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  1. S

    820-00928 A1707 2017 board with 20A but 0A

    PM_RSMRST_L is 0V and never goes high.
  2. S

    820-00928 A1707 2017 board with 20A but 0A

    PM_SLP_S4_L is 0V and does not change when I connect SMC_ONOFF_L to ground.
  3. S

    820-00928 A1707 2017 board with 20A but 0A

    PM_PWRBTN_L drops to 0V when I trigger SMC_ONOFF_L.
  4. S

    820-00928 A1707 2017 board with 20A but 0A

    I have a 820-00281 board that came in with liquid damage and completely unresponsive. After removing a capacitor that had shorted PPBUS_HS_CPU to ground and replacing all four CD3215, I now get 20V on USB-C but 0A. PPBUS_G3H: 12.6V PP3V3_G3H: 3.3V PP3V3_PMICLDO = 3.3V PP1V25_PMICVREF = 1.24V...
  5. S

    820-02016 A2337 Air board with fluctuating voltages

    Here are the Buck converter output test points for the PMUs.
  6. S

    820-02016 A2337 Air board with fluctuating voltages

    I replaced U8100 from an identical Air 2020 donor board. However, the situation is unchanged, with rapid voltage fluctuations on all PMU outputs. MPMU_VREF_ADC is still 0V.
  7. S

    820-02016 A2337 Air board with fluctuating voltages

    Donor board is the only source available, correct?
  8. S

    820-02016 A2337 Air board with fluctuating voltages

    MPMU_VREF_ADC shows 0.58 (300k on Ohmmeter), which is exactly the same as on a good board. Perhaps the MPMU U8100 is bad?
  9. S

    820-02016 A2337 Air board with fluctuating voltages

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

    820-02016 A2337 Air board with fluctuating voltages

    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...
  11. S

    820-02016 A2337 Air board with fluctuating voltages

    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...
  12. S

    820-02016 A2337 Air board with fluctuating voltages

    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)
  13. S

    820-02016 A2337 Air board with fluctuating voltages

    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...
  14. S

    820-02016 A2337 Air board with fluctuating voltages

    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)
  15. S

    820-02016 A2337 Air board with fluctuating voltages

    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...
  16. S

    820-01700 board without DFU mode

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

    820-01700 board without DFU mode

    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
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