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BENQ G2420HD no back light after few sec

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    BENQ G2420HD no back light after few sec

    Hi all,

    I have two BENQ G2420HD. One is working normally the other went dark after 1-3sec of normal screen- before not able to see anything with flash light on screen

    I changed the the screen to the power board of the working monitor and screen worked fine.

    I went and hanged all the capacitors on the power board (dont have means to test capacitors) only have multimeter and soldering iron.

    Once the Capacitors were changed the screen comes on for 2-3 sec then goes dark- shining a light on it you can faintly see the display.

    I have attached some picture to gi with the issue......please help! I am not fully aware on how to test each component or what each component is in the power board so please point me in the right direction for me to read up on stuff
    Attached Files

    #2
    Re: BENQ G2420HD no back light after few sec

    What number is printed on IC801, Q801, Q802, Q803 & Q804 on the underside of PSU.
    Can you compare the voltage on CN701 between the working and non working set
    Last edited by dick_barton; 08-09-2020, 03:17 PM.
    Willing to help but I'm no expert.

    Comment


      #3
      Re: BENQ G2420HD no back light after few sec

      https://www.badcaps.net/forum/attach...4&d=1596998731
      Is the negative leg of C701 soldered?
      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


        #4
        Re: BENQ G2420HD no back light after few sec

        @BudM- C701 is soldered

        @dick_barton- I assume you want to know the chips number?

        Q801 to 804 is A2790115
        IC801- 0Z9933GN,CC780J 30,1139A

        unless you mean the other side of the boards with the components on it.- see attached pics - will try and find CN701 and measure voltage -
        Attached Files

        Comment


          #5
          Re: BENQ G2420HD no back light after few sec

          @budM- I read this case: https://www.badcaps.net/forum/showthread.php?t=40791

          and tested the transformer 1 and 2 points you refer to here on my board-

          Transformer 1- shows 2.06 at 20K reading
          transformer 2 - i get no reading.

          could this cause the 2 seconds to black and for the back lights to go off and not work?

          Comment


            #6
            Re: BENQ G2420HD no back light after few sec

            If the second transformer is not reading approx 2000 ohms as the first transformer then it does looks like the fault.
            Willing to help but I'm no expert.

            Comment


              #7
              Re: BENQ G2420HD no back light after few sec

              Originally posted by daran View Post
              Hi all,

              I have two BENQ G2420HD. One is working normally the other went dark after 1-3sec of normal screen- before not able to see anything with flash light on screen

              I changed the the screen to the power board of the working monitor and screen worked fine.
              when the screen went off... what will happen when you press "wake" (power) bottom, did the screen cone again then off same time? in case the answer "YES" mean you have cut off signal at MB

              Comment


                #8
                Re: BENQ G2420HD no back light after few sec

                Hi guys cant seem to find a new inverter for this board!

                Was browsing this forum and came across this post (using LED board):
                https://www.badcaps.net/forum/showth...hlight=G2420HD

                Could I do the same but use universal CCFL inverter board? like this one:

                https://www.ebay.co.uk/itm/Universal...wAAOSwl4lbvlnD

                or

                https://www.ebay.co.uk/itm/Ultra-MIN...sAAOxy7S5SClL3

                Would just need some advice on where to solder the relevant wires to my board.

                Comment

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