Thank you very much for sticking with this. I can not express how much I appreciate that. This issue is driving me crazy.

Not just SW1, but you know the rest of that story.

As an aside, and somewhat unrelated, I have an occasional issue with my Fireball II not wanting to boot up on first attempt. A quick toggle of the ON/OFF switch always brings it up the second time.

That's a known issue, but it's not a priority at the moment. First things first

Ok, have to ask, pardon me if it seems a stupid question, but what does direct to ground mean? I used a DMM with the leads on Pin 4 and TP2, but it did not simulate the reset. Continuity is good, also read +5vdc at pin 4.

I also purchased a second 6803 about a month ago, so I had two to work with. No difference with either installed on the MPU. Also, an NVRAM would not have any effect here, would it?

I can't see why it would.

edit to add

Is there anybody around here that works on 6803's? I want to continue on my own, but I may be nearing it's above my pay grade territory.

Ok thanks, that is what I suspected, but I wanted to make sure before proceeding, for the very reason you provided.

I've called this one. Sent the 6803 MPU to Eldorado Games. That SW1 issue needs to be diagnosed on a scope. I've been at this for almost a year, and I have reached the end of my ability for the time being.

One last question for this topic for now.

On the power supply board, the 230 in sometimes reads as high as 244vdc. It's unregulated, so that shouldn't be an issue, correct?

All other voltages are good. I did not think that it was an issue. I've got the displays turned down to 170vdc. I am very interested in what a full diagnostic on that board turns up.

And Brtlkat, yes my strobing is gone. Fixed that last year with new caps, and a rebuild of the high voltage section of the power board

Update:

Sent my 6803 MPU board to Eldorado Games. Talked to John yesterday, and was told that there is nothing wrong with the board. He also told me that SW1 on that board doesn't do anything. The board checked out good on the test bench, so it appears that my XPin displays just do not work with this particular version of the 6803 MPU.

So now, I'm "stuck" trying to find some newer displays that this MPU will be able to talk to. He said something about different versions of the 6803, so if that's true - and atm I have no reason to disbelieve that after my 14 month trek with this game and those newer displays, I'm hoping that there are some versions out there like Pinscore or Pinball Solutions that may resolve the issue. I've looked for replacement high voltage 14 digit displays, but those seem to almost as rare as a dinosaur.

I wonder if there is a way to get them to work. I wonder if anybody would even be willing to put the effort forth.

Any opinions? Any suggestions? Does anybody have a D&D pin that is using XPin's? If so, what Revision of the displays are they? I have a pair of Revision A's.

Update and a shout out for Brett at XPin. For the better part of the last 15 months, we tried to work out the issue with these displays, to no avail. I highly recommend XPin for display needs, as Brett is a good guy and stands by his word and his product. He went the extra mile for, and with me, to attempt to resolve this issue.