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820 3115B Green light sometimes, ON/OFF

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  • 820 3115B Green light sometimes, ON/OFF

    Hi, I have another issue with the same board, now I have green light sometimes when I plug the AC charger, sometimes not and when it turns on then turns off.
    When I measure the f6905 sometimes I have 16,75V and sometimes only mV. The AC In adapter is working fine on several boards but not in this one.
    The fan is spinning and it chimes, but no backlight, no image.

    PPBUS_G3H is present but sometimes not, that is why I need help I don't know why this is happening.

    I will explain myself better:

    When I plug the charger green light: PPBUS_G3H is 16,78v for example, then I plug again the charger and I got only 1,6v on pubs_g3h

    Where can I start?
    Last edited by JorgePayar; 04-08-2016, 04:25 PM.

  • #2
    I know you are busy...but...any help is welcome

    Comment


    • #3
      Uhm PPBUS_G3H should never go over 12.6V! Check sense resistor circuit around U7000. R7021/22/51/52. First get this working then we will look at the video/BKL issue.

      Comment


      • JorgePayar
        JorgePayar commented
        Editing a comment
        r7021: 10,2 Ohms
        r7022: 10,2 Ohms
        R7051: 2,5 Ohms
        R7052: 0,003 Ohms

        I think they are good, can a cap be causing that?

    • #4
      Ok thanks a lot

      Comment


      • #5
        What was the original issue on this, and where(if it was a spill)? 16v on PPBUS_G3H is f'd up!

        Comment


        • #6
          Originally posted by larossmann View Post
          What was the original issue on this, and where(if it was a spill)? 16v on PPBUS_G3H is f'd up!
          No, ppbus_g3h is 12,5V
          What is at 16V is the F6905 fuse, and was fluctuating.
          Ok I have reflow U7000 and I soldered better (I think) also I replace R7052 that I thought it was bad but good in appearance.
          Now green light is on most of the times when I plug the charger in. I´ve been following power lines ppbus_g3h is 12,5V good pp3v42_g3h is present too, ppdcin_g3h present but I have a question: must be d6990 fluctuating in voltage? I mean pin 1 2 and 3

          it was spilt on these areas:
          Attached Files
          Last edited by JorgePayar; 04-11-2016, 04:01 AM.

          Comment


          • #7
            D6990 should not be fluctuating. Is PP18V5_DCIN_CONN moving up and down?

            Also, when you plug the charger in, do you get 0 fan spin, or one tiny little flicker of a fan spin?

            Do the caps by the T29 boost circuit look like shit?

            Does U2600 area look like shit?

            Does the SMC look like shit?

            More hints please

            Comment


            • #8
              Originally posted by larossmann View Post
              D6990 should not be fluctuating. Is PP18V5_DCIN_CONN moving up and down?

              Also, when you plug the charger in, do you get 0 fan spin, or one tiny little flicker of a fan spin?

              Do the caps by the T29 boost circuit look like shit?

              Does U2600 area look like shit?

              Does the SMC look like shit?

              More hints please
              Ok, next episode on this mofo mobo, yesterday night everything was good, green light...
              I was going to measure all the things you told me today and...no green light...now ppbus_g3h 2V hmm, then u7000 was shorting!! I quit the U7000 check pins 27 28 and they are shorted!! (diode mode = beep) still shorted without u7000

              Anyway I´ll try to answer you as best as I can

              D6990 should not be fluctuating. Is PP18V5_DCIN_CONN moving up and down?

              PP18V15_DCIN_CONN was not fluctuating when I measured before.

              Also, when you plug the charger in, do you get 0 fan spin, or one tiny little flicker of a fan spin?
              0 fan spin, nothing at all

              Do the caps by the T29 boost circuit look like shit?
              A little bit shity, Im working on it

              Does U2600 area look like shit?
              Kind of... Im working on it

              A little bit yes, Im gonna change caps and resistors

              Does the SMC look like shit?
              No, it is ok

              More hints please
              Sorry about the pics I don't have a camera for the trinocular port yet
              Last edited by JorgePayar; 04-11-2016, 10:07 AM.

              Comment


              • #9
                I think those pins must be like they are now, anyway I have measured u7000 pins without the chip

                Values are:

                pin 1:OL
                pin2:OL
                pin3:OL
                pin4:0.563 V
                pin:5:OL
                pin6:0,663 V
                pin7:OL
                pin8:OL
                pin9:OL
                pin10:0.614 V
                pin11:0,613 V
                pin12:0,337 V
                pin13:0,463 V
                pin14:0,488 V
                pin15:OL
                pin:16:OL
                pin17:0,447 V
                pin18:0,447 V
                pin19:OL
                pin20:OL
                pin21:OL
                pin22: 0V (GROUND)
                pin23:0,447 V
                pin24:OL
                pin25:OL
                pin26:OL
                pin27:0,903 V
                pin28:0,903 V

                Ok U7000 was shorted and I don't have another one right now to test it
                ppbus_g3h f7040: 2V so probably T29bst is responsible as Louis said in one or their videos?
                Last edited by JorgePayar; 04-11-2016, 04:56 PM.

                Comment


                • #10
                  pin 1 0.578 0
                  pin 2 0.568 16
                  pin 3 0.473 3.9
                  pin 4 0.478 3.4
                  pin 5 0.684 1.3
                  pin 6 0.563 3.4
                  pin 7 0.681 0.98
                  pin 8 0.478 2
                  pin 9 0.66 0.032
                  pin 10 0.443 3.4
                  pin 11 0.444 3.4
                  pin 12 0.308 3.4
                  pin 13 0.406 3.4
                  pin 14 0.45 3.3
                  pin 15 0.682 0
                  pin 16 0.605 5
                  pin 17 0.405 12.5
                  pin 18 0.406 12.5
                  pin 19 0.419 5
                  pin 20 0.42 5
                  pin 21 0.416 0.5
                  pin 22 0 0
                  pin 23 0.406 12.5
                  pin 24 0.794 13.3
                  pin 25 0.543 16.81
                  pin 26 0.575 15.93
                  pin 27 0.573 16
                  pin 28 0.569 16
                  diode mode red probe on ground voltage

                  Comment


                  • #11
                    Those are my measurements from a good board a long time ago.

                    Comment


                    • #12
                      Ok thanks but if the pin 1 is OL where can I follow the white rabbit? SMC_DCIN_ISENSE??
                      Attached Files
                      Last edited by JorgePayar; 04-11-2016, 05:01 PM.

                      Comment


                      • #13
                        Woah IGNORE THE FIRST PAGE DIAGRAM NUMBERS it DOES NOT correspond to actual pin numbers on the chip!

                        Check resistance between pins 27/28 and pins 17/18 on U7000 and post values.

                        Comment


                        • #14

                          pins 27/28: 20,2 ohms
                          pins 17/18: 2,8 ohms

                          Comment


                          • #15
                            My best guess at this point is that U7000 is not soldered flatly on the board or is bad. Your measurements show no short on PPBUS_G3H

                            Comment

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