(Topic ID: 227288)

Bally Transformer Bad?


9 months ago

Topic Stats

  • 7 posts
  • 2 Pinsiders participating
  • Latest reply 9 months ago by Quench
  • No one calls this topic a favorite


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    #1 9 months ago

    I’m not getting 12v to power the boards in a Bally Speakeasy.

    On the rectifier board: At 11.9v test point I’m getting 6.0v DC. The rectifier board is brand new and that eliminated a bunch of other issues. But the 12v from the transformer seems to be the last problem. I never deal with transformers — is it time to pick up a used one? Or just throw a cheap switching supply in there?

    I can actually run the new replacement MPU on the existing 6.5v and it works with all flashes, but the symptoms are that controlled lamps, motor, displays all don’t work. GI and coils do.


    #2 9 months ago

    Put your multimeter on AC voltage, then insert the meter leads in the J6 socket of the rectifier board where the two blue wires are. It doesn't matter which way around you put the meter leads.
    The voltage you read across those blue wires should be around 14.2VAC - this is the transformer voltage that delivers the 12 volts for the system.
    If you measure close to this voltage, then there is a problem at the BR1 bridge rectifier on the rectifier board.

    #3 9 months ago

    I think I’ve eliminated the rectifier board as an issue, the AC coming in to the 12v rectifier is low too, I think it was at 7-8? I’d have to measure it again as I didn’t write it down. Thanks!

    #4 9 months ago

    Pull the F3 fuse off the rectifier board and remeasure that transformer output. That bridge rectifier might have an internal short which could be pulling the transformer voltage down. Those transformers are generally tanks.

    #5 9 months ago

    By the way, are you running the game from 120VAC wall power while the transformer is wired for 220VAC input?

    #6 9 months ago

    It’s set up for 120 on a 120 line. The problems arose after a move. Fine before that. I have a 100% new rectifier board in there, newly manufactured, and before that I’d rebuilt the last one, they both have the same behavior. But I will try that test. If it is the transformer, what next?

    #7 9 months ago

    I would disconnect the transformer from the rectifier board (isolate everything off the transformer) and measure all the transformer output winding voltages. Then you'll have a better idea.

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