The Third Magnet Project
There are two special things about the way that this project is done. A drilling template, and an opto board. The drilling template makes it easy to get the holes in the right place on the playfield and the ball guides. It also confirms the drill bit size.
The Opto Board is key to simplifying the electronics in the machine. It is an opto that acts like a microswitch, so it can be connected directly to the switch matrix. No board hacking, no extra boards and about the minimum amount of wiring.
And I have to thank the pioneers for making this possible - Ted Estes for doing the code, and Hans Balk at Shoot'm Again for a great guide that is worth reading (even though I know that he doesn't like my gumball light).
And finally, Cliffy and Ron for helping me to decide to do this one.
Steps 1 - 3 can be done without taking the machine down for long. Steps 4 and 5 are the big ones, and are best done in the same afternoon or morning.
I now have complete kits available with a second-generation circuit board. The price is $70. Buy it from Pinbits.
Step 1: Adding the New Opto Harness
The opto switch needs to be connected to the switch matrix. We do this by running two new wires through the harness to nearby switches.
Step 2: Adding the Extra Driver Transistor
The auxiliary power board under the playfield has the locations for the coil driver. Here's how to add it, and the wiring, for the new magnet
Step 3: Drilling the pilot hole
Step 4: Drilling the Ball Guides
The hardest part, knocking holes in 18GA stainless steel. This is also where we strip the top right corner of the playfield.
Step 5: Drilling the Playfield
The scariest part, making a 3/4" hole in your playfield. The template makes it all line up.
You'll need the coil assembly to do this. You can get it from a parted-out machine, or buy parts from the usual suspects. They don't all have these at the same time. You can do most of the work without this hardware. Mounting the optos requires the most disassembly, plus the pilot hole drilled from the underside of the playfield for alignment. The magnet hole can be drilled by removing just the right ramp.
The core pole piece 02-4773
$19 at BAA;
$16.50 at IPB
The magnet bracket 16460 $21 at BAA; $19.00 at Marco;
The magnet coil 20-9247 $24.95 at BAA; $24.95 at Marco
You will also need the nut. I have these for $2.00 each.
Turning the Pole Faces