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Thread: Switching JAMMA Power Supply (interference)

  1. #1
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    Switching JAMMA Power Supply (interference)

    Hi guys,

    I recently changed my switcher from a generic Chinese PSU to a Meanwell RT-125A PSU.

    It's all working nicely. However, after swapping the PSU, I now have a lot of interference (scrolling diagnal lines).

    It's not PCB specific, it will do it with ANY PCB plugged in.

    If I disconnect everything from FG on the PSU, then the interference disappears (permanently).

    Has anyone experienced this with their switchers?
    Yo.

  2. #2
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    Quote Originally Posted by Zak View Post
    Hi guys,

    I recently changed my switcher from a generic Chinese PSU to a Meanwell RT-125A PSU.

    It's all working nicely. However, after swapping the PSU, I now have a lot of interference (scrolling diagnal lines).

    It's not PCB specific, it will do it with ANY PCB plugged in.

    If I disconnect everything from FG on the PSU, then the interference disappears (permanently).

    Has anyone experienced this with their switchers?
    I have the same power supply and the only issue I have found with it is that it whines (literally) with boards that use less than 1A (MVS MV1C comes to mind) but it produces no interference at all. How's your wiring? what's FG?

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    Quote Originally Posted by aha2940 View Post
    I have the same power supply and the only issue I have found with it is that it whines (literally) with boards that use less than 1A (MVS MV1C comes to mind) but it produces no interference at all. How's your wiring? what's FG?
    FG = frame ground (coin chute, cabinet frame etc.)

    I have experienced no whining.

    I read somewhere that linking FG to common ground will get rid of the interference.

    Disconnecting coin, frame etc. from FG on the PSU fixed my issue - just wondering if there are any negative effects of doing this?
    Yo.

  4. #4
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    Quote Originally Posted by Zak View Post
    FG = frame ground (coin chute, cabinet frame etc.)

    I have experienced no whining.

    I read somewhere that linking FG to common ground will get rid of the interference.

    Disconnecting coin, frame etc. from FG on the PSU fixed my issue - just wondering if there are any negative effects of doing this?
    AFAIK, all the parts of the circuit should use the same ground to avoid having ground loops, which lead to interference. Maybe that's what you were having.

  5. #5
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    Try some ferrite beads.

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    Quote Originally Posted by Craig View Post
    Try some ferrite beads.
    Unfortunately, the ferrite beads didn't work.
    Yo.

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    Bridge DC ground and FG. I've had the same issue on every Happ psu I've ever owned.
    Last edited by skate323k137; 02-07-2017 at 12:16 PM.

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    So a wire from Common to FG like this?

    Yo.

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    Exactly

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    Quote Originally Posted by skate323k137 View Post
    Exactly
    Thanks mate I'll reconnect the cab frame, coin mech etc. back to FG and then bridge that to common.
    Yo.

  11. #11
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    Do you have any idea why this happens on some PSUs?
    Yo.

  12. #12
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    Basically a ground loop causing interference. The only PSUs that I never had the problem with already make this connection internally.

  13. #13
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    skate, you're a friggin' hero! It's working nicely (Common to FG).
    Yo.

  14. #14
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    Yea when I switched out the PSU in one of my candies I had the exact problem. Most likely due to most candies having no ground on the wall plug.

  15. #15
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    Quote Originally Posted by Zak View Post
    skate, you're a friggin' hero! It's working nicely (Common to FG).
    No prob, cheers

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