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820-00165 fan spins once

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  • #16
    22 hours ago
    Check resistance between pìns 17/18 and 27/28 at U7100.
    Also post voltage for pins 9 & 15.


    resistance between pìns 17/18 3.4ohm

    resistance between pìns 27/28 174ohm

    voltage for pins 9 & 15., both 0V

    g3h is stable 8.58V, i have 3.3V 3.4V, green light on the charger


    • #17
      Yes your problem is pins 27/28 should be more like 21 ohms not 174 ohms. Check aforementioned resistors and traces.


      • #18
        Solve the problem with R7121/22.

        Also check sensors at page 42.
        Last edited by 2informaticos; 12-21-2018, 12:07 PM.


        • #19
          i replaced r7121, now its 10 ohm both resistors, but same issue

          also i checked them before, even in the original post i mentioned them, they were both good, r7121 burnt later during diagnosis


          • #20
            on u1950 pin 1 and 3 the 3.3V comes up too for 1 sec, so evey voltage is ok for 1 sec


            • #21
              Then even VCORE comes up 1s too.
              If board starts in SMC bypass, all power supplies are good.
              You have problems with some sensor.
              Check pages 41-43...


              • #22
                If you measure on pins 27/28 of the ISL and I mean the actual pins on the chip, do you get 21 ohms now?


                • #23
                  yes its 21 ohm now, but it was 21ohm before, that was the first thing i checked, than i reballed and replaced the SMC, than the resistor went out, i replaced it, sothat part is ok now.

                  what i found is L5001, the pin after it was corroded, so the 3.4V did not come trough, it looks like that is the main power for the SMC, but than how come i had green light on the charger? now i fixed that connection with a wire L5001 to C 5001, but its the same. IS the SMC getting the 3.4V trough another trace? maybe i will cut the trace on a donor board to measure this...

                  i will check the sensors...


                  • #24
                    SMC main power rail goes to VDD pins.
                    VDDA and AVREF should be used by some analog blocks and AD converters.
                    AD converters are related with your problem, dealing with the sensors above mentioned.


                    • #25
                      C5125 was corroded, i just removed it and now it works


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