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If there is an overcurrent situation, how would you find the culprit?

Thanks, you're right, I got confused by the "LDO" in the rail name. However, note that the schematic does say that PP1V5_VLDOINT_SPMU is an output. Here are my complete output voltages for U7700 and U8100: SPMU: PP0V72_S2_VDD_LOW: fluctuating 0-0.7V PP1V2_AWAKE_PLL: fluctuating 0-1.2V...

I'm trying to understand the fluctuating power rail issue. The wildly fluctuating voltages are all buck converter outputs of the PMUs U7700 and U8100. The PMU power input is steady at 3.8V. The LDOs (PP1V5_VLDOINT_MPMU, CAP_PPSPMU_VLDO9, PP1V5_VLDOINT_SPMU) are steady. What tells the PMUs to...

Interesting. I found an error in the board view file. CE903 should be flipped around: on all three boards, ground is on the left, not on the right. Explains the low diode readings. Actual readings are SPKRAMP_INT_L: 0.32 (good boards: 0.0.33, 0.32)

The other data lines look ok: TOUCHID_PWR_EN: 0.27 (good boards: 0.28, 0.27) SPKRAMP_INT_L: 0.004 (good boards: 0.005, 0.004) CODEC_INT_L: 0.32 (good boards: 0.33, 0.33) CODEC_WAKE_L: 0.38 (good boards: 0.38, 0.38) TDM_CODEC_D2R: 0.33 (good boards: 0.34, 0.34) TDM_CODEC_R2D: 0.34 (good boards...

I2C_SPKRAMP_R_CODEC_SCL: 0.32 (good boards: 0.34, 0.33) I2C_SPKRAMP_R_CODEC_SDA: 0.33 (good boards: 0.33, 0.34)

This 820-02016 board was a test board in a shop and abruptly stopped working during the testing of some bad audio boards. USB-C is at 5V, PPBUS is 12.3V, and PP3V8AON is 3.8V. Many secondary rails are fluctuating between 0 and their expected values, about every 1/2 sec. This includes PP1V25_S2...

Any restriction as to what CD3217 replacement chip I can use?

PP1V8_SLPS2R: 1.8V PP1V1_SLPS2R: 1.1V PP0V8_SLPS2R: 0.8V PP1V8_AWAKE: 1.8V PPVDDCPUSRAM_AWAKE: 0.8 V PP1V2_AWAKE: 1.2V PP3V3_AWAKE: 3.3V

That replicates what I've already tried. Still can't get into DFU. This is my first A2141; I've been using an 87W charger (instead of 96W), but that should not affect DFU issues, right? Edit: Never mind, I just tried with a 96W charger and nothing is changed.

Diode mode readings are exactly identical between J3300 and JB500. No matter what method I use, I can't get SOC_DFU_STATUS to go high. So that suggests a damaged T2, yes?

Yeah, I did, but it looks fine. The CD3217 has its LDOs, CC1/CC2 show good diode mode measurements, and it produces 5.1V output. Anything else to check?

I just noticed that one of the USB-C connector boards has significant corrosion on it.

This 2019 16" Pro board supposedly "randomly stopped working". USB-C is stuck at 5V unless I connect a fully charged battery (20V 0A then). PPBUS is 12.3V and it is missing PP3V3_G3S_T and P3V3G3S_EN. The keyboard method for getting into DFU mode results in SOC_FORCE_DFU to go to 1.8V and stay...

No, CPUCORE and PPVCCGT_CPU are 0V.

This 820-01987 board had light liquid damage in the area near U7420, one of the CPU FETs, and some other minor spots. I replaced several corroded components, including U7420. The machine shows a clicking trackpad and some activity on the fan, but no startup. I'm now trying to determine whether...

Tried that, same result. It's time to say goodbye to this board.

Yes, I forced it into DFU mode using the jumper method. The error above appears during Restore.

After installing the NAND chips from an identical 820-02016 board, I now get a new, undocumented error during DFU restore: error 2006.

So they could be from an older T2 board?