Hi All,
Out of sheer boredom today i decided to look deeper into my display problem.
Looking at the schematic pointed me to a 6821 (PIA) chip that controls the data & strobes to the score display PCB.
The 6821 was in a socket, and the other 6821's on the main board were not, immediately i was suspect of the socketed PIA.
I replaced the 6821 today, and after powering up the pin, i can now see Alpha-numeric words & scoring.
I've played thru many games and everything displays as expected.....so far so good.
However, that's only the 'top' 2 displays (being the 2 Alpha-numeric ones) that work nicely.
The 2 displays under them (7-seg) are still just OFF, nothing at all, ever!
I'll spend more time next week on this, as i need to dig out my logic probe and/or Cro to trace the missing signals that drive the 7-seg displays.
I'm guessing (at this stage) that a buffer chip on the display PCB has paffed out, soon to be confirmed!
I play the machine too much to be bothered getting Techy with it, at the moment
Getting there ...
MM.
