I see from the diagrams that the System 80b sound board has +12v and +5v coming into it. I'm experimenting with replacing this board with a Raspberry Pi, and was wondering if anyone knew how much amperage the original sound board is pulling from either the +12v or +5v rail.

The reason I ask is that ideally I'd like to pull the power for the Raspberry Pi from one of those rails instead of having a separate power supply for it, but of course I don't want to overload anything. Since I'd be replacing the original sound board, I figure that if the amperage it requires was comparable to that of the Pi, I'd be safe.

Thanks! I kind of figured the Pi would be less of a draw but wanted to play it safe.

For stage 1, I'm replicating the current board, but with different sounds. So I'm taking the same five signals that are used by the game, feeding them into the Raspberry Pi, and playing the appropriate wav/mp3 in response to each combination of inputs received. With five signals there are 32 possible sounds (one of them would be all low on the inputs, so really only 31 are useable). My machine (Gold Wings) seems to have sounds or music assigned to 29 of them. I plan to assign a placeholder sound to the two unused ones to see if they are ever triggered by the game but just not used.

Stage 2, I plan to use contextual information to add some extra sounds. So for example, if the game has been started but the game over sound hasn't been triggered and no other sound has been triggered in 30 seconds, you know the player is most likely either holding the ball with the flipper or is sitting there with the ball on the launcher, so play a sound or change up the music. Or like if the "add a new player" sound has been triggered once, play a voice saying "one player," twice play "two players," etc.

Stage 3, open it up to new inputs. One in particular that I'm thinking of doing is letting you change the music using those two buttons that are usually only used for inputting your initials. Or make it so that you can toggle between the original sounds and my custom ones. It will involve what you described with piggybacking extra switches on things.

Yes, they're really simple. There's 5 on this machine. They're all either on or off, high or low, 1 or 0, however you want to put it. It's just binary math, so you can come up with any number from 0 to 31.

I'll post code and pics/videos as soon as I have something worth looking at. Right now I just have a little interface I built that let me play my old iPod or the Raspberry Pi through the machine's amp/speakers, a big pile of wav files, and some ugly Python code I've been playing with. The parts to finish the board build out are in the mail.

Essentially what I'm doing is building a little board that goes between the Raspberry Pi and the original wiring harness for the soundboard. The board feeds the 5 signal lines (and the reset signal) to the Pi via the GPIO header. Once the parts come in, there will be a USB connector on the board that will feed the power to the Pi via a Micro USB cable. The Pi then uses its audio out jack and one of those cables that goes from a headphone style jack to RCA jacks to feed audio back to the machine's amp/speakers. I have an extra little header lying around that I plan to throw on the board too, with one pin going to ground and the others going to unused pins on the GPIO header for if I decide to add some extra inputs (like what I mentioned as Stage 3 above).

My first pass will be ugly, but if it works like I think it will, and I get ambitious, maybe I'll try my hand at etching a custom PCB to pretty it up a bit. I've never tried that before but the instructions online don't sound particularly daunting. But that's getting ahead of myself. So anyway...

On the software side, the Python code is very simple at this point. It's like one of those soundboard apps you see all over the place where you hit a key and it plays a sound, only instead of a key press, I'm using the output from the 5 signal lines to determine which sound it's looking for, and using the reset signal as a 6th input that immediately stops the playing sound. Not sure yet if that's how it's actually supposed to be used, but I'll know soon.

I've got it working. The only part I haven't tried is using the USB connector for power. I didn't have the right cable lying around to try it.

But the sound itself works with the R Pi running off its own power supply. If you had it sitting next to a Gold Wings running the original board you might notice some minor differences, but I feel like it's already "good enough" for what I'm doing.

Some lessons learned so far:

- I needed to build voltage dividers for the signal lines to adapt them from 5v logic to the 3.3v logic used by the Raspberry Pi's GPIO header.
- One of the signal lines (#16) needed a pull up resistor to make it work like the others.
- I haven't seen much out of the reset signal. It's hooked up - I just don't see it getting triggered very often.
- Sound signals 16 and 31 appear to have some sort of special meaning, which is why they're not used for actual sounds. 16 gets triggered constantly when certain other sounds are playing. I think it's some sort of timing/heartbeat signal. But I don't need it the way I'm playing the sounds, so I ignore it. 31 rarely gets triggered. It seems like it might be used to stop all sounds at once. I have it set to do that in my current code, and it seems right.
- The sounds being output by the Raspberry Pi are a little quieter than the original board. Not sure what, if anything, I can/should do about that.
- Boot up time is slower than I'd like. The system takes about 30 seconds to boot, plus another 15 or so for my Python script to launch and fully load all the sounds. I want to tighten that up. I could probably do so by reducing the quality of the sound samples, but I'm looking for other routes first.