Samsung 460CXN - Power Supply Issue

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  • R_J
    Badcaps Legend
    • Jun 2012
    • 9514
    • Canada

    #21
    Re: Samsung 460CXN - Power Supply Issue

    QP802s and QP801S are basically switches, they are turned on and off by the signal on their gates (pulsed at 65Khz) They are normally open.
    Turning them on and off causes the voltage on this side of TM802S coil to be boosted from 160 volts supplied by the bridge to around 300 volts dc across CP810/CP817
    Since the bad fet is shorted to the gate it might be wise to also replace UP801
    Last edited by R_J; 04-19-2018, 01:08 PM.

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    • pantherts
      Senior Member
      • Mar 2009
      • 73
      • USA

      #22
      Re: Samsung 460CXN - Power Supply Issue

      Resistance between source and drain on QP802S is an OL.

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      • pantherts
        Senior Member
        • Mar 2009
        • 73
        • USA

        #23
        Re: Samsung 460CXN - Power Supply Issue

        Okay, I understand now. That makes sense. Thanks so much for the explanation.

        Comment

        • pantherts
          Senior Member
          • Mar 2009
          • 73
          • USA

          #24
          Re: Samsung 460CXN - Power Supply Issue

          Any way to reliably test UP801 in power off mode to see if it's shorted inside?

          Comment

          • R_J
            Badcaps Legend
            • Jun 2012
            • 9514
            • Canada

            #25
            Re: Samsung 460CXN - Power Supply Issue

            got a scope to check the output pulse? it might be ok but if it is not you could blow the fets or the supply just won't work
            Last edited by R_J; 04-19-2018, 01:33 PM.

            Comment

            • pantherts
              Senior Member
              • Mar 2009
              • 73
              • USA

              #26
              Re: Samsung 460CXN - Power Supply Issue

              Nah, no scope available. Alright, I'll get an order together. Thanks so much for your assistance with this. I'll check back in again.

              Comment

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