OK lets try this...

keithsarcade

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Since no one seems to have an answer for my remote JAMMA switcher query, lets just try a simple question and go from there...

Will running only -5v to a PCB for an extended amount of time have any harmful effects to the PCB?

I'm ready to try this but am a little scared of ruining a perfectly good boardset.

Thanks in advance.
 
I'm not sure I understand the reasoning, but I personally wouldn't run -5V to a board without the other voltages, at least not without looking at what uses the -5V.

DogP
 
Does the unit switch ground from board to board? So long as the ground is disconnected, it doesn't matter what voltages are ran to it, as there isn't a complete path for current to flow through. Furthermore, if i understand correctly, it has -5 on one side of the fingerboard but not the other - ie pin 5, but not pin E. If the -5 is switched to the side that its run to, just jumper from 5 to E. If not, so long as the ground is switched, it really doesn't matter.
Fwiw, on all my multis, i run all 3 voltages to the pcb, and just switch the ground. I close the switch and that grounds whichever pcb i want powered up at the time. Clear as mud???
edit - you can also just add a pin to your harness on whichever one isn't connected, and connect it to the one that is, and you'll get your -5 that way.
 
OK, thanks for confirming this... still having the button issue though. I forgot to mention I also went ahead and bridged the pads for the test button, so I can now at least go into the test menu. Acually, the test switch on MK is one thats stuck now, so it just goes straight to the menu anyway. I go to switch test and find that both low punch and low kick for both players are always on along with the left coin switch and now test switch. MKII is not having this issue, working all the way. Any ideas? I'm about to forget this remote switcher idea and go back to swapping the harness around.
 
Does the unit switch ground from board to board? So long as the ground is disconnected, it doesn't matter what voltages are ran to it, as there isn't a complete path for current to flow through. Furthermore, if i understand correctly, it has -5 on one side of the fingerboard but not the other - ie pin 5, but not pin E. If the -5 is switched to the side that its run to, just jumper from 5 to E. If not, so long as the ground is switched, it really doesn't matter.
Fwiw, on all my multis, i run all 3 voltages to the pcb, and just switch the ground. I close the switch and that grounds whichever pcb i want powered up at the time. Clear as mud???
edit - you can also just add a pin to your harness on whichever one isn't connected, and connect it to the one that is, and you'll get your -5 that way.

That's only sorta true though. Ground isn't the only return path for current, and if you have +12V and -5V, you've actually got 17V on that circuit, unless their circuits are completely segregated (and the same for any other voltages). Certainly don't try it on an old board like Space Invaders, where there's triple supply ICs like the RAMs and EPROMs. You also have to look at leakage from I/O pins on ICs.

It also sounds like you're asking for trouble in the case where a ground completes the circuit from a mounting bracket or something... or in the case that the video ground makes connection before the main ground, and the return path is through the video ground switch and wires.

I'd personally wire a relay to switch the -5V... it'd be really easy, just go to radio shack, get a 12V relay, connect it to the switched 12V, and run the -5V from the power supply through it.

DogP
 
swap the connector to the mk and mk2 pcb's and see if the problem follows the connector, or stays with the pcb.

DogP - in my case, the i/o is switched by a parallel port. Ground is the only return current path. Without the schematics, its impossible to say what's going on on his switching unit.
At any rate, adding a relay, while it might be overkill isn't a bad idea, especially if your unsure about whats going on in the switching unit.
 
Since no one seems to have an answer for my remote JAMMA switcher query, lets just try a simple question and go from there...

Will running only -5v to a PCB for an extended amount of time have any harmful effects to the PCB?

I'm ready to try this but am a little scared of ruining a perfectly good boardset.

Thanks in advance.
Iv read were you have to hook up the -5 cause the baord dosent do it but id look into more
 
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