supergun JAMMA audio is very messed up

mecha

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I have a pretty awesome supergun that I built out of a HotRod SE joystick that has switchable video output to either a JROK TV encoder or video game monitor, as well as a kick harness that floats out the back if I ever wanna hook one of my Midway fighters up to it lol.

the only item I didn't outfit it with was a speaker, and I tried several of them yesterday and every single one of them emitted this scratchy nonsense where like half the audio output seemed missing and it produced this obnoxious ground hum.

I compared my wiring to the NBA Jam manual (since that's where the JAMMA harness was parted from) and the wiring is red/violent for + and green/violent for -, and I hooked them up right.

I tested it with two games I know worked in other cabs, my High Impact Football and Smash TV, and the volume pot I have was wired correctly with the shield and all.

am I looking at a case where I need earth ground hooked to a corner of the speaker, or could there be a fault in my sound wiring?
 
I would definitely try the earth ground to the speaker frame, other than that maybe your picking up garbage from the powersupply.
 
wonder if it's something messed up with the -5V too. idk, that's a new power supply. I'll have to grab some voltages next time I hook it up, the JAMMA harness could be garbage too.
 
wonder if it's something messed up with the -5V too. idk, that's a new power supply. I'll have to grab some voltages next time I hook it up, the JAMMA harness could be garbage too.

I thought it was more common on JAMMA games for the audio amps to be powered off of +12V.
 
I thought it was more common on JAMMA games for the audio amps to be powered off of +12V.

you're correct, the amps use the +12, but the Williams/Midway games all used -5 for the sound too though, without -5 they sound... sinister.

I'll take a gander at all the voltages though, see what I'm getting at the JAMMA edge. I just find it peculiar cause it was a new Power Pro I threw on it, and it probably has like an hour total of power on time.
 
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