Scratchy Mortal Kombat 2 Sound

ElRamos

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I've capped the board and tried replacing the main amplifier at U20, the pre-amp at U37, and the DAC at U16 to no effect. What could be causing this? It has to be in the analog section *somewhere*, right? Do I need to start looking at the resistors and pico caps?
 
the DAC needs -5V too, I'm assuming for "pre-amp" you mean the TL084? it could maybe be the yellow tantalum caps, but might be a question for @zenomorp

what part did you use for the DAC replacement? I had a sound board years ago where the guy thought yellow was +12V and orange was -5V and wound up nuking the DAC and filter cap, but they had some different part for the new DAC since the old one I'm certain is obsolete.
 
Yeah, I'm calling the TL084 a pre-amp. That seems to be its function in this circuit, but please correct me if I'm wrong.

I replaced the DAC with a pull from a working board. I built a power adapter to plug the board into an Arcade PowerPro supply. Voltage and wiring are correct and verified working with good boards.
 
Yeah, I'm calling the TL084 a pre-amp. That seems to be its function in this circuit, but please correct me if I'm wrong.

I replaced the DAC with a pull from a working board. I built a power adapter to plug the board into an Arcade PowerPro supply. Voltage and wiring are correct and verified working with good boards.
you are correct. I think the next thing is the yellow tantalum caps. I would have to see the schematics, and I don't have time to look right now.

the only issue with the tantalum caps is how they hooked the legs, they're kind of tricky to get out. I also don't know their values.
 
I have the schematics. I think the next step is to probe the output chain with a scope and see where the static noise first appears.
 
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