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820-00165 no power, Missing PP3V3_S5

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    #1

    820-00165 no power, Missing PP3V3_S5

    Hello,
    Having trouble identifying the problem for this motherboard,
    some one has already been here and messing with U7501, but looks to be repaired, but this time had some corrosion by U3210, removed it and cleaned up the pads, and replaced with new one, still no power. By U7501 saw that C7588 was missing, put it on but still nothing, while doing investigation found that i have PPBUS_G3H - 8.6v; PPDCIN_G3H - 16.5; PP3V42_G3H - 3.44; PP5V_S5 - 5v; but i dont have PP3V3_S5 - 0v there fore don't have any S4; S3; S0 voltages; By U7501 i have P3V3S5_EN_R- 3.3v; SMC_PM_G2_EN - 3.3v; PP3V3_S5_REG_R- 0v; P3V3_S5_REG_L - 0v; pin24;25;27 on U7501 also 0v;
    Since I'm new to Macbook MB repair i cant figure out the problem.
    Already replaced U7501 vice versa from a know good A1502 board and and after that A1502 boots OK but the A1466 doesn't boot.
    Also tried removing U3210 to see if anything changed, but nothing.
    Haven't noticed any shorts on any lines mentioned.
    Will be grate-full for any advice, Thanks!
    Tags: None
    #2
    Re: 820-00165 no power, Missing PP3V3_S5

    check for short on 3,3 coil. check resistance on l7560

    Comment

      #3
      Re: 820-00165 no power, Missing PP3V3_S5

      L7560 measures 1ohm, on donor board it the same, is that a good reading?
      L7560 pin 1 to ground measures 0.480 kohm, the same on pin 2

      Comment

        #4
        Re: 820-00165 no power, Missing PP3V3_S5

        check voltage on l7560 when u put psu. check if there is some voltage spike.
        when wwe ask for resistance: red on gnd and black on measuring point.
        in ur case 0.480komh looks like there is no short on 3,3 rail.
        7501 u sure is good and well soldered ?
        voltage on r7516, r7546; both side of each resistor.

        Comment

          #5
          Re: 820-00165 no power, Missing PP3V3_S5

          Most common issue I see on this converter is corrosion eating at the test points next to it. If they are dark and not shiny, scratch at each one to make sure they actually aren't open circuit. Also check that boost components C7564/R7564 are present and correct. As dellxps15 asked, check for a spike of 3V3 after power is applied, as you may have an active short, rather than a passive one.

          I always do a quick check on the major coils of the board for resistance to ground, especially L7630 as a shorted PCH is a common failure on these boards.

          Comment

            #6
            Re: 820-00165 no power, Missing PP3V3_S5

            480 ohms on a 3.3V power rail is too low.
            OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

            Comment

              #7
              Re: 820-00165 no power, Missing PP3V3_S5

              So while checking R7516 and R7546 voltages witch was btw 0v, I also checked the values of these resistors, and when checking the value of R wasnt getting any, and when poking around the wire trace was not soldered enaght to the resistor so the U7501 wasnt getting an EN signal, I soldered this trace correctly, and BOOM !!! Finaly fans spin!
              Thanks Dellxps15 for guiding me to the real problem, i think i would be given up at that point

              Comment

                #8
                Re: 820-00165 no power, Missing PP3V3_S5

                congratz for the repair

                Comment

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