So on my Pin-Bot the voices, and any sounds generated from the MPU sound ROMs (not the sound card ROMs) are about twice as loud as the normal game sounds/background music/anything that's generated via the soundboard (It was like this when i got the game). I also have a really bad constant "ticking" in the background too, almost like a heartbeat (read more about it in this thread i started https://pinside.com/pinball/forum/topic/pin-bot-mpu-generated-voice-and-sounds-way-too-loud-and-odd-static ). That "ticking" and static goes away completely if i unplug J1 on the sound board, which takes the MPU sounds out of the picture. I have a rottenndog MPU, and there has been talk that it's something to do with that board. So i contacted them and they sent me a new chip to replace the chip on the rottendog board at U36. Unfortunately it made zero difference.

I fiddled with the on board pot on my dedicated soundboard and it makes Everything go up and down, which from my understanding, that tiny pot is only supposed to adjust one or the other to allow you to "blend" the MPU sounds and Sound boards sounds into one constant volume.

So here's my sting of questions for the gurus out there, take note that i have a D-11297-549 sound board ...

1) Am i understanding the purpose of that pot on the soundboard correctly? And if so why is it not only adjusting the volume of either the sound board or the MPU? It adjusts cleanly and linearly, so I'm assuming it's OK.

2) Assuming the Rottendog daughter board is NOT the issue, and it's something on the sound board, is there a resistor i should check that may be bad allowing the full "power" of the voices and sound from the MPU. It almost sound like it's maxed out from the MPU. Like if you cranked the main volume pot in the cabinet all the way up.

3) I went ahead and replaced all the electrolytic caps on the sound board just for the heck of it, and it didn't do anything. Could one of the Amps be bad? I.E. is one amp for the MPU sounds, and one for the Soundboard sounds?

$) Does the main cabinet pot blend the two signals? And if so could that be the issue? (It seems to operate smoothly and correctly too, other then when it's all the way down you it's still relatively loud which for system 11, as i remember, is pretty normal)

Thanks in advance!

On a side note, i was just looking at the schematics, and resistor R32 (The first resistor the MPU sounds hit on the board) is listed as 2.2K Ohm on the schematics, and that is what it is on the board. However if you go to the parts list for the board it's listed as 10K Ohm. If i understand how resistance works, a 2.2K ohm resistor (whats on there now) would provide more resistance then a 10K ohm. So if i put a 10K ohm resistor on there like that parts list suggests it would in theory make things louder. Right? So when i get home I'll check it with my meter and see if it drifted at all. FYI it looks untouched too, so i assume it left the factory like that.

Check out the attached pics...

Resistor 2 (resized).PNG

Resistor (resized).PNG

D-11297 sound board front (resized).jpg

Alright, for anyone following this (or having a similar issue), i did some experimenting this weekend, and instead of hacking up my sound card, i cut the red wire on J1 (pin 1) and installed a pot i had laying around, inline between the MPU and the sound card input, and it solved my issue! It's not perfect, but no boards got hacked. And if someone in the future wants Pin-Bot to scream at them above all the other music, then all they have to do is open the back box and turn the knob, or remove the pot and solder the wires back together.

Quoted from themadman:

The correct answer is a 10K ohm resistor, and 10000 (10 K) is more than 2200 (2.2 K) K means multiple number by 1000, the higher the number the higher the resistance, the more resistance the less voltage makes it through, and the less voltage that makes it through, the LESS volume there will be.

Duh, that makes sense. Thanks! I'm tempted to swap out that resistor on the board now and get rid of my setup.