Hello all -

My Eight Ball has an issue that I need some assistance with. My credit, player 3 and 4 displays are all afflicted with the typical 00-33--55--77 pattern in test mode. In attract they just show junk.

I have replaced all connectors. I am testing with xpin led displays. I know that a bad decoder on one display can cause this behavior downstream...but...I get this problem with no other displays plugged in and using just the xpin.

Players 1 and 2 work perfectly with plasma and the xpins.

So, I suspect the problem is in one of the components on the MPU itself. The MPU connectors are also new. I am having trouble narrowing down if the 33-55-77-99 pattern would be caused by a bad digit enable, digit latch strobe, blanking, or segment data. I am suspecting U20 is the culprit...but wanted a second opinion. Confused as to which of these it may be as it looks like there is no wire that is common to displays 3AI, 4AI and 5AI but not 1 and 2.

Thanks to all -

-scott

Andrew -

So then I would suspect pin 10, 16, 17, 18, or 19 (or some combination) is probably not making good contact on the credit display connector - since the problem starts there and the lines are daisy-chained?

Thanks!

-scott

Andrew wins!

The culprit was BCD D1 from the player 2 display to the credit display. So Player 1 and 2 worked fine, but somewhere in the harness the blue/white wire was apparently broken, affecting everything downstream.

I'm not sure if the actual symptoms are a way to narrow down which of the BCD lines are the culprit or not (e.g. does D1 cause a '00-22-44-66' pattern while a broken D2 would cause '00-11-33-11-33' pattern). I tested for continuity with a meter to find the problem. I had assumed that the harness was all good - bad assumption for a game that's almost 40 years old, and I also had replaced all of the connectors, so I REALLY assumed all with the wiring was good!

So - add to Pinwiki and other repair boards: Don't always necessarily assume that the Decoder chip on one display could be the problem with odd number sequencing in display test. If any multiple displays cause the same behavior in the same location, suspect the connector/harness in the connection just prior.

Thanks again all!