thread top ad

Collapse

Announcement

Collapse

READ BEFORE REGISTERING SO YOUR ACCOUNT WORKS

In order for your account to be activated INSTANTLY, your PayPal email MUST MATCH THE EMAIL YOU USE TO REGISTER YOUR ACCOUNT ON THIS FORUM!! If your PAYPAL email address differs from your FORUM email address, your account will have to be activated MANUALLY when a customer service agent gets around to it.

I realize this sucks, and I do apologize.
See more
See less

820-00281-A Critical Update and Touchbar doesn't work

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 820-00281-A Critical Update and Touchbar doesn't work

    Boot fine in safe mode but touchbar and backlight keyboard doesn't work (I assume it's normal bc of safe mode). With normal boot the macbook ask me for a critical uptade, tried with wifi, wired cable and I also tried what this guy say on a forum (https://apple.stackexchange.com/ques...al-update-loop). No liquid damage, I had some weird stuff around U4200 (picture attached), the rest of the board is nice, I cleaned this area but still have the problem. I tried with a known good Touchbar, a know good casing and keyboard, also with disconnected display, still have the problem of critical update. I tried to boot on an external SSD (same), I also tried clear ME Region.

    With all this done, I think it's a board level problem and I have make some measurements on J4401 and J4402.

    J4401
    PIN 10 DFR_DISP_INT = 0,05
    PIN 12 DFR_DISP_RESET_L = 0
    PIN 18 PP3v3_S0SW_DFR = 3,3V

    J4402
    PIN 20 PP1V8_S0SW_DFR = 1,8
    PIN 19 DFR_TOUCH_ROM_WC = 0,04
    PIN 18 DFR_TOUCH_RESET_L = 1,8
    PIN 13 DFR_TOUCH_INT_L = 0,08
    PIN 9 DFR_TOUCH_SPI_CLK_R = 0,08

    U4406
    PIN 4 DFR_DISP_SMC_RST_L = 3,42V
    PIN 2 DFR_DISP_RSDT_L = 0V
    PIN 6 PP1V8_S0 = 1,8V
    R4400 = 98K OK
    R4490 = 0,125MOhms NOK

    So it's missing DFR_DISP_RESET_L and there is a strange value on R4490, it is a "no stuff" resistance and it should be 0ohms. Should I run a wire there ?

  • #2
    "J4401
    PIN 12 DFR_DISP_RESET_L = 0
    --------------
    U4406
    PIN 4 DFR_DISP_SMC_RST_L = 3,42V"
    There is an error; please post accurate information.
    U4406 requires high level on both inputs.


    R4490 is NO STUFF, do NOT solder anything there.

    Check lid, reset and detect signals at J4402.

    Comment


    • #3
      "U4406
      PIN 4 DFR_DISP_SMC_RST_L = 3,42V
      There is an error; please post accurate information."


      My bad I mean PIN 1 DFR_DISP_SMC_RST_L = 3,42V

      "Check lid, reset and detect signals at J4402."
      J4402
      - PIN 2 DFR_TOUCH_LID = 1,76
      - PIN 1 TOUCH_PANEL_DETECT = 0,05
      - PIN 15 DFR_CLKIN_RESET_L = 0,09
      - PIN 18 DFR_TOUCH_RESET_L = 1,8

      I haven't try with Touchbar connected but I don't thing I need it to have the right voltage at panel_detect.

      I also made some measurement on U3900 :
      - DFR_TOUCH_ROM_WC = 0,04
      - GPIO2 = 0,09
      - TOUCH_PANEL_DETECT = 0,05
      - SOC_PANIC_L = 1,62V
      - SOC_PCH_DBELL_L = 1,6V
      - S2R_ACK_L = 1,77V

      It seems to be strange to have SOC_PCH_DBELL_L = 1,6V, I thing it should be 1.8V. At R1562 I have PP1V8_SUS = 1.8V.

      U3900 could be the cause of all of this, I tried a simple reflow but no change, not sure that it worked well actually. I will try to reball it but I'll need a stencil for this, not easy to order it with the delivery limitation atm.

      Does someone think of an other possibility that could avoid to remove U3900 ?


      Comment


      • #4
        Touchbar itself controls detect signal.
        You must check other signals with touchbar connected...

        Comment


        • #5
          Understand, I'll check every signal with touchbar connected. And what do you think about the voltage of SOC_PCH_DBELL_L = 1,6V ?

          Comment


          • #6
            No idea if should be low, or high; compare with good board, if available.
            However, if should be high, 1.6V is good enough; is more than 80% from 1.8V...

            Comment

            thread bottom ad

            Collapse
            Working...
            X