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DELL 2005FPW - mystery....

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    #1

    DELL 2005FPW - mystery....

    Hi,

    this is my first post and, first of all, let me congratulate with all of you for the wonderful work you are doing, really appreciated!

    My Dell 2005fpw has a symptom that I read in some other posts: when it powers on it flashes for something like 0.2s (I can quickly see the Dell logo) and then goes black. But LCD works cause I can - hardly - see Windows screen on it, only lamps shut down after the 0.2s.

    I tried replacing all the caps on power supply board with no luck.

    Then I wanted to understand if the problem was on faulty CCFLs, so I completed dismantled the LCD panel and, with my big surprise, here is the mystery: connecting everything - with dismantled pieces - the monitor works!!!

    And with everything I mean that the LCD panel itself is dismantled from CCFLs structure.

    But, as soon as I put back the LCD part together with CCFLs structure, it does not work!!!

    It seems like if there something discharging improperly to ground but I checked for wrong electrical contacts and found nothing. Furthermore, no one before me opened this monitor, so it's hardly due to wrong electrical contact rather then some component failing.

    Four your information, I also reflowed both power supply and logic boards, and also replaced C637 capacitor. All of these based on other posts found here.

    If there's any angel over there, please help me !!!!

    Thanks so much in advance for any would had the patience to read so far...

    Best Regards
    Riccardo
    Tags: None
    #2
    Re: DELL 2005FPW - mystery....

    One more "detail":

    with monitor completely assembled and all cables plugged except video ribbon to LCD, CCFLs do work! But as soon as I attach video cable they do not...

    Therefore, the only way to make it work with all cables plugged is to have it dismantled (all pieces far each from the other).

    Comment

      #3
      Re: DELL 2005FPW - mystery....

      Good job of troubleshooting so far; excellent job of describing the problem.

      Arcing from high voltage lead of CCFL to the LCD frame. It's probably happening at an end cap, or where the high voltage lead touches the LCD panel. I'd make a 'sniffer' probe using a jumper wire and a plastic handled screwdriver. One end of jumper to the frame of the monitor, the other end to the shaft of the screwdriver. By running the blade of the screwdriver along the wire you may be able to locate the bad spot.

      You could even use a finger tip as a probe. Theoretically the current isn't high enough to stop your heart.

      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

        #4
        Re: DELL 2005FPW - mystery....

        PlainBill,

        thanks so much for your help.

        Reading more posts I started realizing it's a matter of arcing, happy to have a confirmation from you!

        But, I apologize, I am not sure to well understand the 'sniffer" probe suggestion...

        Regards
        Riccardo

        Comment

          #5
          Re: DELL 2005FPW - mystery....

          Here is a tool I made; it’s nothing more than a single chopstick with a sewing needle epoxy to the plastic with a grounding wire soldered to the needle.
          Works great for small pin testing, and you could probably use it as a sniffer
          Attached Files
          Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

          Comment

            #6
            Re: DELL 2005FPW - mystery....

            Originally posted by vulkan.72 View Post
            PlainBill,

            thanks so much for your help.

            Reading more posts I started realizing it's a matter of arcing, happy to have a confirmation from you!

            But, I apologize, I am not sure to well understand the 'sniffer" probe suggestion...

            Regards
            Riccardo
            I think what PlainBill is suggesting is this:

            Take a test lead with a alligator clip at both ends. Clip one end to the shaft of the screwdriver and the other end to the metal frame of the LCD panel. With the CCFL's on, run the tip of the screwdriver along the CCFL wires and endcaps. Once the CCFLs go off, then you've found the source of the short.
            Last edited by jetadm123; 06-14-2011, 09:42 AM.

            Comment

              #7
              Re: DELL 2005FPW - mystery....

              Great, tonight I'll try, thanks both of you!

              Comment

                #8
                Re: DELL 2005FPW - mystery....

                Originally posted by jetadm123 View Post
                I think what PlainBill is suggesting is this:

                Take a test lead with a alligator clip at both ends. Clip one end to the shaft of the screwdriver and the other end to the metal frame of the LCD panel. With the CCFL's on, run the tip of the screwdriver along the CCFL wires and endcaps. Once the CCFLs go off, then you've found the source of the short.
                Excellent description. Perhaps I should hire you as my editor. Would you work for bad capacitors? I have plenty of them.

                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

                  #9
                  Re: DELL 2005FPW - mystery....

                  Originally posted by PlainBill View Post
                  Excellent description.
                  With my background, I automatically thought back to a network diagnostic product that Network General made called a "sniffer". It is a DOS based network protocol analyzer that ran on old Compaq "portables". The equivalent of a data logging multimeter.
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                  Comment

                    #10
                    Re: DELL 2005FPW - mystery....

                    Originally posted by PlainBill View Post
                    Excellent description. Perhaps I should hire you as my editor. Would you work for bad capacitors? I have plenty of them.

                    PlainBill

                    Hah! Hah! I would consider it, but only if you throw in a few shorted mosfets!

                    Comment

                      #11
                      Re: SOLVED - DELL 2005FPW - mystery....

                      S O L V E D !!!!!

                      Thanks so much you guys, I will build a monument for you!!

                      I sorted out it was a connection of the thin wire to one CCFL which was disconnected, probably causing the arcing to LCD metal chassis.

                      I repaired a monitor and I learnt so much!!!!

                      Work with you soon again,
                      Riccardo

                      Comment

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