Beginner's Notes

1 Introduction

Pinball machines are electronic and mechanical devices with a large number of parts and given enough time, one or several of these parts will eventually fail to work as designed. This is not to say that pinball machines are fragile--all major pinball machine companies built their games as commercial-grade equipment, specifically designed to take the abuse of being on location. However, most pinball machines have far outlived their originally intended service life, which was typically 2-5 years.

So as components get dirty, parts wear out or break, or electronics fail, they will likely need cleanings, repairs, and adjustments in order to keep the machine looking nice and working as optimally as possible.

The information in this Wiki should go a long way toward helping you fix and maintain your pinball machine. If there is something unclear on any specific topic, feel free to ask questions on any of the Online Pinball Communities. Often times, the knowledge found there eventually finds its way onto this wiki.

2 Other Sources of Information

The pinball community is blessed with a fantastic group of dedicated hobbyists and parts suppliers.

In addition to this Wiki, a tremendous resource for pinball information can be found within various Online Pinball Communities.

Another tremendous source is the Internet Pinball Database (IPDB). The IPDB is a great place to research games. The database contains photos, descriptions, history, production counts and other valuable information. The database is an ongoing project with data added continually. The administrator of the IPDB takes great care to ensure that the information contained within is clear and accurate. While not a repair site, the IPDB can provide helpful information with game specific issues. Many machines are documented with both external and internal photos that can assist in restoring or repairing your game. Make this database your first stop when researching a game.

Pinball Owners and the Internet Pinball Serial Number Database help keep track of the games that still exist.

3 Electro-Mechanical or Solid State Games

Pinball machines come in two basic flavors: Electro Mechanical (EM) or Solid State games. EM games can usually be recognized by the score display. EM machines have either light box scoring (lights on the backbox indicate score) or score reels that click over when points are registered. Solid State (SS) games have electronic scoring with either gas plasma displays, or in more recent vintage, dot-matrix displays.

EM machines generally do not have any circuit boards, all scoring and playfield devices being mechanical fired off with relays, switches, and solenoids. Solid state games will have relays and solenoids with all scoring and game rules contained in the circuit boards. SS games can and do have a richer rule set because of the advantages of solid state circuitry. SS games also have more sounds, speech, and music, whereas EM machines are limited to bells and chimes. For a table of comparisions between the two types see EM / SS Pinball Comparison.

During the manufacturers conversion from EM to SS games, some games were released in both an EM and an SS version. The Bally game Mata Hari being an example. Bally produced over 16,000 games in the SS version and only 170 as an EM machine. If you can find an EM Mata Hari, you have a real collectible.

4 Opening Your Pinball Machine

4.1 Coin Door & Playfield

One of the first tasks you need to learn to work on your pinball machine is how to open the front door and remove the glass. Most pinball machines come with a locked front door. Often this key is lost. Before you drill out the lock search around for the key. Look in the backbox if it is open to see if a key is hanging in there. Sometimes the latch on the back side of the lock has been removed and the only thing holding the door closed is the dirt, gunk, or even minor bends in the door itself, so give a bit of a tug on the coin return area to try to open the door before going any further. If you can't find the key and the lock is still intact you will need to drill the lock out to open the door.

Coin Door of a Gottlieb Machine (Haunted House)

Open Coin Door of a Gottlieb Machine (Haunted House)

Once the door is unlocked or the lock drilled out simply swing it open. If it is stuck, you can put your hand in the coin return slot to get a better grip.

Once you have the door open, look inside and you will notice a bar near the top of the machine. Move the lever down by pushing on it. This action moves a locking bar and releases the lock down bar. If the machine has been setting idle for years it may be difficult to swing the lever from accumulated gunk. One method I have heard to get the bar moving is to tie a weight to the bar and let it hang there for awhile. Eventually, the gunk will give way and the lever moved to the open position. When the lever is in the down position pull up on the lock down bar and remove it from the game. On some games (Chicago Coin and Data East) the lever may be spring loaded requiring you to hold the lever in the open position while removing the bar.

Opened machine

With the lever removed it is a good idea to clean all of the surfaces to prevent more sticking problems. The next step is to remove the glass. One must take safety precautions in removing the glass. Most pinball glass is tempered, some are not. Before I remove any glass I put on heavy work gloves and safety glasses. Before removing the glass have a safe place to put it. I use a thin foam pad to place my glass on and not on a concrete basement floor. If moving the glass across the room make sure the path from the machine to the glass storage area is clean with no obstacles on the floor that you could trip on.

Using a Suction Cup to Remove the Playfield Glass (Optional)

Start by placing your hands on the glass and sliding it out along the track. You can also use a suction cup to assist in removing the playfield glass. These are available at Harbor Freight or other fine retailers. You could have more gunk in the track making sliding the glass difficult. I have also encountered machines where the cabinet is not square, putting pressure on the glass and making it difficult to remove. If the machine was dragged across the floor, which puts pressure on the legs, the cabinet could be out of square. Use the Armstrong lifters to raise and lower the machine to hopefully put it back on square, at least some.

Once you have moved the glass somewhat you can push it from the upper part of the playfield. Proceed with caution and remove the glass and place it aside. You now have access to the innards of the lower cabinet and can start to make repairs.

4.2 Backbox

The backbox typically contains most of the electronic circuit boards for a game. The backbox can come in a variety of styles. The first step is to find the key. The key can be different than the one used on the coin door. Sometimes this key can be found hanging on a hook on the back side of the coin door or somewhere on the inside of the cabinet.

Next, locate the lock. Sometimes it is on the top of the backbox, the side, or under the top lip of the backbox in front of the backglass.

Attempt to unlock it if the key is available. If not, there's a small possibility that the lock has been disabled in some way, so proceed under that assumption.

While there are a few exceptions, in general, there are two major styles of backboxes--the ones that swing out, and the ones where the backglass lifts up and out.

For the style where the backglass lifts up and out, there is a metal lift channel at the bottom of the glass--a metal lip that sticks out about 1/4". Try to lift it up enough so that it clears the wood on the bottom. Then swing it out a bit, lower it, and carefully remove it from the backbox.

For the backbox style that swings out, give it a tug on the same side where the lock is. If it doesn't open, try lifting the door section up a little bit then giving it a tug.

For EM games or very early solid state games, the rear of the backbox has a door that needs to be opened in order to access the game's innards.

4.2.1 Missing Key

If the key is missing and there has been no success in opening the backbox, there are a few things to try before resorting to drilling the lock.

• Stick a large flat head screwdriver in the lock and try to turn it. Sometimes it is loose enough to turn. If not, don't try to force it.
• If the lock is in front of the backglass and held into the backbox with a rectangular plate, remove the hex screws, bend the plate, and maneuver the lock assembly out of the backbox.

4.2.2 Lamp/Light Board/Panel

On some games, there is a lamp/light board/panel behind the backglass to provide illumination. It can be called several different names (lamp board, lamp panel, light board, light panel, etc). This needs to swing out in order to access the circuit boards behind or on it. There are a few different ways to open this panel, depending on the style used.

• Sometimes the panel has a sliding vertical latch on the left or right side. This latch is sometimes secured with wingnuts. Loosen the wingnuts, lift up the latch, and then swing the panel out.
• Sometimes the panel has a handle is latched onto rollers like a kitchen cabinet. Give the handle a gentle tug, and it should pop open.
• Sometimes the panel is sitting in a slot in the backbox. The hinge on this style is typically 1/3 of the way from the left or right side. Lift it up with two hands and swing it out.

Light panel that lifts up and swings out

5 Cleaning Your Pinball Machine

There are two approaches to cleaning. One is just routine maintenance, which should be done occasionally according to how many games are played on the pinball machine. The second approach is thorough cleaning as part of a restoration.

• A good guide on cleaning can be found here, which addresses many opinions and misconceptions of certain cleaning products as they fell in and out of favor over the years.
• A list of general cleaning and restoration supplies can be found here.

5.1 Restoration Cleaning

Typically, when performing a restoration, a playfield likely has not received any proper attention in years or decades. Parts may need to be cleaned, de-rusted, polished, and waxed.

1. The first step is to pick out any loose parts or labels and save them for later.

2. Thoroughly vacuum the playfield and cabinet. You will need a micro vacuum attachment kit from Amazon, Harbor Freight, etc. This will allow you to get into small spaces and tight corners.

3. Use a air compressor to spray out anything you may have missed with a vacuum. Vacuum up any new debris that may have appeared.

4. Disassemble the playfield as appropriate. For a full restoration, some people remove all the parts from a playfield for cleaning. Others only remove as much as necessary in order to reach all areas of the playfield.

• Most parts can be safely cleaned with simple green. For metal parts, de-rust in either Evaporust or CLR. Rinse with warm water. Polish by hand, put in a tumbler, and/or buff on a buffing wheel (depending on the size and shape of the parts, a combination of the three polishing techniques can be used).
• For plastics, clean with naphtha or simple green. Use care when cleaning the printed side of the plastic. Depending on how scratched or scuffed the plastic side is, it's sometimes appropriate to start with novus #3 (but not always), then move down to novus #2, and finish with novus #1 as a final polish.
• For cabinets, they can be safely cleaned with a product like Simple Green or Goo Gone. Be sure to test the cleaner in an inconspicuous area first to make sure no paint is removed. Different eras of machines are more susceptible to paint loss using certain cleaning chemicals over others.

5. Wipe down the playfield with naphtha. Use proper ventilation when using this chemical. Do not use water-based cleaners, since they will raise the wood grain in your playfield and cause planking. Under no circumstances should you use Windex or any other glass cleaner on the playfield.

6. (Optional) Use Novus #2 to even out any scratches or ball swirls. Novus #2 should be used sparingly and only for a single major cleaning. It is an abrasive compound, which will wear down any protective surface or paint on the playfield, so use with care. Novus products offer no protection from future damage. It is essentially very fine liquid sandpaper. Novus #3 should never be used on a playfield.

Before and after cleaning with Novus #2 and naptha

Not much Novus #2 is needed when cleaning a playfield

7. Wax the playfield to give it a protective layer and slick surface for the ball to travel on. There are many waxes to choose from, but many are not appropriate for pinball use because they either use silicon, are too soft to offer protection from the ball, or use additives that ruin plastics and ramps. A safe wax which offers a good protective coat is Blitz Wax, which is a carnauba paste wax. In the past, manufacturers recommended products called Wildcat or Mill Wax, but both have been shown to cause various problems.

8. If the playfield rubbers are dry and cracked, they should be replaced. Kits to replace all rubber on a machine are available from all of the pinball suppliers. Rubber that is is good shape but dirty can be cleaned with Naptha or lighter fluid.

9. Replace the balls, especially if they are dull, scratched, rusty, and/or pitted. A scratched up ball will act as sandpaper on a playfield and wear it down that much faster.

5.2 Regular Maintenance Cleaning

1. Vacuum up any dust or debris. 90% of the cleaning takes place here.
2. Wipe down the playfield with a damp cloth. Do not use water or water-based products. Novus #1 should be appropriate, since it is a non-abrasive polish. Unlike with a restoration cleaning, Naphtha should not be used in a regular maintenance cleaning since it will remove the old layer of wax.
3. Wax the playfield to give it a protective layer and slick surface for the ball to travel on. There are many waxes to choose from, but many are not appropriate for pinball use because they either use silicon, are too soft to offer protection from the ball, or use additives that ruin plastics and ramps. A safe wax which offers a good protective coat is Blitz Wax, which is a carnauba paste wax. In the past, manufacturers recommended products called Wildcat or Mill Wax, but both have been shown to cause various problems.
4. If the playfield rubbers are dry and cracked, they should be replaced. Kits to replace all rubber on a machine are available from all of the pinball suppliers. Rubber that is is good shape but dirty can be cleaned with Naptha or lighter fluid.
5. Replace the balls, especially if they are dull, scratched, rusty, and/or pitted. A scratched up ball will act as sandpaper on a playfield and wear it down that much faster.

6 Fuses

All pinball machines have fuses. Fuses are used in the machine to protect the internal components from damage in case of electrical problems, such as shorts, surges, or failed components along the paths that supplies power. The fuses in a machine all guard a particular section or a line supplying a particular voltage. One fuse may be for score displays, while another is for solenoids, and still another for the general lighting.

Fuses are designed to be the weak link in a circuit, so a cheap fuse can blow before a more expensive component gets destroyed, or before something burns and causes a fire.

A blown fuse is usually indicative of a problem somewhere. However, occasionally, they can blow for no obvious reason. Sometimes they are fatigued from long-term use, or sometimes they get jostled too much during a move and fail.

If you are attempting to diagnose a game that was recently obtained, be sure to go through the Post-Purchase Checklist to check for problems before turning on the game for the first time.

If a fuse blows in a known working game, check that the voltages match the schematics, check for damaged/burnt components, and check for loose parts or screws (which may cause shorts).

In replacing a fuse, always make sure you are using the correct value, or amperage. The amperage of a fuse is stamped on the one of the electrical contacts of the fuse. DO NOT assume that the fuse in the machine is the value that should be used, always check the game manual or schematic to verify the correct rating. Someone repairing the game earlier may have put in a higher fuse value to circumvent an electrical problem. Do not swap out fast acting fuses for slow blow fuses, always use the correct rating and type.

The best way to check for a blown fuse is with a multimeter set to diode/continuity mode. Place the probe on each side of the fuse. A good fuse will beep. A bad or blown fuse will not. A visual inspection might not always be enough since a break in the filament might be hidden in one of the ends of the fuse, or small enough not to be immediately noticeable.

Fuses can be located anywhere within the game. Often there is a bank of fuses in the bottom of the cabinet. Other fuses may be located on the underside of the playfield and more in the backbox. In solid state games, fuses can also be found on the individual circuit boards. Each fuse should have a label next to it indicating which fuse it is for reference in the schematic and game manual. Sometimes these labels have gone missing in the machine over the years. Additionally, some games have recommended modifications, which call for the use of additional fuses that would not be in the schematics. If this is the case in your machine, when the correct fuse to use has been determined, add a label so that it is easier to find out what the correct fuse is next time.

Always have a good stock of fuses on hand in your parts drawer. Fuses can be obtained from any number of Pinball Parts Suppliers. There's no telling when you will encounter an issue that causes a fuse to blow--sometimes it could take several blown fuses before finally narrowing down what the problem is.

Sometimes fuses can be difficult to remove from the machine. You can gently pry them free with a small screw driver, being careful not to pry on the glass part of the fuse, but instead on the metal sides. Insert the small screwdriver under the fuse in the fuse holder and pry. If you find that the fuse holder no longer has much tension, it needs to be replaced as it will not make good electrical contact. This can cause intermittent problems, which can be troublesome to find.

7 Batteries

Batteries are the bane of electronic pinball machines. They are used to keep memory chips active, so things like high score and game settings are maintained while the power is off. Over time, they leak, and the alkaline compound oozes onto the electronic circuit board destroying the traces and components.

Plan on replacing the battery with something else. Each replacement solution has its benefits and drawbacks when it comes to the potential to leak again, the amount of work it takes to implement, and the cost of the solution.

• A remote battery pack
• A memory capacitor
• A lithium coin cell battery
• A battery-less NVRAM board (to replace the board's RAM chip(s)

This is always a required modification to any pinball machine you own.

8 Lamps

Lamps are used throughout the machine to indicate game features, scoring, and to light the playfield. Lamps that illuminate the pinball playfield and backglass that are not part of the scoring are called General Illumination (GI) lamps. These lamps run on their own circuit and fuse and typically run around 6.3v AC.

As machines age, the lamps burn out and need replacement. Most lamps in a pinball machine are type 44 as installed at the factory. The 44's run hot and can cause burning over time to the adjacent wood or plastics. These can be replaced with type 47, which run cooler. Type 44 bulbs are brighter than the type 47. They draw more current and because of this, also put more stress on any related connectors.

It is at the discretion of the reader, but some people prefer to use 44 lamps under playfield lamp inserts. 44 lamps are brighter, and tend to stand out better while playing the game.

Within the past couple years, specialty LED vendors have begun producing lamps specifically for use in pinball machines. These are very bright relative to incandescent lamps, but draw less current. The look of the LEDs are subjective, as in some situations they can flicker or are simply too bright for comfortable play. Current pinball manufacturers are also incorporating LEDs from the factory, and using software to control their intensity and color.

Making certain an old 9v battery is putting out an acceptable lower voltage

Testing a 6v bulb with a dying 9v battery

As mentioned previosuly, most bulbs used in any game are powered by ~6 volts. A great way to quickly test a bulb is to use a dying 9v battery. Don't use a fresh 9v battery, or you will shorten the life of the bulb. Find a battery that is roughly putting out 7v - 8.25v. An old battery from a smoke detector works pretty well.

Place the tip of the bulb on one of the battery terminals, and cock the outer metal casing of the bulb to touch the other terminal. Orientation of the bulb with regards to the positive and negative terminals does not make a difference in this case. Do not hold the bulb across the battery terminals for very long. Just long enough to determine if the bulb's filament is lighting or not.

Testing a flasher bulb

Flasher bulbs can be tested the same way, however, a fresh 9v battery should be used.

When replacing bulbs they often can be difficult to remove due to their location. Lamps under the playfield can be removed by bending the lamp holder back to get access to the bulb. Burnt out lamps on the top side of the playfield can be accessed by removing the overlaying plastic piece. To remove really stubborn lamps, or ones that you can not grab use an old shooter tip. Place the shooter tip over the bulb and push and twist it out, installation is a reversal of removal.

• Removing a recessed lamp
• 

  Recessed Lamp
• 

  Installed shooter tip
• 

  Lamp removed

Another great and cheap removal tool is a small, approximately 3" - 4" piece of clear vinyl tubing. The same process in using a shooter tip applies.

CAUTION: when removing bulbs, have the game turned off. Having it unplugged is even better in some instances. Keep in mind that most bulbs are constructed of half glass and half conductive materials. If a bulb is accidentally dropped during removal or installation, a 50% chance of the bulb shorting across objects it falls onto is there.

It is also a good idea to get a lamp socket cleaning tool. This tool is inserted into the lamp socket and rotated about to clean the socket connection. Some lamps and sockets can develop corrosion that needs to be cleaned or the socket replaced.

9 Coils

Coils are used in pinball to convert electrical energy into mechanical motion. Coils have been an integral part of pinball since 1933. They are used in pinball games in three different forms. 1. Relays - The coil is used to operate a switch. Used mainly in electro-mechanical (EM) games. 2. Solenoid - The coil is used to move a plunger which in turn moves a mechanical device. 3. Magnets - Used in newer games to divert or capture the ball.

9.1 Top 5 things to know:

1. Test a coil by measuring its resistance. Typical coil resistance is 5-30 ohms, but may be as small as 2 ohms or as large as 100-150 ohms.
2. Coils don’t fail very often.
3. SS machines have a diode to protect the driving transistor.
4. Flipper coils have two windings, a power winding and a low-power hold winding.
5. Most coils are not designed to be on constantly and should blow a fuse if they are stuck on.

9.2 Coil Numbering

The correct coil number is usually listed in the game’s manual and for EM games it is usually marked on the schematics. Some coils will have numbers of the form X-25-850-Y, where 25 is the wire gauge and 850 is the number of turns. The prefix X and suffix Y usually indicate the form the coil is wound on, the lug orientation, and possibly the length of the coil sleeve. Gottlieb coils do not follow this scheme and you must refer to a coil chart to determine the wire configuration.

The coil bobbin used for most Bally/Williams solenoid coils has places for three terminal lugs; left edge, middle, and right edge. The AL has lugs on the left and middle (Left), the AE has lugs on left and right (Ends), and the AR has lugs on the right and middle (Right). The positions are as viewed with the lug end of the coil facing you and the lugs facing upward.

9.3 Coil Strength

The strength of a coil is determined by the current through the coil, the number of turns or wire, and the dimensions of the coil. One representation of the strength of an electro-magnetic coil is magnetomotive force, given as: MMF = N * I where N is the number of turns of wire on the coil and I is the electrical current through the coil. Increasing the number of turns (at a fixed current) or increasing the current will increase the strength of the coil.

Removing turns of wire to strengthen coil. This is counter-intuitive at first, but removing wire from a coil makes it stronger. This is because the reduction in wire resistance has a larger impact than the number of turns. Less resistance results in larger electrical current and hence increased coil strength.

9.4 AC vs. DC

Coils do not have polarity. This may also be counter-intuitive, but a solenoid pulls the plunger INTO the coil regardless of the direction of current through the coil. This is why a solenoid can operate on alternating current (AC). Since a coil is an inductor it resists changes of electric current, a property known as reactance. Reactance can be thought of as increased resistance when the coil is driven with AC. The lack of reactance increases coil current and thus the coil strength when driven with DC.

A coil of wire is an inductor, an electrical component that resists any change of electric current. Inductors also store energy in their magnetic field. Fast changes in electric current create an electromotive force (EMF) from this stored energy that opposes the current change. Due to this opposition it is often called back-EMF. The largest change in current occurs when the coil is switched off and the back-EMF can create a high voltage spike of thousands of volts. In EM games, this voltage spike can result in arcing across the switch. In SS games, a diode is used to snub the voltage down to levels safe for the drive transistor.

9.5 Coil Diodes

SS games use a diode to prevent the back-emf induced voltage from damaging the drive transistor. The diode must be installed correctly, so if you are replacing a coil be sure the wire color on the banded end of the diode is the same on the new coil as it was on the old coil. The banded end of the diode must connect to the positive coil voltage. Typically, EM coils are driven with AC voltage and must not have a diode on the coil.

9.6 Coil Mounting

The primary consideration when orienting a coil during installation is avoiding any nearby objects that the coil or coil lugs could hit and possibly short out. Beyond that, there is an argument that it’s better to orient the coil with the lugs at the opposite end of the coil stop with the belief that it will lessen the vibration and reduce the chance of the wires breaking off.