Introduction

What parts are needed

Assembling the plane

Timer/driver PCB

Wiring

Finishing touches

Introduction:

Question: What kind of person would modify their Indiana Jones Pinball machine to add a motorized Biplane?

Answer: A real pinball addict whose sickness drives them to do cool projects at the expense of their free time, or worse… sleep.

I'm one of those people. This web site chronicles my method for motorizing the Biplane on my IJ.

I have to thank Clay from www.pinballhq.com and Tom Callahan from www.repairconnection.com for allowing me to steal ideas from their sites. Neither Clay nor Tom takes any ownership over this modification, so PLEASE don't bother them with questions.

Before I installed anything in my machine, I tested everything electrically with an old IBM AT computer power supply. This provided the 12V, 5V and Ground that I needed. I made sure that the motor turned when the switch was tripped.

I DO NOT TAKE ANY RESPONSIBILITY FOR DAMAGE THAT MAY OCCUR ON YOUR MACHINE. DO THIS MODIFICATION AT YOUR OWN RISK!!

Small motor

Timer driver PCB

Motor shaft extender

Plastic sheet

Toy propeller

Wire

Molex connectors

Roll over switch

You will need the standard pinball tools, wire cutter, wire stripper, digital multimeter, soldering iron, and patience.

The first thing to do is to remove the plane and its support wire from the playfield. When you turn it over, you will notice that there isn't very much room to work with. The hardest part of this modification is trying to find the right motor. I was able to find a 12V motor in an old NEC 2X SCSI cd-rom that fit perfectly. Other suggestions for motors would be certain children's toys such as slot cars, small RC cars or battery powered cars.

Remove the middle wing screw/nut as that is where your motor will sit. The two screws at the end will hold the black spacer in place. You could also use a little epoxy or silicon to hold it there.

After finding a motor that will fit, you need to build a support structure for the motor and the wire that will support it on the playfield. I used some 1/16" Lexan that I had laying around (because I sell it). You need something thin so you can reuse the screws that hold the wings together. Aluminum would probably work also.

Cut the support to about the same size as the wings, and add holes that machine the outside screws.

You will also need a motor support bracket. I just reused the support bracket that was in the cd-rom that I removed the motor from.

Unless you can find a really small motor, the motor may have to site back a couple of inches in the wider part of the fuselage. In my case, I used a BiC pen refill as a shaft. It was lightweight, and it provided the right strength. I had to use a little silicon grease to get it on, but it worked out perfectly.

Next, fit the motor, motor mount and shaft in the fuselage.

The picture below shows the motor mounted to the plastic support, and the plastic support screwed to the wing screws. The motor support screw will be used later to mount the biplane to the wire support.

There will be some fine adjustment required to make sure that the shaft is centered in the hole. I enlarged the hole in the front of the plane a little to give me a little slop when adjusting the motor position. You definitely don't want the shaft rubbing on the plane.

Next you have to find a propeller that will look good. I found that a propeller from a toy helicopter (sorry Son) would fit on the shaft very well. The hole was slightly bigger than the shaft, but a tiny amount of electrical tape on the shaft made for a nice tight fit. I had to also trim the length of the prop, or it would hit the wire ramp on the game.

The next step is to make a new wire support for the biplane. The biplane sits in a very tight spot on the playfield. It is very close to the glass, so it cannot be much higher than it is, and it is sandwiched between 2 ramps. Since you have added a motor, you have raised the height of the biplane if you use the old wire support. This is why you must bend a new wire compensating for the motor. I used the same screw that mounts the motor to the plastic support, to attach the wire support. I also bent the wire so that the back of the plane sits on the wire for support, similar to the original wire support.

I used a 1/16" diameter wire from my local hardware store.

Make sure you run a few tests with a ball on each wire ramp to make sure you don't hit the biplane. You may end up making a new support wire once or twice before you get it right.

Remember, there isn't much room here. If the support is too tall, the biplane will hit the playfield glass, and if the wire is too short, then the ball will hit the biplane when it comes down the wire ramp.

You can see that I rewired the motor with smaller gauge wire with a connector on the end. The motor wires run along the support wire and go through the playfield with the other ramp switches.

There also needs to be a switch that actuates the biplane's motor. This must be a new switch, so you don't cause problems with the game's switch matrix. I added a roll over switch below the left ramp just left of the plane. This was convenient because there was a screw there to hold the ramp support, and I just bent a small piece of aluminum to make a switch support.

This integrates with the game really well, since the switch at the top of the ramp causes the game to give the airplane sounds and the dogfight animation.

After the switch and the biplane are mounted and the wires are passed through the playfield, we can start working on the electrical part. As stated earlier, I tested everything while on the test bench and after the plane and switch were mounted using an old IBM AT power supply. It was completely independent of the pinball machine's power system until I was sure everything worked.

You will need a timer/driver to make the motor turn on and off. I used a Gottlieb System 80 pop bumper board. You can buy these by posting a request on rec.games.pinball, or Steve Young's Pinball Resource. You can also buy a custom driver/timer from Tom Callahan at: http://www.repairconnection.com/other_pc_products.htm.

If you choose to use a Gottlieb board, there are a couple of suggested modifications that can be found at:

http://www.marvin3m.com/sys80/index1.htm#popbump

You will also have to modify the R2 and C3 values to get the motor to turn on for the right amount of time.  I have mine turning on for 7 seconds.  Use the chart and diagram below.

R2 Value   C3 Value    "ON" Time
--------   --------    ---------
  12K      4.7 mfd     Normal (pulse)
  12K      47 mfd      1 Second
  12k      100 mfd     1.5 Seconds
  12K      470 mfd     5 Seconds
  22K      470 mfd     7 Seconds
  56K      100 mfd     7 Seconds

You will also need to decide where to mount your Timer/driver PCB. I found an open spot below the playfield above the flippers. Be VERY CAREFUL not to put a screw through the bottom of your playfield when mounting this PCB. Also make sure there are spacers so your electrical components aren't sitting against the wood.

Here is the basic wiring diagram that I stole (with permission) from Tom Callahan for his Tiger Saw kit. It is basically the same concept. Please DO NOT ask Tom for help with this modification.

You will notice that I added an optional resistor to the picture. I did this so that my motor would turn slower. I found that the motor was turning so fast that you couldn't even see the prop! You will have to experiment with the motor you use. You should probably just use a 1K potentiometer to find your sweet spot. If you turn down the voltage too far, the motor will not be able to overcome the static friction from a rest. Mine is set to 260 Ohm.

Next, you have to wire the power connections to the pinball machine's power. I HIGHLY recommend that you test everything with an alternate power supply such as a computer power supply prior to doing this next step!

We are going to get the power for the Timer/driver PCB and the motor from the Bridge Driver PCB assembly that operates the Path of Adventure mini-playfield motor. This PCB is located in the upper left-hand corner underneath the mini-playfield. The PoA motor will be connected to this PCB.

The 12V power and ground are easy, they are located on pins 4 & 5 of J1 (4-GND, 5 - 12V).

The 5V power is a little harder. You have to solder a wire to the + side of C1 & C2.

You are basically done. All that remains is to test and play. I added some white stripes to the prop so it was easier to see it turning.

You may have to make a few adjustments to make sure the ball doesn't hit the biplane's wing as it goes down the ramp. I basically just bent the plane towards the left ramp to raise the right wing.