home · games · tech info · articles · about · contact us
Disclaimer: This information is provided as is. There may be errors in this information. You may use this information only if you agree that Minimalist / Coinop.org, its employees, and noted authors will never be held responsible for any damage, injury, death, mayhem, etc. caused by errors in the information. When working with high voltage, never work alone and always follow safety precautions.

Document Title: [Galaxian To JAMMA.html (html file)]

Conversion of Galaxians from AC to DC by Paul Swan This is what I did to convert my "Galaxians" before building a wiring harness to convert it to JAMMA. One of my boards had three of the four 7V AC supply edge connector fingers burnt away and so I "commendeered" the coin counter/lockout +7V DC supply pins to improve the power distribution. All the wire links added were 1mm solid core domestic wiring cable, rated 15A, unless stated otherwise. 
Remove  IR2 (78GU I.C.)   
Remove  IR1 (D44VM4 transistor)
Remove  R88 (50Ohm 5W resistor)
Replace D4  (A15F diode) with a wire link
Replace D5  (A15F diode) with a wire link
Replace D6  (A14F diode) with a wire link
Replace D7  (A14F diode) with a wire link
Replace R87 (4Ohm 10W resistor) with a wire link
Add a wire link from edge connector pair 5,E to edge connector pair 4,D
 (0.6mm solid core, via to via)
A fuse, F1, was listed in the schematic but didn't seem to be implemented (explicitely) on any of my boards. If it does exist, it should be bypassed with a wire link and the whole supply fused at source.

For reference, here are the pinouts for both the original AC supply and the DC converted supply:-

AC SUPPLY

 

       PARTS               SOLDER   
--------------------X--------------------
GND               A   1               GND
GND               B   2               GND
7V AC "+"         C   3         7V AC "+"
7V AC "-"         D   4         7V AC "-"
+7V DC out        E   5        +7V DC out
1P Start Lamp     F   6     2P Start Lamp
Coin Lockout      H   7      Coin Counter
Coin 1            J   8            Coin 2
Test              K   9           Service
1 Player Start    L  10    2 Player Start
Player 1 Left     M  11    Player 1 Right
Player 1 Fire     N  12     Player 2 Fire
Player 2 Left     P  13    Player 2 Right
Table             R  14     (spare input)
GND               S  15         Video GND
Video Red         T  16       Video Green
Video Blue        U  17        Video Sync
Speaker A         V  18         Speaker B
12V AC "+"        W  19        12V AC "+"
12V AC "-"        X  20        12V AC "-"
GND               Y  21               GND
GND               Z  22               GND
--------------------X--------------------

CONVERTED DC SUPPLY

       PARTS               SOLDER   
--------------------X--------------------
GND               A   1               GND
GND               B   2               GND
+5V DC            C   3            +5V DC
+5V DC            D   4            +5V DC
+5V DC            E   5            +5V DC
1P Start Lamp     F   6     2P Start Lamp
Coin Lockout      H   7      Coin Counter
Coin 1            J   8            Coin 2
Test              K   9           Service
1 Player Start    L  10    2 Player Start
Player 1 Left     M  11    Player 1 Right
Player 1 Fire     N  12     Player 2 Fire
Player 2 Left     P  13    Player 2 Right
Table             R  14     (spare input)
GND               S  15         Video GND
Video Red         T  16       Video Green
Video Blue        U  17        Video Sync
Speaker A         V  18         Speaker B
+12V DC           W  19           +12V DC
+12V DC           X  20           +12V DC
GND               Y  21               GND
GND               Z  22               GND
--------------------X--------------------