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Samsung S7 G930F Dead

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  • Samsung S7 G930F Dead

    DCPS 0mA before PTB
    PTB 60-70mA. Remove tweezers from power on pins drops back to zero
    1. Main power rail VBAT IS present
    2. Power on signal (PWR_ON)from power button press present
    3. The seated resistance on the main power rail as compared to known good checks ok.

    Behaviour as observed on known good board
    When the power on button is pressed for a few seconds Two voltages are produced

    PWR_ON (4.0v) and AP_PS_HOLD (1.8v)
    AP_PS_HOLD 1V8
    Circuit diagram shows that it is an input voltage to both PMIC and CPU.
    When AP_PS_HOLD persists PMIC creates its power rails. If AP_PS_HOLD is not present the phone does not boot.

    Desoldered PMIC, Soldered on 6 PMICs in total. Tested - desoldered, then soldered on the next one.

    2 PMICs pulled the main power rail low. seated resistance went to zero(didn't power on these - no point)threw out PMICs
    With known good battery power on pins shorted....................

    3 PMICs dead - no power rails - no AP_PS_HOLD - no change, seated resistance normal
    1 PMIC pulled the main power rail down to 1.7volts that's the last PMIC I left on when I decided to call it a day,

    I thought this would be a case of PMIC dead - replace PMIC.
    Now I'm not so sure - these ARE ICs from China. Or am I missing something?

  • #2
    Try the PMICs on the known good if you want to differentiate between bad chip and bad technique.


    • #3
      Thanks - that makes sense.. I'll put this on the backburner until I can pick up a few more known good boards