I'm trying to get a Sega Harley Davidson up and running. It was broken when I joined up with the company. It had no display, and the playfield had been messed up. Bought a new playfield for it, and did a playfield switch. Dear lord, it took forever! I've got it mostly back together, playfield in the machine. I just needed to snap in the lamps to the correct location, and install the missing DMD.

I booted up the machine, no display in it. GI turns on, it plays the little song, I can even hear it go into PORTALS when I push the service button. All good. So I stick the DMD in, and pop the display board on top. Turn it on, and....nothing?

Hmm, F23 popped, that's strange. So I disconnected the DMD related stuff, replaced the fuse, and turned it on. It's fine. Through trial and error, I figured out that when I plug in the 5 volts to the display driver, it pops F23 and won't boot.

Well, good thing this Ripley's is right next to it, working fine. Lemme borrow it's DMD. Hmm. Same thing. Maybe borrow the Power board? Same thing. CPU board? Display power board? Display board? All the same thing. At this point, I literally have every single board from the RBION inside. Still doesn't work!

At this point, my boss says we need the RBION to go out on location. So I remove all the boards, and pop them back where they belong. The RBION boots up fine, plays fine, and is now happily working in a bar.

So it has to be something about the wiring. But I've traced the 5 volts line from the power board to the display board, and nothing is wrong with it. I'm stumped. I see one reference to a similar problem on RGP back in Feb., but it doesn't look like anyone solved it then, either. Any ideas? I'm desperate!

On the power driver board...there is no other F23, is there?

So the answer appears to be: the shaker motor. Because it shares a line with the 5 volts for the display. I guess I forgot that it existed, being so pre-occupied with rebuilding the playfield. But I unplugged it, and now everything works.