(Topic ID: 233354)

Bally - missing leftmost digit at same display location

By swampwiz

6 months ago

Topic Stats

  • 5 posts
  • 4 Pinsiders participating
  • Latest reply 6 months ago by barakandl
  • No one calls this topic a favorite


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    #1 6 months ago

    (NOTE: I had posted about this about a month or so ago, but the recommendation was to fix something that I have verified is not the problem.)

    The MPU is an AllTek, and the memory had been cleared.

    All the displays except for #3 work fine. The leftmost digit for the display @ #3 is always out no matter what display units are swapped around, so it is not the display units. There is a daisy-chain wire that goes to #3 from #4, but I have verified continuity (while the wire harnesses are connected) between the TP2 between each display unit, so that wire is not the problem.

    I have also tested continuity (while the wire harnesses are connected) for the single unique connection between display #3 & the MPU (the strobe line?) from the point on the display to the resistor on the MPU, so that wire is not the problem either.

    I can't see how this is not some problem with the MPU board. What other stuff should I be checking?

    #2 6 months ago

    Have you repinned the connector? Pin 12 should be the one controlling the 1 mil digit display.

    #3 6 months ago
    Quoted from Thrillhouse:

    Have you repinned the connector? Pin 12 should be the one controlling the 1 mil digit display.

    Right after I posted this, I thought about that. You must be referencing the 7-digit display game; mine is the 6-digit display, but I get the idea. I'll check the continuity there.

    #4 6 months ago

    Does the problem move with he display? Always help to know the game name.

    #5 6 months ago

    non working digit on a single display that moves with the display would first be verifying the digit enable connector pin on the display board itself is not cracked.

    If the display connector is OK. check the 100k resistor for that digit. If it is burned open i'd replace the resistor(with half watt 100k), the digit driver and level shifter for that digit. Typical fail mode for this I think goes like this.... level shifter fails locking on the digit bright. This makes too much current go through the 100k resistor and it burns open. Once the 100k resistor goes open the digit is out.

    Also can have a display glass itself go bad. I have some glass where a single digit refuses to light up. I find it in stern 7 digit glass the most often for whatever reason. I'd exhaust other stuff before declaring the glass bad.

    I hate probing around the high voltage, so as long as you have skills to solder on the board... this is a case where i'd whack-a-mole / shotgun replace part.

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