What is the voltage?

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  • Life Goes On
    Badcaps Veteran
    • May 2014
    • 264
    • Curacao

    #1

    What is the voltage?

    Hi Guys

    I need a little help about this hp dv7, when start, it turn on but with black screen, now i try with the schematic LA-9042P to check on the LVDS CONN that evry pin get the right voltage, but on the +LCDVVD and C479 i don't get any voltage and i can't cee what for voltage that has to be neither, can anyone tell me what is the voltage for that, plus the voltage for usb20 P5 and N5,

    Hope you guys can help.
    [cee picture]
    Attached Files
    The Night Drop Down, I Will Keep Try Until..., You Never know.
    Dushi Kòrsou, Nos Tei.
  • SteveNielsen
    Retired Tech
    • Jun 2012
    • 2327
    • USA

    #2
    Re: What is the voltage?

    Not sure about +LCDVDD but would be within 3 to 5v depending on what the LCD panel uses, the USB20 P5 and N5 are data i/o + and -, you're not likely to measure any voltage with a meter there.

    Comment

    • Life Goes On
      Badcaps Veteran
      • May 2014
      • 264
      • Curacao

      #3
      Re: What is the voltage?

      But i have 0 volt on the +LCDVDD, do you have any idea where i can find that right voltage for, and where the voltagre came from in the schematic, cuz i can't find that neither.
      The Night Drop Down, I Will Keep Try Until..., You Never know.
      Dushi Kòrsou, Nos Tei.

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: What is the voltage?

        3V 80 milliAmp, It comes from the main board through the switched MOSFET Q43 (P CH). Q144A control the GATE BIAS for Q43, When Gate of Q144A (N CH) is HIGH (VGA_ENVDD, VGA ENABLE SIGNAL), Q43 is ON, when it is LOW, then Q43 is BIAS OFF.
        Last edited by budm; 06-09-2014, 09:17 AM. Reason: Corrected the on/off statement
        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

        • Life Goes On
          Badcaps Veteran
          • May 2014
          • 264
          • Curacao

          #5
          Re: What is the voltage?

          Originally posted by budm
          3V 80 milliAmp, It comes from the main board through the switched MOSFET Q43 (P CH). Q144A control the GATE BIAS for Q43, When Gate of Q144A (N CH) is HIGH (VGA_ENVDD, VGA ENABLE SIGNAL), Q43 is ON, when it is LOW, then Q43 is BIAS OFF.

          But on the 16 VGA_ENVDD and the R276 i don't have any voltage,
          what do you think s that ok or not?
          The Night Drop Down, I Will Keep Try Until..., You Never know.
          Dushi Kòrsou, Nos Tei.

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: What is the voltage?

            That signal is generated by the mother board, it should go high once the laptop boots up, if not, you will need out the connection in the SCH to see where that control line goes to. It should change state when the laptop is switched between on and off.
            Last edited by budm; 06-09-2014, 05:25 PM.
            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

            • Life Goes On
              Badcaps Veteran
              • May 2014
              • 264
              • Curacao

              #7
              Re: What is the voltage?

              It come from U5F page 16, take a look, and tell me what you think.
              Attached Files
              The Night Drop Down, I Will Keep Try Until..., You Never know.
              Dushi Kòrsou, Nos Tei.

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: What is the voltage?

                Do you get all three voltages feeding that U5F?
                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

                • atsio
                  Badcaps Veteran
                  • Oct 2013
                  • 819
                  • Greece

                  #9
                  Re: What is the voltage?

                  Reflow gpu.

                  Comment

                  • Life Goes On
                    Badcaps Veteran
                    • May 2014
                    • 264
                    • Curacao

                    #10
                    Re: What is the voltage?

                    Originally posted by budm
                    Do you get all three voltages feeding that U5F?
                    Yep all three
                    The Night Drop Down, I Will Keep Try Until..., You Never know.
                    Dushi Kòrsou, Nos Tei.

                    Comment

                    • Life Goes On
                      Badcaps Veteran
                      • May 2014
                      • 264
                      • Curacao

                      #11
                      Re: What is the voltage?

                      Originally posted by atsio
                      Reflow gpu.
                      i did, but did not work.
                      The Night Drop Down, I Will Keep Try Until..., You Never know.
                      Dushi Kòrsou, Nos Tei.

                      Comment

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