Hello,
I have a Data East 520-5050-00 Rev C sound card. It presents distorted audio.
When you start the game, the sounds that are heard are the ones that should come out at that moment, but they seem distorted.
I detail below, the tests and measurements that I carried out.
First I measured the voltages of CN2 (12v, -12v, 5v, GND) they are all OK.
Then I measured the voltages of the 7805 and 7905 regulators (5v and -5v) correspondingly and they are also fine.
Then I thought it might be the electrolytic capacitors and I checked them all and they are all fine.
Then, thinking that it was an amplification problem, I decided to inject a 400hz square signal at the output of the DAC (TDA1543) and verify its signal at the output and it is correct, in fact I placed a speaker and the sound is clean and varies its gain correctly with the potentiometer.
Other things I checked the ROMs (U7, U17, U21) have the correct information.
Then Since I had a BSMT2000 (U9) chip available, I also replaced it and the sound had the same problem.
Up to that point I have reached, I am not sure if the ram memory can cause something like what is happening, or the DAC (TDA1543) or the intermediate circuitry between the bsmt and the DAC
I leave you a video with the audio, so that you can better understand what is happening.

https://www.dropbox.com/s/0bqsw4xa4pdtxu2/Jurassic.mp4?dl=0

Thanks in advance.

HI, Music and Voices are distorted.