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i need help with hp 840 g5 no display

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    #1

    i need help with hp 840 g5 no display

    hi everyone
    hp 840 g5
    computro 6050A2945601-MB-A01
    this laptop comes to me with no display issue
    sometimes only the led blinking with 0amps consumption
    sometimes power on with 0.24amps consumption but black screen
    i test every voltage needed and everything is ok except PVCCGT which is for GPU no short on output
    the ic who generates this voltage has all requirement
    this laptop comes from another repair shop and the try to flash the bios and i think they lost the original
    i also try to flash new one but with no difference .
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    #2
    Re: i need help with hp 840 g5 no display

    Remove all power. Meter in resistance mode. Measure the resistance to ground of each coil / inductor.

    At 0A current consumption, the logic board is not turning on. Start with the basic DCin adapter voltage and the usual 2*DCin mosfets review. If there is a shorted cap, the current draw will be higher than normal and will force the regulator to shut off.

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      #3
      Re: i need help with hp 840 g5 no display

      Originally posted by mon2 View Post
      Remove all power. Meter in resistance mode. Measure the resistance to ground of each coil / inductor.

      At 0A current consumption, the logic board is not turning on. Start with the basic DCin adapter voltage and the usual 2*DCin mosfets review. If there is a shorted cap, the current draw will be higher than normal and will force the regulator to shut off.
      please understand me
      i don't have here any type of short and i already did what you said nothing unormal
      everythig is OK except PVCCGT is missing .
      Last edited by mo000; 06-03-2023, 08:10 AM.

      Comment

        #4
        Re: i need help with hp 840 g5 no display

        The GPU may not always be on. It depends on the design of the logic board. Some designs will enable the GPU power rail only when there is a heavy demand for the graphics.

        sometimes only the led blinking with 0amps consumption
        0A current consumption = nothing is working.

        This must stabilize to be consuming current of a non-zero value, each and every time you power on.

        Comment

          #5
          Re: i need help with hp 840 g5 no display

          Originally posted by mon2 View Post
          The GPU may not always be on. It depends on the design of the logic board. Some designs will enable the GPU power rail only when there is a heavy demand for the graphics.



          0A current consumption = nothing is working.

          This must stabilize to be consuming current of a non-zero value, each and every time you power on.
          blinking but after a while a laptop power on but no display
          i think the blinking related to bios reset but i'm not sure .

          Comment

            #6
            Re: i need help with hp 840 g5 no display

            The blinking will often be a pattern to identify a fault. It is usually a power on self test code.

            What is the blink pattern?

            Comment

              #7
              Re: i need help with hp 840 g5 no display

              Originally posted by mon2 View Post
              The blinking will often be a pattern to identify a fault. It is usually a power on self test code.

              What is the blink pattern?
              power/charging led continuous blinking .

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                #8
                Hello, I have a similar model, it is 6050A2977601-MB-A02. Although they have the same KBC, it has video integrated into the CPU. I'm checking and there is no VCCGT either, but there is a very low resistance of 8 ohm at the output. Would it be too low for that line? Or will the integrated U66310 (SIC534) be short circuited? Note that the DRVEN or ZCD-EN# pin remains at HIGH LEVEL.

                Comment

                  #9
                  Resistance to GND at VCCGT is correct. VCCGT cant be measured with multimeter.If you connect a oscilloscope on VCCGT,you will see a burst of pulses and go away for a moment. Your problem lies elsewhere and not VCCGT.
                  What is the status of DRAMRST#?

                  Comment

                    #10
                    Originally posted by mcplslg123 View Post
                    Resistance to GND at VCCGT is correct. VCCGT cant be measured with multimeter.If you connect a oscilloscope on VCCGT,you will see a burst of pulses and go away for a moment. Your problem lies elsewhere and not VCCGT.
                    What is the status of DRAMRST#?
                    Hello Sir mcplslg123, DDR4-DRAM RST# pin at 1.22v when powering on with a consumption of 451mA on the board, there is also VTT 0.615v. I am also noticing that the machine turns on for only 10 seconds and drops to 36mA in consumption. I will try with another ram, since in the VDD RAM coil the resistance is very very low, 2 ohms. I will comment on the result.

                    Comment

                      #11
                      It seems that the problem is connecting the ram. I have tried several rams but the device turns off, it only lasts 10 seconds with an average consumption of 415mA, then the device seems to protect itself at 36mA. Now where to measure this piece of vegetable? In the meantime I will measure the RT3602AE ic to see if something is wrong with the cpu. I need advice.

                      I am guided by this similar schematic: GRANGER-6050A2977601-MB-A01 Schematic - Badcaps

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