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[SOLVED]820-2915-a no power, no green light

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  • [SOLVED]820-2915-a no power, no green light

    this board works with a third party charger, found that out when fixing it, but does not turn on with a genuine apple charger, green light comes on for a split second then goes off. my guess is that the U7000
    is not recognizing the charger, but im at a loss on how to check what has went out . because the charger wont turn on, all i get is 1-2v anywhere, this board came in with a dead mag-safe, blown f6905, blown off the board c9000. replaced it all and it worked with my third party charger that at the time i didn't know was a third party charger. "replaced the charger with a genuine charger already"

  • #2
    First suspects are R7005/21/22, Q7080/85. I assume PPBUS is 12.56V with the fake charger.

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    • #3
      wish i had a fake charger still, we got rid of it once we found out it was fake, the customer fried theirs using a fake charger.

      i will test voltages at thoes locations tomorrow when i get back into work

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      • #4
        They are useful for trouble shooting.

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        • #5
          changed out u7000 with a board that has a bad gpu, but still powers, still nothing, tho i was confused, i removed u7000 and the green light still comes on on the bad gpu board. yet on the board im working on it wont come on. i dont have a fake charger to test it out. what am i missing?

          is there a way to test Q7080?

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          • #6
            Uhm, take the board with the bad GPU to Apple for a free repair.....
            Get a fake charger for trouble shooting.

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            • #7
              if u7000 is removed what makes the green light still come on? my problem lies there

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              • #8
                ACOK is not being pulled low by U7000. Is 3V42 present now?

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                • #9
                  with or without u7000 i get no 3v42 power , green light for one second then it goes off, and wont come back on unless i leave it unpluged for a few min

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                  • #10
                    Short on PPDCIN, 3V42? Also remove F7040/41 without U7000 you risk getting the full adapter voltage on PPBUS!!

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                    • #11
                      the mac works with a third party charger, at least it did, if i had a short wouldnt it never have worked? it i remove the fuses 7040 and 7041 i shouldnt get any power since PPBUS_G3H would be disconnected to the system.

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                      • #12
                        Last time, get a fake charger for trouble shooting. Then we can go further with this.

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                        • #13
                          Remove F6905. Place 18.5v from a real bench power supply on pin 2 of F6905. Then plug known good 85w charger in with known good dc in board. If it works, Q7080 is bad.

                          If you do as duke says and get a knockoff charger this will be easier to troubleshoot.

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                          • #14
                            ok so even putting in 18.5v in on pin 2 of f6905 and plugging in the 85w apple charger, did not give a green light. i do have a fake charger on its way, praying its fake, spending less than 20$ on it and it has no apple logo. lol, is their any more testing i can do before the new charger arrives?

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                            • #15
                              When you put 18.5V in the system the 3V42 bus should at least come high.

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