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Samsung S7 G930F Troubleshooting a short downstream?

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  • Samsung S7 G930F Troubleshooting a short downstream?

    DCPS 4.0V max current set to 3A
    into V_BATTERY 50mA B4 PTB*
    into V_BAT (VDD_MAIN)2.13A B4 PTB
    V_BAT seated resistance = 0
    desoldered MAXES 77854k charging IC(I know MAX creates the main power rail)
    DCPS 4v into VBAT
    2.38A B4 PTB
    V_BAT seated resistance = 0.230 (normal is 0.3 > 0.4)

    I tried using freeze spray - nothing stands out. I don't fully understand but think that I'm troubleshooting a short that is not on the main power rail but downstream l. I think this because if the short were on the main power rail when I injected 4v into VBAT I would have gotten the full 3A current draw B4 PTB. Desoldering the MAX's charging IC caused the seated resistance on V_BAT to increase( 0 to 0.230) but not to normal(0.3 > 0.4) There were NO shorts underneath MAX - I had a clean lift. Are these sorts of readings consistent with a downstream short? Thanks

    *B4 PTB = before prompt to boot


  • #2
    No. You definitely have a main short. This is how main shorts behave on Samsungs. You will find heat. But you need a thermal cam to see it.

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    • #3
      Thanks. Would it be correct to say then, based on the posted readings, that the short on the main power rail is a not a full short but a partial short.

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      • #4
        Sure, Maybe you had 10-20ohms to ground. Seems like a pretty classic main short though.

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