Hi. I've been lurking here forever and can generally either figure out my issues with various games or search around on here and get some direction however this one has me at a dead end.

I have an Earthshaker and here's the background.

The sound was intermittent when I got it and now it pretty much doesn't work at all.

When I press the self test button on the CPU board it will just beep forever. Beep, beep, beep, beep..... steady beeping.

When in the test menus the music menu has no sound nor does the sound menus.

Here's what I've done so far.

I verified 5v at the 6809 & 6821. Right around 4.9v

I pulled all roms and checked them vs romident and they all identify fine.

I started checking around the sound board with my logic probe and here's what I can't figure out.

I have zero activity on the address lines / data lines.

I have no activity on the clock lines at the 6809.

I went backwards on the clock line and got to the 7410 @ U21. No activity.

Kept going backwards to the 7474 at U16 and do have clock at 3 & 11 but the outputs at 5,6,8 and 9 do not toggle at all.

I pulled the 7474 and it tested good but since it was out I socketed it and replaced it.

I'm pretty new at this level of troubleshooting so forgive me if this is a question that's easy but if I have activity at 3 & 11 shouldn't I also have activity at 5,6,8 and 9?

1,4,10 and 13 are all high and from what I can tell they're supposed to be.

Could a bad ribbon cable prohibit clock activity? I just can't see how the ribbon cable would stop this when looking at the schematics.

Thanks for any ideas!

Clock (resized).jpg

Same tone beep consistently every second or so.

Nothing in test menus. No sound on sound test, no music on music test.

Turns out the 6809E was causing the no background music. Swapped it and the background music works fine.

I am still having an issue with no other sounds. No voices etc.

Clock (resized).jpg