system 1 Jamma harness for marble madness

HanKouh

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Donor 2011, 2015
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Hoboken, New Jersey
I have a System 1 Indy Jamma harness. I'm trying to modify it to work with Marble Madness. looks like i just need to connect the trackball to J103 on the main board, pins 6,7,8 and 10. the trackball has +5 and ground connections from the jamma connector. so, i didn't connect pins 1 and 11 on J103. looks like it should work, but can't move the marble. game coins up and starts, but no movement. is there any other connections i need to make for MM? thanks!
 
Make sure that their is a LETA chip at location 12C on the System1 motherboard. Not all games used that chip and so some of the pcbs do not have that chip present. Without that chip, the trackballs will not work.

Brian
 
I'm testing three main boards and they all have the LETA chip near the J103 connector. All three have the same marking, 137304-1001. But, same problem with all three, no response from the trackball. The trackball I'm using is a centipede size Wico. I'm assuming any trackball should work. Anything else I should check? Is there a setting or a jumper that needs to be set for MM?
 
problem solved. it turned out to be my crazy jamma test setup. i have the trackball and player 1 joystick connected together, so that i can connect the trackball inputs to player 1 u,d,l,r on the jamma connector. this worked fine for missile command jamma adapter, but MM doesn't like this. i connected another trackball to the system 1 jamma harness and MM works fine. thanks all.
 
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