HELP NEEDED- reverting jamma cabinet back to mono from stereo

[SouthernFist]

hey guys
  i will try to make this as clear as possible, however if it is convoluded feel free to ask for more clarification.

I removed a stereo amp from my cabinet and am having problems figuring out how to wire normal jamma back in. The speakers leads were connected directly to the stereo amp, each with theyre own ground. The leads coming from the jamma loom (pins L-10) are both wired into the front of the cabinet on the volume control knob.

I am not concerned with losing the volume control knob, but how do I reconnect the speakers (L/R + 2 grounds) to the loom that only supports 2 wires? Here is what I am thinking though, connect the 2 speaker wires appropriately and run a new ground from the loom to one speaker(-) and daisy chain that ground to other speaker(-).

Does this sound right? If not, can anyone please help me out here? I am still learning alot about this stuff and any help is greatly appreciated. Thanks very much.

[Kevin Mullins]

If the wiring (L & 10) from the JAMMA harness is going to the volume control (potentiometer)..... then what do you have "leaving" the volume control going "where"?

I assume it went from the JAMMA harness connector to the volume control then to the amp that was in there and from there to the speakers.
So you should have some wiring left over coming from the volume control that is not connected to anything now, right? (used to connect to the amp)

What kind of speakers are they?
I ask because I'm curious if you will have enough power to drive them just from the JAMMA harness without an amp of some sorts.

Is this a MAME setup or true JAMMA tha requires a game pcb?

[SouthernFist]

hey kevin
thanks for the reply. these are standard Jamma cabient speakers nothing fancy and the cabinet is running normal jamma PCBs and not MAME. I am guessing the simplest option is to just lose the volume control and wire each speaker into pins L/10 and have it grounded by the loom. Is that going to work? I think maybe I was making it more confusing for myself then neccesary.

The potentiometer was not wired back into the AC convertor from what I could tell. The AC convertor was plugged into the stereo amp via a 3 pin connector as were the speaker connections on a 4 pin (2 leads, 2 grounds) from there the AV plugs connect to the PCB. I am guessing the speakers were wired independently so running them off the loom is only a matter of losing the potentiometer and hooking the speakers up in it's place. I think? If they were wired independently then i guess that would explain them each having theyre own ground. The AC convertor was used only as a means to lower interference from my understanding, i know a guy who has installed these same stereo boards in his cabinets minus the AC convertor by running a 12v line to one of the pins that the AC convertor plugged into.

Do you think the above is best or would you advice connecting pin 10 to Right speaker (+), pin L to Left speaker (+) and then maybe use a scotch lock to tap off the ground and wire the ground to Right speaker (-) and then daisy chain it to Left Speaker (-).

Hope this all makes sense man and thanks again for the help.

[Kevin Mullins]

I meant to ask before if there was any "Ohm" rating marked on those speakers?

The other thing you need to think about is whether or not the JAMMA boards you will be running will have there own volume control, either a small potentiometer on the board or by changing it in some sort of on screen menu.
Not sure off hand if there are any JAMMA boards out there that do not have any built in control.

[SouthernFist]

hey kevin
   yup the only thing being run on this cabinet will be CPS2 games which all have both a volume control on the board itself and via the test switch, which was why I was not too converned about losing the potentiometer in the cabinet itself. Given that, does one of the methods I suggested seem best? If so which one. As for the speaker Ohm rating, I'll get back to yo on that in a little bit. Thanks for all the help man.

[Kevin Mullins]

Both methods you mentioned are close.....
One of two ways you can do it simply.

L = negative
10 = positive

(don't use  the term "ground" for this)

Method 1:
Run from pin L to the negative side of one speaker and then daisy chain from there to the other speakers negative.
Run from pin 10 to the positive of one speaker and then daisy chain from there to the other speakers positive.

Method 2:
Run from pin L to the negative side of one speaker.
Run from pin 10 to the positive of the OTHER speaker.
Daisy chain BETWEEN the remaining positive and negative of each speaker. (connecting the two directly together)

I had asked about the Ohm rating of the speakers because I can't recall what JAMMA generally looks for as far as that goes. I just didn't want to overload the built in amp on the game pcb.
Method #1 will only be the resistance of each individual speaker as they are now. Method #2 ties both speakers together as if they were one, so this will DOUBLE the resistance or "Ohm" rating. 

[SouthernFist]

thanks alot Kevin, I really appreciate the help. Im going to get in there this week sometime and finish this job up, I'll post of follow up when it's done. Thanks again man.