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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    Tags: None
    • 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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