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PSU Clicking

Discussion in 'Power Electronics' started by mwint50, Mar 24, 2019.

  1. mwint50

    mwint50

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    Mar 24, 2019
    Hi everyone. First time poster and fairly amateur enthusiast.

    I am determined to repair a powered speaker that is failing to produce and output other than a very regular (metronomic) click. It only starts after the protection sequence completes once turning on. Ay ideas?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,132
    2,663
    Jan 21, 2010
    If the device completed a power up sequence, then the power supply must be basically working (when switch mode power supplies are grossly overloaded they can produce a clicking sound, but this also results in a zero or near zero output voltage).

    If you can open the unit up and take a few photos, we may be able to point you in the right direction for more investigation

    Have you tried another signal source to verify that the signal source is not a problem itself?
     
  3. mwint50

    mwint50

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    Mar 24, 2019
    The previous post was without a signal input at all
     
  4. mwint50

    mwint50

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    Mar 24, 2019
    IMG_1011.jpg
     

    Attached Files:

  5. mwint50

    mwint50

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    Mar 24, 2019
    IMG_1010.jpg
     
  6. dave9

    dave9

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    135
    Mar 5, 2017
    To back up a bit, are you sure it is the PSU clicking and not a protection circuit on the amp board?

    What I would do is look over the PSU board to see if it has resistors on the output to give it a minimal load. If it does, I'd try powering it without being connected to the amp board to see if it repeats the behavior. If it does not, I would devise a minimal load on the most loaded power rail, the highest voltage in this case which can be traced backwards from the power pin on the amp output stage (transistors or amp IC), then repeat the power on test to see if it clicks.

    I am wondering if the problem is the amp board has a fault, like the output stage has blown a transistor closed circuit. Another alternative is whip up an alternate PSU to power the amp board, low amp (2A should do it with no signal but slow blow since you have capacitors charging) fused in series with the board, to see if that trips the fuse.

    It would be easier to advise if we had more info. Is the make and model of the amp a secret? ;)
     
  7. bushtech

    bushtech

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    Sep 13, 2016
    Might be an optical illusion but is the top of the left hand big cap swollen?
     
  8. mwint50

    mwint50

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    0
    Mar 24, 2019
    No secret. It’s a dB Opera 605 powered speaker. I did notice an arc from a transitor to its shield when I powered it in a disassembled state. That can’t be good....
     
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