Reg, did you try reseating the short ribbon cable that runs from the MPU to the Power Driver board? Pretty sure that's your problem.

Small ribbon cable going to the colordmd reversed ?

I would unhook everything and reconnect it. Garbled stuff like that always makes me think pins are off a bit

Your DMD has entered ................................ The Twilight Zone!

But seriously, if it both the color DMD and regular, it will most likely be the long ribbon cable from the DMD board. Unplug it, check the red line is on pin 1 on both boards, reseat. But - if in the empty post there is something about other lights being out - fuse check in order.

Did a pin(s) on either of the headers for the short wide ribbon cable get bent on the PCB?

Was this ever resolved?

I too, would be curious. My WCS still has a very, very random (energize everything before the CPU boots) issue. I've replaced so many boards, all ribbon cables replaced, repinned everything...convinced there is a wire shorting somewhere. My TZ occasionally "blinks" hard enough to trigger some activity, but the WCS will actually blow fuses. Odd indeed........

What does your voltage measure across C31 on the MPU board? Anything between 4.75 and 4.85 volts can cause intermittent loss of power tripping the watchdog circuit causing a reset or intermittent boot up. At 4.70 volts, I experienced the MPU will not even boot up.

Could even be a MPU that is on the verge of going out. It would be good to try this WPC-S MPU in another game.

The WPC-S MPU is a new Rottendog.....sent it to Chris Hibler some time back, and he said it checked fine. I know I'm paranoid, but I'm big on the " if it's not broken" scenario, so very reluctant to start screwing w a board change on a machine that is behaving.

I had convinced myself that I fixed it when I changed the thermistor AND power switch out.....got about 2 months of " soft" starts...then problem slowly, randomly appears, only on energizing the machine.

You mention checking voltage across C31....is there any chance the transformer could be wonky? Kept hoping the problem would just get worse until a complete failure happened, but it will vanish and reappear randomly......

I'll take to pm land, as this will probably get geeky, and a bit off topic.....

PM sent. Thanks.

excellent info and documentation! thanks for sharing!