820-02841 Problems

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  • Zparts01
    Senior Member
    • Nov 2021
    • 107
    • Canada

    #1

    820-02841 Problems

    I have a 2023 14" MacBook Pro A2779, logic board 820-02841. I bought it off of eBay (probably my first mistake these days). The keyboard was destroyed and strangely enough many keys looked melted off. I found out was it was damaged by a liquid spill into the keyboard (looked like coffee) and maybe someone tried to dry it out with a heat gun and melted the keys, failing miserably. It was disclosed to me that the keyboard didn't work and that the MacBook would shut down right after clicking English (or any language) from setup and clicking to go to the next step. The power just goes off. If you go into options the MacBook will stay running without any issues. Because the MacBook still booted up, my logic was that maybe replace the keyboard and maybe some minor repair to the logic board, but after fully replacing the keyboard and backlight and cleaning up any corrosion on the logic board, where I replaced a dozen or so caps and resistors with exact parts as well as the two PCAL6416A chips with brand new ones and ran a wire to one bad pad to a cap. Now having the MacBook Logic board looks like new and the MacBook look perfect with a new keyboard that was meticulously restored to new, the MacBook still acts the same way. Booting it up, it gets to the setup screen where you select language and as soon as you try to go to the next step it powers off. Does anyone know what might be causing the issue? nAny help is much appreciated.
  • mon2
    Badcaps Legend
    • Dec 2019
    • 13838
    • Canada

    #2
    Try to boot in safe mode. Suspecting that there is an attempt being made to ping a sensor or SMBUS linked device that is failing. Suggest to test the voltage of each such SMBUS pair of lines (SCL / SDA). Confirm these measurements against the schematics.

    Comment

    • Zparts01
      Senior Member
      • Nov 2021
      • 107
      • Canada

      #3
      Thanks for the info mon2! Not sure why I didn't think to try to boot in safe mode, but I guess I was thinking if the built in keyboard was not working I could not do it. Worked with the external keyboard and I was able to complete the macOS setup. Only problem was, at the end of the setup, where is asks if I want to use dark mode or light mode, after selecting then clicking to get to the desktop, it shuts down again. After that it just boots to the login screen when I am not able to enter a password into the password field, as no keyboard works now. I can remember when I accessed the terminal in setup I had changed to security settings to not be fully secure. At the time I was thinking it might give me a different way of getting the MacBook into DFU mode and try a restore, but I was not able to get that to work. Anyway, I am getting a bit nervous taking the logic board in and out, as eventually I'm going to end up breaking a connector or something and it's a pain to get this logic board in and out compared to most other MacBooks. it's installed now, with everything plugged in and only 4 of the logic board screws holding it in place for now. I did measure voltage while it was running (In setup) on SMBUS pair of lines SCL / SDA (at J5101) and the voltage was pin 6= 1.5 - 1.7v back and forth and pin 4 = 1.2v ... I can't fin in the schematic what the voltage should be. Should it be 3.3v?

      Comment

      • Zparts01
        Senior Member
        • Nov 2021
        • 107
        • Canada

        #4
        Can anyone tell me with 100% certainty if there are any 'NOSTUFF" around the PCAL6416A chips and if so can you please tell me what pads are supposed to be "NOSTUFF" as my schematic doesn't say for some reason and I have several that might be missing around these chips. I notice from close ups of the M1 and M3 boards that they don't appear to be empty, but on my M2 Pro they do. If anyone even has a 820-02841 logic board and can post a close up of that area that would be great!​

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        • Zparts01
          Senior Member
          • Nov 2021
          • 107
          • Canada

          #5
          Anyone?

          Comment

          • Zparts01
            Senior Member
            • Nov 2021
            • 107
            • Canada

            #6
            Ok, well maybe I have enough info to get more help. I know where the NOSTUFF is now and verified I have everything where it needs to be on the board. I removed the PCAL6416A chips again and tested without them. I was able to use a USB-C external Mac keyboard and the MacBook was working fine. Replaced the PCAL6416A again with two more new ones from MobileSentrix and once again, the keyboard isn't working, no does that external Mac wired keyboard. Track pad works. I'm not sure what to look at next as I have been on this for a few days now.

            Comment

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