Post-Purchase Checklist

1 Introduction

After purchasing a pinball machine, it is not usually a good idea to simply flip the power switch an hope for the best--especially one that is in unknown condition or has not been serviced in a long time.

There can be any number of problems with the game and any one of its systems. There are several things to check before even turning on the game to help identify common problems and help prevent them from causing damage, burning up, and from becoming bigger problems. It will take some time and patience to go through everything properly. It is important to do so since these machines can have quite a lot of voltage coursing around through their systems, and if that voltage gets redirected to the wrong place, it can easily damage components, boards, solenoids, and even start fires in some cases.

This checklist is intended to be generalized to cover most pinball machine systems and is not intended to dive significantly into troubleshooting specific problems that are otherwise addressed on the pinwiki pages specific to each particular system. This guide also assumes that you already have basic familiarity in using a mulitmeter for testing.

2 New-In-Box Games (New & Vintage)

For vintage new-in-box games, be sure to follow the entire checklist and treat the game as one found in an unknown state.

For new-in-box games that have recently been manufactured and came from a distributor, you can usually bypass the steps in the checklist for disconnecting the playfield and circuit boards. Just do a thorough physical inspection, check for loose parts (in the cabinet, backbox, and for parts caught in assemblies or wiring), check for the correct fuses, and check for loose connectors. Sometimes screws or other small parts get dropped in the game while it's on the assembly line in the factory, and don't re-appear until after the game is tipped on its end for shipping.

3 Checklist

3.1 Loose Parts

Open the game up and collect any loose parts, screws, washers, labels, bulbs, springs, solder drippings, etc. Save the parts and labels in case you need them later.

Loose parts in the rear of a cabinet

3.2 Cleaning

After removing all the loose parts, make sure to vacuum the game. This will help prevent stray parts or dust buildup from causing an electrical short in the game.

To vacuum in small areas or corners, use a micro vacuum attachment kit from Amazon, Harbor Freight, etc.

Micro Vacuum Attachment Kit

3.3 Photos & Records

Take photos of the game and serial number for your records. This may help as a reference if you unplug something and aren't sure where it goes to later. Photos may also help with insurance claims on the off-chance that the game is stolen or destroyed by flood, fire, or other means.

Additionally, to help keep track of the games that still exist and have survived, be sure to add the serial number to the Internet Pinball Serial Number Database.

If you own multiple games, put the photos of each game in separate folders for easy access.

3.4 Documentation

Before proceeding further, make sure that you have a copy of the game's manual and schematics. Most manuals have digital copies available on the Internet Pinball Database and Planetary Pinball's Reference section, with the exception of games manufactured by Gottlieb. Since these are digital scans of original manuals, the quality can vary wildly--some might have unreadable or missing pages.

The Gottlieb rights-holder does not allow digital distribution of manuals, so physical copies must instead be purchased. The Pinball Resource is the primary source for manuals, but other distributors also carry them. Used copies can also be found at pinball shows or on eBay.

Be sure to also review repair guides for your game's system. They sometimes have specific power-on guides available beyond this overall checklist and point out common problem areas, weak spots, or recommended modifications for reliable operation.

• Classic Bally/Stern - Powering up for the first time
• Gottlieb System 1

3.5 Electrical System

3.5.1 Power Cord / Line Cord

Inspect the power cord.

Replace the power cord if any of these conditions are met:

• It only has two prongs (rather than three). This means that the game would not be grounded, and could cause several problems in the came and also possibly shock the player.
• It is frayed. This is a fire hazard
• The outer insulation is cracked or falling off. This is a fire hazard.
• A big yellow plug has been added on on the end. You don't know if it was done correctly. This is also against fire code in commercial locations. This plug is also large, and there might not be enough space on power strips to accommodate it if neighboring sockets on the strip are already being used. This can be especially problematic if the game is brought to a pinball show.
• It is very short and doesn't even reach the floor. This can lead to needing to add an extension cord, which can be a fire hazard in a home, and is against fire code in many commercial locations. Depending on how short the cord is, the extra weight on the cord may also put additional stress on it.

Use a replacement cord that is a minimum of 14ft. Since the cord often snakes somewhere inside the game, and also has to reach the floor, that can sometimes easily add up to a length of 4 feet or more. Here are some tips on power cords and here is a good guide on replacing a power cord in a game.

3.5.1.1 Testing

If the line cord passes visual inspection, test all three prongs to make sure they all make contact to their connection points inside the game. It is doubly important to make sure to test the grounding prong to avoid being shocked by the game later after power is turned on.

Use a multimeter in diode/continuity mode to test for continuity between each prong of the power plug and their corresponding connection point inside the game.

3.5.2 Line Filter

Be sure to inspect the line filter. The power cord connects to this component.

In some games, it is bare and clearly visible, and in others, it may be hidden and enclosed in a metal box, which is usually open on the bottom. It is especially important to do a visual inspection on the innards of the metal box to make sure that the primary fuse has not been cut out of the circuit, and for any other electrical or wiring issues.

Some games have a small disc-shaped component attached to the line filter called a MOV, which helps guard against electrical surges. If it is absent, check the game's schematics to make sure that it has not been removed at some point. Add the MOV if it appears in the schematics, or replace it if it appears damaged or burnt. The same applies for a thermistor (however, note that a thermistor can still fail even if it passes a visual inspection).

A burnt MOV in a Williams Firepower

The underside of a power box in a Williams Star Trek

3.5.3 Transformer

Inspect the transformer for damage. Make sure that all the lugs are intact and there are no wires that have broken off from the lugs. Also inspect the wiring to make sure it isn't burned or fused with other wiring.

If the transformer appears to have been water damaged, the innards may be corroded, making it questionable to actually try to power it up.

If the transformer has scorch marks or looks like it caught fire, it may be questionable to actually try to power it up.

Make sure that the transformer is correctly configured for the proper voltage, especially if it is a foreign import. On some games, this is done by connecting the proper wires to the proper lugs. On other games, there can be a plug with jumper wires connected to the power module box. Check the game manual to verify the correct configuration for your game.

3.5.4 Filter capacitors

Inspect the filter capacitor(s) for physical damage and leaks; they there is any damage to the casing or if it has started leaking, do not turn on the power with these capacitors--it may be dangerous to do so. Replace them.

If they use terminal connectors, make sure they are tightly connected.

For some systems, you can get away with an initial power on test without any problems. However, if they are the original electrolytic capacitors, they will likely need to be replaced because they have dried out after 20-40 years--most of them were originally rated for 10-14 years. When they age, they can put out wacky voltages and current which can be difficult to troubleshoot and even cause damage in some situations. Sometimes you can get away with not replacing the large capacitors that are about the size of soda cans (or larger), but the capacitors that are about the size of spice jars really need to be replaced.

The bottom line is that these capacitors are responsible for ensuring good, smooth, steady power flows through the game, so it usually a good idea to replace these capacitors if they have not already been replaced.

3.5.5 Bridge Rectifiers

Depending on the game system, the bridge rectifiers could be stand-alone components, on a dedicated circuit board (bridge rectifier board), or integrated onto another circuit board in the game. The bridge rectifiers are responsible for converting from AC to DC voltage.

Bridge rectifiers can be tested with a mulitmeter.

If a bridge rectifier is burnt or does not pass a multimeter test, they may need to be replaced.

Additionally, on some game systems, the the specs of original rectifiers were sometimes barely adequate to operate the game, so it may be recommended to replace them with higher-rated bridge rectifiers anyway for trouble-free operation.

3.5.6 Fuses

• Inspect all the fuses in the game and make sure they are correct type (fast blow vs slow blow) and are the correct rating. Sometimes, the wrong fuses are added as a band-aid for a fuse that keeps blowing because of a problem somewhere, or the wrong fuse is added because it was the only one on-hand.
• Make sure to test each fuse with a multimeter continuity test. To do a proper test, either remove the fuse or pop at least one end out of the holder. If the test fails, the fuse will need to be replaced.
• Check to make sure that the wires connected to the fuse holders are actually connected and not loose. Desolder, tin the metal, and re-solder as necessary.
• Check the fuse holders for problems, and replace if necessary. Make sure that the tabs holding the fuse are not broken. Make sure that the holders have enough tension to hold the fuse tightly.

3.5.7 Diodes

Some systems have banks of diodes throughout the game, as well as on individual assemblies, switches, coils, etc. Use a multimeter on the diode setting to test them. Replace any that are bad. Glass diodes are known for being easily cracked/damaged.

Note that in some cases, glass germanium diodes should only be replaced with new germanium diodes--not standard silicon diodes. Germanium diodes are typically used in low-voltage areas, such as in switch matrixes. Silicon diodes are designed to handle higher voltages.

When testing diodes on coils, the only way to reliably test is to disconnect one leg of the diode. However, if you go through the trouble of doing that, you might as well replace it. The chances are good that a few of them have gone bad due to heat and vibration from plunger strikes over the years.

3.6 Wiring

Inspect all the wiring in the game.

• Make sure there are no loose/floating wires.
• Check for wires with damaged insulation and exposed bare wire.
• Check to make sure wires are not being pinched by the playfield, coin door, backbox, or any other mechanisms. Sometimes, the insulation gets damaged by stress and could cause a short with neighboring wires.
• Check for burnt wires. They will need to be replaced, and the problem that caused the burnt wires will need to be addressed as well.
• Check for any wires that are wrapped up with tape. It could be a perfectly valid repair, but it could also hide a hack or short. A proper repair typically involves the wires being twisted together, soldered, and then secured/protected with heat-shrink tubing.

3.6.1 Grounding Wires

Grounding wires are very important. Be sure to pay special attention to these wires and at each point where they connect in the game's cabinet and that wires have not broken off from their connectors or terminal rings.

In some games, there is a ground wire/braid/strap that connects through the neck of the cabinet body and attaches in backbox. This ground wire was sometimes disconnected if the backbox was ever removed from the game at some point. It is an easy wire to forget about since there is not a matching plug for it in many cases.

3.6.2 Connectors

Inspect all the connectors. Replace pins or connectors as necessary. A bad pin or a poor connection can sometimes cause intermittent issues that can be hard to track down.

Visible problems include:

• Broken wires.
• Corroded or tarnished contacts/pins.
• Broken contacts, pins, or edge connectors.
• Loose wires on IDC connectors.
• Wires pulled from their connectors; sometimes only connected with a few strands.
• Burnt contacts/pins.
• Burnt connector housing.

Before troubleshooting any electronics, it is important to first address any and all connector issues since they are always a very common point of failure.

3.6.3 Coin Door

Most solid state and modern games have one or more diagnostic/test buttons on the coin door, as well as slam switches, coin switches, and sometimes the credit/start button. Normally, there is a thick bundle of wires running from these devices into the cabinet. Because the coin door is a part that is frequently opened, it is common to see frayed, stripped, pinched, broken, or hacked wiring on the wires that rub against metal near the hinge of the coin door.

Be sure to inspect that wiring, and be aware that it could be a source for potential problems if anything is malfunctioning or refusing to activate on the coin door.

3.7 Electrical System Prep & Test

Make sure that there enough photos showing each of these connectors from the Photos & Records section. In some games, there are connectors that can be flippped 180 degrees, or are similar enough to be plugged into multiple spots--both situations can lead to serious and damaging problems later if the game is powered back up with connectors in the wrong places.

If everything on the checklist up to this point has been cleared or addressed, you should now be ready to test the game's electrical system.

Disconnect everything from the electrical system in the game--the playfield, backbox, lighting, circuit boards, power supplies, coin door, etc. This will isolate the important components of the game from electrical damage if there is a problem during the first time power-up.

Plug the game in and flip the power switch. If you see a bright flash (likely a fuse blowing), sparks, or anything burning, turn the game off immediately and unplug it. You will need to troubleshoot these issues before turning it on again.

Do not plug in or unplug anything while the power is on.

Some games have an interlock switch that turns off the power to the game when the coin door is open. You can either pull out the stopper on this switch, or simply close the coin door.

Interlock Switch

3.8 Fuse modifications

Certain game systems have suggested modifications when it comes to fuses. Sometimes a recommendation calls for a different fuse type or value than what is indicated in a game, either because of a later service bulletin, or because of other findings. Also, sometimes it is recommended to install additional fuses to help protect known problem areas in games.

Now that you have tested and verified the operational status of the electrical system, be sure to review those and implement those recommendations before proceeding further. Then, test the electrical system again to make sure that you didn't introduce any new problems after completing the modifications.

3.9 Circuit Boards

Disconnect and remove the boards from the game and do a thourogh inspection of both the front and the back of the circuit boards.

3.9.1 PCB Support Mounts & Spacers

When removing boards from support mounts, nylon mounts usually have a tab that needs to be pressed down before the board can slipped off. You can either use a small tube called a "circuit board removal tool" or "circuit board extraction tool", or a pair of fine-tipped needle-nose pliers.

Circuit Board Removal Tool

When renistalling the boards back into the game, make sure that they are mounted securely and won't fall of the PCB mounts. If the nylon PCB mounts are broken, replacements are usually available from various sources. If the boards are screwed down, make sure the screws are reasonably snug.

3.9.2 Loose Parts

Sometimes loose parts (screws, washers, scrap wire) can end up lodged on circuit boards or heat sinks. These parts and pieces can sometimes cause shorts on the circuit boards, so be sure to check for them.

3.9.3 Physical Damage

Inspect the board, traces, sockets, and components for physical damage. Damaged components will need to be replaced. Damage to axial components and transistors tend to be common since they stand up off the board. Also check for heat-damaged areas or scorch marks.

Any damaged components, traces, burn damage, or battery damage will need to be addressed before attempting to connect it in the game, otherwise these smaller issues may lead to bigger issues if power is fed to the board.

Be sure to inspect electrolytic capacitors for leaks or dents. Replace as necessary.

• 

  Blown tantalum capacitor on a classic Bally sound board

• 

  Dented capacitor on a classic Williams sound board

3.9.4 Modifications

Inspect the board for any modifications, additional jumper wires, and cut traces. Sometimes these were factory modifications to correct an error, sometimes they are modifications to accept new EPROMs, sometimes they are modifications to replace obsolete components, and sometimes they are attempts at fixes that might mask other problems. Do your research to figure out what the case might be.

3.9.5 Batteries

If the MPU has a battery on it, remove it and throw it away. Some boards use removable AAA batteries, and some boards have batteries soldered directly to the board. If the battery legs/leads are exposed, It's better to trim out the soldered batteries if possible, and then desolder the connectors later. The heat from desoldering could potentially trigger a leak.

Plan on replacing the battery with something else. Each 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)

If the battery has already started to leak, the issue will need to be addressed in one of a few different ways. Each approach has their own benefits and drawbacks. Battery damage might not be limited to just the MPU, since the alkaline can leak down onto other boards if the leak is bad enough.

• Repair the board by treating it with vinegar or yellow mustard, removing the affected components, sanding or sandblasting the affected area, sealing the exposed copper, and re-populating with new components.
• Send the board out for repair (note that some technicians will not repair extensive battery damage because it might not be economical).
• Simply replace the board with a clean/rebuilt original or an aftermarket replacement (if available). You can also try to sell the damaged board, since some people like to try to repair them.

3.9.6 Cracked Solder Joints

Cracked solder joints

Cracked solder joints are when cracks develop in solder. This is typically caused by stress from movement. Cracked solder joints are common on header pins due to the stress of the connector hanging on the pins, as well as stress from plugging/unplugging the connector. To repair them, simply re-heat the joint to reflow the solder.

Cracked solder joints can cause all sorts of intermittent issues because of the break in connectivity. Be sure to check the back side of all circuit boards for this issue.

3.9.7 ICs/Chips & Sockets

Inspect all the socketed chips to make sure that they are oriented the correct way by comparing them to the schematics. Do not rely on the notch in the socket--it is possible that it was oriented in the wrong direction. If a chip is oriented in the wrong direction and the power was turned on, it will likely be damaged and need to be replaced.

Scanbe sockets will need to be replaced without question, as they are very susceptible to failure (because they were cheaply made), and will sometimes prevent an MPU from booting properly or cause other wacky behavior due to poor contact with the chip legs.

• 

  Scanbe IC socket example

• 

  Scanbe IC socket example

3.9.8 Diodes

Most boards have diodes installed, and will cause wacky behavior and/or damage if they fail. Use a multimeter on the diode setting to test them. Replace any that are bad. Glass diodes are known for being easily cracked/damaged.

3.9.9 Cleaning

Filthy boards will need to be cleaned before proceeding, otherwise the grime and whatnot may cause shorts or cause chips/components to overheat.

First, remove all the socketed chips (make sure to take photos beforehand). Gently vacuum using a Micro Vacuum Attachment Kit. Next, spray the boards with Simple Green and rinse with warm water. Use a soft-bristle toothbrush to gently scrub as necessary. Rinse with isopropyl alcohol to displace the water, then blow off the excess with an air compressor. Be sure to blow underneath components and chips. After that, let the board air dry for about a day.

3.9.9.1 Edge Connectors, Header Pins, and Chips

For tarnished edge connectors, use a pink rubber eraser to shine them up. Do *not* file them--this will thin the material. Tarn-X has also been recommended to clean them up.

For tarnished, corroded, mangled, or burnt header pins, it is usually best just to replace them, otherwise you may encounter all sorts of connectivity issues.

For tarnished pins on chips, a pink rubber eraser or Tarn-X can be used to clean them up.

3.9.10 Power Supplies

Some systems can have one or multiple power supplies, each driving different boards.

Check the board for burnt components and replace as necessary. Additionally, any electrolytic capacitors should also be replaced, as well as header pins.

Check the back side of the board for cracked solder joints, especially on the header pins. Those can cause a break in connectivity and prevent a board from working correctly.

Check the voltages each one of them one at a time with a multimeter against what is notated in the game manual or silkscreened near the board's test points.

Some power supplies have a potentiometer (aka "POT") to make adjustments to the voltages if it is too high or too low. Note that after you put a load on the power supply (such as connecting the MPU), it may need to be adjusted a second time.

3.9.10.1 Modifications

It is sometimes recommended to replace certain components on the power supply driving the displays in order to slightly reduce the voltage for the displays in order to extend the life of the displays. The downside is that the brightness of the displays will be slightly reduced, but that usually isn't too noticeable unless there is a side-by-side comparison with another set of displays running at full voltage.

3.9.11 MPU

Connect the MPU to the power supply so that it receives power. Make note of any on-board diagnostic lights and troubleshoot accordingly.

Feel the temperature of each IC on the MPU; if it almost feels painfully hot, there is something causing the IC to short. Turn off the game immediately to prevent further damage. It's likely that the chip that overheated will now need to be replaced since it wasn't designed to handle the voltage that caused it to overheat. It's possible that the short is on the board, in a socket, or the IC itself was bad; troubleshoot accordingly. It's also possible that a short will travel through one IC and into others on the board.

Once the indicator lights show a full boot, proceed to the next step. If your game does not have diagnostic indicator lights, the displays will need to be connected next to further test/troubleshoot.

3.9.11.1 Slam & Tilt

Some systems will not perform a full boot if one of the slam or tilt switches is engaged or not making proper contact. Check the pinwiki page for your specific game system for the symptoms and possible solutions/workarounds for this issue. Some games require slam switches to be closed, while others require them to be open.

3.9.11.2 Dip Switches

If the MPU has dip switches, be sure to go through all of the settings for them. Incorrect settings can sometimes lead to unexpected behavior, or might seem to cause problems or disable features that are options actually controlled by a dip switch.

3.9.12 Displays/DMD

Some displays can be tested prior to being installed in a game, so check the pinwiki pages for specific systems for those procedures.

On some games without diagnostic indicators on the MPU, the displays are the only way to get visual feedback on the status of a game boot.

3.9.12.1 Score Displays

Many score displays have a glass nipple on the back. If this nipple is broken, that lets out the gas found in a display, and renders the display useless. However, a good glass can be transplanted onto the display's PCB.

For games in a master/slave display configuration, for incremental testing, first only install the master display for testing, then the slave displays. Note that in some situations, it's possible that the glass on the master display will not light, but could still have functioning circuitry to allow the slave displays to operate.

Williams/Stern/Bally displays that have burnt segments may be dim or might not light at all. However, be sure to check the appropriate pinwiki pages for repair information since there are several common issues that can be address by replacing failed electronics components.

3.9.12.1.1 Quick Tests

For classic Williams/Stern/Bally displays, a plasma globe (a cheap $10 one will do) can be used to excite the display's segments and make them glow. If they glow, the glass is probably good.

For Gottlieb 6/7-digit displays, a 9v battery can be attached to the display to test the glass's filaments.

For segments that are stuck on or refuse to light, that may indicate a connection problem somewhere between the glass and the MPU, or a bad IC on the display or on the MPU. See the specific game system pinwiki pages for more specific troubleshooting on this type of issue.

3.9.12.2 DMDs

For games with DMDs, outgassing and/or noisy displays can put a strain on the power supply, so displays in that condition should be replaced. DMDs with scorch marks should also be replaced. Darkened areas or areas with text/graphics visible when the display is turned off are usually fine, since that is normally a result of long-term operation, usually referred to as "burn-in".

A DMD with a black scorch mark plus burn-in ("game over" can be seen in the lower left corner)

DMDs that are missing vertical or horizontal lines are perfectly usable, although they might not look too presentable. The issues is sometimes caused by cold solder joints or bad connections between the board and the glass, but sometimes the contacts that lead up to and into the glass display are damaged.

For displays that do not light or do not display images/text as expected, check the pinwiki pages specific to the game system.

3.9.13 Driver/Lamp Board

The configuration of driver and lamp boards vary across different game systems. Sometimes they are all separate boards, sometimes they're combined, and sometimes they're combined with the MPU.

Connect and test each board separately.

3.9.14 Flipper Board

If the game system has a flipper board, connect and test it at this point.

3.9.15 Magnet & Shaker Motor Boards

Some games have separate boards for shaker motors and magnets. Test those individually. If a shaker motor is installed, make sure that it is an official shaker motor and/or that it is compatible with the game. There is a known issue with 3rd-party shaker motors being used in Stern Spike system games, which will cause board damage.

3.9.16 Sound

Sound can be set up in a variety of different ways, depending on the system. Some games use solenoids for chimes, some have dedicated sound boards, some games have multiple sound boards (sound effects, speech, and music are sometimes separated), and some have sound integrated into an MPU or driver board.

Most of the time, sound is dependent upon other boards working first, which is why it is last on the checklist. However, on a few early solid state systems, certain sound boards can operate and be tested independently of the other boards.

The weak spots on sound boards are usually the capacitors and/or amplifiers. Original capacitors should be replaced. Amplifiers sometimes fail or blow. On WPC-89 and WPC-S games, the sound boards have tantalum capacitors that are known for failure, and sometimes blow and catch fire on the first power up, especially after a long period (months or years) without being turned on.

Also be sure to inspect the speaker(s) for physical damage. The paper cone on the speaker is what helps produce the sound, so if that is damaged or torn, the speaker will not work well or possibly at all.

3.10 Playfield

3.10.1 Physical Inspection

3.10.1.1 Cleaning

Be sure to vacuum up any dust, cobwebs, droppings, dead insects, metal shavings, bits of wire, and splashes/drops of solder. These could cause issues with operation.

3.10.1.2 Coils/Solenoids

There are a few things to check on coils.

• Make sure the plunger moves smoothly. If it is stuck, the coil may be swollen, sleeve may be worn and/or the plunger may be mushroomed. Any one (or all) may need to be replaced.
• Check the coil for burn marks or a melted label. This may indicate that the coil locked on at some point and the coil or transistor driving it had a problem.
• If the diode is broken, cracked, or burnt, replace it.
• In most cases, especially on the flippers, the lugs of the diode should be oriented so that it is not adjacent to the coil stop. If the coil is resting on the bracket like this, it can cause cracked solder joints. Inspect the lugs for loose wires. Resolder and flip the coil around as necessary.
• Compare the coils in the game to what appears in the manual. Sometimes when repairs were made, an incorrect coil was substituted. However, there are a few instances where a stronger coil was indicated in a later service bulletin or later recommendation.
• Use a multimeter to check the resistance of all coils and compare them to the resistance in the chart at Pinball Medic or at John's Jukes. If a coil varies more than 5%-10% from the spec, the coil is either not the right coil, or it has suffered heat damage and some windings are shorted together. If the coil measures less than 2.0 ohms, then either the diode is shorted and must be replaced, or the coil has developed a significant short and must be replaced. Testing coil resistance is easy. Set your DMM to resistance, or ohms, and place one probe on each solder lug.

Don't forget to inspect the knocker and chime coils (if your game is equipped with them).

3.10.1.3 Loose Nuts/Screws

Make sure that any nuts/screws on assemblies with coils or moving parts are reasonably snug so that they don't bind up when a solenoid or motor is activated.

If a screw that is screwed into wood just spins endlessly, the screw hole is likely stripped and will need to be repaired by filling the hole and drilling a new hole.

3.10.1.4 Flippers

Check that the coils are the correct ones and the EOS switch contacts are clean and make proper contact.

Typically for a game that has not been serviced in a long time, you will need to get a rebuild kit for the flipper assemblies to replace the parts that are commonly worn out.

3.10.2 General Illumination

Disconnect the circuit boards again.

Connect the plugs for general illumination and turn on the game. If there are obvious electrical problems, such as sparks or a blown fuse, turn the game off and troubleshoot.

If things seem normal, use a multimeter one the playfield connectors that are currently disconnected and check for stray AC voltage (VAC) from the general illumination. If there is voltage where there isn't supposed to be, that will indicate a short, and it will need to be found and addressed before proceeding further.

3.10.3 Switches

Plug in the connectors for the playfield and cabinet switches and go through the game's switch test diagnostics. There are normally either individual problems with switches, or issues with the switch matrix which cause the incorrect switches to register.

3.10.4 Feature Lamps

Plug in the connectors for the playfield and backbox feature lamps. Go through the game's diagnostic tests for the lamps, followed by the switch tests again to make sure that no shorts surfaced.

Use the appropriate approaches for your game for diagnosing non lighting, incorrectly lighting, or locked on lamps.

3.10.4.1 LEDs

Note that not all games can operate the feature lamps properly with LEDs installed. On early solid state or DMD games, LEDs may flicker, blink, or not fully turn off. Modifications to the game, add-on boards, replacement boards, updated game code, or special LED bulbs (ie, non-ghosting bulbs) may be necessary to correct the issue. The Pinwiki pages for each game system should have details on how to resolve issues with LEDs that may be specific to each game system.

If an LED is not lighting at all, but works in another socket, the wires soldered to the socket might be reversed (this can be a common issue in some Gottlieb System 3 games). Since LEDs are polarized and incandescent bulbs are not, test the socket using an incandescent bulb. If the incandescent bulb does not work, then the issue might be elsewhere, but if it lights, it may be a polarity problem with swapped wiring on the socket.

For early solid state or DMD games that use AC power on the GI (General Illumination), LEDs may appear to flicker at a very high rate (like a florescent bulb found in a ceiling fixture), due to the AC power line frequency. Some people may notice this, some might not. The only easy fixes for this is available on certain DMD systems--the LEDOCD GI Board or EnerGI Maestro board. For earlier systems or systems without these boards available, a modification is needed, which may require some more advanced repair knowledge. In short--a bridge rectifier (with a heatsink) and 15,000uF 25V capacitor would need to be installed in the GI circuit to rectify the current to DC power and smooth out electrical ripple. However, few people actually attempt to make this modification because of the level of difficulty compared against how minor of an issue it usually is.

3.10.5 Solenoids

Plug in the connectors for the solenoids. Go through the game's diagnostic tests for the solenoids, followed by the lamp tests, and switch tests.

4 Wrap-up

At this point in the checklist, you have most likely been able to safely inspect and turn on the game. The next step would be to make note of what is or isn't working with the electronics and mechanics, and proceed to address those problems. Once those problems are addressed and the game is in working order, it should then be worthwhile to address cosmetic issues, replace the rubbers, rebuild the assemblies and replace coil sleeves and other commonly worn parts, clean/wax/repair the playfield, and complete an overall shop job.