Bally pin that can't count right.

rcoonjr

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I've been helping a buddy fix his bally SI pin. Game can't count to save our lives. I've disconnected and tested all displays on another pin. So the displays are ok. There isn't any bad connectorson the hardnesses. Checked them all out... I've tested both PIA's and swapped U20 with a new chip... My last option is a new mpu... I think most of my problem someone else worked on the board prior and did some nasty hack and slash...
Anyone else see counting issues... it counts like 111111...333333...555555.777777.999999
 
This symptom you get when one of the data lines is missing.. (probably the 2nd but I don't have schematics with me now)

Maybe bad connector, pin with bad contact, or trace going to a pin that's damaged..
 
This symptom you get when one of the data lines is missing.. (probably the 2nd but I don't have schematics with me now)

Maybe bad connector, pin with bad contact, or trace going to a pin that's damaged..

Thats what I was thinking as well... but I gotta dig up a schematic...
 
Could also be the 5101 CMOS RAM at location U8 on the MPU board. It's responsible for "flash" memory (scoring, audits, etc.) so it may be suspect in this case.

Chris
 
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