No sound on Super Mario, not the audio board?

travisbmartin

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I'm working on a Vs. Unisystem Super Mario right now. Thanks to lilman, I have Mario back instead of a silly Skate Kid hack. And thanks to Bob Roberts, a fresh set of caps on both the monitor AND the sound board.

My problem is that there is still no sound. I switched audio boards with our Mario Bros. here at the arcade, and from what I can tell, the board I just capped works. So I've written that off as the culprit.

Poking around, I hooked a oscilloscope up to Pin X on the board, which should be the sound (if I'm reading the pinouts right from Mike's Arcade,) and I get what I can only describe as a constant sawtooth wave. It's there whether I am playing the game or if it's just on.

Is there anything on the board I should be looking at or replacing? I'm kindof lost.


(Also, if I put the dip settings to 2 coins = 1 credit, why are the player 1 and player 2 controls switched when I run it on 2 players?
 
check the two op amps on the PCB. 5n and 5r (2 chips, part #LM39900N)
I had to replace 2 on a PCB once to get sound.
You can still get them from mouser and they are dirt cheap.
I have like 20+ if you need one, I can drop it in snail mail for ya.
 
Did you mean LM3900? I'm not at the arcade to look at the board, but on the horrible board schematic I have, it looks like they are LM3900. I can't find LM39900 chips on Mouser either.
 
Yup, that's the one. Precaffeine reply at 530am. I would check those. Down by the edge connectors.

It's cool. I just had to be sure. I need to order some caps anyway, so I'm going to order the 3900s while I'm at it
 
Sadly, no. I've had no luck on this one or the Mario Bros. game we have at the arcade. I've thrown them on the back burner for a while.
 
No they are in their own cabinets. Both of them don't have sound leaving the boards.

On the Mario Brothers, I can get a signal up to MUX1, where it goes in but doesn't come out.

On the Super, I haven't dug around on it enough I guess.
 
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