The Proper Tools
The proper tool to use is a dedicated switch adjustment tool. You can make your own from a section of 3/16″ metal rod – about 7″ long. Then cut a notch with a cutoff wheel from a Dremel. Or purchase one from The Pinball Resource, Marco, Pinball Life, or other pinball parts supplier.
Never use needle nosed pliers. Just do not do it. The angle of the tool seems to result in twisting of switches.
While purchasing this switch adjustment tool, also get a flexstone file.
Other tools required are screwdrivers, isopropyl alcohol (not rubbing), Q-tips, thin cardboard (business cards work). Solder and a soldering iron may be needed if removing or replacing a switch.
Note: Click on most images for a larger photo.
Cleaning the Contacts
Never use a contact cleaner, WD40 on the switches. Many of these liquids are flammable and the sparking of a switch can cause a fire.
Prior to adjusting, it is important to clean the contacts. For SS and EM pins with gold contacts, it is easy to clean with a Q-tip and isopropyl alcohol. Isopropyl alcohol is the only exception to the ‘No Liquids’ rule because it quickly evaporates and does not leave a residue.
Caution: Be certain to not use very much isopropyl alcohol and use only in a well ventilated area. Follow precautions on the container.
Sometimes there is dirt that does not come off with the alcohol. In that case, put a thin piece of cardboard between the contacts, push them together and pull the card between the contacts.
Never use a flexstone, file or any other abrasive material on gold plated switches.
With EM games, the power to fire a relay travels through the playfield switches. These switches have silver contacts. To clean these switches, use a flexstone file. Flexstone files can be ordered from pinball supply houses. 400 grit sandpaper or a small metal file can be used, but flexstone is better.
In addition to the switches located under the playfield and the flipper switches, EM games have switches in the backbox and, usually in the cabinet under the playfield. Dirt or wear on these switches can lead to malfunctioning games.
For EM silver contacts, they can be cleaned with isopropyl alcohol. Then insert a flexstone between the contacts, press them together and move the flexstone back and forth. It is important not to press too hard and bend the leafs as that will cause them to file not parallel to each other.
The cabinet flipper switches and those at the flipper switches (EOS or end of stroke) handle higher currents, have tungsten contacts and are designed differently*. Worn or dirty flipper and EOS switches will lead to weak or non-functioning flippers. They can be filed with a standard metal file, or they may need to be replaced. A flexstone file used on EOS switches will wear out the flexstone and destroy the file.
* Except those on newer solid state or Fliptronics flipper systems. They use gold contacts.
For details on cleaning, filing and adjusting EOS switches, see the section on Rebuilding Flippers.
Switch Components and Proper Positioning
The most common switch in games is the leaf switch. It is used in pop bumpers, roll over lanes, stationary targets, star rollover buttons, sling shots, etc. The key to making them work properly are to clean the contacts and to adjust them the proper distance apart.
To understand how a leaf switch works, it is necessary to understand the components and what they do. There are two (or more) flexible leaf‘s (also called switch blades). Each of these has a contact. There is usually one or more stationary blades (or dampening blade) that are not flexible.
The longest flexible leaf is the one that moves when the pinball hits. It needs to be positioned against what is moved by the pinball (rubber ring, target, button, pop bumper ring, etc.).
The other shorter flexible leaf is stationary until the moving long leaf hits this short leaf.
The thick stationary blade (dampening blade) holds the short flexible leaf in a fixed position and keeps the short flexible leaf from swinging around or dampens the movement.
The next picture shows a mangled, improperly adjusted, leaf switch. This sort of twisted switch usually occurs when someone uses the wrong tool and adjusts the switch at the wrong point.
Plus, the shorter leaf should always be adjusted hard against the thick stationary (dampening) blade. Here, the shorter leaf is ‘swinging in the wind’. The purpose of the stationary blade is to hold the second shorter flexible blade in a fixed position. That allows the longer leaf to be positioned as close as possible to the shorter leaf, without the short leaf bouncing around causing false hits.
The next picture in this section shows the shorter flexible leaf properly bent against the thick stationary (dampening) blade. Done this way, the shorter leaf will stay in one position, while the longer leaf is moved by the action of the pinball.
This switch is used under a star rollover button. The longer switch acts as the only spring, pushing up the rollover star. The shorter flexible leaf is bent against the thick stationary blade. The thick stationary blade holds the shorter flexible leaf in position.
In the next photo, a lane switch is properly adjusted. When the ball rolls through the out lane, the ball pushes a lever down against the switch. The long flexible leaf moves down and hits the short flexible leaf.
Because the short flexible leaf is bent against the heavy stationary blade, the two contacts can be adjusted close together without fear that machine activity will cause enough bouncing for the switch contacts to hit.
Adjusting the Switch Leafs
Generally, the leafs should only be bent with the leaf switch adjusting tool and the bending should only be done near where the ‘sandwich’ is located and held in place by the two screws. The rest of the leaf should remain unbent and straight – no curves or angles.
If there is a thick dampening stationary blade and a flexible leaf together, generally they are bent together.
When the flexible leaf is bent away from the thick stationary blade, it can be difficult to bend only the flexible blade. Try using your tool on the flexible leaf, only.
Here is a star rollover being adjusted for the proper distance from the long flexible leaf. Note that in this application, the long flexible leaf must be bent up as it is the ‘spring’ pushing up the roll over button.
Star roll over switches are particularly difficult to get right. The contacts have to be as close as possible so that a fast roll over by the pinball registers with the game. Using the thick stationary blade properly to set the gap, the two contacts can be quite close together without the switch ‘bouncing’ and causing false points.
Other Rollover Switch Adjustment
Rollover leaf switches have another component: the part above the playfield. When the pinball moves through a rollover, a small wire lever is pushed downwards against the leaf switch. If this is not adjusted properly, the leafs can be adjusted correctly, but the switch still does not activate.
It is pretty easy to use the switch adjustment tool to bend the wire so that it sticks up further into the playfield. But be careful as some of these are meant to allow the ball to move in either directly. If the wire is bent improperly, the pinball may not be able to move ‘against’ the switch.
The most difficult leaf switch to adjust properly are the pop bumper switches. Too close and the pop bumpers will activate without a pinball hitting it. Too far apart and a the game has a dead pop bumper.
First, clean the contacts. Then, most importantly, loosen the screws holding the switch and move the switch so that point coming down from the skirt is in the center of the ‘spoon’. If it is off center, the pop bumper will work when the ball hits one side of the pop bumper, but not the other. To make this easier to see, darken the end of the skirt point with a black sharpie.
Then adjust the switch in the same manner as the rollover switch.
Note that sometimes the plastic ‘spoon’ gets worn and should be replaced.
Stationary targets are another type of leaf switch. This one has two flexible leafs and two stationary blades. It is important that the flexible leafs be against the stationary blades to hold everything from bouncing.
Sometimes we find it easiest to adjust these switches by removing them from the playfield. But, on occasion, they are adjusted perfectly, but when reinserted into the playfield, the hole pushes the target back and causes the switch to be stuck closed.
EOS (End of Stroke) switches are another type of leaf switch used on flippers and some pop bumpers. Adjusting them is covered in detail in the Rebuilding Flippers section.
Newer pinball machines have done away with most open leaf switches. These microswitches stay clean and are more reliable. However, they cannot be repaired or cleaned. When they do not work, it is usually because the wire above the playfield is bent. That can be adjusted just like in the rollover switch (above). But if they do not work, they must be replaced.
When activating a microswitch, listen for a faint ‘click’. If not there, the microswitch might be broken. But the only certain test is to use a DVM and check resistance.
As with all non-working switches, a broken wire or open diode can also cause a failed switch and should be checked.
When ordering a new switch, sometimes it is possible to order the ‘naked’ switch and move the old switch attachment to the new one.
Here are two different micro switches. Both can be adjusted by bending the wire or tab coming off the switch with a switch adjusting tool.
The smaller of these two switches are commonly used in Stern ball troughs. Both of these switches are usually in a switch matrix and needs to have a diode installed.
Opto switches are switches that use LEDs instead of a physical connection. In theory, they are more reliable. Unfortunately, they burn out and get dirty.
If an opto is not working, or if it is flaky and unreliable, it could be because it is dirty. Clean it with a Q-tip and isopropyl alcohol.
Most of the time, optos stop working because the transmitter (light source) burns out in a 20+ year old pinball machine. The optos used in Williams pinball machines are UV and not visible by the naked eye. However, it is possible to see if the transmitter is working if a camera can be aimed directly into the transmitter – not off to the side. Note: Some cell phone cameras can ‘see’ this UV light but others may not.
Newer Stern pinball machines use optos that are visible to the naked eye.
Some Williams pinball machines use optos in the cabinet flipper switches. These can be cleaned for reliability. However, cleaning them will not make the flippers stronger – this is an ‘old pinball tech tale’ and there is no truth to it.
If replacing the optos, it is suggested to replace both the transmitter and receiver to insure that they are both on the same wavelength. It is also possible to purchase the raw LED from Great Plains Electronics, unsolder the burned out LED and solder in a new one.
Alignment may be an issue with optos. Sometimes it may be necessary to loosen the screws holding the optos and move them slightly to get optos to work.
Optos are usually plugged into separate opto boards usually located under the playfield. The opto board supplies power to the transmitter and converts the information from the receiver for use by the computer in the switch matrix.
Reed or Eddy Switch
A few games use a reed or eddy switch. It is a sealed box that is magnetic and senses the iron in a pinball. They are completely sealed. Other than checking the wiring and plug, there is nothing that can be done to clean or repair these switches.
Comments, including suggestions, improvements, errors, etc. are welcome (see below).
If you have a specific question about your game that does not directly apply to adjusting switches, please see our FAQ section.