BenQ BL2400PT no backlight

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  • meciu
    Member
    • Nov 2016
    • 37
    • Germany
    #1

    BenQ BL2400PT no backlight

    Hey!
    So starting yesterday - my old 24" LED display doesn't work well - device displays image but there is no backlight and I can hear hissing from power supply.

    I've tested lcd 6pin power cable and here are the :

    Black standby 0.4v power on 3.7v
    Brown standby 0.4 power on 3.4v
    Red standby 21.8v power on 28.9v
    Red standby 21.8v power on 28.9v
    Yelow stand by 0.4v power on 3.7v
    Green stand by 0.4v power on 4.8v

    Any ideas what's wrong with it?
    Attached Files
    Tags: None
    • meciu
      Member
      • Nov 2016
      • 37
      • Germany
      #2
      Re: BenQ BL2400PT no backlight

      Resistance test of (yellow) transformer 10pin
      P1 P2 3.5K Ω
      P1 P3 1.4MΩ
      P1 P4 0.2-0.5Ω
      P1 P5 200K-1MΩ
      P1 P6-10 0L

      P2 P3 0.3Ω
      P2 P4 39MΩ
      P2 P5 0.5Ω
      P2 P6-P10 0L

      P3 P4 6M-33MΩ
      P3 P5 0.3Ω
      P3 P6-P10 0L

      P4 P5 0.6M-1.5MΩ
      P4 P6-P10 0L

      P5 P6-P10 0L

      P6 P7+P8 0.18Ω
      P6 P9 0.16Ω
      P6 P10 0.16Ω

      Pin7 and pin8 are soldered together

      P7+P8 P9 0.12Ω
      P7+P8 P10 0.12Ω

      P9 P10 0.19Ω
      Last edited by meciu; 11-13-2019, 12:59 PM.

        Comment

        • digitalpc
          Badcaps Veteran
          • Jun 2016
          • 305
          • .DLL
          #3
          Re: BenQ BL2400PT no backlight

          do u check output capacitor and diode

            Comment

            • R_J
              Badcaps Legend
              • Jun 2012
              • 9529
              • Canada
              #4
              Re: BenQ BL2400PT no backlight

              I doubt your problem is with the power supply, check the voltage on the led driver board.
              I suspect you have a problem with the led's themselves, Check the voltage going to the led's when you first turn on the monitor.

                Comment

                • meciu
                  Member
                  • Nov 2016
                  • 37
                  • Germany
                  #5
                  Re: BenQ BL2400PT no backlight

                  This tested by me 6 pin cable is actually a LED power cable.
                  So it is time for a LCD screen disassembly to check led diodes.

                    Comment

                    • meciu
                      Member
                      • Nov 2016
                      • 37
                      • Germany
                      #6
                      Re: BenQ BL2400PT no backlight

                      Okay,
                      Almost half of leds aren't working correctly.
                      Question is - what kind of LEDs I need to look for.
                      I assume that I need to find LEDs in 4 pin PLCC package (5x3x1mm) but which one?

                      This led bar has two markings
                      "AS-24M07005-N5HEX-X-1-11G-0057" and "N5HE"
                      Attached Files
                      Last edited by meciu; 11-14-2019, 09:45 AM.

                        Comment

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