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[SOLVED]820-3462 fans spin for 2 sec

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  • [SOLVED]820-3462 fans spin for 2 sec

    Hello. I have got a 820-3462 motherboard whit light water damage and when i connect the magsafe the fan start spinning for around 2 second and then shut down.
    whit out nothing connected the magsafe shows red light. sometimes after removing magsafe it use a couple of seconds and some times minute before it show red light .

    on ppbus_g3h i get 12,58 volt (after i have power up and i measure in diode mode from F9700 its starts from -1.244 and goes piping all way up til 0.139 then stop piping) (diode i measure whit out power connected.) can somebody point me to the next step ?

    add som pictures of the water damage area.

    Thank you
    Glenn

    Update some more measurement:

    PP3V3_S5: 3,3V

    PPDCIN_G3H 16,66V Diode mode 0.657

    PP5V_S5 5V
    PPVRTC_G3H 3,3V

    PP3V3_SUS 3,3V

    PP1V05_SUS 1,06V



    Update 2: Now it change from green to red)
    Last edited by Glenn; 08-18-2016, 03:47 PM.

  • #2
    what i found now is a C5379 that look burned and if i measurement between pin 1 and 2 i get 4.513Ω and if i measurement between pin1 and ground in diode mode i got 1.505.
    C5379 is something for SMC could that bee the reason for the macbook start up and shout down after 1-2 seconds ?

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    • #3
      after replacing the C5379 i now get 46.68K Ω

      Any tips for next step?

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      • #4
        Firstly never measure diode or resistance mode with power applied. Was any corrosion by U2600? Was this ultrasonic'd? Is vcore coming on for the second that the fan spins?

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        • #5
          L6995 give me 1.2-1.13 ohm. That is to low?

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          • #6
            Sorry my bad english. I saw it could be construed a bit wrong that i had measure diode or resistance with power applied but i have not do that i unplug magsafe before that.
            LB is not washed in ultrasonic wash no. only toothbrush to isoprobanol
            I can not see any corrosion by U2600 but can with u6990. No chime before it die.

            Yes it was a corrosion round U2600 area. my foult i read wrong.
            Last edited by Glenn; 08-20-2016, 10:33 AM.

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            • #7
              Update whit fans spins:

              L3895 2.45V
              L7030 12.6V
              L7330 1.35V
              L7220 5.02V
              L7260 3.33V
              L7100 0.80V
              L7560 0.00V
              L7550 0.00V
              L7510 0.87V
              L7520 0.87V
              L7630 1.00V
              L7750 5.02V
              L7760 1.80V
              L7720 1.06V

              ALL_SYS_PWRGD gives 2.55V when the fans is spinning.
              In diode mode it gives 0.452.
              Last edited by Glenn; 08-20-2016, 10:31 AM.

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              • #8
                I would start with replacing U2600. A spike on PP3V42_G3H would spike U2600, which would screw up the clock, which could cause the quick fan spin nonsense you're getting now. Further, you said you had corrosion on it.

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                • #9
                  Thanks for answer loius. I will tray to cange u2600 just need to find one from a donor board.

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                  • #10
                    replace the u2600 and still the same result the fan is spinning for a couple of seconds then stop. and still no more happy apple sound on startup.
                    charge dont light up every time but when it dose it dos from green to red light. (need to disconnect the magfase 1 or 2 times before it show light and the charger is 85W original from my own macbook)
                    Last edited by Glenn; 08-22-2016, 03:00 PM.

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                    • #11
                      ALL_SYS_PWRGD and S0 trace give me only 3.3V when the fan is spinning right when the fan stopp the Voltage goes away (need to unplug and plug in magsafe to get fan spinn)

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                      • #12
                        Honestly at this point it can be anything, it will be some corroded trace somewhere or some component we are not seeing. I can't point out what is corroded since you provided a boardview prntscrn rather than a picture of the actual board. If you look closely enough you will find some random corroded shit.

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                        • #13
                          *solved* new SMC and isl6259

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