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Discussion in 'Datasheets, Manuals and Component Identification' started by aleksabu, May 13, 2012.

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  1. aleksabu


    May 13, 2012
    Hi everyone!
    I need Schematics for repairing this power supply

    Attached Files:

  2. davenn

    davenn Moderator

    Sep 5, 2009
    welcome to the forums :)

    I have used many of those PSU's and repaired a few of them mainly the 12V or 24V output versions. I have never found any circuit info for them
    From your blurry pics, it looks like its blown one or more of the MOV's on the AC input to the bridge rectifier

    Testing wise, the PSU will work without them, as they are only for over voltage protection on the input.
    Does your PSU still come on and put out 48V or is it dead ?
    there shouold be a fuse on the mains input just behind the terminal strip, has it blown ?

    will await your answers on those 2 questions :)

  3. aleksabu


    May 13, 2012
    Hi Dave
    sorry for the blurred pic, PSU is dead, fuse is OK! and 2SC3320L also OK!

    it ain't gonna be quick repair!
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    try taking pictures with natural light and from a little further away if it will improve the focus.

    I would be checking the output rectifiers as a failure here is a pretty simple way of getting zero output.

    Shorted rectifiers often result in the power supply shutting down immediately it is powered up. This may be accompanied by an audible click from the transformer (as it is exposed momentarily to a huge overload.

    This may also result in failures of the main chopper transistor(s) if the power supply doesn't (or can't) shut itself down fast enough.

    You say the main chopper transistor is OK, so that leads me to suspect the rectifier. You should be able to measure it in circuit and you should see something other than zero ohms in both directions.
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