So I had my WMS IJ completely torn apart (playfield removed all connections in the backbox removed) to do all new decals. Finally got it put back together and fired it up......no display, no sound, idol just spins and a few various lights on.....that was it.
Narrowed my troubleshooting down to the CPU board. When I turned it on LED's D19 & D20 are off and D21 is lit. So I have power but the CPU is not booting. Unplugged everything but the power (J210)....better, D19 lights for a few seconds and then goes off as D20 starts blinking (D21 remains on). Looks like a proper boot sequence.
Plug the "power/driver" ribbon cable in (J211) and fire up....still good. Plug in J202 (I/O Sound ribbon)....still good, plug in J201 (I/O Extended)......no go. I do power off and back on for each test.
I noticed when I unpluged J201 leaving J202 still connected that it would NOT boot. So, if I plugged in one of the top ribbon cables (either one) it still booted. As soon as I plugged in the other it will not boot and won't boot properly until I unplug both.
I'm thinking it's the TTL circuits just below the top ribbons.....U1-U3. But is it all three? Do I need to replace or just reflow? Thanks.