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Pinball Reset Problems & Solutions
NOTICE: For some very important information, please read the Technical Article Notice and Disclaimer, found on our Technical Articles Index page before performing any of the work described below. The information given below assumes you have read the Notice and Disclaimer first.

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This article deals with problems where a pinball machine "resets" or "reboots" on it's own- either randomly or predictably. This may happen when you hit the flippers, when the game is cold or warm, or just "out of the blue" while playing or while the game is just sitting there doing nothing.

Most problems like this are related to power supply problems in most games and more details are given below about various causes and solutions. Sections below are organized by game manufacturer/type to deal with their specific design and known causes of reset problems.

Page Contents:
General Info- All Makes/Models

Power cord connections: On many used games, it's not uncommon to have a worn out plug on the game's line cord- something that just simply isn't making a very good connection with the contacts in the wall plug. Or even a worn-out wall plug that isn't making good contact with the game's line cord plug end. Even wires inside the game's plug can be damaged from years of use- being bent or yanked from the wall outlet, etc. Some may become intermittent and simply "jiggling" the cord where it connects to the plug can make the game go on and off.

If your line cord/plug does show signs of wear/tear or abuse, or is in any way questionable, you may consider replacing it with a new cord/plug. Always use a grounded cord/plug in a grounded outlet to help protect the game and ensure it has the appropriate power it needs.

If the wall plug in your home/location is suspect, consult a licensed electrician about replacement.

Line Voltage: A very common cause of game resets is simply low power at your wall plug, fluctuating power, or "dirty" power. Most pinball games were designed to run at 117 volts AC (VAC). If the voltage at your wall plug drops below this point, then your game may be susceptible to resetting. If your voltage is substantially higher than 117 volts AC (usually 125 or higher), then your game may be susceptible to "lock up" problems, which are similar to resetting problems- where the game simply "locks up" or shuts down and doesn't reset unless you turn power off and back on.

It should be noted here that some games are more susceptible to resetting than others. So even with two games plugged into the same power outlet, you may still see just one game reset, while the other continues operating fine. The reason for this is that some games have more high-current devices than others (magnets, coils, hi-powered flippers, etc) which will draw more current during use and put more of a "load" on the power supply in the game. When this happens, the game is more susceptible to resetting, especially if there is a weak point or component in the power supply that may make the game more likely to have problems with resetting.

If you have a voltage of 125VAC or higher at your wall plug, you may want to consult with a licensed electrician regarding possible problems with line voltage in your home, with your electrical service/meter, or with power lines running through your neighborhood. Some specific problems with power lines and connections at the service panel can cause higher voltages like this and should be repaired to avoid damage to electronics that are vulnerable to high voltages and power surges/spikes.

If you have less than 117VAC at your wall plug, then there are a couple things you can do to get more power to the game:
  • Try another outlet or circuit in your house. All homes on 117vac power will have two "phases" or two separate lines of 117vac power, so if one "phase" is low, the other may be a bit higher. Try another outlet or circuit in the house to find out if voltage differs.
  • Contact an electrician or your local power company about checking the power to your home to see if there are any bad connections, or other problems that may be causing your home to be receiving lower voltage on the power line.
  • Re-jumper the power input connector (or the transformer lugs) on the game's transformer. This is a modification that is not recommended if you aren't skilled with electronics and reading wiring diagrams (schematics). The wiring diagrams for the transformer lugs or input connector are often listed in the wirigin diagrams or "schematics" of your game's instruction manual. Most jumper settings listed in the schematics will cover different settings for voltages of 230vac (Europe, etc), 120vac (USA, etc) and 105vac (Japan, or "low line condition"). If the power in your home is constantly lower than 117vac, then this may be the best solution to a resetting problem.
Extension Cords: Avoid using extension cords for your game whenever possible. Longer-length extension cords can cause what is known as "line drop", which is a drop in actual voltage due to the resistance of the wire in the extension cord- due to it's length. Line drop can be anything from 1 to 4 volts, depending on the length of the extension cord. Old worn out extension cords with poor connections at each end (or repaired connections along the cord) can cause a drop in voltage/current, too. This is more commonly seen in longer cords like 50 feet or more in length. Try plugging the game directly into a wall outlet to avoid line drop problems.

Furnaces, Air Conditioners, and Other Appliances: If your game is sharing the same circuit as a heavy duty appliance in your home such as an air conditioner, furnace, microwave oven, cooking range, oven, etc., then power on the line may drop a few volts when the appliance kicks on. It is not uncommon to see drops in the range of 4-5 volts with some circuits, and this can be just enough to allow your game to reset. Try moving your game to another circuit within your house.

Coil Diodes: If your reset problem occurs when a particular coil fires (bumper, kicker, flipper), check to see that the coil has a diode on it (if required). If the coil is supposed to have a diode on it, but it has fallen off from vibration, etc., then replace with a new diode. If diode(s) are present on the coil, you may consider clipping one leg of each diode and testing to be sure the diode is not open or shorted. If so, replace. Missing or failed diodes, especially on flipper coils, can cause reset problems in certain games, so always check for these if your reset problem is related to coil activity.

Bridge Rectifiers: Several bridge rectifiers are commonly used for the power supply in most electronic pinballs, and depending on the make/model of the game, some may be more prone to failure, which can cause reset problems. See the game-specific sections below for more details on bridge rectifiers in different types of games that are more prone to failure and may require replacement.

Filter Capacitors: Capacitors across bridge rectifiers or large electrolytic capacitors that may otherwise be used as filters in power supply circuits should be considered for replacement any time the bridge is replaced, and large electrolytic capacitors that these games use can dry up over time which can cause excessive AC ripple on DC power lines, and reduced DC voltage, which can cause game resets.

Voltage Regulator: The 5 volt voltage regulator used in most electronic pinball games can be a source of resetting problems if it is failing and on it's way out. Most games will use a LM323K type regulator (large transistor-looking regulator mounted in large heat sink). Some may used other types or additional parts associated with the regulator that may also require testing/replacement. This component doesn't fail very often, but should be considered if other means (above) have not yielded any solutions to the reset problem. We carry LM323K regulators on our
Electronic Parts page.




Bally/Stern Solid-State Games (1977-1985)

In addition to the
General Info for all makes/models (above), here is some info that is specific to early Bally and Stern solid-state (electronic) games regarding "reset" type problems.

Early Bally and Stern solid-state games are more commonly known for "locking up" rather than doing an actual reset (re-boot) but both problems can be caused by similar problems within the game. Here are some things to check:

Connectors: It is very common to find burned, scorched, dirty, or otherwise damaged connectors in these aging games and most have to be replaced and overhauled completely to bring back reliability to the game. Check power supply connectors and connectors going onto the right side of the solenoid driver board to ensure all are in good condition and no signs of scorching or overheating are present. If so, replace the connectors.

C23 Filter Capacitor: Probably the most common cause of game resets or lock-ups, this capacitor is mounted near the top center of the solenoid driver board and is usually an original part in most of these 25+ year-old games and should be replaced if it looks like it's been there for some time. This capacitor can dry up inside over time and cause voltage to drop on the 5vdc logic line, which can cause the CPU to quit or reset. We have new C23 Capacitor Kits available on our Electronic Parts page.

Poor Chip/Socket Connections on MPU Board: Also a very common cause of game lock-ups, especially in the early Bally and Stern games that used the AS-2518-17 Bally MPU board, or the MPU-100 Stern MPU board. These boards had very poor quality chip sockets installed on them which after aging all these years have become notorious for developing intermittent poor connections between the chip and the socket.

Often, simply removing and reseating socketed chips (ROM chips U1-U6 and others) can cure the problem, but usually only temporarily- the problem often returns. The only real solution is to have the chip sockets replaced with modern, higher-quality sockets, or replace the whole circuit board. Often the chips themselves have to be replaced, too, especially if any black oxidation is present on the chip legs. This oxidation decomposes the metal of the chip legs and eventually will render the chip useless.

Voltage Regulator: Voltage regulator Q20 is mounted on the large black heat sink in the upper right corner of the solenoid driver board. This regulator can fail periodically, especially if an old or original part, so may be considered for replacement if other tests don't yield any good results. Q20 is an LM323K regulator and we have these available on our Electronic Parts page.

For more helpful information on repairs, modifications, and upgrades you can do to your Bally or Stern game to help prevent reset problems and increase reliability, see our Bally & Stern Solenoid Driver Board Modifications article.


Bally/Williams "WPC" Games (1990-1995)

In addition to the
General Info for all makes/models (above), here is some info that is specific to late-model Bally & Williams games regarding "reset" type problems.

There are several things in the Bally and Williams "WPC" model pinball games that can cause a reset to take place. Several aspects of these games should be looked at and considered first before attempting to replace parts or make repairs, to be sure that the defective part or actual cause of the problem is properly identified. The causes listed below are listed in order of "easiest" to "hardest" to check and repair. Sometimes this problem in these games requires no repair of the game, so be sure to consider and inspect all possible causes before planning a repair of your game.

Power cord connections: If your game is a newer-model Bally or Williams game that has a cover on the back where the line cord goes into the game, you may consider removing this cover and seeing if the cord and plug inside are secure. Some games use a line cord that simply plugs into a 3-prong socket inside the back of the game (hidden by the black metal cover) and the cord/plug can occasionally work loose in this connector, which can cause intermittent power problems. So always worth a quick check at the back of the game to make sure all is well.

Line Voltage: See the General Info section above for standard info on line voltage problems and checking for adequate voltage for your game.

If your line voltage at the wall plug is low, you can re-jumper the transformer input connector in the game for a "low line" setting. The wiring diagrams for the transformer input connector are listed in the front cover of the "WPC Schematics Manual" which is a manual that covers the non-game-specific electronics in WPC games (or electronics that are the same from game to game) such as power wiring, and the circuit boards/display in the backbox. The jumper settings listed in the WPC Schematics Manual cover different settings for voltages of 230vac (Europe, etc), 120vac (USA, etc) and 105vac (Japan, or "low line condition"). If the power in your home is constantly lower than 117vac, then this may be the best solution to a resetting problem.

The game Twilight Zone actually has a "Low Line Condition" software setting in the game adjustments where you can put the game on "low line" if the power at your wall plug is low. The software will compensate for the low power and this may help avoid reset problems with this particular game (other possible causes listed here should be reviewed as well). This adjustment is only available in later versions of the software for Twilight Zone which can be ordered through our ROM Chips Page.

Overheated Power Input Connector: The transformer secondary power input connector on the right side of the circuit board (red and blue wires) can develop poor connections on the red wires (12vac supply for 5vdc regulator circuit) especially in games that have been run 24/7 in some commercial locations. It is common to see signs of overheating such as scorching or discoloring of the wires and IDC connector housing at this location, as well as oxidation of the connector pins on the board. If such signs are present, replace the header pins on the board, and the connector housing on the wires with a new heavy-duty unit or older-style molex connector housing using Trifurcon connector pins- crimped AND soldered. Be sure to cut back the wires if any are overheated and stiff/rigid- get to some fresh wire for the crimping onto the connector pins. Replacing the whole connection here is a must to ensure all connection points are clean and healthy. If any part is left unrepaired/unreplaced, then the prob

Bad Connections in Inter-Harness Connector: Demolition Man, Indiana Jones, Popeye, Road Show, Star Trek: TNG, Twilight Zone. In these [wide-body] games, the harness coming off J114 on the power/driver board will have a gender-changer connector (female-to-female) in it, a few inches off the board from J114. This is sometimes referred to as a "Z" connector. In a few rare cases, this connector has been known to be the cause of reset problems, when it's connections are dirty, oxidized, or damaged from possible overheating or excessive current draw. Reseating this connector (or replacing it if it is damaged) may help cure a reset problem. Bypassing the connector altogether (cutting it out and hard-wiring the wires) is the best option to eliminate it as a cause of reset issues- at present and in the future.

Bridge Rectifiers: See the General Info section above for standard info on bridge rectifiers and replacement in your game.

Several bridge rectifiers are used on the power/driver board in WPC games- some of which may cause a game to reset if the bridge is failing. The bridge that is most commonly blamed for resets is BR2- used for the 5vdc regulator circuit on the power board. When this (or any) bridge starts to fail, it can cause a drop in voltage and under the right conditions, can cause a game to reset due to low voltage in the circuit.

Bridge BR2 is located at the top of the board- near the right side- and is one of two bridges mounted under a large aluminum heat sink. BR2 can be replaced if you have the proper skills and tools to do so (see our Electronic Parts page for replacement bridges and capacitors).

When replacing BR2, it is strongly recommended that the associated filter capacitor C5 is replaced along with the bridge. This is the capacitor that is tied directly to the + (positive) and - (negative) leads of the BR2 bridge rectifier. We carry a heavy-duty replacement capacitor (better than original part) on our Electronic Parts page.

It is also strongly recommended that 2 jumper wires are installed on the back of the board, running from the + and - leads of BR2, to the corresponding + and - leads of the C5 filter capacitor. The reason for this is that during replacement of BR2 it is easy to accidentally remove the "plate-through" holes around the legs of BR2 that carry electricity from the back to the front side of the board. Even if the plate-through holes are left undamaged, it is difficult to get solder to flow through the holes and make good contact with the front side of the circuit board, so installing jumper wires between the bridge and capacitor will ensure a good solid connection. Use #16 or #18 guage wire for best connection. A lot of repair persons make the mistake of leaving these out and find that even after replacing BR2 and C5 (with good new parts), the game still resets. Make sure the connections are good with use of the jumper wires to avoid this pitfall.

Other bridge rectifiers besides BR2 can be to blame for resets, but it is rare. The next most likely is BR3 which rectifies solenoid (coil) power for flippers, bumpers, etc. If this one starts to go bad, it can cause resets when flippers or coils are activated.

The bridge rectifier on the Fliptronics II board (or off-board mounted rectifier for Fliptronics I in Addams Family) can cause similar symptoms as a failing BR3 rectifier.

Filter Capacitors: See the General Info section above for standard info on filter capacitors and replacement in your game.

Capacitors across bridge rectifiers should be considered for replacement any time the bridge is replaced, and large electrolytic capacitors that these games use can dry up over time which can cause excessive AC ripple on DC power lines, and reduced DC voltage, which can cause game resets.

It is recommended that anytime you replace a bridge rectifier on the power/driver board in a WPC pinball game, that you replace the corresponding filter capacitor (if used) at the same time. Cost is roughly the same for both parts, and it's always easier to do the replacement work for both parts all at the same time while you have the board out of the game.

We carry new replacement filter capacitors for use in WPC pinball games- 15,000 uF 25-volt radial-lead snap-in caps. More information, and online ordring for these capacitors can be found on our Capacitors page.

Voltage Regulator: The LM323K voltage regulator (large transistor looking regulator mounted in large heat sink) can fail, especially in games that have been run 24/7 and that show signs of heat/scorching around or behind the regulator. This component doesn't fail very often, but should be considered if other means (above) have not yielded any solutions to the reset problem. We carry LM323K regulators on our Electronic Parts page.


Williams Solid-State Games (1977-1985)

In addition to the
General Info for all makes/models (above), here is some info that is specific to early Williams solid-state (electronic) games regarding "reset" type problems.

Most problems in early Williams solid-state games that would normally cause a reset in other games, usually just cause a Williams game to "go dead" or "play dead" when power is turned on. Usually they don't reset or lock up, but just go "blank" and stay that way.

For the best information on dealing with such problems in Williams games, see our Dead Williams Games article in our Technical Articles section.

Bridge Rectifiers and Diode Rectifiers: Most early Williams games will use two off-board-mounted bridge rectifiers in the backbox below the power supply. These rectifiers are used for coil power and feature (switched) lamp power and will rarely fail. If one does fail, you'll usually notice problems with the feature lamps or the coils, but in rare cases, a failing bridge here may cause a reset problem. We recommend reviewing other more-likely possible causes first, then replacing these bridges if all else fails- these bridges rarely are the cause of reset problems.

Most games from 1977 through 1980 will use two large diodes on the power supply board which rectify the incoming 18vac and prepare it for use by the 5vdc regulator circuitry. If either of these diodes goes bad (opens up) then your game may still actually run, but may be susceptible to resets due to the lost rectification from one of the two diodes.

If either of your recitifer diodes tests bad or if they look worn or "scorched" from heat over the years, we recommend replacing them. Replacements are cheap and easy to install. We carry new replacements- part # P600D, available on our Electronic Parts page.

Later Williams games (1981-1990) use a rectifier on the main power supply board, and games with an Auxilary Powe Supply board will use a few rectifiers on that board. The one rectifier on the main power supply board is fused by two 7-amp slow blow fuses. It is possible for the rectifier on these boards to go partially bad, blow one of the 2 fuses, and yet allow the game to continue to run. But in this case the game is susceptible to resetting, so rectifier replacement is fairly common and definitely recommended as one of the first things to try if you have a game like this that is resetting.

Other rectifiers on the aux. power supply board are usually used for flipper and other coil power, and usually won't cause a reset, but may be suspect if other means don't resolve the problem.

Filter Capacitors: Williams games from 1977-1990 will use a large electrolytic capacitor on the power supply board to filter out and smooth the rectified DC power used by the 5 volt regulator. The job this capacitor does is crucial to good game operation, and is usually the first thing to replace if you run into reset problems in these games.

While capacitor values vary slightly in these games from 1977-1990, we use one standard replacement capacitor in all of them- a 25 volt, 15,000 uF electrolytic capacitor which is an ideal replacement and will outlast and outperform original capacitors. For more info, and online ordering of this part, see our Capacitors page.

It is also recommended that the filter capacitor is replaced anytime the bridge rectifier (or rectifier diode(s)) is replaced on the power supply.

Voltage Regulator: Most Williams games will use either a LM323K 5 volt regulator (early solid state games and late solid-state game), and some in-between will use a 2N6057 transistor with accompanying regulator IC chip.

Regulator transistors will rarely fail, but may be suspect if other means don't resolve the problem. If you have a Williams game from roughly 1981-1986 that uses the 2N6057 power transistor and accompanying LM732 (MC1723CP) regulator IC, you may want to consider replacing the LM732 IC if your regulated 5.0vdc is 4.95 or lower and can't be brought back up with other means (filter cap and rectifier/diode replacement). This isn't a very common replacement part, but can go bad occasionally and hold the voltage down just low enough to cause resetting of the game.



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