Electricity is to a pinball machine as blood is to the human body. Restrict the flow of blood by a blood clot and the body will function poorly or fail. Likewise, oxidized contacts impede the flow of electricity in a pinball machine and the game will be sluggish or parts of it will fail to work.
The Relays are the heart of a pinball machine. Like the heart, they are what make the pinball go. Since all EMs are 42 years old, or older, it is important to thoroughly clean and adjust them so they can work almost like they were new again. Here is what I have learned to be the best way to clean and adjust Relays so they stay adjusted for many thousands of games.
All Relay work should be done with the game off. I like to remove the Mech Board or Playfield when working on the Relays. Your back will thank you.
- Remove the screws holding the Relay to the Mech Board. Some Relays are tied together with a wire. All of these Relays will need to be removed at the same time so you can get to the bottom of the Relays with double Switch Stacks.
- Clean the Mech Board and any labels that were beneath the Relays. Remove dust and dirt first with a dry cotton pad and then clean with 91% Isopropyl alcohol on a cotton pad. Be careful when cleaning labels; the ink might come off.
- The following Contact cleaning instructions are for EMs only! Solid State pins have gold plated Contacts and should ONLY be cleaned with 91% Isopropyl alcohol and a Q-Tip!
The bottom Switches on the Double Level Relays will need to be cleaned and adjusted. Clean the Switch Leafs and the Contacts of the bottom row of Switches with 91% Isopropyl alcohol and a Q-Tip. Use a Dremel with a #443 wire brush, the 'Magic Brush', to polish the Contacts. I use a small regular screwdriver to open the switches and then brush away.
I heard of the 'Magic Brush' from nicovolta and have become an avid devotee. Warning! Little bits of carbon steel metal are spit out of the brush when being used - use eye protection!
Clean the Contacts with 91% Isopropyl alcohol and a Q-Tip again. Tungsten Contacts may be pitted and blackened and need extra polishing or even some light sanding with 500 grit sandpaper. If you do not have a Dremel Tool and don't want to buy one, you can use a burnishing tool.
The Pinball Resource has a Plastone® Flexstone burnishing tool. "An emery like flexible file for cleaning regular contacts from Plastone®."
I do not recommend sandpaper. It will remove some of the Contact metal.
The Switches of an OXO before cleaning with a Dremel Tool and a #443 wire brush:
- Straighten out all Leaf Switches. These often get mangled and are hard to adjust if not perfectly straight. Use one screwdriver as a fulcrum and the other small regular screwdriver to straighten the Leaf. Continue until the Switch Leaf is straight. Sometimes a mangled or fat-fingered Leaf Switch will come out of the Actuator Slot. Before straightening, put the Leaf Switch back into the Actuator Slot.
- Tighten the Switch Stack screws on the bottom Switch Stack Only.
- On the bottom Switch Stack only, adjust the Switches so the movable, longer Leaf Switch is touching the Actuator (Ladder), biased TOWARD the Armature. You want the Switch to be just touching the Actuator. Too much bias may hinder the movement of the Actuator.
- On the bottom Switch Stack only, adjust the stationary Switch(es) so there is a 1/16" or a little less gap between the Contacts.
I used to use a Leaf Switch Adjuster Tool, like this one at Pinball Life:
But it broke - it seemed to be made out of pot metal - and I never replaced it. This is the best tool to adjust Switches and if you can find one that is made out of steel, buy it! I now use a small regular screw driver.
- On the bottom Switch Stack only, manually move the Armature and Actuator toward the Coil as if to simulate the Coil being energized and pulling the Armature toward the Coil. All Make (Normally Open) Switches should be gapped to 1/16 of an inch or a little less and should close, touch the stationary Switch AND you should see a small deflection of the stationary Switch. All Break (Normally Closed) Switches should open to about 1/16th of an inch and when closed should deflect the movable Switch.
- Optional. Polish the screws removed from the Relays. You can use a tumbler if you have one, but I clean them manually.
This doesn't take that much time and the screws can be polished and ready in a few minutes and not hours.
- Put the first Relay removed back onto the Mech Board with your newly polished shiny screws.
- Now, repeat steps 3-8 for the Single Switch Stack Relays or the top Switch Stack on the Double Switch Stack Relays.
- Optional, but recommended. Clean the entire Relay. These get very dirty and look horrible. Clean everything with 91% Isopropyl alcohol - spacers, plastic lug protectors, metal base and wires. This is a good time to clean the Leaf Switches, if you haven't already done so.
- The wires to the Relays get matted down. Pull the wires out so they are in-line with the lugs and form a loop with the wire. This not only looks better, but gives you a chance to check for loose wires that need to be resolderd, wires that have fallen off or wires that have their insulation frayed. Look for wires and lugs that are touching.
In the pic below, the wires to the left Relay have been straightened and checked for loose/missing wires. Notice how jumbled and matted the wires are to the Relay on the right.
- Check for other problems. The steel plate that is pulled into the Coil, when energized, is called the Armature. The Armature should be properly seated into the Relay Metal Base so that is moves freely. The spring may be weak or missing. There may be other mechanical issues.
There is something wrong with the leftmost Relay. Notice how the Actuator is at a different angle than the Actuators on the other Relays.
Bally tended to use more short style Leaf Switches. Williams tended to use more long style Leaf Switches, but, they too, used the short Leaf Switch Relays. The short Leaf Switch Relays require more care getting the Switches adjusted - TLC required!!
After you have followed all of the steps above, check the Switch adjustments a second time by manually moving the Actuator. This is especially important for the short style Leaf Switch Relays. After the Mech Board or Playfield have been put back into the cabinet, check the Switch adjustment a third time! I have checked, rechecked and reverified switch gaps only to find one or more that I have missed.
If you get anything out of these instructions, please remember 'BIAS' and 'DEFLECTION.' These are the keys to having Relays that will stay adjusted for tens of thousands of plays. If you have no bias, the Switch deflection will be reduced and the Actuator may not return to 'Home' position. If you have no deflection, your Contacts will not have the all important self cleaning action! Pay special attention to these important tricks when properly adjusting your pinball machine's Relays and you will have a very reliable EM pin for years to come.