Milwaukee, WI
Whoa! Let's not start pulling chips until we go thru the basics of Sys 6 and 7 games. One thing that happened on Firepower is that most of the playfield switches are put together wrong from the factory. This condition will cause intermittent switches. This makes them intermittent.
Playfield switches are 'leaf' switches, which are made up of switch blades (flat brass arms) contacts (rivets at the open ends of the blades) and Bakelite insulators (down where the screws are, they separate the blades). The contacts are made of a silver alloy plated with an extremely thin layer of gold. The contact rivets have a wide side (this 'contact' face should touch the other contact) and a peened side where the shank of the rivet was hammered to fix the rivet to the blade. What Williams did was assemble the switches blades wrong so that the rough peened side of one rivet would be touching the contact side of the rivet on the other blade, trying to make contact. This causes problems two ways: 1. the peened rivet does not have gold plating and oxidizes, and 2. the peened side scrapes the gold off the contact face of the other rivet, and it oxidizes.
Look carefully at some of your switches and see if this reversed contact issue is your problem.
How to fix:
Two bad ideas: 1. If you clean the switches with alcohol and a strip of paper from a business card you can remove the oxide and the switch may work OK for days/weeks. But then it's back to intermittent function. 2. Another lame fix is to take the switch apart and reverse one blade. It may work OK for a while, but eventually it will start to get flaky.
The two true solutions: New switches or new contacts. 1. New switch: buy a switch and replace the bad switch. Problem is that leaf switches come in many variations, and they cost money. 2. Contact Steve Young at Pinball Resource and buy a quantity of gold plated contact rivets. Unsolder flaky switch, go to the workbench and with a Dremel grind off the peened side of the two contacts on the bad switch, then remove the contacts. Clean the brass leafs (fine sandpapaer), then rivet on new contacts, facing each other, of course. Rivet them using a small hammer and punch on the rivet shank, while the face of the contact is on a piece of hardwood protected with a layer of duct tape, to avoid damage to the contact face. Hammer lightly but tightly. Reinstall switch.
Yes, it's all money and time, but I chased the damn intermittent "F" and the lock switches for literally YEARS!!! Now it has been many years since and the switches are rock solid.
Best of luck,
Don C.
