a couple questions about ground wiring on the ipac4

[struby]

ok, so i cut a red wire the right length and put a quick disconnect on one end of each one for every button on my 4p cp, each with a joystick 1 and 2 players have 6 buttons each, 3 and 4 have 4 each, i have a start and coin button for each player and 3 misc buttons on top, trackball in the middle, just to give you my basic layout, on the ipac4, there are 2 ground slots, when I hook them up, how do i do so here are my questions:

are the 2 slots so i can daisy chain it from one ground slot looped around and hooked into the other, or do i just daisy chain half of the buttons to one and half to the other?

the daisy chains don't loop right, they just end at the last button?

are quick disconnects used for the power (ground) wire, or are they not worth the trouble because you would have to jam 2 wires into one QD?

[Jeff AMN]

I just have one big long daisy chain ground wire coming out of my MiniPac for all of my buttons and sticks. You could, however, run multiple lines out as long as you're always maintaining a complete circuit.

[struby]

can anyone post me up a pic or send me a link to a pic of the underside of an ipac4 4 player cp all hooked up?

[Jeff AMN]

I'll dig up a link, but if you look at Knievel's Woody project thread, you'll see a nice example of his wiring.

EDIT: Here are the pics. The green is his ground line.

[struby]

ok, that's the best one i've seen as far as clearness goes, i looked all through the big cp thread at the top and they were hard to see, so there is one ground port on that...keywiz?   and it goes out, daisy chains to all buttons, and does not make a loop/come back to the keywiz right?  and it's always ground on top thing, and button wire on the higher of the two side things, all looks good, so i guess I take one wire from my ipac 4 and hook it to the left side of my panel and the other port to the right...thanks.

[Jeff AMN]

You do not bring the ground loop back to the encoder. You just end it at one point, but, I repeat, don't bring it back to your encoder.

[javeryh]

God I love that wiring job every time I see it.

[um3k]

You do not bring the ground loop back to the encoder. You just end it at one point, but, I repeat, don't bring it back to your encoder.

There is no reason why you cannot being the ground loop back to the encoder, as long as it is tied into the same terminal or to another ground terminal.   In fact this is how I have my CP wired, a big loop from one ground terminal of the IPAC4 to the other ground terminal.   The advantage of this is that if one connection in the loop breaks, it won't effect anything because you can still ground through the other side of the loop.  (Of course if you had two or more breaks, the controls in between them would not be grounded, and therefore not work.)   In a single line grounding scheme, if one connection breaks, all the controls after that connection would stop working.

[BobA]

You do not bring the ground loop back to the encoder. You just end it at one point, but, I repeat, don't bring it back to your encoder.

This is not true.  It is no harm to bring the ground back to your encoder in a loop.  Now ground loops in audio cause problems but in the case of encoder it is a benefit.  With both ends of the ground taken to the same ground you can get a problem in your ground wiring and it will self correct because it has another path.   You will only loose your ground if you have 2 faults in the ground wiring.

NEVER do this in audio or video but for encoders it is fine.

[Jeff AMN]

I think I misunderstood what he meant by bringing the loop back. I thought he was going to bring it to a different terminal to try to make a "complete wire loop" of sorts instead of having an endpoint.

[struby]

so you guys are saying make two loops one with each terminal, like lets say i have terminals a and b for ground, and buttons 1 and two, are you saying this:

take ground wire from terminal a to button 1 to button 2 then back to terminal a, and do the same for terminal b, or are you saying go from terminal a to button 1 to button 2 and then to terminal b and do that twice?

The other option being:

that or just go from terminal a to button 1 and stop, and from terminal b to button 2 and stop

[Jeff AMN]

It seems that they've gone like this:

Ground terminal A --> Button 1 --> Button 2 --> Ground Terminal A

Come out of one terminal, daisy chain it, and return to the same terminal. At least, I'm pretty sure that's what they're doing. I actually have an endpoint in my ground line, but I might bring it back home as it would be nice to have that self-correcting failsafe.

EDIT:

Mine currently goes like this:

Ground Terminal --> Button 1 --> Button 2 --> Button 3 --> [....] --> Button 16 (end point)

[struby]

and then repeat with terminal b so you have a loop going with both, i have like a 48 inch wide cp so i dunno if i even have the wire to do that, so i might just loop one per side or not loop it,

 but basically, make a ground terminal make it's way to every button somehow and you are good right?

[Spaz Monkey]

Here's a pic from the Ultimarc website.  Notice the ground wire hitting each switch?  If you wanted to, you could run a wire from the last button to the P2 ground.  You don't have to if you don't want to, but if the wire comes loose between buttons 2 & 3 and you only have one connection, some of your buttons won't work.

[um3k]

and then repeat with terminal b so you have a loop going with both, i have like a 48 inch wide cp so i dunno if i even have the wire to do that

No, you only have to make one loop from Terminal A --> Button 1 --> Button 2 --> ... --> Terminal A (or B).   You get the extra redundancy because when there is a break in the wire, everything before the break can flow through the "left side" of the loop and everything after the break can still flow though the "right side" of the loop.   Or to put it another way, if there is a break, it has basically just created two independant single-path grounds (with endpoints).

[struby]

but as long as a black ground wire makes it's way to every button somehow, i'm good right?

[Tiger-Heli]

Right, er . . .

Also, P1 and P2 Ground are electrically the same on the I-PAC/2 - the two terminals are just for convenience - you can wire to only one of them, loop from the P1 Gnd and back to the P1Gnd, or loop from the P1Gnd and back to the P2Gnd, doesn't matter. . .

[ahofle]

If you don't want to connect every single ground around to every single button, you can also get a barrier strip and bridge from radio shack and run several grounds to it (and then run one ground from the barrier strip to your encoder):

barrier strip and bridge

[struby]

ah so confused, i think i'm going to end up taking the one ground terminal loopless to half the buttons like in the pictures with hand painted wires, and use the other terminal for the other buttons, on a side question, is the player order of 4p  cp     4p 1p 2p 3p? or 3p1p2p4p or what?

[Tiger-Heli]

More often than not

3P 1P 2P 4P

but it depends on the game.

Most dedicated 4P machines used

1P 2P 3P 4P,

but this would be bad for MK.

You could also always map the controls in MAME to the 2nd stick was P1 for 2-player games and the 1st stick was P1 for 4-player games.

In short, it's up to you !!!!

[struby]

okay thank you thank you all