Some obscure jamma questions

[Ummon]

The first thing has to do with using an audio amp. In my cabinet, it looks like the +12 volt leads from the edge connector go to the audio amp. Does this mean powering it is dependent upon the board connected? What's happening here?

The next question is simpler and repair-oriented. I was doing something ridiculous and disconnected the wires from the harness. In soldering them back on, I bent and broke one of the connections off the wire side of the harness. How would you suggest fixing this?

[CheffoJeffo]

The first thing has to do with using an audio amp. In my cabinet, it looks like the +12 volt leads from the edge connector go to the audio amp. Does this mean powering it is dependent upon the board connected? What's happening here?

Are you talking about an off-board audio amp that you want to run w/o a game board ? (It's early and I may be missing the point of your question).

The next question is simpler and repair-oriented. I was doing something ridiculous and disconnected the wires from the harness. In soldering them back on, I bent and broke one of the connections off the wire side of the harness. How would you suggest fixing this?

Remove the pin and put in a new one. You may need a pin extractor to remove the pin cleanly. I think Bob Roberts and Mikes Arcade sell them.

* CheffoJeffo slaps his head and remembers that he needed one this weekend to rewire a harness and forgot to put it on his order list

[Ummon]

The first thing has to do with using an audio amp. In my cabinet, it looks like the +12 volt leads from the edge connector go to the audio amp. Does this mean powering it is dependent upon the board connected? What's happening here?

Are you talking about an off-board audio amp that you want to run w/o a game board ? (It's early and I may be missing the point of your question).

I'm just trying to figure out what is required for the amp to operate.

Remove the pin and put in a new one. You may need a pin extractor to remove the pin cleanly. I think Bob Roberts and Mikes Arcade sell them.

Ah, thanks. I couldn't tell by looking at the board side that the pins were separate.

[Ummon]

Bumping this. It looks as if the audio amp requires something kind of input from the board connected to the JAMMA interface, as the +12 goes from somewhere in the harness (I'm assuming it's coming from the PS), to the edge connector and then to the amp. Is this the case?

[Bleagh]

It sounds like someone took one of the 12 v wires and ran it from the jamma harness to the amp instead of the power supply.  Since all the 12v wires are connected at the jamma harness when a game is inserted, the amp will then be powered.  You would be best off if you ran the 12v to the amp directly from the power supply.  Honestly, you don't even need the amp unless you have some weird setup.  You don't want to power your cabinet without a board installed, if the power supply has no load it can burn up.

[CheffoJeffo]

I'm still confused -- JAMMA uses onboard amplification, so the game board obviously has to be plugged in.

There are some boards that are sometimes called "JAMMA" (because they use a JAMMA pinout) that use an external amp (I have one installed in a cabinet for my kids), but in my experience, they are the exception not the rule.

Perhaps Ummon can provide some specifics or pictures so that I can understand where he is coming from.

[Ken Layton]

The vast majority of JAMMA boards all have an amplifier built into the board. It operates on the +12 volts coming into the board from the JAMMA harness.

Some games like Mortal Kombat (and other late Williams/Midway games) had a seperate sound board, but the speakers were 'jacked through' to the JAMMA edge connector to use the existing JAMMA cabinet speaker(s).

[Ummon]

This is what it looks like inside my Capcom Impress. You can see at the far left a bunch of wiring that comes out of the harness, apparently coming from the edge connector (it is looped 180 vs bent 90 degrees from the PS side of the harness) and going into the amp.

[CheffoJeffo]

QSound amp ? Not JAMMA and I think it connects with a separate audio cable, although I wouldn't be surprised if it had some sort of pass-through from the harness. I believe that it has its own transformer, so wouldn't use the 12V from the harness.

But, my knowledge on the subject is very limited -- I don't have any candy cabs nor any QSound games.

[Ummon]

Ahhhh. Yeah, a Qsound. I noticed I missed pic'ing the stereo RCA plug that goes from the amp to I guess whatever is plugged into it. However, by the wiring and the volume knob on the amp housing it seems mono sound from the edge connector should play through, and with the Tetris board that came with it none did. As well, when I hooked up my computer to the RCA plug, with the PS on of course, there was no sound. I'm not sure how to further troubleshoot this.

[CheffoJeffo]

Are you saying that you have never had any sound from this cabinet, either via JAMMA harness or by plugging directly into the amp ?

Have you traced where the audio connections from the JAMMA harness actually go ? If you have a DMM or continuity tester, use it -- don't want any short s!

As for the Q-Sound amp, have you verified the voltages going in to the tran sformer ?

[Ummon]

Correct, I've never gotten any sound either way.

I have generally followed the wires along the bundle from edge connector to amp, though I haven't specifically traced wires. Apparently, the grounds and +12v come from the PS, go to the edge connector, and those same pins have a second wire that go to the amp.

I haven't checked anything electronically as I'm not sure how. Do I need technical information for this unit in particular?