Troubleshooting a Bally Squak and Talk board. I get the initial LED flash and then I think three flashes after that (the second and third one are pretty close together it looks like?). Pinwiki says that "If there is no fourth blink, first swap a known good 6821 into U11." I tried this with one from a fully working board and there is no change. 5v measured fine, the 11.5 is a little high at 15, not sure if that would matter.

I also swapped over every other chip from the working board except U1 and couldn't get past the third LED flash.

Any thoughts on where to go from here?

I swapped that chip too but will take a closer look.