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i6S w/ open line on PN5v7_LCM, not filter or IC?

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  • i6S w/ open line on PN5v7_LCM, not filter or IC?

    Ok guys I need help... had a 6S come in that was slightly water damaged and came on with no image. Tested and found that the PN5v7_LCM pin metered as an open line. Figured probably the filter but it tested fine for continuity so I guessed that I would find some corrosion underneath the board where chestnut is. Took it in as a water damage repair and didn't think it would be too hard. When I removed the board I was pleased to find exactly what I expected judging by a small area of white residue on the black sticker over the top portion of the board. But when I pealed it back, the area looked completely clean. The balls under the chip that I could see looked fine as well. Since there's only 2 caps and 1 filter on the line between the chip and the connector, I assumed it must have just failed internally somehow. I removed it and still had an open line... put a new one on, same thing. How is this possible???
    Last edited by AmarilloCellularRepair; 12-09-2017, 02:12 AM.

  • #2
    The trace between the two is probably burnt, you need to add a new line to complete the circuit.


    • #3
      Open Line on that line is not a common fault for no image 6s after water. Never seen that be the fault but anything is possible.
      So let’s think, and lay out all the possibilities
      1–You don’t really have an OL there and are getting trolled by multimeter
      2–you have an OL and measured across top of filter, filter itself is good, but is no longer adhered to its pads
      3–you have an OL under chestnut
      4–you have an OL due to torn/burned trace in the board.

      i think that only 1 and 2 are likely since you already changed chestnut.

      change the filter and then go back to diode mode in the connector


      • #4
        Thinking more—this is definitely multimeter troll. The PN line from memory is very high like 1.5 diode mode, which is going to register as OL on some multimeters. Flip the probes around and measure the inverse—black probe on ground, red on line and you’ll get a low number like .2-.5. Compare that to known good. If it is actually OL you’ll get OL in that direction as well.

        then go hunt for your real problem —think about image power and start there.


        • #5
          Thanks Jessa!