Announcement

Collapse
No announcement yet.

Macbook 820-01700 Stuck at 5V

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

    Macbook 820-01700 Stuck at 5V

    Can't get my 820-01700 to boot. ammeter says 5v and 0.05 amps. Board is a few years old, has no signs of corrosion at all.

    I went through the power rails and measured them:
    PPBUS_G3H - 12.3v
    PPBUS_HS_CPU - 12.3v
    PPBUS_HS_GPU - 12.3v
    PPBUS_HS_OTH5V - 12.3v
    PPBUS_HS_3V3G3H_T - 12.3v
    PP3V3_UPC_XA_LDO - 3.38v
    PP3V3_G3H_T - 3.37v
    PP3V3_G3H_RTC_X - 3.38v
    P3V3MAIN_PGOOD - 3.3v
    PP1V8_SLPS2R - 1.86v
    PP0V8_SLPS2R - 0.797v
    PP1V1_SLPS2R - 1.1v
    PMU_ONOFF_L - 3.37v
    PMU_RSLOC_RST_L - 3.38v
    PP1V2_AWAKE - 1.19v

    PM_SLP_S4_L - 0v - 98k resistance to ground

    PP5V_S5_LDO - 0.0v - 3.8k resistance to ground
    PP5V_G3S - 0.0v - 260 ohm resistance to ground
    P5VG3S_PGOOD - 0v - 69k resistance to ground

    PP1V8_G3S - 0.0v - 211 ohm resistance to ground

    Behavior and measurements are the same for all 4 usb ports.

    Any ideas on where I need to look? The apple store wants $800 to replace the board. I'm trying to learn so I can do it cheaper.
    Last edited by powerblackout; 01-09-2022, 11:44 PM.

    #2
    Re: Macbook 820-01700 Stuck at 5V

    When I plug the motherboard into another macbook to do a DFU restore it immediately shows up on the other machine as DFU. When I tried to do a revive I get an error about expecting recovery mode.

    When I start the revive the board goes to 20V 0.01A then I get an error

    "Unexpected device state 'DFU' expected 'Recovery' (Probably forced into DFU mode externally) [com.apple.MobileDevice.MobileRestore – 0xFAE (4014)]"

    Comment


      #3
      Re: Macbook 820-01700 Stuck at 5V

      No personal experience with this but @Piernov noted that T2 bridgeOS must be there for the 20V power delivery contract to work on this logic board. So your approach is logical.

      See here:
      https://boards.rossmanngroup.com/thr...roblems.61662/

      also T2 based.

      Comment


        #4
        Re: Macbook 820-01700 Stuck at 5V

        Thanks, after giving that a read my 0V9_SSD is 0.00v, and has a 0.342 diode reading. It goes into DFU mode without having to press any keys, it happens when the board is outside the case disconnected completely. Is there something on the board that can do that?

        My AWAKE and SLPS all look fine I think:
        PP1V8_AWAKE - 1.8v
        PP1V2_AWAKE - 1.19v
        PPVDDCPUSRAM_AWAKE - 0.8v
        PPVDDCPU_AWAKE - 0.756v
        PP3V3_AWAKE - 3.37v

        PP1V8_SLPS2R - 1.86v
        PP0V8_SLPS2R - 0.797v
        PP1V1_SLPS2R - 1.1v
        PP1V25_SLPS2R_SMC_AVREF - 1.25v
        Last edited by powerblackout; 01-10-2022, 02:09 PM.

        Comment


          #5
          Re: Macbook 820-01700 Stuck at 5V

          After more researching it appears U9500 controls U9580 via the SSD0_VR_P2V5_EN which on this board is always 0v, would this mean the U9500 is having issues?

          Comment


            #6
            Re: Macbook 820-01700 Stuck at 5V

            Yes, it may be. Confirm the presence and voltage of PP3V3_G3H_SSD0_SNS.

            Comment


              #7
              Re: Macbook 820-01700 Stuck at 5V

              PP3V3_G3H_SSD0_SNS is present, 3.38v.

              I didn't realize there was another set of these for SSD1, I checked these two
              SSD1_VR_P2V5_EN - 0.0v
              PP3V3_G3H_SSD1_SNS - 3.38v

              What are the chances that both U9500 and U9000 are broken? Or maybe I need to look further upstream for something that controls both of these?

              Comment


                #8
                Re: Macbook 820-01700 Stuck at 5V

                Is it normal that the macbook immediately shows up in apple configurator 2 as soon as i plug it in? i don't have to do the keyboard shortcuts.

                If I plug the charger in, then start the revive process, the charger will jump to 20V 0.01A, but PPBUS_G3H will still be 12.3V

                Comment


                  #9
                  Re: Macbook 820-01700 Stuck at 5V

                  Not familiar with the Configurator 2 tool so wait on others to comment.
                  20V 0.01A, but PPBUS_G3H will still be 12.3V
                  This is correct that the power delivery contract with 20V is ultimately selected by the ACE controller and the PPBUS_G3H steps this voltage down to 12v3. Thought I read on Logiwiki that 12v6 is the sweet spot after some more states are enabled on the power rails. Either way, you are very close on the PPBUS_G3H rail.

                  reference:
                  https://logi.wiki/index.php/PPBus_G3H

                  Comment


                    #10
                    Re: Macbook 820-01700 Stuck at 5V

                    https://apps.apple.com/us/app/apple-...37126344?mt=12 the app that allows DFU revive/restore?

                    Comment


                      #11
                      Re: Macbook 820-01700 Stuck at 5V

                      Do you know what controls the creation of the 0.9, 1.8, 2.5v from this chip? I checked SSD_PMU_RESET_L (1.8v), is it controlled via the SCL/SDA communication?
                      Attached Files

                      Comment


                        #12
                        Re: Macbook 820-01700 Stuck at 5V

                        Another discovery. I hooked my oscilloscope up to I2C_PWR_SDA and I2C_PWR_SCL lines going to the charger, i see them go up to 1.785v but they do not have any traffic on them. I see i2c is controlled by T2 chip, this would suggest why battery isn't charging and why U9500 isn't turning SSD on? because T2 is messed up and not communicating over i2c?

                        Another discovery! I put the ammeter between the two machines, when the revive process starts the ammeter reads 4.93v 0.2a, and the T2 chip gets to about 80 F while the rest of the board is at 70 F. While it is doing this the PP2V5_NAND_SSD0 etc are still 0
                        Last edited by powerblackout; 01-12-2022, 12:03 AM.

                        Comment


                          #13
                          Re: Macbook 820-01700 Stuck at 5V

                          I got it up to 4.46V 1.03A using a beefier usb cable. it appears it is charging the battery from the other macbook, I see the PPBUS_G3H voltage rising and I see i2c traffic on the ribbon going to the battery. This all only happens once a revive is started.

                          The DFU revive failed with error code 4005, I finally found a site that had some information on what that means https://logi.wiki/index.php/DFU_Mode_Restore_(Macs)

                          4005 = SSD not found.

                          So if T2 chip is actually starting to be revived, but can't find SSD for the T2 partition, and i2c appears to be functioning, where else should I look to find why it can't turn SSD on? Why U9500 Why!
                          Last edited by powerblackout; 01-12-2022, 12:53 AM.

                          Comment


                            #14
                            Re: Macbook 820-01700 Stuck at 5V

                            U3900 (SMC) is the I2C bus master and the voltage readings for I2C_PWR_SCL and I2C_PWR_SDA look good.
                            I got it up to 4.46V 1.03A using a beefier usb cable.
                            This voltage sounds low. Personally have not yet used the configurator 2 tool but working on some T2 logic boards now so may have this need.

                            SSD_PMU_RESET_L is driven by U3900, J32 ball (marked as OUTPUT).

                            Meter in resistance mode, remove all power. What is the resistance to ground for PP2V5_NAND_SSD0 ?
                            Attached Files

                            Comment


                              #15
                              Re: Macbook 820-01700 Stuck at 5V

                              Measured SSD_PMU_RESET_L it is 1.8v, the L means it pulls the line to 0v when it wants the chip to reset? So 1.8v means it should be working?

                              Resistance for PP2V5_NAND_SSD0 immediately after i remove power is 62 ohms. is 87 ohms 30 seconds later and keeps rising. 1 minute later it's passed 100 ohms.

                              Comment


                                #16
                                Re: Macbook 820-01700 Stuck at 5V

                                Resistance looks ok.

                                Confirm the voltages for the attached locations on U9580 which creates this 2v5 rail for the SSD.
                                Attached Files

                                Comment


                                  #17
                                  Re: Macbook 820-01700 Stuck at 5V

                                  PPBUS_G3H_SSD1_SNS - 12.3v
                                  PPBUS_G3H_SSD0_SNS - 12.3v

                                  SSD1_VR_P2V5_EN - 0.0v
                                  SSD0_VR_P2V5_EN - 0.0v

                                  SSD1_VR_P2V5_EN_R - 0.0v
                                  SSD0_VR_P2V5_EN_r - 0.0v

                                  Comment


                                    #18
                                    Re: Macbook 820-01700 Stuck at 5V

                                    Remove all power.

                                    What is the resistance to ground for the following ?

                                    SSD1_VR_P2V5_EN
                                    SSD0_VR_P2V5_EN


                                    Technically, these are enable pins for the local 2v5 regulators. If the resistance on this rail is not low, then you could in theory, remove the series resistor (R9098 for SSD1; R9598 for SSD0) bridging the driver & this local TI regulator -> then hard strap the enable pin to be logic high to force it always ON. This in turn should turn on the regulator to power on the SSD (of your choice).

                                    The enable pin will consider a voltage > 1V to enable. You can strap the ENABLE pin to 3v3 on the board.

                                    If you decide to do this, ping back so we can agree on a proper location for this rail.
                                    Attached Files

                                    Comment


                                      #19
                                      Re: Macbook 820-01700 Stuck at 5V

                                      SSD1_VR_P2V5_EN - 3.2 megaohms
                                      SSD0_VR_P2V5_EN - 3.1 megaohms

                                      Yes I could force enabling the pins to see if the SSD even works. Would this be a permanent solution?

                                      Comment


                                        #20
                                        Re: Macbook 820-01700 Stuck at 5V

                                        First, I would test it but gathering that with the power rail always enabled, the battery will drain faster.

                                        However, this could be a case of the chicken and the egg - you need to manually enable the SSD so that you can restore the T2 firmware and after this is resolved, apply the series resistor back onto the logic board and test again.

                                        In theory, this may be the resolution. Very curious and wanting to hear of your success.

                                        Comment

                                        Working...
                                        X