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820-00165 No green light. powers on, boots to O/S

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  • 820-00165 No green light. powers on, boots to O/S

    Morning all.... as usual, I am stuck.
    So, MBA A1466 820-00165- liquid ingress. Initial presentation... no boot, no power, no magsafe LED.
    Opened up, JTAG corroded- removed- pads cleaned.
    U5110- corroded- removed, pads cleaned, U5110 put back on from a donor board.
    I now get PP3v42_G3H and PPBUS_G3H.... I get fan spin ( like a loon). When connected back to the screen I get the folder symbol. Connect customers SSD, boots to O/S. Still no magsafe LED. Battery symbol shows 52% on login screen but unable tio get to desktop as customer has not given correct password, so I go to guest account and although the battery symbol shows 52% it shows charger not connected. When left the % rises which would indicate to me it is charging. I have done a PRAM and SMC reset ( as far as I can tell the SMC reset may not have got through as no LED on magsafe). But now, when I connect the magsafe it goes straight to orange... no green. However this is not all the time. Sometimes it will remain off but the MBA will power on and boot to the login screen. After about 3-5 mins the magsafe will go orange. And I have swapped to 2 other adapter, both genuine apple.

    I have swapped the Q6060 and now the fan spin rises and falls as the cpu temp changes.. so I suspect I have sorted that as well.

    Things to add but may/ maynot be relevent:-
    U5110
    pin 1= 3.45v
    pin 2= gnd
    pin 3= 3.448v
    pin 4= 2.72v
    pin 5= 3.41v ---- when testing the voltage on this pin the MBA will restart ( fan stops, then about 2 secs after probe removed fan spins)
    pin 6= 3.42v
    pin 7= 3.44v
    pin 8= 3.315v

    Now, I am also curious... 3.44 to 3.45 on the 3.42v rail..... am i being paranoid?

    No other corrosion present on the board.

    Replaced DC in board with another known good and also trackpad ribbon had a bit of corrosion and this has also been swapped.
    On occasion, after doing the PRAM reset I get a no backlight issue. But pulling the battery and adapter off and replaceing them, power on the screen energises and the image can be seen. When there is no illumination placing a torch I can see the display so it is the backlight not an image issue.

    BTW, just to add, I have got a new meter.... did a quick test for short to ground on pin 5 and I get a reading of .5347v... is that good or bad. Reason i tested here for a short was because of the restarting when testing the voltage.

    Any words of advice please.
    Thanks in advance....
    Marc
    Last edited by RESQ-MYTECH; 04-08-2019, 05:30 AM.

  • #2
    Use ONLY original Apple 60/85W Magsafe 2 charger.
    1-->2 adapter generates weird issues, like backlight one.

    On this machine Magsafe light stays amber even without battery.
    It switch to steady green ONLY when battery is fully charged 100%.
    Battery cannot be charged if no Magsafe light present.

    On the LIO board are 2 chips for SYS_ONEWIRE; usually marked U6900/01.
    Compare with available LIO board schematics, or other MLB; i.e. 2936/3115 (U7000/01 on 3476/4924).
    Be sure to have good contact for SYS_ONEWIRE between both boards.

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    • #3
      Once again... You Da man 2informaticos.
      Even though all 4 connectors look fine the charge ribbon was the fault.
      Replaced this then I got the green LED changing to orange. All charges OK, powers on OK. Fans running at a sensible speed .

      Just goes to show, even if it looks good it may not be. Good call on checking on sys_onewire connection for both boards. 20190408_115655_001.jpg
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