OK, I've got an odd issue that I'm struggling to diagnose on my Jack*Bot. It displays garbage (similar to a blown U24 RAM.) Initially it only happened occasionally when the game was on for a couple hours. Then it would happen after half an hour. Now it displays garbage starting as soon as the game boots.

I've swapped the following between my Jack*Bot and Shadow to rule out possible causes of the problem:
DMD
Display controller board
Both ribbon cables

This has me thinking it may be MPU related. (I don't see acid damage.)

The gradual onset tells me it's not that some component failed suddenly (I think) but rather something has gone bad over time, maybe a solder joint or socket somewhere.

I think I'm on the right path, but have hit a bit of an impasse. Any words of wisdom?

Swapped MPUs, and the problem persists.

I just checked voltages at the DMD, and the 5v was crazy low - like 2.6v. I disconnected the DMD, and that 5v is still around 2.6v.

The 5v on the driver board test point is pretty much dead on.

I'll text 5v coming off the driver board from J117-4 next

Well, I think my J117 connector is a bit loose; I reseated it, and have a solid, stable 5v at the display. I'll leave the game on for a while to verify that everything is good.

Worst case Ontario, I'll have to replace a connector, it appears.