Hi guys, looking for some experienced opinions on this. My displays are getting bad digit information. The player 1 and 2 displays (in the 2nd,4th and 6th digits position is EITHER a "0" or a "1." The player 3 and 4 displays have the same problem, except those digits are alternating "1" and "2." And the match/credit display follows the 3/4 player problem.

Here's a link to a video of whats happening...

Here's what I know: The master display board is NOT the problem because I've tried it in another Firepower machine.
I have continuity on all connectors and cables from the MPU to the display boards
I am getting PULSING with the logic probe on all data lines starting at the PIA, all the way down to the
connectors at the Master Display board.
I've replaced the IC18 PIA and the encoder IC just to eliminate them as the problem, but no such luck.
Clay's guide mentions PIAs on the driver board causing missing digit problems on the displays, so I swapped those
out as well, but no change.

Anyone have a clue whats going on?

TAGS System 6 williams firepower display

Yes, I have continuity and data making it to all the connectors on the master display board. The 74154 is brand new NTE replacement, all traces have continuity in and out.

Yes, its incredibly bizarre behavior. I'll look over the ROMs and sockets but don't see that interfering with the counting of the digits. But, stranger things have happened... its pinball. I have a friend with a Firepower, may have to get these two boardsets together and compare a bit further. I've never seen or heard of a game doing this.

Alright, I finally figured out that the MPU board had a bad 6810 RAM chip was causing this issue for some reason. I had already re-socketed everything and touched up all solder and pins, plus replaced the PIA. I swapped the 6810 with another and now the displays work fine. Glad that problem is finally over.