NeoGeo MVS Sound issues :(

super56k

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Hello KLOVers. As many of you may know, I have been in the process of restoring a Neo-Geo cab. Well to make a longs story short, all issues have been resolved except for audio.

I have two MV4F boards that both had the same issue. Low volume. Both boards have been plugged into JAMMA harasses by their previous owner and so the audio amps were blown. When plugged into my cab, either board would have low right audio and zero left audio.

I bought a cap kit for both and installed it on one of the boards. I plugged in just the EDGE connector and the game came up loud and clear. I plugged in all the harnesses and I got only a hiss for audio. I turned it off and unplugged the headphone connector. That got the audio back. I'll worry about the headphone jacks later. Now my issue is The volume is loud and crisp but only out of the right speaker. I tested the left speaker and it's blown so I disconnected it, however, the wires to the left speaker only produce low volume when connected to the right speaker.

Did I blow the left channel again by having the game connected to a dead speaker? Can I replace just a few caps to fix that without doing the cap kit all over again? What gives?
 
Check the caps to make sure you are replacing the right ones...

You aren't going to blow the audio amp chip by plugging it into a JAMMA harness. If you do the opposite (plugging a JAMMA board into an MVS harness) you will damage the audio amp chip... but those MVS boards are VERY tolerant of miswiring on the speakers.

Not sure what harnesses you are plugging in that would cause some hiss for the audio. Never heard that one before.
 
Check the caps to make sure you are replacing the right ones...

You aren't going to blow the audio amp chip by plugging it into a JAMMA harness. If you do the opposite (plugging a JAMMA board into an MVS harness) you will damage the audio amp chip... but those MVS boards are VERY tolerant of miswiring on the speakers.

Not sure what harnesses you are plugging in that would cause some hiss for the audio. Never heard that one before.

I followed the cap kit instructions carefully and triple checked things.. I wonder why both boards where the same issue?
 
Have you checked that the speaker wiring is correct?

Hooking the left speaker leads to the right speaker produces low volume and the left speaker does nothing with the right speaker wires.
 
Ignoring the physical speakers themselves for now... Both channels are working but the left channel is really quite. :/
 
You should grab the manual for the board and follow the wiring.
 
You should grab the manual for the board and follow the wiring.

Are there schematics for MVS boards? I have an MV-2F with P1 control issues on about half of my carts (the other half work fine, and the controls are perfect in the board's test mode).

I would love to be able to look at a schematic to figure out what to test. Following the traces hasn't gotten me anywhere so far.

Brian.
 
I'm talking about the wiring diagram for the cabinet.
 
Are there schematics for MVS boards? I have an MV-2F with P1 control issues on about half of my carts (the other half work fine, and the controls are perfect in the board's test mode).

I would love to be able to look at a schematic to figure out what to test. Following the traces hasn't gotten me anywhere so far.

Brian.
Try to clear backup ram.
 
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