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Bally Night Rider SS - 10s digit display issue - need help

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  • Bally Night Rider SS - 10s digit display issue - need help

    I have a Bally Night Rider SS game that I have replaced all 5 of the displays with new low voltage LED displays built by Pinscore. Each display plugged in by itself works fine in every one of the 5 display slots (so they all work individually). And two displays plugged in at the same time in any position also seem to work fine. But once I add a 3rd display then ONLY the 10’s digit gets dimmer in that 3rd display. As I add the 4th and 5th display then 2 thru 5 (in wiring order) all get successively dimmer but only in the 10’s digit place. All other digits in all displays are fine. The game also has modern Alltek MPU and Solenoid Driver boards. When I add in two of the old HV gas displays, they work fine no matter what so I assume all the logic signals like enable and blanking are good. When I have the two HV displays in and add an LED display, once again only the LED display has a very dim 10s digit.

    I have talked to Pinscore about this but they don’t have an answer. I sent a note to Alltek to see if maybe the MPU board might have the ability to cause this due to some type of control or timing issue but they said it wasn’t possible. So, I’m looking for some advice.

  • #2
    It’s too much drain on the 5v

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    • #3
      At the J1 connector of the MPU board, pin 2 (blue wire) controls the 10's display digit.
      Remove the blue wire terminal from pin 2 and also the green wire (1,000's control digit) terminal from pin 4 and swap the wire locations around by installing the blue wire at pin 4 and the green wire at pin 2.
      If the fault stays with the 10's display digit, the problem is the cabling/displays.
      If the fault moves to the 1,000's display digit the problem is on the MPU board

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      • #4
        Put a multimeter on the 5 volts and see how much voltage drop is there. If none check for dirty connectors.

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        • #5
          I had checked the 5V before at the input to each display and there was no drop, which makes sense as all the digits but the 10s were fine. Good idea Quench, I did the pin swap between the 10s and 1000s and the the problem moved to the 1000s digit. Interesting the Alltek told me the MPU couldn't be causing the issue.

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          • #6
            Originally posted by bchop7 View Post
            I did the pin swap between the 10s and 1000s and the the problem moved to the 1000s digit. Interesting the Alltek told me the MPU couldn't be causing the issue.
            The display digit enable signals come from one of the two 6821 PIA chips on the MPU board.

            If your Alltek board is a Rev L or higher board, it's the 6821 chip at U2.
            If it's a Rev K or lower board, it's the 6821 chip at U5.

            These MPU boards have a second 6821 PIA chip for other functions. If you're willing you can try to swap them over to see if it resolves the display issue.
            So Rev L and above boards, swap U2 and U6 (confirm they are the same chip model first).
            Rev K and below boards, swap U5 and U8 (confirm they are the same chip model first).

            Be careful not to bend any chip pins on insertion, and make sure the chips are oriented in the original direction. Take a photo of the board beforehand.

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