You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
Museum of the Game® & International Arcade Museum® Forums
So the sound went out on my KFM. I started poking around and I'm a bit stuck. First thing I did was swap out the 2 AY sound chips with known good ones because that was super easy to try, No change. Then I started checking the 6803 sound cpu. Reset is good, I have clock on pin 40 but I'm not sure what I should expect to see on pins 2 & 3. It looks like it goes out and through the crystal and then back into the 6803? This is also the first cpu I have seen that has P lines. I know address and data lines but haven't seen P lines yet. I have activity on IRQ & NMI but R/W is static so that tells me it's not executing code. What really gets my attention is pins 8 & 10 of the cpu are floating. They come out of the AY sound chips at pins 29 & 27 but there is also a 74ls368 that ties into them. All connections are floating between the 3 chips. Pins 13 & 11 of the 368 are floating and pin 15 is high. I pulled the 368 and it tests good in my tester but I also swapped it out since I had it out and no change. Not sure where to go next.