SMPS 750W 25VAC out not working correctly

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  • foshland
    Senior Member
    • Jan 2017
    • 122
    • Spain
    #1

    SMPS 750W 25VAC out not working correctly

    Hi, I have a power supply that now is working but generating a lot of heat (200ºC) in the resistors circled by green (see photos) with a minimal load (60W). Output voltage is correct with that minimal load. What cai I look now?


    Thanks a lot
    Tags: None
    • foshland
      Senior Member
      • Jan 2017
      • 122
      • Spain
      #2
      4 Photos

        Comment

        • CapLeaker
          Leaking Member
          • Dec 2014
          • 8183
          • Canada
          #3
          check em out where they go? Going from positive output to GND? Then they are loading resistors and also make the secondary not hold any voltage when you unplug it.

            Comment

            • foshland
              Senior Member
              • Jan 2017
              • 122
              • Spain
              #4
              Finally i discovered what the problem was, they are limiting resistors in the main section (120VAC), when the power supply works ok, it closes a relay and it bypass the resistors, the problem was that the relay had the coil open and the line was allways through the resistors.

              Hope it helps someone

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