I have a pinbot with a very odd sound issue I am trying to narrow down and possibly fix or send off to get fixed. When I bought this machine last week, the owner told me that the machine had no sound at all, just a loud hum coming out of the speakers. He had bought an extra sound board in hopes that would fix the issue and it did not. After some cleaning, reseating of chips on the sound board and MPU and getting the red, black, white cables plugged into the correct sockets, I can hear the startup DONG but it is very faint with the volume all the way up (I adjusted the POT on the sound board and no real change). The volume knob "works" as in it increases and decreases the hum. There are no other sounds after the initial dong. I have gone in the menu and played sounds as well as done the sound test button on the MPU.
I am at a loss and this is my first system 11 board. I have done some hunting on here and cannot find my issue...anyone want to help me out and point me in the correct direction to start diagnosing? I want to make sure if I have to send this off that the issue lies with the MPU or sound board and not something else that I am just overlooking because I have not worked on these before. I have good soldering skills and have a basic DMM and oscilloscope and know how to look for signals. Thanks in advance for any help!
I have a video of what it does but did not really think it would help all that much since it only just does the dong at startup. Let me know if I should post that up.