Installing the Judge Dredd Locking Mod Opto Harness

This solution, unlike Don Weingarden's version, requires two easy solder joints under the playfield. So it is a little harder to install, but is a bit less obtrusive. It uses electronics designed for the Twilight Zone third magnet upgrade kit. Note that the Deadworld mod usually results in a credit dot because t he software expects to see switch 28, which it doesn't appear to need. But most machines don't have it, so there is an error. There is a modified ROM out there that fixes this problem.


How It Works
The switch matrix opto board connects a standard opto receiver to the switch matrix, without going through an opto board. It effectively makes an opto receiver look like a microswitch. We use this board to move the ramp entry opto from switch 67 to switch 32 on the switch matrix. So installation requires tow things:

    - making a connection to switch column three and switch row 2
    - Connecting the ramp entry opto receiver to the switch matrix opto.

First, here's a roadmap of where we will be working. You'll need to remove the balls and lift the playfield.

Area 1- where the board will be installed.
Area 2 - where the green and white wires diverge
Area 3 - the right kicker, where the white wire ends up
Area 4 - the left post target, where the green wire goes


Install the switch matrix harness

This proceedure requires:

 - the long green and white harness
 - cable ties
 - A soldering iron and solder for two joints.

Start by feeding the wire ends through the P clip at the left bottom of the playfield (area 1).




Next, feed the wire under the nearest cable tie on the switch matrix harness, which is mostly green and white wires. I find that it is usually easiest to sneak it under the latch area where there is usually a gap. If this is troublesome, use one of the supplied cable ties.


Snake the wires up the switch harness and repeat this cable clip procedure until you get the wires to the big intersection in area 2.

Run the white wire to the right kicker area 3.
Run the green wire to the left post target area 4. Cut the green wire so that it goes past the connection by about an inch and a half. Strip about 1/2" of insulation from the wire, and twist it with your fingers. Do this for the green and white wires.
Wrap the wire around the post connector with the two green wires on it. Put a cable tie around all three wires so that they are all held together and the wrapped wire wants to stay in place. Do the same thing for the white wire. I chose to wrap it around the leg of the diode because it is easy. By the way, that cable tie trick really helps for replacing switches that have more than one wire going to them.
Now, you have to solder the joints. This is really no harder than replacing a switch, and there are dozens of tutorials out there about soldering. But here are my few comments.

1) Make sure that the wire wants to stay in place. The cable clip makes this easy. And the wire just has to hook around a corner to have enough grip. We aren't trying to make a knot, just to ensure  that there is a decent surface contact.

2) With solder in hand, apply the iron to the wire.

3) Briefly touch the end of the solder to the gap where the iron and the wire meet. The solder will run into the gap, and give you good heat transfer.

4) Apply the solder to the joint. When it is hot enough, the solder will run towards the heat and fill the gaps in the joint and the wire.

That's the hard part done!


Finally, install the board and harness. First, connect the green and white harness to the board connector. Next, locate the ramp entry opto connector. This is a six-pin connector with four wires - black, orange and two grey. Disconnect the connection, and insert the harness conenctors.

Your ramp entry opto switch is now connected to switch 32.

Test Procedure

Lower the playfield, turn the machine on and head off to the switch matrix test. Interrupting the ramp entry opto will cause a beep and a report of  "Switch 32 - Not Used".

This is a good time torun through all the switches on your machine. The Deadworld lock

If the test does not work:

1) Carefully raise the playfield while in switch test mode.

2) Disconnect the six-pin harness. A beep indicates a problem with the opto board - but our boards are all tested in a machine so this should not happen. Contact us if it does. No beep means check the green/white harness wiring.

3) Reconnect the six-pin connector without the board and test again. The switch test should report "switch 67". If it does not, you have an opto problem.

Final Installation

The hard work is done. Put in the new ROM, make sure that everything works as it should. Then install the new ring.


You are done!