

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On F-14 Tomcat pinball machines, there is a light board mounted on the right side of the back wall of the playfield.  This light board holds the 6 flashers that are under the red (or white) domes.  Almost every F-14 Tomcat pinball machine I’ve worked on has had a damaged light board.

Original F-14 Tomcat light board with broken sockets.

Original F-14 light board, with damaged circuit board traces and someone’s attempt at fixing them.

The Williams part number for the circuit board is 5768-12151-00.

After searching around for an after-market replacement, and not finding one, I decided to design and make a new one.

New replacement board by Peak Pinball at the bottom.

The new board features #906 wedge type sockets with “L” brackets for support, beefier circuit board traces, repositioned connector and LED type flasher bulbs. I installed the new board into my customer’s machine and it worked perfectly.

(I no longer have have boards for sale.  I currently don’t have plans to manufacture more boards because there isn’t enough interest.)

Space Mission Pinball Machine (Williams, 1976)

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Symptoms: 50 or 5000 points repeatedly scoring.
Locations: Denver and Fort Collins

I’ve worked on several Space Mission pinball machines over the past 3-4 years. One problem they’ve had in common is the sometimes the 50 or 5000 point relays will get stuck and stay engaged.  The problem would often go away when I raised the playfield, making it very difficult to diagnose.

The 50 and 5000 point relays are mounted on the underside of the playfield in the upper left corner (lower left when playfield is raised and viewed from the underside).

The problem is the main wiring harness which comes onto the playfield on the right side shorts against the bracket holding one of the stepper units. Over the years repeatedly raising and lowering the playfield causes the edge of stepper bracket to wear through the insulation on some of the wires in the main harness.  The stepper bracket has voltage on it via the main Yellow power supply wire. This creates an intermittent short between the Yellow supply wire and whatever wire(s) on the outside of the harness which happen to have their insulation compromised.

The symptoms are variable with the most common problem being the 50 and 5000 point relays staying on.  But I’ve seen other symptoms including hitting the center target when the 5000 point lamp is lit and not scoring and not scoring bonus points at the end of the ball. One machine had 3 wires that were occasionally shorting against the bracket which caused constantly changing symptoms, most of which would go away when the playfield was raised.

The fix is to remove the stepper unit near where the harness attaches to the playfield and then remove the screws holding the harness clamps. Wrap the harness with several layers of electrical tape near where the bracket is. Then reattach the clamps and the stepper unit.

I will try to remember to take some photos next time I work on a Space Mission and update this post. Often the last thing I’m thinking about when I’m at a customer’s working on their machine is taking photos of what I’m doing. A picture is worth a 1000 words.

 

Junk Yard Pinball Machine (Williams, 1996)

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Symptom: Randomly kicks out balls into shooter lane.
Location: Arvada, CO

When playing the machine, occasionally a ball would be kicked up from the ball trough and then launched into play.  This would happen mostly during multiball when an additional ball wasn’t supposed to be launched, but I witnessed it once during single ball play.

There are a couple of automatic functions working regardless of the state of the game. The first is when the Trough Eject opto is blocked (switch 31 on the matrix), the machine software will kick up another ball from the trough. The second is when a ball is sensed in the shooter lane, and it’s not the initial ball of the turn, the ball is auto-launched into the playfield. So, a false signal on the Trough Eject opto during play will cause a ball to be kicked up from the trough and launched into the playfield.

After checking that the optos were functioning properly and reflowing some solder joints, the problem still existed.

After playing the machine some more, the owner discovered it was related to the flippers.  Intense flipper use would cause a ball to be ejected and launched.  This also explained why the problem was more prevalent during multiball, because the flippers were being used a lot more.  This is very similar to the WPC flipper reset problem, but instead of reseting the machine, it would kick out another ball.

We were able to verify this in the Switch Edges test. Hitting both flippers at the same time would cause the column of optos, switches 31-37, to momentarily go away (with no balls in the machine).  At this point, the problem was easy to reproduce.

Power portion of 16-Opto Switch Board Assembly

The signals for the optos are processed by the 16-opto Switch Board Assembly (A-16998). The board is powered by the unregulated +12V supply circuit from the Power Driver Board. The oscilloscope revealed that the +12V power was dipping during heavy flipper use. This was expected since it’s not regulated. However, on the Opto Switch Board, there is a diode (D19) and a filter capacitor (C6) to filter out transients and dips in the supply voltage.

The important part of the circuit is the Vref (reference voltage) generated by R52, 100K and R31, 22K. This signal shouldn’t have a lot of variation or electrical noise. But the oscilloscope revealed it did.  My first choice would have been to replace C6, but I didn’t have a suitable replacement with me. But since Vref is the most important, I added a 22uF capacitor across R31, the 22K resistor.  This fixed the problem.

This same circuitry is used on the 12-Opto Switch Board and the 10-Opto Switch board (and probably others) used in other Williams pinball machines of this era. The component designators are different on the other boards, so look at the schematic for the matching circuit as shown above. Look for the power coming into the board and going to a diode.  If you’re having this problem, replace the main capacitor (C6 in the diagram above) and if that doesn’t help, add a 22uF capacitor across the 22K resistor.