J-PAC/Jamma Plus

[xads308]

Hello, I have a Street Fighter 2 CE that I'm going to do an EXTREMELY simple MAME conversion on; I just need some help with the controls. I ordered a J-PAC, and I'll only be using it for the controls (I'm just going to get an LCD monitor...yes, you read that right, and connect it straight to the computer). Now, there was a time where the arcade machine worked perfect; I could play SF2CE on it, and when I wanted to play something else, I could just swap out the board for, say, Pit Fighter or Double Dribble. Now, my question is this: do I need to do any extra wiring to get all of the switches to work on the machine? For each player, there is an 8 way joystick, 6 player buttons, one start button, and one coin button. Since it is JAMMA+, do I need to wire the extra 3 player buttons each player gets to the J-PAC? Sorry for the exhaustive question; ANY help is appreciated.

[BobA]

This is a direct quote from the Ultimarc site:

"Game boards which need more buttons have an auxiliary button connector which can vary in type. This is not part of the JAMMA standard. The J-PAC caters for these extra buttons by having screw terminal inputs for these extra inputs.Inputs supported directly through the JAMMA connector are:Player 1 and 2 joysticks, Player 1 and 2 buttons 1,2,3,4. Coin 1, Coin 2, Start1, Start2.
Inputs supported by the screw terminals are:
Player 1 and 2 buttons 4,5,6,7,8.
Note that button 4 can be connected via either method as some JAMMA harnesses route this button through the connector.
If you have a 4 player cabinet you can use an I-PAC2 board as well as a J-PAC and plug the I-PAC into the pass-through connector of the J-PAC. You will need to re-program the I-PAC board for correct player 3 and 4 keycodes."

So you can wire your extra buttons 5 and 6  for each player direct to screw terminals on the Jpac board.   This means cutting the existing connectors for these buttons and wiring them direct to the Jpac since the jamma does not handle them.

[xads308]

So, if I wire the 5th and 6th buttons to their respective positions on the J-PAC (for player 1, 1SW5 and 1SW6 and for player 2, 2SW5 and 2SW6) they'll work, right? And finding out which buttons are designated as 5 and 6 is as simple as trying to map all the buttons in MAME and finding the two that don't respond? And (sorry for all these questions), the start buttons/coin doors will work right off the bat, right (like, these won't be counted as extra buttons beyond the 4 allowed by the J-PAC)?

[BobA]

Start and Coin are normal Jamma buttons so are connected via the Jamma harness.   5 and 6 will need to be wired via the terminal strip on the jpac. Button 4 will have to be wired depending on how it is setup on the Jamma harness or on the kick harness.   If wired via a kick harness it will need to be connected to the terminal strip.   Since there is no standard for button 4 on the jamma connector it will depend on how it was wired on the original game.

[xads308]

Ok, that seems easy enough, just wiring buttons 5 and 6 to the screws. But do I need to do anything with the grounds?

[BobA]

The main ground should be daisy chained to the COM terminal of all your switches.   Most of the grounds are connected together when a board is plugged into the jamma harness.

[paigeoliver]

If it is a Street Fighter 2 then button 4 should also be on the extra harness and not on the main jamma edge.

It seems like Neo Geo was the only common game that put button 4 on the edge connector.