Tag Archives: EM

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.

 

Old Chicago Pinball Machine (Bally, 1976)

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Symptom: None of the lights working.
Location: Superior, Colorado.

One of the most common repairs I do is related to burnt connectors for the lights on a pinball machine.  Most of them are on solid state machines built by Williams and Data East. But even an EM machine can have this problem.

Burnt lighting connector from Bally EM pinball machine.

Unlike the newer machines where new connectors can be installed, the old ones require a work-around. In this case, the connector was between the control board plywood with all of the relays mounted on it and the fuse block on the right side of the cabinet near the tilt mechanism.  This is a little used connector which would only be used if one were removing the control board from the pinball machine, which is pretty rare. Most EM pinball machines don’t even have this connector, so I had no problem just splicing the bad wire together and bypassing the connector.

Had it been a connector for removing the backbox or playfield, I probably would have installed a single pin Molex connector or something similar for the bad wire.

Since the lights on this machine hadn’t worked in years, there were a few tune-up related items that needed to be done, such has replacing burned out bulbs and cleaning some relay and stepper contacts to get all of the lights working again.

 

Sea Ray (Bally, 1971)

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Symptom: Machine shuts down when flippers are activated.
Location: Denver, CO

Many people are familiar with the Williams flipper reset problem. I’ve written about reset issues in the past. This is the first time I’ve come across an EM that shuts down due to the flippers being activated.

Usually when a pinball machine shuts down due to the flippers, there is a high-resistance path in the power chain.  An EM is no different in this regard.  So, the first place I looked was the fuse holder.  Bally EM machines from the 1970’s are known for having bad fuse holders.  As soon as I touched the fuse the machine came back to life.

Burned fuse and fuse holder.

Burned fuse and fuse holder.

In this case the fuse wasn’t making a solid connection to the fuse holder for a long time (years).  The melted solder blob on the side of the fuse end cap is indicative of high temperatures, caused by the high resistance connection to the fuse clip.  Plus there was the black scorch mark on both the fuse and the clip.  With the high temperatures, the fuse clip turns from being springy to being brittle. It broke off the fuse holder when I tried to remove the fuse.

The fuse holder was replaced and a new fuse installed.  This was quick to diagnose and quick to repair.

Electromechanical Pinball Machines

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I’ve been working on a lot of EM (electromechanical) pinball machines lately. I usually don’t write about them here because the repairs don’t make for interesting reading and wouldn’t be very helpful to owners of other pinball machines.

Electromechanical pinball machines are the ones with the score reels instead of digital readouts, and have chimes and bells instead of electronic sounds. These machines use mechanical motors and stepper relays instead of digital circuits. It’s pretty amazing what they were able to accomplish using mechanical devices before the digital age.

As pinball machines become more popular, many of these old machines are being pulled out of storage and need a little TLC to get them up and running again.

Some of the EM pinball machines I’ve worked on recently are:

Dealer’s Choice (Williams, 1974)
Straight Flush (Williams, 1970)
Aladdin’s Castle (Bally, 1975)
Bally Hoo (Bally, 1969)
Super Star (Williams, 1972)

There are two common problems that most EM machines have: Dirty or mis-adjusted contacts or gummed up stepper units or score reel mechanisms.

There are hundreds switch contact points in an EM machine. Usually about one percent of the contacts are dirty or out of adjustment. What happens is the contact will get some dust on it. When the contact opens or closes, it sparks, which turns the dust into carbon. Carbon acts as a resistance, reducing the amount of power flowing through the contact. If the carbon build-up is substantial enough, no current will flow through the connection when the contact closes. Sometimes the current will flow through the contact generating heat, which is my theory on why they get out of adjustment.

The second most common problem is gummed up stepper units or score mechanisms. Usually the manufacturer put a thin layer of grease on the disk contacts. Over time this grease gets dirty and also turns into a sticky gel. The solution for this is to clean/rebuild the steppers.

I often get asked about the value of an EM pinball machine. Looking at the Mr. Pinball 2014 price guide, most EM pinball machines I’ve encountered are worth about $500, give or take, in very good condition. The items that affect the value the most are cosmetic, such as the playfield paint and wear, the backglass paint (which often peels), and the cabinet paint. These are the same things that affect the value of a solid state game, except supply and demand plays a bigger role.

Most of the time, electromechanical pinball machines are worth fixing, especially if the cosmetics are good.

Quick Draw Pinball Machine, Gottlieb 1975

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Location: Fort Collins, Colorado.
Symptoms: Score reels sticking, not resetting, 50 and 500 points items not scoring, not always advancing to next player or ball, bonus countdown issues, score accumulating when switching players.

The machine has been missing the rear door for the backbox for a long time and a lot of dust had settled in there.  The switch contacts on the player unit needed cleaning and adjusting.  This accomplished a lot in eliminating problems. The score advancing when changing players was due to the reset contacts (switch stacks P3 and P4) vibrating or set too close.

The player unit keeps track of ball numbers, player turns, and controls the reset of the scores. What makes working on the player units difficult is that the switch stacks are very close together. I’ve made a home-made switch adjusting tool that is able to fit in between switch stacks. I’ve also made some cleaning strips with a jogged shape them to help with switch cleaning.

Some of the decagon units needed to be rebuilt and contacts cleaned. A majority of the time was spent in the backbox.  The owner will craft a new back door to help keep the dust out.

There were a few other mis-adjusted contacts on the bonus unit and the 50 and 500 point relays.

Another EM pinball machine saved.

Close Encounters of the Third Kind Pinball Machine (EM version), Gottlieb (1978)

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Location: Parker, Colorado.
Symptoms: Machine not resetting, points not registering, drop targets not resetting, bad light socket, and various other problems.

This is the rarer electro-mechanical version of this pinball machine.

On most EM machines, you can disconnect the credit subtract coil to put the game in Free Play mode.  However, on this machine, there are switch contacts on the credit subtract lever that trigger the Start Relay (S). I bypassed those with a wire.

Next, the relay coil spring on the Reset Relay (AX) had been previously replaced with the wrong one that was much weaker.  I traded the spring from the Hold Relay, where the spring tension is less critical, to the Reset Relay and then re-adjusted the contacts. This fixed the problem with the machine not resetting correctly.

Next, many of the point scoring relays such as the 500 point and 5000 point were not holding though a cycle of the score motor.  They are all common and routed through the normally closed Motor 2B switch.  This switch was simply out of adjustment.

Eight relays are routed through a common hold switch on the score motor.

Eight relays are routed through a common hold switch on the score motor.

One of the formed switch blades had broken off the score motor and a replacement was obtained from The Pinball Resource.

Broken formed switch blade from Score motor.

Broken formed switch blade from Score motor.

Some of the contacts on the player unit needed to be cleaned and adjusted, which is a typical problem with Gottlieb multi-player machines. The bonus stepper unit was gummed up and not advancing or awarding bonus.  It was cleaned and rebuilt.

The spinner switch needed adjusting because it was scoring points with just vibration from the playfield.

After replacing a broken light socket and spraying the back side of the backglass with Krylon Triple Thick Clear Glaze (to help stabilize the paint and keep it from peeling), the machine was looking and working great!

 

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.

 

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.

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.