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Dell E156Fpb backlight turns off when VGA connected

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    #1

    Dell E156Fpb backlight turns off when VGA connected

    I have a Dell E156Fpb 15" monitor that I suspected had a CCFL gone bad causing it to shut down after 2 seconds. It did in fact have a bad CCFL on the bottom side, however, after replacing it with a good CCFL I found the same symptom (shutdown) exists when the VGA cable is connected. If I release the VGA cable, the CCFL's light back up. So far, here is what I have done in terms of troubleshooting:

    1. swapped out the controller board from another E156Fpb with no changes in symptoms.

    2. searched for similar issues with no luck.

    3. replaced the two C5707's and the FU9024N on the inverter. Nothing.

    4. resoldered all the pins on the two transformers.

    Suggestions at what to look at?
    Tags: None
    #2
    Re: Dell E156Fpb backlight turns off when VGA connected

    Hello & Welcome To Badcaps,

    First off if you were to take a picture of the top and bottom of the larger board
    (inverter circuit board) and use the "manage attachments" button that might be the best place to start. Without that from a quick Google image search for Dell e156fpb I see a fuse near the white power connector that might be blown. Thats only a guess since I don't know that the image on Google is the same as the board you indeed have? I would say it very well could be a capacitor issue or another fuse possibly a pico fuse that could be bad? Is there a component that has the letter "F" in front of a set of numbers? Perhaps another member of this site has had experience with this model Dell monitor and could give you a better path to troubleshoot.

    Good Luck With Your Repair,
    lcdman

    Comment

      #3
      Re: Dell E156Fpb backlight turns off when VGA connected

      Id say its unlikely to be a fuse on the inverter board problem as the inverter works and only shuts down when the vga is connected. Do you mean the Internal vga cable or the vga cable from the pc. If the latter have you tried that cable on another monitor or another cable on this one?


      Was the board you swapped in working in the other monitor?
      Did you try swapping the internal vga cables.
      If the other monitor was working can you connect the panel from to this one.

      You should post pictures also of the front and back of the logic board with close ups of the connectors.
      There are a number of different Power boards for this and if it doent show clearly in the picture can you state the board number and revision- a close up pic of it would be good
      Please upload pictures using attachment function when ask for help on the repair
      http://www.badcaps.net/forum/showthread.php?t=39740

      Comment

        #4
        Re: Dell E156Fpb backlight turns off when VGA connected

        Sorry, the weekend came about and I stepped away from the project. Below are pictures of the separate boards involved.
        Attached Files

        Comment

          #5
          Re: Dell E156Fpb backlight turns off when VGA connected

          Update. For whatever reason, I decided to swap out the CCFL that I believed was good with another one (it lit up on power up for 2 seconds so I assumed it was good). Problem solved. Since the CCFL's are gas bulbs, can anyone recommend a convenient means of testing them without removal from the glass substrate?

          Comment

            #6
            Re: Dell E156Fpb backlight turns off when VGA connected

            Sorry you have lost me - are you saying the one you swapped in originally was not good and now you have tried another and it now works.

            And is this
            Since the CCFL's are gas bulbs, can anyone recommend a convenient means of testing them without removal from the glass substrate?

            just an enquiry for future testing?
            Please upload pictures using attachment function when ask for help on the repair
            http://www.badcaps.net/forum/showthread.php?t=39740

            Comment

              #7
              Re: Dell E156Fpb backlight turns off when VGA connected

              Originally posted by ahickman View Post
              Since the CCFL's are gas bulbs, can anyone recommend a convenient means of testing them without removal from the glass substrate?
              Something like this?

              http://lcdparts.net/IT.aspx

              Some have DIY versions documented on the Internet.
              --- 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.

              --- end sig file ---

              Comment

                #8
                Re: Dell E156Fpb backlight turns off when VGA connected

                DIY

                You need an inverter to get the light to start.

                I use an old laptop - it has a smashed screen but the lights still work so it is dual purpose _ I use the inverter to test ccfls and I use the panel to test inverters in other screens.

                You can Buy a tester for about £15 on ebay or build your own
                for about half see http://www.fonerbooks.com/laptop14.htm
                Please upload pictures using attachment function when ask for help on the repair
                http://www.badcaps.net/forum/showthread.php?t=39740

                Comment

                  #9
                  Re: Dell E156Fpb backlight turns off when VGA connected

                  Originally posted by retiredcaps View Post
                  http://lcdparts.net/IT.aspx
                  Arrgh, wrong URL. I meant this one.

                  http://lcdparts.net/LST.aspx
                  --- 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.

                  --- end sig file ---

                  Comment

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