Category Archives: Repairs

Bram Stoker’s Dracula Pinball Machine (Williams 1993)

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Location: Broomfield, Colorado.
Symptom: Error message indicating several switch rows shorted to ground.

The owner had checked the playfield and the coin door wiring, looking for any obvious shorts.  None were found.  I suspected there was a problem on the MPU board, where all of the columns and rows of the switch matrix connect.

Lower portion of the Williams MPU board (click for larger), U20 is just left of center. Note battery holder above it.

I disconnected all of the switch connectors from the MPU. With the pinball machine in the Switch Edges test routine, I took a couple of jumper leads and a diode and connected a Row 1 with Column 1.  Instead of seeing a single switch closure, the entire Row 1 lit up as being closed.  I repeated with a few of the other rows and got the same result.  This pointed to the column driver chip U20 (ULN2804).

To be sure, I checked the column outputs with my oscilloscope. Instead of seeing a signal pulsing from 12 volts to ground, I saw a signal pulsing from about 2 volts to ground.  I checked that there was 12 volts on the pullup resistors to make sure the PCB wasn’t damaged from leaky RAM batteries.  The 12 volts on the pullup resistor was fine.  I then checked the input to U20 to make sure the upstream chip was functioning correctly.

I replaced U20 with a socket because this is a common problem with these Williams MPU boards.  I then placed a new ULN2804 into the socket.  The board was retested in the machine and everything was fine.

Fast Draw, Gottlieb pinball machine

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Location: Boulder, Colorado.
Symptoms: Pinball machine wouldn’t reset.

A machine not resetting is the most common problem with an electromechanical pinball machine.  In a way, it’s like a self-test, because a lot of things have to be working for the machine to reset.  The reset sequence is like a series of dominoes, one item affects the next item and so on.  If one item fails to reset, then the sequence is either halted, or more likely, gets stuck in a continuous reset cycle.

This Fast Draw had been not working for nearly 12 years.  And typically with an EM machine that hasn’t been used for years, it usually needs some contact cleaning, contact adjustment, and the steppers rebuilt.  This particular machine also had a broken wire associated with the reset relay.

 

Rockola 460 Jukebox

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Location: Castle Pines, Colorado
Symptom: At the end of record play, the gripper arm would start to return the record to the magazine without actually gripping the record.

This one stumped me for a while.  If I turned off the gripper motor and turned it by hand, the gripper arm worked just fine.  But if I energized the motor and ran it at normal speed, the gripper arm would miss the record, leaving it on the turntable.

It turned out to be a lubrication issue.  The old oil/grease was just gummy enough work fine at hand speed, but not work at normal speed.  There are two gears, side by side, with one gear mounted on the shaft of the other.  See 12 and 13 below.  Oiling between the two gears and getting some oil down on the shaft fixed the problem.

The cooler temperatures of winter seem to cause a lot of problems with both jukeboxes and pinball machines.  Although pinball machines don’t use as much lube as jukeboxes, in both cases old gummy lubrication gets more gummy in cooler temperatures.

 

Gripper Arm Assembly. Click for larger.

 

Cadette (CMM4), AMI/Rowe Jukebox (1970)

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Location: Denver, Colorado
Symptoms: Wouldn’t make correct selections, if any.  Right channel sound was fuzzy.

I wasn’t able to obtain a service manual for the CMM4.  The closest thing available was a CMM1 manual, which ended up being of no help.  There were quite a few electrical differences in the mechanism, like different cam switches (CMM1 has 8 cam switches, CMM4 has 5 cam switches).  Also, the CMM4 has a tube amp and the CMM1 has a solid state amp.

The “write” side of the selector plate was working well.  The “read” side scanner would usually jump right over the selector pin, unless it was actuated by a pin on the outer ring. The pin reset solenoid wasn’t actuating.  Long story short, it turned out to be a bad stop switch.  The switch was reading many thousands of ohms when it should have been zero.  I drilled a hole into the side of the microswitch to try chemically cleaning it.  It helped bring the resistance down to about 180 ohms, but that’s was not good enough.  I found a compatible switch in my pinball parts and replaced it.  The jukebox made the correct selections after that.

The amplifier had a tube that looked bad.  Looking at it more closely, it had a crack in the glass at the base.  It was a 12AX7.  We used the tube from the left channel and the right channel started working.  The owner had a spare 12AX7 from a guitar amp that we used to get the amp fully working.

I also looked at the owner’s AMI G-120. It had a few minor problems that I was able to fix with some cleaning, adjustment and lubrication.

Moulin Rouge, Williams Pinball Machine (1965)

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Location: Aspen, Colorado.
Symptoms: A variety of things not working.

The Williams Moulin Rouge is an electro-mechanical (EM) pinball machine from the mid-1960’s.  The owner has owned this game for over 30 years.  However, the game hasn’t been used in over 8 years.

When I first opened the machine, I saw some disconnected wires dangling from the playfield.  These were associated with the left flipper.  I re-soldered these wires to their respective places.

In the backbox, there were a couple of steppers that were sticky and needed to be cleaned.  The ball count stepper and the match stepper.  Even if a pinball machine has been set for free-play, the match stepper is important to have working.  The match stepper is used continuously throughout a game and is triggered by various switches in the playfield.  In this case, it controls various playfield features that alternately illuminate.

The machine wouldn’t power up due to a broken in-line switch that had been placed on the line cord.  I replaced the line cord, which had been previously spliced and installed a better quality switch.  Originally these games didn’t have power switches.  To turn the game off, you kick the bottom of the machine, which trips a “kick-off” switch.  To turn the game on, you press the left flipper button.  Kicking the bottom of the machine is awkward, so I prefer an in-line cord switch.

Once the machine was powered up, it was in continuous reset mode.  This is not unexpected with an EM game that hasn’t been used for a while.  A game will get stuck in reset mode when something isn’t detected as being reset.  In this case, the score reels were not being reset.  They were sticky and not turning freely.  Also, there was a dirty contact that was preventing the “100” digit to not get the reset pulses.  Once the score reels were fixed up, the game would reset.

The next thing I noticed was that the outhole wouldn’t register a ball after the first ball. Therefore it wouldn’t give an end of ball score, wouldn’t advance the ball count stepper, and therefore wouldn’t eject the ball to the shooter lane.  After checking the schematic to see what else was in that circuit and manually tripping the outhole relay, I noticed the scoring motor wasn’t indexing to its home position after either a trigger of the outhole relay or the eject relay. It turned out to be a couple of dirty contacts on the score motor bank that were supposed to keep the score motor running until it was indexed.

Next up, there were many lamps not working.  This wasn’t because the bulbs were burned out, but because the sockets and the lamp bases had corrosion on them.

Next up, the right slingshot wasn’t working correctly.  As the slingshot arm would kick the ball, it would get hung up on the playfield plastic over it.  The plastic was warped. I placed washers under the plastic to raise it up high enough so it wouldn’t interfere with the slingshot.

I replaced all of the rubber pieces on the playfield.

The left flipper needed a new bushing and was missing its torsional return spring.  The right bushing was okay, but both will be replaced on a future visit.

All in all, this was pretty typical work for a pinball machine of this vintage and the years of non-use.  People always ask me for estimates on this kind of work.  It’s very difficult because you have to start fixing things to see what else doesn’t work.  But it’s almost always in the 3-6 hour range.

Wurlitzer “One More Time” 1015-CD jukebox

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Location: Soda Fountain, Lyons, CO

Symptom: Arm that holds CD on spindle wouldn’t release properly causing CD to fling against the back of the cabinet.

I don’t normally work on CD jukeboxes, but I made an exception because Lyon’s Classic Pinball is located across the street and that would give me an excuse to go over and play some of Kevin’s 35 pinball machines from the 1960’s through present day.

Sometime after Wurlitzer stopped making jukeboxes in 1974, the remaining Wurlitzer company in Germany began making some nostalgic jukeboxes with modern CD players. In the past I’ve worked on the original 1015 from 1946 that plays 78 RPM records, so this was interesting.

I spent some time familiarizing myself with the mechanism.  I looked at the lever that actuates the lift rod. Someone in the past had placed some rubber pieces at the bottom of the lift rod.  Not having a service manual for this jukebox, I didn’t know how it was originally designed.  It didn’t make sense how it was assembled.  So I disassembled the bottom section of the lift rod and reassembled it.  The lift rod and spindle arm worked correctly after that.

Examining the cam that actuates the lever, it appeared mushroomed in various places, which would have reduced the height of the lift rod, which probably prompted someone to put additional rubber pieces under the lifting rod. That cam will need to be replaced someday.

This post would make a lot more sense with either photos or some drawings.  Maybe in the future I will update it.

 

Golden Eye, Sega/Stern Pinball Machine (1994)

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Location: Centennial, CO
Symptoms: Auto-launch ball shooter would not launch ball.  Lower playfield lights not working.

I opened the coin door on the pinball machine and immediately saw a coil dangling from the playfield.  It was the shooter coil and it was resting on the metal junction box.  It probably grounded out against the box causing the 50V supply fuse to blow.

The coil bracket had broken from the stresses and vibration of years of use.

The lower playfield general illumination lights were not working. I suspected a connection problem on the IO Power/Driver board.  I couldn’t find any problems with the connector. The lights started working momentarily on their own.  I could hear a faint buzzing that seemed to be emanating from the fuse.  I tapped the fuse and the buzzing would change. I removed the fuse and tested it.  It wasn’t blown, but there was a connection problem inside of it (more on fuses here).  I replaced it and the lights began working reliably.

Once the lights and the shooter coil were fixed, I played a test game and discovered a playfield ramp switch that was dangling with nothing holding it. I wasn’t able to locate any screws lying in the cabinet.  So I reattached it with a new screw.

Wurlitzer 2600 Jukebox (1961-1962)

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Location: Boulder, CO

Symptoms: Some selections not played, record arm jamming.

When I first arrived the mechanism motor wasn’t working.  This was due to the Service Switch being off.  This is used to turn off the motor when making adjustments to the mechanism.  The normal operating position for the switch is on.

Once we got the mechanism running, the record lift arms were occasionally jamming against the sides of the record carousel.  Both right and left record arms are designed to raise at the same time.  If the carousel is aligned properly, one will glide into the record slot, while the other will stop against the record divider on the opposite side of the carousel.  Some of the record dividers were bent which caused one of the arms to get caught and then free itself, launching the record across the room.  Once I straightened the dividers, we didn’t see that problem again.

The jukebox played most records without problems, but some selections didn’t seem to work.  I tested each letter and each number selection to make sure the solenoids and switches were working.  There was no correlation between the non-working selections (i.e. there was letter group or number group that was not working).  I had the owner make selections while I watched the selector mechanism.  The rocker arms that release the selector pins were working but the pins were stuck.  After some cleaning and light lubrication, the problems started going away.  The owner is going to finish the cleaning and lubing on his own and will call back if he has any problems.

 

 

Sharkey’s Shootout, Stern Pinball Machine (2000)

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Location: Boulder, CO

Symptoms: Ball trough solenoid not working — ball not delivered to shooting lane.

For some reason, this past week I’ve gotten a lot of Stern/Sega pinball machine service calls, and all machines are roughly the same era.

I started a game and no ball was delivered to the shooting lane.  The Dot Matrix Display (DMD) indicated it was ball 1, so the computer thought the ball should have been there.  I checked the flippers and they weren’t working either.  At this point, I suspected a blown fuse.

The flippers, pop bumpers, vertical up-kickers, and ball trough solenoids all are “high current” solenoids and run on 50 volts DC.  I checked fuse F21 on the IO Power Driver board and it was blown.  F21 is a 3 amp slow-blow (time delay) fuse for the 50 volt power supply used on these high current solenoids.

Portion of control board showing F21 and power LEDs (click for full res).

A quick visual check of the various voltages can be made by looking at the bank of power LEDs.

I replaced the fuse and the solenoids began working again.  I did a coil test from the diagnostics menu to see if there were any problems that would have caused the fuse to blow.  I then tested all of the switches.  Not seeing any problems, I concluded it was simply what I call a “fatigued fuse”.

Fuse fatigue occurs if the current in the circuit exceeds the rated value of the fuse for a brief moment.  The F21 fuse is a MDL time delay type of fuse rated at 3 amps.  If 3 amps is passing through the fuse, it won’t blow.  If 4 amps is passing through it, it will blow within an hour. It can handle 6 amps (double) for up to 5 seconds before it blows.  So a fuse like this can handle spikes in current without blowing.  But if coil or a drive transistor shorts out, it will blow protecting the circuit.

During multi-ball, the flippers and bumpers can energize all at the same time causing current spikes much greater than 3 amps.  After years of this, the fuse filament gets weaker and eventually breaks, like a light bulb burning out.

Which fuse is blown? The center fuse. See text.

The fuse on the left sure looks suspect with it’s black residue.  This is a fuse that I took from a high powered coil circuit from a different machine.  It still works.  It still measures good on an ohm meter.  I doubled checked by putting exactly 3 amps through it with my bench power supply.  It’s what I would call “fatigued” and probably will blow in the near future.

The center fuse is blown, but it’s difficult to tell visually.  The fuse on the right is intermittent.  It works for 15 minutes then stops.  If you turn off the power, it will start working again.  It’s the most bizarre behavior I’ve ever seen in a fuse.  It had me thinking the loss of power was somewhere else.

When it comes to fuses in pinball machines, don’t trust your eyes or your meter.  But if the fuse looks like the one on the left, replace it anyway because it’s about to blow.

 

Star Pool, Williams Pinball Machine (1974)

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Location: Broomfield, Colorado

Symptom: Not powering up, not working.

This pinball machine is located in a youth center in a church basement.  No one seemed to know much about it, other than it was probably donated. So it was unknown when it last worked.

Given the age of the machine, before powering it up, I checked the mechanical operation of all of the steppers and visually checked the contacts on the relays and score motor cams.  Several of the steppers were gummed up, but the rest were in good condition.  I rebuilt the steppers and fixed the left slingshot linkage which was binding.

We had to drill out the lock in the back box because no one had a key and we couldn’t find one in the machine.

Once all of the mechanical parts were working freely, I powered it up.  The machine would get stuck in continuous reset mode.  The reset cycle description in the manual was nearly incomprehensible.  So I was on my own.

I checked all of the obvious things, like the score reels resetting to zero, the ball count stepper unit, player count stepper unit, etc.  Everything was being reset and all reset switches were working.  The only weird thing was the credit stepper was stepping up to the maximum allowed credits during reset, when it should be subtracting 1 credit.

It occurred to me to check the coin switches, which I hadn’t checked earlier.  They were a mess.  I think someone thought they could get freeplay mode by bending all of the contacts together on both coin inputs.  Once I got the switch wires and contacts untangled, the machine would reset properly.

I bent the switch contacts on the credit unit to give free plays.

After that, there was still some minor tuning needed and got 98% of it working well.  I discovered a broken switch contact on the Spinner Advance Stepper (EOS). It was broken right at the insulator which prevented me from soldering another contact on.  I am currently researching a replacement switch or contact.

I will update when this is done.