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graf
6th August 2006, 07:43 PM
Ok going to finally start my Arcade mame box. I am using a PC + jamma harness and a jamma finger board. So the most curtial part is the keyboard encoder.

What should I go for I-PAC2 or J-PAC Keyboard Encoder ?

elvis
6th August 2006, 08:15 PM
A J-PAC is an I-PAC2 with a JAMMA connection on it.

JAMMA is 3 button by spec, so for the extra buttons needed by some games, the J-PAC has extra screw-terminals for easy connection of wires.

If you have a cabinet with an existing JAMMA harness, definitely go for a J-PAC. The simplest reason for that is so that if you ever change your mind and want to use it as a standard JAMMA cab, or if you collect boards and want to play the real deal on your cab as well as MAME, it's a trival matter of unplugging the J-PAC and slotting in a board.

My JAMMA cab at home is currently set up for PCB play only (there's a scratch-built MAME cab next to it for MAME). But I'm in the process of throwing the MAME setup inside the JAMMA cab, as well as some consoles. I'll be converting the lot across to J-PACs for MAME, and custom-built "JAMMA+" fingerboards with CPS2 kick harnesses (available from jammaboards.com) connected to gutted console controllers.

Of course, if you have no intention ever of playing/collecting PCBs, an I-PAC2 is cheaper and easier. But for only a few extra bucks you can essentially "future proof" your cab if you ever want to go the PCB route later on.

graf
6th August 2006, 08:23 PM
elvis,

My mate got the jamma harnes from you the other day. I notice that it has 1 - 5 buttons. Cause I am going to use a mame only cabinet can i just use eg the test screen cable as button six ?

I think I will go for the I-PAC2.

elvis
6th August 2006, 08:40 PM
JAMMA by official spec only allows use of 3 buttons, but there are some spare points on JAMMA harnesses, and some manufacturers excercise a little creative license calling these buttons 4 and 5.

Here's a good example:
http://www.system16.com/jamma.php

Neo Geo uses the extra 4 spaces for P1 and P2 button D (ie: button 4), and "Select Up/Down" (ie: for multi-slot boards). The JAMMA harnesses we have label these as P1/P2 buttons 4 and 5.

There's no reason why you can't direct-wire an I-PAC2 as well as a JAMMA harness to the same sticks and buttons. As long as you don't do something silly like connect a PC and a JAMMA board at the same time, it is fairly safe.

Or as you said above, go with an I-PAC2 to JAMMA fingerboard to JAMMA harness. The J-PAC is a shortcut there, but both will do the same job.

Of note - a J-PAC includes a video amplifier on the unit. This is sometimes necessary when connecting a PC's video card to an arcade monitor. But again, you can pick up a video amp as a separate unit (or make a simple version with some 220uF caps on the R, G and B lines).

Viper
6th August 2006, 08:57 PM
If you are keeping the arcade monitor and using the JAMMA harness use a J-PAC. If you are ditching the arcade monitor in favour of a PC monitor then use and I-PAC and also ditch the JAMMA harness. The JAMMA harness is a waste of time if you are going to use an I-PAC and the J-PAC is a waste of time if you are using a PC monitor.

graf
6th August 2006, 09:03 PM
I was thinking of using the jamma harnes to the i-pac as it will just make the wiring neater. I am going to ditch the arcade monitor + power supply ... Put a pc in it

Viper
6th August 2006, 09:10 PM
I was thinking of using the jamma harnes to the i-pac as it will just make the wiring neater. I am going to ditch the arcade monitor + power supply ... Put a pc in it
Right, so you're chopping the edge connector off the end and basically just using the wires. Yeah, use an I-PAC2.

graf
6th August 2006, 09:12 PM
yep thats right sort of. i am using the finger jamma finger board. so that if i ever want to go back to a jamma cabinet i can

Viper
6th August 2006, 09:19 PM
yep thats right sort of. i am using the finger jamma finger board. so that if i ever want to go back to a jamma cabinet i can
Hmm, seems like a total waste of wiring and soldering to me. But it is your cab after all! :)