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6 buttons in opt for 750 elf jammer

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PL1:

--- Quote from: Tumuchfun8487 on January 31, 2026, 11:53:11 am ---So I understand.  You recommend soldering input wires with qd to the 26 pin? 

My wire harness already has a soldered wires with qd on 27, e but the manual says not to connect grounds to the buttons.

--- End quote ---

Sounds like this is what you have on your JAMMA harness because a JAMMA PCB uses pin 27 as a ground:

Pin 27 ________________  QD
                                   |
                                   |___  QD
                                   |
                                   |___  QD
                                   |
                                   |___  QD

This is how you would modify it for a CHAMMA PCB like your Game Elf that uses pin 27 as an input:

Pin 27 ________________  QD
                                   X  <--------  Cut the wire to the un-needed daisy chain QDs.
                                   |___  QD
                                   |
                                   |___  QD
                                   |
                                   |___  QD

Connect the pin 27 QD to the NO tab on the P1B6 microswitch.

Connect a daisy chain ground from pin 28 to the COM tab on the P1B6 microswitch.

When you press P1B6, ground from pin 28 goes through the pushbutton to the input on pin 27 which is seen by the game as a button press.


Scott

Tumuchfun8487:
Thank you.  Appreciate the. detail. 

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