Dell 2007wfpb inverter

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  • delaware74b
    Badcaps Veteran
    • Apr 2009
    • 628
    • USA

    #1

    Dell 2007wfpb inverter

    I was 'gifted' with the above monitor, powers up but no display. On the inverter board (#5EL2J04011), I found one of the 2 transistors driving the center ccfl transformer had burned up.

    My issue is the Rohm SP8M3 mosfets aren't available in the USA unless I go to China. I did find the Fairchild FDS8958B mosfet available from Mouser and Digikey. These mosfets appear to be better than the originals.

    Question: Should I replace all 6 for a balanced drive of the ccfl section?

    Obviously, I plan to recap the power supply and inverter to eliminate the Elite problem although none are bloated.

    I'll post pictures of the inverter board tomorrow.
    Stupidity should be a crime, especially for drivers. I have NO patience for them.
  • delaware74b
    Badcaps Veteran
    • Apr 2009
    • 628
    • USA

    #2
    Re: Dell 2007wfpb inverter

    I have uploaded pictures of the inverter board.

    The third one shows the damaged mosfet.

    Is there a good way to test the transformer (T802) either in circuit or out of circuit with just a DMM? I was looking at possibly getting the Anatek Ring Tester to test the transformer.
    Attached Files
    Stupidity should be a crime, especially for drivers. I have NO patience for them.

    Comment

    • PlainBill
      Badcaps Legend
      • Feb 2009
      • 7034
      • USA

      #3
      Re: Dell 2007wfpb inverter

      Originally posted by delaware74b
      I have uploaded pictures of the inverter board.

      The third one shows the damaged mosfet.

      Is there a good way to test the transformer (T802) either in circuit or out of circuit with just a DMM? I was looking at possibly getting the Anatek Ring Tester to test the transformer.
      It's not a definative test, but about all you can do is measure the resistance of the secondaries. If either secondary on this transformer is more than 3% low, that is an indication it is shorted.

      PlainBill
      For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

      Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

      Comment

      • retiredcaps
        Badcaps Legend
        • Apr 2010
        • 9271

        #4
        Re: Dell 2007wfpb inverter

        Originally posted by delaware74b
        I have uploaded pictures of the inverter board.
        Those are excellent pictures.

        Is there a good way to test the transformer (T802) either in circuit or out of circuit with just a DMM?
        This is NOT your transfomer, but it gives you an idea where the primary and secondary pins are.

        http://www.lcdparts.net/TransformerD...ProductID=2726

        The secondary pins should be within 3% of each other.

        If it helps, I have this exact board in front me (waiting for repairs on the USB and logic board - shorted diodes and voltage regulators).

        I get the following ohms readings on my Fluke 75

        T801
        S1-S2 = 1021
        S3-S4 = 1016

        T802
        S1-S2 = 1028
        S3-S4 = 1023

        T803
        S1-S2 = 1026
        S3-S4 = 1021

        edit: PlainBill beat me again while I was taking resistance measurements on my board.
        Last edited by retiredcaps; 01-15-2012, 07:25 PM.
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        Comment

        • delaware74b
          Badcaps Veteran
          • Apr 2009
          • 628
          • USA

          #5
          Re: Dell 2007wfpb inverter

          retiredcaps - thank you for your guidance. I definitely have something going on between the primary circuit and secondary for the center transformer. I am reading 15K between pins 1 - 2. Getting the same thing on 3-4, 5-6, 7-8. These pins are numbers on the board counterclockwise from the white dot.

          The other two transformers were reading 10M minimum on the same pins. All secondary readings were pretty close, all between 1036 and 1043 ohms.

          I am in the process of lifting the mosfets for t802 and going to take new readings

          Photos were taken with cell phone (8.0MP Motorola Droid X) with macro turned on. I re-sized the photos to 1024x768 on my desktop before uploading.
          Stupidity should be a crime, especially for drivers. I have NO patience for them.

          Comment

          • delaware74b
            Badcaps Veteran
            • Apr 2009
            • 628
            • USA

            #6
            Re: Dell 2007wfpb inverter

            I got the mosfet lifted off the board and T802 transformer readings match the other 2 on the board.

            I am looking at replacing the mosfet with the Fairchild FDS8958B. I am going to order enough to replace all 6 of the Rohm SP8M3's on this board and replacing the Elite Caps on the inverter and power supply boards.
            Stupidity should be a crime, especially for drivers. I have NO patience for them.

            Comment

            • retiredcaps
              Badcaps Legend
              • Apr 2010
              • 9271

              #7
              Re: Dell 2007wfpb inverter

              Originally posted by delaware74b
              Photos were taken with cell phone (8.0MP Motorola Droid X) with macro turned on.
              Looks like the cell phone in another generation might actually be good enough to replace the low end consumer camera.

              Most of the current phones still take photos that are too grainy.
              --- begin sig file ---

              If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

              We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

              Please do not post inline and offsite as they slow down the loading of pages.

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              Comment

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