And, flight is delayed a second time. Yeah, I'm posting this right after the prior message, but I'm sitting at the airport waiting on my flight and updating progress.
After dinner, and finding out I had another hour of "unplanned free time", I decided to give Ms Pacman a bit more love. While I was eating, it dawned on me that if the hsync signal wasn't making it to the monitor, then no amount of pot twisting would work. I had pulled the wiring harness connector off the filter board, but I hadn't disconnected the filter board from the main board. I didn't take pictures, but there was signs of some corrosion on the main board fingers. I re-installed the filter board and...
Now totally stoked! Even better, the joystick and buttons all work. Each plays a different sound at the menu. Hit the credit switch on the back of the coin panel and...
You can't tell, from the crappy blurred picture, but Ms Pacman is all corrupted due to playing with half Pacman and half Ms Pacman ROMs since the daughter card is removed, but the game plays. Sound works and has more than enough volume. Joystick seems to respond well, as does the 2 player button. The 1 player button doesn't seem to do anything, but I'm assuming thats due to the DIP switch settings.
With a functioning system, I plugged the Ms Pacman daughter card back in and went back to the garbage screen in the first picture I posted. I pulled the daughter board off it's mount and started unsocketing chips. When the plastic from the socket for the middle EPROM came off with the EPROM... Well, that socket will have to be replaced. But, there wasn't any damage to the wipes and I fit the plastic back in place and plugged the EPROM back in. Plugging it all back together resulted in slightly different garbage on the screen. While I was looking at it, I noticed that there was a wire hanging loose off the ribbon cable that runs from the main board to the daughterboard. It looks like there was a problem with conductor #1, near where it entered the plug on the daughterboard, so someone snipped it back and soldered a jumper wire to it. However the other end was hanging loose. I tried plugging it into pin one on the socket, but that didn't do anything.
So, the mainboard works. I need to build a new ribbon cable, and replace all the socket on the daughter board. At least thats the start. I'm going to try and get the parts ordered this week, so they are waiting when I get home.
At this point, the decision has been made. The cabinet will get a full reconditioning. There didn't appear to be any burn in visible on the monitor, but the plexiglass is so dirty, it's hard to say what the actual state of the monitor is. I'll likely clean things up a bit more and turn up the brightness a little. If the monitor isn't too burnt in, I'll order a new set of caps for it, and the mainboard as well. I'll tackle all that when I pull the guts out to sand down the cabinet.