Finding an elusive IPAC short

[pmc]

My player-2 j/s stopped going to the right a few months ago. Tired of playing alone, I recently decided to fix the problem. But I'm stuck.

I have a 2-player PS/2 IPAC in parallel with hacked Dreamcast controllers. I make a cable swap to switch between the two. When I plug the CP into the hacked controllers, everything works fine. So I figure the problem is with the IPAC or its wiring (versus the CP).

I run the Interactive Programming and Test Mode (i.e., control-alt-p) and it indicates that Player-2 right (the "g" key) is shorted or stuck. All other controls work correctly. If I disconnect my CP completely, I'm still shorted. So I pull the wire completely off the IPAC, and I'm still shorted.

Is it possible that the IPAC is shorted internally or something? I'm not sure what else to try next. Any ideas?

-pmc

[bvicarious]

Are you using a regular ipac2, or an ipac VE? What happens when you take a piece of wire and touch one side to the ground terminal and the other to the player 2 right terminal? Does it register a keypress? If you have a multimeter, does it detect 5V between that switch and ground?

[AndyWarne]

As always with this kind of problem, I can help very quickly via email.
On the I-PAC the use of the self-test LED should not be overlooked as well, for troubleshooting. This LED will indicate any shorts present and if so, which connection is causing the problem.
Best drop me an email: andy@ultimarc.com

[pmc]

Sweet. I'll try both of those things. Andy, I'll email you tonight.

This is an early 2003 IPAC model (right before the chips changed). I don't remember seeing an LED on it and would have likely noticed a lit one. I'll look again. There's a not-so-great picture of it here.

Two other things that may or may not be relevant:

1) The pause button has fairly consistently sent an ESC when in a game. Testing shows that it maps to "P", and that a "P" keypress on the pass-thru keyboard will pause MAME. Despite that, a "P" sent from the CP results in an ESC. It's possible that my "P" wire is touching my "ESC" wire? Casual troubleshooting never turned up the problem so I stopped pausing and kept gaming. 

2) Sometimes when I leave Mamewah and go to a Windows desktop, I can't double-click things. Hitting ESC a few times clears the problem. Could be a short or stuck keypress gumming up the works?

Thanks

-pmc

[pmc]

I just got a chance to attend to this today.

What happens when you take a piece of wire and touch one side to the ground terminal and the other to the player 2 right terminal?

Nothing happens. I tried different ground points as well. Every other control works correctly. Just this one doesn't.

If you have a multimeter, does it detect 5V between that switch and ground?

It registers about 1/4 of the voltage that the rest of them register. Feels like a problem with the IPAC or the physical connection on the IPAC board itself.

I'm gonna email Andy cuz I'm stuck.

-pmc