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AOC U28G2AE monitor can’t adjust the brightness

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    #1

    AOC U28G2AE monitor can’t adjust the brightness

    Hi, I have this monitor with this problem: go to menu picture of monitor and try to adjust the brightness, the cursor is moving to 100 but the screen still darker, without any change. Inside of the monitor, on power board I measured 32.42V output voltage on backlight inverter, which is constant for any value of brightness cursor ( 0 - 100 ) . It's possible to have a memory error on the logic board?
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    #2
    Re: AOC U28G2AE monitor can't adjust the brightness

    I had tested the led backlight with a different inverter, everything it's working. I have to check PWM signal at the input of OZ9998

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      #3
      Re: AOC U28G2AE monitor can't adjust the brightness

      Also check any small caps around the LED backlight inverter circuit. If those are bad, that could also possibly mess with the PWM backlight adjustment.
      Pictures would help too, BTW, so we can see what you're seeing.

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        #4
        Re: AOC U28G2AE monitor can't adjust the brightness

        Picture of powerboard inverter side
        Attached Files

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          #5
          Re: AOC U28G2AE monitor can't adjust the brightness

          The solder joints on some of the jumpers around U801 look bad. Probably not the problem, but certainly worth going over with your soldering iron.

          Were you able to check the PWM signal going to the input of U801?

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            #6
            Re: AOC U28G2AE monitor can't adjust the brightness

            Thanks for your reply,
            I change IC U801 and what I got now is brightness on maximum but without control.
            I don't have any oscilloscope to see PWM on the input

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              #7
              Re: AOC U28G2AE monitor can't adjust the brightness

              Re check your solder connections on U801, maybe one pin is not soldered or two pins are shorted? Does the voltage on pin 16 change when the brightness is adjusted in the menu?
              Last edited by R_J; 03-08-2022, 06:13 PM.

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                #8
                Re: AOC U28G2AE monitor can't adjust the brightness

                @tehmatix Did you manage to fix the problem?
                I have the exact same issue on a Dell P2722H monitor.

                It feels like the brightness is stuck on 50%.
                If I can get it to 100% I'm considering adding a potentiometer to be able to adjust the backlight.

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