MacBook A1989 repair / no CPU voltage no boot signs

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Nikan.e
    Member
    • Nov 2023
    • 17
    • Germany

    #1

    MacBook A1989 repair / no CPU voltage no boot signs

    Hello everyone.

    I have recently obtained a MacBook Pro A1989 model with a touch bar and Apple ID. Unfortunately, it does not want to start up.

    No CPU Voltage.
    U7800 Does produce voltages.
    T2 Chip warming up very very little.

    I do have voltages like 1.8, 0.9, 3.3, 2.5 volts, etc., present. I did not find any short circuits. Unfortunately, the device has no touch ID/start button. So, I have used the debug jumper to put the device into DFU mode. - It is getting recognized as a Macintosh while not in DFU mode and as Apple (DFU) while in DFU mode.

    I thought to myself that it might need a BridgeOS revive. Unfortunately, I am not in possession of another Mac, so I have used VMware to set up a Mac Sonoma system. Apple Configurator does see the device in DFU mode. But whenever I try to revive it, it starts but unfortunately does not complete.

    I am wondering, do you need to have a Mac, or does the revive option also work in a virtual machine? What about the touch ID/start button? Does the Macbook need to have one installed to be able to revive it (does the T2 chip check if that module is installed) or can it be ignored for now to revive the T2 chip?

    Any help or what I should check would be appreciated.
    Thanks in advance and best regards from Germany,
    Nikan

Related Topics

Collapse

  • MyronViegas
    MacBook Pro 2018 A1989 820-00850-A Stuck at 5.00V and 0.150A
    by MyronViegas
    Hey guys,

    I got a MacBook Pro a1989 820-00850-A dead for repair. The MacBook itself was off for a month or so and it didn't power on. I tested using ammeter and it was stuck on 5v. Opened the machine and found a short on ppbus_g3h, corrosion near the right spkr_amp. removed the spkr_amp and saw short on ppbus_g3h. plugged in to power, boosted to 20v .600A and then back down to .300A. Trackpad was clicking when on .600A but no image etc.

    Later, I tried again but it dropped down to 5v and never boosted back to 20V. checked board again and found ppbus_g3h shorted again....
    10-06-2025, 08:45 AM
  • Madoy104
    Macbook Pro A1989 - No image, working fine with external monitor
    by Madoy104
    Hi everyone,


    I have a MacBook Pro A1989 that was likely exposed to liquid. It doesn't display an image on the built-in screen, but the screen is backlit (you can't see the Apple logo or any other elements when held up to light). The laptop provides 20V and 1.5-2A, and it works fine when I use it with an external monitor. Currently, the connector for the display (J8500) is disconnected. I'm writing to ask for help in diagnosing the issue. I've heard that when the J8500 is exposed to liquid, the processor pin responsible for the display might short-circuit, and I'd like to know...
    08-15-2024, 10:01 AM
  • Woodsworth
    MacBook Pro A2289 no signs of life except clicking trackpad and charging
    by Woodsworth
    Hi,

    I hope this is the correct place to post about this device. I originally posted regarding this on iFixit so see the details from that post below:

    "I'm hoping someone can give their opinion on the symptoms I'm seeing before I spend any more time and put money into this. I got this MacBook from a customer and after looking at it they decided they didn't want it.

    It doesn't turn on and there's no visual signs of life. I have tried resetting the NVRAM, SMC, power cycling, unplugging the battery, using the charger with the battery unplugged. Removed the...
    03-15-2024, 04:06 AM
  • tommy97
    MacBook A1989 No power
    by tommy97
    Hi,

    I’m having an issue with an A1989 board after water damage, it’s stuck at 5V 0.20A. I’ve checked the measurements, and all readings are the same across all four CD3215 chips. I replaced them one by one (using chips from a donor board), but nothing has changed.

    I don’t need a fully functional board, as the repair is only for data recovery purposes.
    • PP3V3_G3H: 3.3V
    • PPBUS_G3H: 12.26V
    • PP20V_USBC_XB_VBUS 5V
    • PP3V3_UPC_XB_LDO 3.3v
    • PP1V8_UPC_XB_LDOA 1.8V
    • PP1V8_UPC_XB_LDOD 1.8V
    • PP1V1_UPC_XB_LDO_BMC 1.1V
    Can the A1989 work with just one master CD3215? What would...
    10-16-2025, 01:57 PM
  • PITERPENY
    Macbook A1989, 820-00850, won't boot. 20V, 0A.
    by PITERPENY
    Today I have a MacBook A1989 at work 820-00850. When assembled, the laptop switches to 20 volts but the consumption is 0.00 ampere. if the motherboard is on the table then the consumption of all ports is 5 volts and0.35 amperes and does not go to 20 volts only if you assemble a MacBook.
    Here are some measurements, maybe someone can tell what the problem is.
    The initial problem was a burnt out induction coil L8504 (replaced).
    When connected to another MacBook, it constantly hangs in dfu and cannot install updates, something is wrong.
    here are some measurementsmotherboard...
    01-16-2024, 02:19 PM
  • Loading...
  • No more items.
Working...