Category Archives: Pinball

AC/DC Pinball Machine (Stern, 2012)

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Location: Denver, Colorado.
Symptoms: Ball getting stuck at ball flap.

From talking to people who buy brand new machines, it’s not uncommon to spend some time getting it to work right.  This was my second visit to this machine.

The first visit, which I don’t think I posted, involved replacing the canon motor, filing the bushings on the bell, and getting the lock-down bar to lock.  I guess there is not any quality assurance inspection after the pinball machine leaves the production line.  The things I fixed were very obvious problems.

This visit was for a problem that wasn’t very obvious.  The ball would occasionally get stuck at the ball flap in the upper right of the playfield. After unsuccessfully trying to get the ball stuck, I resorted to just using my fingers to discover there was an electrical wire hanging down that was catching on the ball. I couldn’t see the wire, but I could feel it.

I bent the wire out of the way and the everything seemed to work fine.

acdc-0480

Black Knight Pinball Machine (Williams, 1980)

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Location: Fairplay, Colorado (home of South Park).
Symptoms: Speech only, but no background sound; Multi-player bonus round not working; Some drop targets not resetting.

I tackled the sound problem first.  When I started the game the speech was working fine, but the background sound effects were not there.  I checked the connections to the speech board.  On this era of Williams machine, the analog sounds leave the main sound board and go to the adjacent speech board, where the analog sound and speech are mixed together.  Then the sound travels back to the main sound board for amplification and then to the speaker.

The connections were all good.  I disconnected the speech board and jumpered W1.  This will send the analog sounds directly to the amplifier, bypassing the speech board.  Still nothing.

With my oscilloscope, I could see the sound coming out of the digital to analog converter (IC13). From there it goes to a transistor (Q2) which acts as a current to voltage converter.  The transistor was acting like it wasn’t connected. I pulled it from the circuit and tested it with my meter and determined the transistor was bad (normally they short when failed, but this one was open).

D/A converter with Q2 transistor.

D/A converter with Q2 transistor.

I replaced the transistor, and for the first time in 5 years it made sound!

Next, I decided to check the drop targets.  A couple of the drop targets in the middle bank would pop up during reset, but would not stay there. This turned out to be a missing screw that held part of the assembly together.  I found the screw in the coin box and reinstalled it.

Next, I noticed problems with other switches in the matrix.  I removed the balls from the machine and ran the switch diagnostics.  It showed that switches 5, 13, 21, 29, 37, and 45 were all closed. They all share the same row (White/Green Row 5). so it looked like they were shorted to ground someplace.  To isolate whether the problem was in the machine wiring or with the driver board circuit, I unplugged 2J3.  The diagnostic still showed the switch row shorted to ground.  IC16 was bad.

The shorted switch row was the reason the multi-player bonus round was not working.  One of the switches in that row is the shooter lane, so the machine always thought there was already a ball there and wouldn’t deliver another to the shooter lane.

The switches all worked once IC16 was replaced.  Next I solved some minor connection issues with the flippers and G.I. lighting.  The Black Knight was ready for battle again!

 

Fairplay, CO, aka South Park. Cartman's face is missing.

Fairplay, CO, aka South Park. Cartman’s face is missing.

 

Flash Pinball Machine (Williams, 1979)

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Location: Erie, CO
Symptoms: Pinball machine “goes crazy” during play.

I played the machine and the “goes crazy” aspect seemed to be something related to the switch matrix.  I put the machine in Diagnostic Mode and checked the switch status. It seemed to be a row of switches was grounding out intermittently.  The switches would work fine then suddenly there were 4 or 5 stuck switches.

I found the problem at the coin door, with one of the coin switches shorting out against the coin mechanism.  The coin switch was looking pretty beat-up because the owner, or the previous owners, didn’t know how to put Flash into freeplay mode.

With these early solid state machines from Williams, you can put the game into freeplay mode by following these steps:

  1. In game over mode, open the coin door and switch the Up/Down switch to UP.
  2. Press the Advance button.  The Credit/Ball display should show “04 00”.
  3. Keep pressing Advance until the display shows “04 18”. This is the Maximum Credits setting.
  4. In the player 1 display you should see a current value of 20 (default).
  5. Switch the Up/Down switch to Down.
  6. Press the Game Start button (not the Advance button) until the number in the player 1 display is “00”
  7. Press the Advance button, then turn off the power.  When you switch the power back on, it will be in Freeplay mode.

After fixing the short, a few switches needed cleaning and adjusting.  The machine was working fine at this point.

About 2 weeks later, I was called back because the machine was skipping balls, for example going from Ball 1 to Ball 3.  I determined that there was a really sensitive switch on the playfield causing scoring without even shooting the ball.  That, combined with a mis-adjusted ball trough switch, was causing the problem.  The trough solenoid would fire the ball to the shooter lane, and the vibration would cause the sensitive playfield switch to close causing it to score, and the ball trough switch would still be closed because the ball hadn’t left the trough yet.  The machine “thought” the ball had been shot, scored and drained all in a split second, giving the appearance that the ball was skipped.

Once the switches were adjusted, the game was working fine again.

Superman Pinball Machine (Atari, 1979)

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Location: Westminster, CO
Symptoms: Wouldn’t boot, flipper not working, drop target reset short, + more

Atari made a hand full of pinball machines before they closed that division to focus solely on video games. Superman is one of two games made with the 2nd generation pinball system.

This machine had not worked for a long while while it sat in a basement.  The RAM batteries had leaked. The owner thought they probably hadn’t been replaced since the 1980’s. So the first task was to get that cleaned up and locate a remote battery pack off of the board.  (Unfortunately, the AnyPin NVRAM module will not work with Atari machines.)

Once I got it to boot, I discovered the left flipper didn’t work.  The flipper coil was badly damaged by something hitting it. A new coil was ordered.

The Atari system has a coil protection circuit that is supposed to shut down the coil power if it detects a shorted coil, in order to protect the drive transistors.  In this case there was a shorted transistor driving the drop target reset coil.  So basically every time another playfield coil was activated, the center drop targets would reset. I replaced the transistor it the coils started acting normally.  It was a bit confusing at first because unlike other pinball machines which use NPN transistors to drive the solenoids, these drive transistors are PNP.

Needless to say, with the lack of service on this machine, all of the rubber pieces were dry, cracking and brittle.  So I replaced all of the rubbers, about 20 burned out lamps, and cleaned the playfield.  The ball was also rusting, so I replaced that, too.

The target switches are hexagonal white, which nobody sells anymore. One of them is broken (and remains that way for now).  Perhaps I’ll run across one at some point, or maybe I’ll take a rectangular target and cut the corners off.

Aside from the target switch, it’s working great.  It’s the first time I played Superman and it seems like a fun game.

The owner let me borrow the complete set of schematics of this machine for scanning and will be available on the Internet Pinball Database (has not been approved as of this date).

Whirlwind Pinball Machine (Williams, 1990)

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Location: Highlands Ranch, CO.
Symptoms: Ramps tries to lower even though it’s already down; delivers two balls into shooter lane.

After checking the mechanical operation of the ramp and running switch tests, I concluded (or guessed) that the microswitches on the ramp and ball trough were acting intermittently.

Sometimes when a machine acts weird like this, you have to think about what the firmware is attempting to do.  In the case of the ramp, it tries to lower the ramp because it hasn’t sensed that it has been lowered.  So it would keep trying 4 or 5 times before giving up.

The reason the computer was delivering two balls to the shooter lane is that it wasn’t sensing the first ball had actually made it to the shooter lane, so it would try again.

Both of these problems weren’t consistent which led me to the intermittent switch idea. The microswitches were probably dirty and worn inside.  Unfortunately, since they are totally enclosed they can’t be easily cleaned.  Sometimes I can flush the switches out with contact cleaner, and get them working again.  In this case, it worked!

Gold Ball Pinball Machine (Bally, 1983)

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Location: Highlands Ranch, CO.
Symptoms: Wouldn’t boot, rubber rings crumbling.

This machine sat neglected prior to the current owner purchasing it.  Although the NiCad battery looked ok and looked like it had been replaced relatively recently, there was a lot of corrosion on the CPU board.  It was even affecting the RAM sockets, where I could see blue-green corrosion in the socket holes.  During the boot process, the LED would only flash a couple of times, indicating a RAM failure.

Normally I would try to fix something like this.  In this case, since there was an aftermarket CPU board available, I recommended the owner purchase the new board.  With the old board, I could fix one thing, only to learn something else was damaged by the corrosion.  It turned out I was correct, except the corrosion had spread to the sound board, which sits right below the battery.  It had damaged the sockets there as well.

I was able to get the sound board working with some cleaning.

The rubber rings and burned out bulbs were replaced, and the playfield cleaned as well.

Tee’d Off Pinball Machine (Gottlieb, 1993)

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Location: Cheyenne, WY
Symptoms: Flipper problem, Spinner problem

It seems like every Gottlieb – Premier pinball machine I work on has over-fused flippers.  The fuse should be 2.5 amps and in this machine there were 5 amp fuses installed.  When the flipper link broke, it caused the flipper arm to not engage the End-Of-Stroke switch, which caused the coil to melt.  Had the correct fuse been installed, the coil would have been saved.

I replaced the coil, the fuse and the broken link and everything is fine with the flipper.

The other problem, and I’ve seen this on a Monte Carlo pinball machine (which is the same vintage) is that the switches on the center spinner don’t work.  In this case, the spinner wasn’t spinning very fast either.  I cleaned and oiled the wiper contacts and the gears.  I checked every hole in the spinner and verified that each switch was working.

Funhouse Pinball Machine (Williams, 1990)

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Location: Up Poudre Canyon, west of Fort Collins, Colorado.
Symptoms: Needed to be “shopped” (basic restoration).

This pinball machines gets the award for the worst leaking batteries I’ve ever encountered.

Forgotten batteries causing a lot of damage.

Forgotten batteries causing a lot of damage.  Click for larger.

The corrosion was so bad that the battery holder nearly fell off the board when I started cleaning it up.  The corrosion had eaten through the metal pins that hold the battery holder to the board.  As you can see from the photo above, the corrosion was also affecting the nearby circuitry.

I finished removing the battery holder from the board and flushed the board with white vinegar and scrubbed with a toothbrush.  The vinegar helps to neutralize the alkaline. After letting the board dry out for several hours, it still was able to boot up.  I installed a remotely mounted battery holder on the inside of the backbox, where if the batteries leak in the future, it won’t damage anything.

I “shopped” the rest of the machine, replacing rubbers, cleaning the playfield, and replaced the bad bulbs.  The machine is working great and looking great.  I’ve now worked on more Funhouse pinball machines than any other model, breaking the previous record held by Star Trek: The Next Generation.

 

No Fear: Dangerous Sports Pinball Machine (Williams, 1995)

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Location: Castle Rock, CO.
Symptoms: Needed to be “shopped” (basic restoration).

The biggest problem that this machine had, which I’ve come across a lot lately, is forgotten batteries.

Batteries dated 2006 badly leaking and damaging the battery holder and switch connector (not shown).

Batteries dated 2006 badly leaking and damaging the battery holder and switch connector (not shown).

Fortunately, on the WPC-95 systems, the batteries are mounted on a separate piggy-backed board which saved the CPU board from certain death.  But even so, the alkaline affected the cabinet switch connector located right next to the batteries.

The battery holder was removed and the RAM chip at U8 replaced with an anyPin NVRAM module that doesn’t require batteries.

The playfield was cleaned, all of the rubber parts were replaced, as well as the slingshot plastics.  The machine is looking good and playing well.

Terminator 2: Judgement Day Pinball Machine (Williams, 1991)

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Location: Castle Rock, Colorado.
Symptoms: Machine needed to be “shopped” (basic restoration).

The owner had just purchased the pinball machine from an acquaintance. The playfield was one of the dirtiest I have ever come across.  Fortunately, with a lot of elbow grease, Novus 2 polish and some Mill Wax, I was able to get the playfield looking pretty good.

To clean the playfield and replace all of the rubber parts, the ramps had to be removed, then replaced.  This is time consuming, but was worth doing.

I installed a new flying hunter killer ship kit for the playfield, since it was missing.

The pinballs were replaced with new ones because the existing ones were badly pitted.  The main reason the balls were badly pitted was that the left side kickback was badly damaged. Each time it would fire, it would slam, metal to metal, against the ball, making small pits in it.  The metal that was on the ball would come off and wear into the playfield.

Damaged kicker on left, new kicker on right.

Damaged kicker on left, new kicker on right.

By the looks of it, this kicker had been broken for years. Never allow any device that comes in contact with the ball to go un-repaired.  The playfield is the most valuable asset in a pinball machine and pitted balls will shorten its life.

The switch on the cannon was intermittently bad.  Usually it’s the wires that have broken after the cannon has twisted them back and forth thousands of times.  But in this case, it was the switch itself.  It was replaced.

It goes without saying that any burned out bulbs were replaced.

By the end, the pinball was playing well and looked great.  Some of the mylar on the playfield is bubbling and that will have to be addressed at some point in the future. The biggest problem with removing it will be that the decals on the playfield inserts will not survive the process and I haven’t seen any decal sets for this machine.