Proview blown primary

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  • Behemot
    Badcaps Legend
    • Dec 2009
    • 4845
    • CZ

    #1

    Proview blown primary

    Got only the board, found rotten input capacitor with blown primary side (found bad transistor, rectifier, MOX resistor and fuse). Replaced all of it (FQPF7N80C for 2SK3264, 0R36 resistor for 0R22), with bulb in series the bulb shines like hell and I got almost no voltage on input cap. I got very low resistance over C206 which seems to be filtering VCC for LD7575. The diode there tested fine alone so either bad transformer, or LD7575? Or may it be something else?
    Attached Files
    Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

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  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: Proview blown primary

    The SMPS IC 201 may be damaged when the MOSFET blown up, it drive output may stuck HIGH so the MOSFET is not switching on and off like it should. You can try check the resistance of the IC between the ground pin against all the pin, and VCC pin against all the pin.
    Never stop learning
    Basic LCD TV and Monitor troubleshooting guides.
    http://www.badcaps.net/forum/showthr...956#post305956

    Voltage Regulator (LDO) testing:
    http://www.badcaps.net/forum/showthr...999#post300999

    Inverter testing using old CFL:
    http://www.badcaps.net/forum/showthr...er+testing+cfl

    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
    http://s807.photobucket.com/user/budm/library/

    TV Factory reset codes listing:
    http://www.badcaps.net/forum/showthread.php?t=24809

    Comment

    • Behemot
      Badcaps Legend
      • Dec 2009
      • 4845
      • CZ

      #3
      Re: Proview blown primary

      GND to:
      RT 660R
      COMP 885R
      CS 790R
      HV 686R
      VCC ~0
      OUT 790R

      VCC to:
      RT 883R
      COMP 883R
      CS 792R
      GND ~0
      HV 682R (infinity the other way)
      OUT 1786R
      Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

      Exclusive caps, meters and more!
      Hardware Insights - power supply reviews and more!

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Proview blown primary

        The VCC to Out (Gate drive) seems low to me, I expect it to be in K Ohm range. You can lift the drive pin off the board. and see if the lamp will still light up bright and stay on bright.
        Attached Files
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment

        • Behemot
          Badcaps Legend
          • Dec 2009
          • 4845
          • CZ

          #5
          Re: Proview blown primary

          Still full on. I guess this one is good to go…
          Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

          Exclusive caps, meters and more!
          Hardware Insights - power supply reviews and more!

          Comment

          • viziks
            Member
            • Mar 2012
            • 33
            • India

            #6
            Re: Proview blown primary

            Check Bridge BD201 and confirm polarity +,-, ~,~ sequence,also C201 and FET 7N80 again.0.36ohms may not work and cause shutdown at full load.

            Comment

            • Behemot
              Badcaps Legend
              • Dec 2009
              • 4845
              • CZ

              #7
              Re: Proview blown primary

              I removed the LD7575, somewhat damaged the paths but it is not shorted now so it was it. I also found practically the same problem with same board from different display, there was also the driver bad.

              Schematic here http://www.ebastlirna.cz/modules/For...isplej_135.jpg

              Will probably try to get it from eBay and somehow fix the bloody mess I did there with 150W transformer iron Well, can always connect tiny wires to the legs instead of the burned paths
              Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

              Exclusive caps, meters and more!
              Hardware Insights - power supply reviews and more!

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: Proview blown primary

                I always replace the IC along with the MOSFET when the MOSFET is damaged, you are lucky since you have the lamp connected to protect it from blowing up the new MOSFET.
                Never stop learning
                Basic LCD TV and Monitor troubleshooting guides.
                http://www.badcaps.net/forum/showthr...956#post305956

                Voltage Regulator (LDO) testing:
                http://www.badcaps.net/forum/showthr...999#post300999

                Inverter testing using old CFL:
                http://www.badcaps.net/forum/showthr...er+testing+cfl

                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                http://s807.photobucket.com/user/budm/library/

                TV Factory reset codes listing:
                http://www.badcaps.net/forum/showthread.php?t=24809

                Comment

                • Behemot
                  Badcaps Legend
                  • Dec 2009
                  • 4845
                  • CZ

                  #9
                  Re: Proview blown primary

                  Replaced IC, still nothing so I'll ditch it for parts…
                  Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

                  Exclusive caps, meters and more!
                  Hardware Insights - power supply reviews and more!

                  Comment

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