I have a millionaire with display problems. The player 1, player 3 and credit/match displays are dark. The player 2 and player 4 displays work except for the 1st digit on each being completely out. To confirm that player 1 and 3 are not out gassed, I connected the display to another system 11 game to see if the player 1 and 3 light up and they do. I swapped data cables between games and there are no changes. I checked the obvious things. No open solder joints anywhere on MPU or Display board, no acid damage and no burned chips or connectors. Power supplies are displaying correct voltage.

Any suggestions on what to test next?

Also, when I connected the display to another game (Cyclone), display 1 and 3 did show signs of life but player 2 and 4 were completely dark. I guess I only confirmed that the displays have not out gassed but that's about it.

Yes, it's the correct display for the game. The display glasses are not out gassed. Trying to figure out if it's an issue with the displays not getting power or data or both. Also trying to figure out if the problem exists on the MPU or the display board itself.

No, but I just ordered one. Admittedly the display board already has a bunch of socketed chips showing some of the 6118, 7180 and 4050s were replaced. The board work looks to have been done well. I guess what's throwing me off is that fact that display 1 and 3 are out and 2 and 4 mainly work (digit 1 is out on both displays 2 and 4). However, move the display to a different game and I have the opposite effect. Player 1 and 3 light up (not displaying anything legible because the display is in the wrong game) and 2 and 4 go out. I was expecting to see the same result (display 1 and 3 are out and 2 and 4 mainly work) on the display when moving to a different game if it were a problem on the display board since the circuitry is what it is.

indeed they are different. I will be checking the ICs next.. Thanks

Logic probe arrived today. U44 is bad.

In addition, I had to replace a number of 4050, 6116 and 4001 chips in the display board. Something must've zapped the circuitry. Display board is back up and running except for the credit/match display which is probably gassed out...