Determining a faulty capacitor

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  • speedypro
    Badcaps Veteran
    • Feb 2013
    • 561
    • United Kingdom

    #1

    Determining a faulty capacitor

    Im working with one of these amps: no power. Turns out a faulty transistor and blown fuse. Replaced both but still no power. On further testing, red circle is damages. How to know what to replace with? Yellow oval is the transistor ive replaced. Transistor was a NDF04N60ZGOS-ND.



    Attached Files
    Last edited by speedypro; 10-28-2016, 07:05 AM.
    Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: Determining a faulty capacitor

    So that C105 snubber cap shorted out too beside the 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

    • keeney123
      Lauren
      • Sep 2014
      • 2536
      • United States

      #3
      Re: Determining a faulty capacitor

      So where is the brown wire connected to one the board?

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Determining a faulty capacitor

        BTW, that big MOX resistor for the Source pin of the MOSFET is still showing <1 Ohm?
        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

        • speedypro
          Badcaps Veteran
          • Feb 2013
          • 561
          • United Kingdom

          #5
          Re: Determining a faulty capacitor

          Originally posted by budm
          So that C105 snubber cap shorted out too beside the MOSFET?
          Yes. On MM is show up as DISC or DESC, not sure but it's gone.

          Originally posted by keeney123
          So where is the brown wire connected to one the board?
          It's just for the fuse. Original fuse was a 2a. Now Im temp using a 1amp.

          Originally posted by budm
          BTW, that big MOX resistor for the Source pin of the MOSFET is still showing <1 Ohm?
          That resistor is fine to be honest. I think it's showing 3K, Im not at work to confirm. But Im pretty sure it's ok.
          Last edited by speedypro; 10-29-2016, 12:29 AM.
          Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: Determining a faulty capacitor

            I do not understand what you mean, Disc. Bottom line is the cap shows resistance reading or not. So what resistance do you get on the cap?
            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

            • speedypro
              Badcaps Veteran
              • Feb 2013
              • 561
              • United Kingdom

              #7
              Re: Determining a faulty capacitor

              Originally posted by budm
              I do not understand what you mean, Disc. Bottom line is the cap shows resistance reading or not. So what resistance do you get on the cap?
              I'll let you know when I'm at work later.
              Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: Determining a faulty capacitor

                That power MOX resistor if I am correct, it should be connected to the Source pin of the MOSFET, when the MOSFET shorted out it will also cause the resistor to go open citrcuit. It should be very low resistance of less than 1 Ohm.
                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

                • speedypro
                  Badcaps Veteran
                  • Feb 2013
                  • 561
                  • United Kingdom

                  #9
                  Re: Determining a faulty capacitor

                  Originally posted by budm
                  That power MOX resistor if I am correct, it should be connected to the Source pin of the MOSFET, when the MOSFET shorted out it will also cause the resistor to go open citrcuit. It should be very low resistance of less than 1 Ohm.
                  Yea it was burnt. I part of the outer part was blown off. I'll confirm in 5hrs time.
                  Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

                  Comment

                  • speedypro
                    Badcaps Veteran
                    • Feb 2013
                    • 561
                    • United Kingdom

                    #10
                    Re: Determining a faulty capacitor

                    Originally posted by budm
                    So that C105 snubber cap shorted out too beside the MOSFET?
                    No resistance for cap. Resistor has about 16Meg Ohms (tested in circuit).
                    Last edited by speedypro; 10-29-2016, 04:24 AM.
                    Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

                    Comment

                    • CapLeaker
                      Leaking Member
                      • Dec 2014
                      • 8133
                      • Canada

                      #11
                      Re: Determining a faulty capacitor

                      that resistor is FUBAR

                      Comment

                      • speedypro
                        Badcaps Veteran
                        • Feb 2013
                        • 561
                        • United Kingdom

                        #12
                        Re: Determining a faulty capacitor

                        Originally posted by CapLeaker
                        that resistor is FUBAR
                        LOL! Ok so what about that cap?
                        Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

                        Comment

                        • stj
                          Great Sage 齊天大聖
                          • Dec 2009
                          • 30997
                          • Albion

                          #13
                          Re: Determining a faulty capacitor

                          probably fine.

                          Comment

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