Williams Games to JAMMA Conversion
For Defender, Stargate, Robotron, Joust, Sinistar and Bubbles


Introduction
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Conversion of a Williams game to JAMMA is not exactly simple, nor is it complex. Most conversions consist of merely the cables, a few switches to access the setup and test menus and a volume pot. If you follow this illustrated guide you should easily be able to get your Williams game up and running in a JAMMA cab in just a few hours. This document aims give you all the information you need to convert a Williams boardset, finishing with an Example Robotron to JAMMA Conversion. This article applies only to original Williams Defender, Stargate, Robotron, Joust, Sinistar and Bubbles video games and assumes that your boards are compatible and working properly. You can identify you boards on my Williams Hardware Identification and Compatibility Page.

All the connectors used on Williams boards are designated with a three-letter code, for example the power connector on the CPU is 1J1. The first '1' meaning the CPU, the 'J' meaning it is the male connector on the board (which will mate with female connector 1P1) and the second '1' meaning that it is the first connector on the CPU board. All connectors will be referred to using this method.



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Parts Required
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For your Williams JAMMA adapter you will need:
  • 1x JAMMA fingerboard
  • 1x 50Kohm Logarithmic Volume Pot rated at 1w
  • 3x 10 Way Female Molex .156" connectors and pins
  • 4x 9 Way Female Molex .156" connectors and pins
  • 1x 7 Way Female Molex .156" connector and pins
  • 1x 6 Way Female Molex .156" connector and pins
  • 4x 4 Way Female Molex .156" connectors and pins
  • 3x subminiature toggle switches
  • Suitable wire in assorted colours





Standard JAMMA Pinout
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Solder Side   Pin No Pin No   Component Side
Ground   A 1   Ground
Ground   B 2   G round
+5v   C 3   +5v
+5v   D 4   +5v
-5v   E 5   -5v
+12v   F 6   +12v
Key   H 7   Key
Coin Counter 2   J 8   Coin Counter 1
Coin Lockout 2   K 9   Coin Lockout 1
Speaker-  L 10   Speaker+
No Connection  M 11   No Connection
Video Green  N 12   Video Red
Video Sync  P 13   Video Blue
Service  R 14   Video Ground
Tilt  S 15   Test
Coin 2  T 16   Coin 1
Player 2 Start  U 17   Player 1 Start
Player 2 Up  V 18   Player 1 Up
Player 2 Down  W 19   Player 1 Down
Player 2 Left  X 20   Player 1 Left
Player 2 Right  Y 21   Player 1 Right
Player 2 Button 1  Z 22   Player 1 Button 1
Player 2 Button 2  a 23   Player 1 Button 2
Player 2 Button 3  b 24   Player 1 Button 3
Player 2 Button 4  c 25   Player 1 Button 4
No Connection  d 26   No Connection
Ground  e 27   Ground
Ground  f 28   Ground





Power Wiring
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The CPU, ROM and Sound boards all need various voltages to power them. The interface board and the Sinistar speech board do not need power as they obtain it through their ribbon cable, though the inputs to the interface board will need grounding, but that will be covered in the controls section. If you wish to replace the Williams PSU in your game with a modern switching PSU, this part of the JAMMA conversion is all you need.



The CPU Board
The CPU board requires +5v regulated, -5v regulated, +12v regulated, ground and +12 unregulated power supplies. Since the CPU will work fine if you use +12 regulated instead of the +12 unregulated, a JAMMA PSU will work fine here. All the power connections to the CPU board are made to connector 1J1, which is a 9 pin Molex connector. See the diagrams below for exact wiring details:

1J1
View a high resolution image of the Early Series Defender CPU Board
Early Series Defender CPU Board
Click to Enlarge
1J1
View a high resolution image of the Later Series Defender CPU Board
Later Series Defender CPU Board
Click to Enlarge
1J1

View a high resolution image of a typical CPU Board for other games (layout may vary slighty depending on revision)
A typical CPU Board for other games
(layout may vary slightly depending on revision)
Click to Enlarge

CPU Board
Power Connector 1J1
All Board Types

Pin Connection Notes
9 -5v DC Top
8 +12v DC Unregulated DC
7 +5v DC  
6 +5v DC Not connected on factory harness
5 +12v DC  
4 Key No Connection - pin removed
3 Ground  
2 Ground  
1 Ground Bottom, Not connected on factory harness


The ROM Board
The ROM board requires +5v regulated and ground so a JAMMA PSU will also work fine here. All the power connections to the ROM board are made to connector 2J2, which is a 4 pin Molex connector on Defender and Stargate boards and a 6 pin Molex connector on all other boards. Since the pins that are used are the same for all games we can still make a loom that will work for all games. See the diagrams below for exact wiring details:

2J2
View a high resolution image of the Early Series Defender ROM Board
Early Defender ROM Board
Click to Enlarge
2J2
View a high resolution image of the Later Series Defender ROM Board
Later Defender ROM Board
Click to Enlarge
2J2
View a high resolution image of the Stargate ROM Board
Stargate ROM Board
Click to Enlarge


ROM Board
Power Connector 2J2
Defender and Stargate

Pin Connection Notes
4 +5v DC Top
3 Key  
2 No Connection  
1 Ground Bottom


2J2
View a high resolution image of the Robotron/Joust ROM Board
Robotron/Joust ROM Board
Click to Enlarge
2J2
View a high resolution image of the Sinistar ROM Board
Sinistar ROM Board
Click to Enlarge
ROM Board
Power Connector 2J2
Robotron, Joust,
Sinistar and Bubbles

Pin Connection Notes
6 No Connection Top
5 No Connection  
4 +5v DC  
3 Key  
2 No Connection  
1 Ground Bottom


The Sound Board
The Sound board requires +12v unregulated, -12v unregulated and ground. The +12v and -12v are rectified on the sound board to produce its own regulated +5v supply. If you use -5v and +12v from the JAMMA PSU it will work fine. All the power connections to the sound board are made to connector 10J1, which is a 9 pin Molex connector. Note that some sound boards may not have the keying pin removed! See the diagrams below for exact wiring details:





Click to Enlarge
D8224 Sound Board (all games)
View a high resolution image of the D8224(later series) sound board
Sound Board
Power Connector 10J1

Pin Connection Notes
9 No Connection Right
8 -5v DC -12v DC if using Williams PSU
7 Key  
6 No Connection  
5 Ground  
4 No Connection  
3 No Connection  
2 +12v DC  
1 No Connection Bottom

10J1





Video Wiring
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The Video wiring is the most difficult part of a Williams to JAMMA conversion. The Manuals state that the boards only output Vertical (Vsync) and Horizontal (Hsync) sync pulses with positive polarity, yet a true JAMMA monitor requires negative composite (Csync). However, in most cases we are lucky, as all boards except for early Defenders have positive Csync available. This can either be inverted or a simple modification can be carried out to give you the required negative Csync.



Video On Early Series Defender Boards
OK, so we don't have Csync at all so we must create it ourselves. In a nutshell we take the Hsync and Vsync combining them to be Csync. Since the Csync we have created is the wrong polarity we then invert it. The circuit below shows how we achieve this:

Early Series Defender Comosite Sync Circuit
Early Series Defender Composite Sync Circuit

Since we now have the means to make JAMMA friendly Csync on our early series CPU, all we need to do is wire the connector up as shown in the diagrams below:

1J3
View a high resolution image of the Early Series Defender CPU Board
Early Series Defender CPU Board
Click to Enlarge
CPU Board
Video Connector 1J3
Early Series Defender Boards

Pin Connection Notes
7 Key Top
6 Horizontal Sync  
5 Vertical Sync  
4 Ground  
3 Blue Signal  
2 Green Signal  
1 Red Signal Bottom


Video On All Other Boards
An undocumented feature of all the 2 Decoder Williams boards (i.e. later series Defender games onwards) is that pin 7 of the video connector 1J3 carries positive Csync. All we need to do to make this JAMMA friendly is invert it. There are two ways of doing this:

1. Invert the Csync video signal from 1J3 pin 7 using the circuit below:

Composite Sync Inversion Circuit
Composite Sync Inversion Circuit

2. Modify the CPU board to output negative Csync. This is easily achieved by removing link W1 from the CPU board. W1 is not so much of a link though as the schematics might suggest but a track on the PCB. There are holes on the PCB each side of the track though so you can easily reverse the modification by fitting a wire link or zero ohm resistor to bridge the gap. The two photos below show where you need to cut on later series Defender boards and Stargate and later games boards:

Composite Sync Inversion Modification for Later Series Defenders
Later Series Defenders
Click to Enlarge
Composite Sync Inversion Modification for Stargate and Later Games
Stargate and Later Games
Click to Enlarge

Since we now have the means to make JAMMA friendly Csync on our CPU, all we need to do is wire the connector up as shown in the diagrams below:

1J3
View a high resolution image of a typical CPU Board for other games (layout may vary slighty depending on revision)
A typical CPU Board for other games
(layout may vary slightly depending on revision)
Click to Enlarge
CPU Board
Video Connector 1J3
Stargate and Later Games

Pin Connection Notes
7 Composite Sync Top
6 Horizontal Sync  
5 Vertical Sync  
4 Ground  
3 Blue Signal  
2 Green Signal  
1 Red Signal Bottom





Coin Door Wiring
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The coin-door controls consist of the inputs from the coin mechanisms and the three switches (Auto/Manual, Advance and High Score Reset) which are used to control the pricing, difficulty and bookkeeping of the game. The Advance and High Score Reset switches should be momentary and normally open; whereas the Auto/Manual switch is latching. Each switch should be wired to ground on one side and the input to the ROM boards coin door connector 2J3, which is a 10 pin Molex connector. The connection is the same for all board variants. See the diagrams below for exact wiring details:



2J3


2J3
ROM Board
Coin Door Connector 2J3
All Board Types

Pin Connection Notes
10 Ground Right
9 Key  
8 No Connection  
7 No Connection  
6 Center Coin  
5 Left Coin  
4 High Score Reset  
3 Right Coin  
2 Advance  
1 Auto/Manual Left
View a high resolution image of the Robotron/Joust ROM Board
Robotron/Joust ROM Board
(layout may vary with game)
Click to Enlarge
View a high resolution image of the Sinistar ROM Board
Sinistar ROM Board
Click to Enlarge





Player Controls Wiring
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The player controls consist of the inputs from the control panel; each switch should be normally open and wired to ground on one side and the input to the interface board on the other. There are four types of interface board which are used in various games so the exact wiring for each will be dealt with separately below:

Note: All the pinouts shown here assume that you are wiring up an upright game.

Early Series Defender Interface Boards


View a high resolution image of the C8353 (early series) Defender interface board
3J2

3J3
Early Series
Defender Interface Board
Controls Connector 3J2

Pin Connection Notes
10 Ground Top
9 No Connection  
8 No Connection  
7 No Connection  
6 Key  
5 No Connection  
4 No Connection  
3 No Connection  
2 No Connection  
1 Up Bottom
Early Series
Defender Interface Board
Controls Connector 3J3

Pin Connection Notes
10 Ground Top
9 Key  
8 Down  
7 Reverse  
6 1 Player Start  
5 2 Player Start  
4 Hyperspace  
3 Smart Bomb  
2 Thrust  
1 Fire Bottom
Early Series
Defender Interface Board
Click to Enlarge




Later Series Defender Interface Boards

View a high resolution image of the C8573 (later series) Defender interface board 3J2

3J3
Later Series
Defender Interface Board
Controls Connector 3J2

Pin Connection Notes
10 Ground Top
9 P2 Up Cocktail Games Only
8 P2 Down Cocktail Games Only
7 P2 Reverse Cocktail Games Only
6 Key  
5 P2 Hyperspace Cocktail Games Only
4 P2 Smart Bomb Cocktail Games Only
3 P2 Thrust Cocktail Games Only
2 P2 Fire Cocktail Games Only
1 P1 Up Bottom
Later Series
Defender Interface Board
Controls Connector 3J3

Pin Connection Notes
10 Ground Top
9 Key  
8 P1 Down  
7 P1 Reverse  
6 1 Player Start  
5 2 Player Start  
4 P1 Hyperspace  
3 P1 Smart Bomb  
2 P1 Thrust  
1 P1 Fire Bottom
Later Series
Defender Interface Board
Click to Enlarge




Stargate Interface Boards

View a high resolution image of the C8783 Stargate interface board 3J2

3J3
Stargate Interface Board
Controls Connector 3J2

Pin Connection Notes
1 Up Top
2 No Connection  
3 No Connection  
4 No Connection  
5 No Connection  
6 No Connection  
7 No Connection  
8 No Connection  
9 No Connection  
10 Ground Bottom
Stargate Interface Board
Controls Connector 3J3

Pin Connection Notes
1 Fire Top
2 Thrust  
3 Smart Bomb  
4 Hyperspace  
5 2 Player Start  
6 1 Player Start  
7 Reverse  
8 Down  
9 Inviso  
10 Ground Bottom
Stargate Interface Board
Click to Enlarge




Robotron Interface Boards

View a high resolution image of the C8783 Robotron interface board 3J2

3J3
Robotron Interface Board
Controls Connector 3J2
(Remove Jumper W1 to Enable P2 Cocktail Controls)
Pin Connection Notes
1 Fire Left Top
2 P2 Move Up Cocktail Games Only
3 P2 Move Down Cocktail Games Only
4 P2 Move Left Cocktail Games Only
5 P2 Move Right Cocktail Games Only
6 P2 Fire Right Cocktail Games Only
7 P2 Fire Up Cocktail Games Only
8 P2 Fire Down Cocktail Games Only
9 P2 Fire Left Cocktail Games Only
10 Ground Bottom
Robotron Interface Board
Controls Connector 3J3

Pin Connection Notes
1 Move Up Top
2 Move Down  
3 Move Left  
4 Move Right  
5 1 Player Start  
6 2 Player Start  
7 Fire Up  
8 Fire Down  
9 Fire Right  
10 Ground Bottom
Robotron Interface Board
Click to Enlarge




Joust Interface Boards

View a high resolution image of the C8783 Joust interface board 3J2

3J3
Joust Interface Board
Controls Connector 3J2

Pin Connection Notes
1 No Connection Top
2 Player 2 Move Left  
3 Player 2 Move Right  
4 Player 2 Flap  
5 No Connection  
6 No Connection  
7 No Connection  
8 No Connection  
9 No Connection  
10 Ground Bottom
Joust Interface Board
Controls Connector 3J3

Pin Connection Notes
1 Player 1 Move Left Top
2 Player 1 Move Right  
3 Player 1 Flap  
4 No Connection  
5 1 Player Start  
6 2 Player Start  
7 No Connection  
8 No Connection  
9 No Connection  
10 Ground Bottom
Joust Interface Board
Click to Enlarge




Bubbles Interface Boards

View a high resolution image of the C8783 Bubbles interface board 3J2

3J3
Bubbles Interface Board
Controls Connector 3J2







NOT USED
Bubbles Interface Board
Controls Connector 3J3

Pin Connection Notes
1 Move Up Top
2 Move Down  
3 Move Left  
4 Move Right  
5 1 Player Start  
6 2 Player Start  
7 No Connection  
8 No Connection  
9 No Connection  
10 Ground Bottom
Bubbles Interface Board
Click to Enlarge




Sinistar Interface Boards

You may find the using a standard 8-way joystick with Sinistar page useful

View a high resolution image of the C9191 Sinistar interface board 3J2

3J3
Sinistar Interface Board
Controls Connector 3J2

Pin Connection Notes
1 Up/Down Switch A Top
2 Up/Down Switch B  
3 Up/Down Switch C  
4 Up/Down Direction  
5 Left/Right Switch A  
6 No Connection  
7 Left/Right Switch B  
8 Left/Right Switch C  
9 Left/Right Direction  
10 Fire  
11 Sinibomb  
12 No Connection  
13 1 Player Start  
14 2 Player Start  
15 Ground Bottom
Sinistar Interface Board
Controls Connector 3J3











NOT USED
Sinistar Interface Board
Click to Enlarge








Sound Board Wiring
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The power supply for the sound board has already been dealt with, next we need to wire up the speaker, volume control and the control inputs from the ROM board. All quite straightforward here, but make sure you use a 50Kohm Logarithmic 1Watt Potentiometer here. If you are wiring up a Sinistar then you'll also have to connect the Speech board to the Sound board via the 40 way ribbon cable. See the diagrams below for exact wiring details:




Click to Enlarge
Sound Board
View a high resolution image of the D8224 sound board
Sound Board
Speaker Connector 10J2

Pin Connection Notes
1 Speaker + Left
2 No Connection  
3 No Connection  
4 Speaker - Right
Sound Board
Volume POT Connector 10J4

Pin Connection Notes
1 Sound In (POT Centre) Left
2 Sound Out (POT Left)  
3 Key  
4 Ground (POT Right) Right

10J210J410J3

The cable between the ROM board and the Sound board carries the binary signals that trigger each individual sound. Simply wire each of the 7 wires pin to pin between the boards as shown below:

2J4
ROM Board
Sound Interface Out 2J4

Pin Connection Notes
1 Key Left
2 Sound Bit 1  
3 Sound Bit 2 Bottom
4 Sound Bit 3  
5 Sound Bit 4  
6 Sound Bit 5 Bottom
7 Sound Bit 6 Top
8 Sound Bit 7  
9 No Connection Right
Sound Board
Sound Interface In 10J3

Pin Connection Notes
1 Key Left
2 Sound Bit 1  
3 Sound Bit 2 Bottom
4 Sound Bit 3  
5 Sound Bit 4  
6 Sound Bit 5 Bottom
7 Sound Bit 6 Top
8 Sound Bit 7  
9 No Connection Right
View a high resolution image of the Robotron/Joust ROM Board
Robotron/Joust ROM Board
(layout may vary with game)
Click to Enlarge





Example Conversion
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In order to build a complete JAMMA loom the first thing we need to do is decide how we are going to lay out the boards. In a Williams cabinet the boards are mounted on a grounded metal plate making sure all the boards are bonded together, however if you do not have the metal plate this is not necessary since all the boards are grounded through their Molex connectors. You can either mount them on a piece of MDF, directly to the inside of the JAMMA cab or on a metal plate if you have one. The pictures below show two suggested layouts, though of course the final choice is up to you.


Suggested Board Layout
Suggested Board Layout
Click to Enlarge
Alternative Suggested Board Layout
Alternative Suggested Board Layout
Click to Enlarge

Once you have laid out the boards, mark out the cable routing, number of cables and length on some paper so you can cut all the wires to length.

Cable Length and Number of Wires Marked Out
Cable Length and Number of Wires Marked Out
Click to Enlarge

Now we are ready to make our loom. The best way is to cut all the cables first and make them into a rough loom using whatever colour scheme you have chosen. I just used red for everything except the ground wires which are black, however I have used a smaller gauge wire for economy on the controls and video wiring.

The loom cut and laid out ready for connectors to be fitted
The loom cut and laid out ready
for connectors to be fitted
Click to Enlarge

Terminate the loom's Molex connectors one by one ensuring that the wires are going to the right place as detailed previously in this document. DO NOT terminate the JAMMA fingerboard, volume pot or set up buttons at this point. Now connect the Molex connectors to the boards and take up any slack in your loom.

The Molex connector's all terminated
The Molex connector's all terminated
Click to Enlarge
Take up the slack in the loom and tie the cables together. This is best done with the boards connected to the PCB's
Take up the slack in the loom and tie the
cables together. This is best done with
the boards connected to the PCB's
Click to Enlarge

Next we need to wire up the volume control and set-up switches. Remember that the Auto/Manual switch should be normally closed and latching, and the Advance and High Score Reset switches are normally open with non-latching switches preferred but not essential. The best method of mounting the switches is to build the three switches and volume pot into a small box, although you could add switches to your JAMMA cab and use the JAMMA loom.

The control box built and wired up
The control box built and wired up
Click to Enlarge

Finally we need to wire up the JAMMA connector. The best way to do this is to use an ohmmeter to identify each wire from the Molex connector to the JAMMA loom. Identify and solder the wires in place one by one, being careful not to make any wrong connections.

The JAMMA Connector
The JAMMA Connector
Click to Enlarge
The completed loom
The completed loom
Click to Enlarge

Getting ready to power up your JAMMA adapter for the first time

Once our JAMMA loom is complete, and you are sure there are no mistakes you are ready to power it up. IMPORTANT! Just to be sure that you have not made any mistakes, power up the loom without any boards connected and measure the voltage at EVERY pin of the Molex connectors to ensure that all voltages are correct and there is no volts present where there should be none. When connecting all the various boards and cables up don't forget to connect the ROM and Interface ribbon cables to the CPU! Once this is done you are ready to go! CONGRATULATIONS!

The Completed JAMMA loom wired up
The Completed JAMMA loom wired up
Click to Enlarge


The CPU board connectors
The CPU board connectors
Note that there is NO connection
to the 4 pin Molex connector
Click to Enlarge
The ROM board connectors
The ROM board connectors
Click to Enlarge
The Sound board connectors
The Sound board connectors
Click to Enlarge
The Interface board connectors
The Interface board connectors
Click to Enlarge



Disclaimer: Although I have done my best to ensure that all information contained on this
page is correct, I can take no responsibility for damage to your game, its boards or yourself!