[SOLVED] Audio Wiring Question / Situation

Here's a noobish question regarding audio rigging. Any insight would be greatly appreciated.

This past weekend, I picked up a 2 slot conversion in rough shape for virtually nothing. It looks like somebody had dropped the guts of an MVS into an Atari Blasteroids cab. Everything appeared to be functional, except for the sound.

Anyway, after a great deal of cleaning and external repair, I started to tackle the wiring. I've been an AES guy for a long time, and my knowledge of cabs is limited (yet increasing), but it was pretty damn obvious why there was no sound. Turns out that the audio wires were disconnected and caked with solder. I cleaned the solder off, and took some photos, which are below.

Now, I know that for any stereo set up you need both L and R wires connected to the speakers, along with an extra ground. The strange part is that I can't seem to find a spare ground to run, and on top of that, the two speakers seem to have four separate wires connected via quick connects (two white, two colored) leading down into the cab. This is completely different from my dedicated MVS.

What should I do to get this thing correctly wired for audio? I have a feeling that there is something simple I'm missing. I tested the audio through headphones via the jack, and it was crystal clear.

In addition, just to complicate things a bit, there is a third speaker in the cab, mounted on the front. This is also disconnected. Is there any practical way to make use of this additional speaker in a setup, or should I just ignore it?

So I think I figured out the audio rigging in this cab.

The problem is that the center audio channel seems extremely low compared to the left and right. Output from the headphone jack is perfect.

Could this be in need of a cap kit even though the headphone jack is outputting clear audio, or is it probably something related to the strange audio wiring?

Xionicist said:

So I think I figured out the audio rigging in this cab.

The problem is that the center audio channel seems extremely low compared to the left and right. Output from the headphone jack is perfect.

Could this be in need of a cap kit even though the headphone jack is outputting clear audio, or is it probably something related to the strange audio wiring?

Click to expand...

Just use the left and right...ignore the center speaker.

Just my opinion. I never like to complicate things.

If center is low, then you might have it wired wrong....

If center is low, then you might still have it wired for mono.

Gotcha.

When I referred to the center channel, I was referring to it in terms of the sound test in the bios. Left is strong, right is strong, but the center is weak. I also think that both left and right channels are outputting as mono, obviously. Referring to the pictures I've posted, the only way I've been able to get sound is by tying in both white wires to the top speakers (ground) to the "L" position on the pinout, and the colored leads from the speakers to the "10" position. Trying to separate the colored wires between "L" and "10" results in no sound.

In games, this results in a weak main sound effect set while the stuff normally keyed for L/R stereo is loud. It is interesting to here some of the background musical channels in Samurai Shodown II isolated, however.

And yeah, the output from the headphone jack is absolutely crystal.

Has your board been modified?

Some ops would modify the board for mono.

norton9478 said:

Has your board been modified?

Some ops would modify the board for mono.

Click to expand...

Any quick way to check for that type of mod? I have the board pulled now for cleaning, and everything looks fairly normal, but I could be missing something.

Problem fixed!

Looks like the issue was a ground that wasn't making connection with the rest of the daisy chain. Once it was replaced, the stereo sound was perfect, including out of the center cab speaker.

Thanks, everyone.