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[SOLVED] 820-3115-B Pulsing charger light

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  • #16
    Yes. Find the broken link in the line.

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    • #17
      Originally posted by jason_microsoldering View Post
      OL is open line, the exact opposite of no resistance. Check all the resistors between those pins and check continuity between them.
      Ok, so I retested the continuity. Same results.

      Pin 27 has continuity to C7020, C7022 and R7022 which tests correctly @ 10ohm
      Pin 28 has continuity to C7020, C7021 and R7021 which tests correctly @ 10ohm


      Pin 17 has continuity to C7050 and R7052 which tests @ 0.3ohm, schematic says 0...?
      Pin 18 has continuity to C7050 and R7051 which tests @ 2.5ohm, schematic says 2.2...


      I'm a little lost of where to check next. I can't understand why, if the components are testing fine and continuity is fine why I'm not getting a reading between pins 17+18 and pins 27+28. Is the only explanation that the U7000 from the donor board is also bad or is there something else to check?

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      • #18
        https://youtu.be/hpbzO2UjQQA

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        • #19
          Have always been testing from the pins. Just checked at higher zoom and no line breaks. Continuity confirms this also, tested between pins and pads and every combination.

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          • #20
            I don't know how many other ways there are to tell you the same thing. Either you are using your multimeter incorrectly or you're looking at the wrong thing on the board.

            Look at the schematic and find the two current sensing circuits, CSI and CSO. Trace them out and back into the ISL with your finger. Measure the three resistors for the correct resistance. Then measure that there is no resistance between each resistor along that path that you traced with your finger. Do the same for both circuits.

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            • #21
              Although very much a beginner, I have used a multi meter many times before. I'm confident that I'm using the meter right and looking at the right thing on the board. I am definitely pushing the limits of my electronic knowledge though. Hence coming here.

              So I have traced out with my finger and checked the board view for the traces. The resistors check out fine. Something that I missed before, in tracing out and testing, I did find that there is an OL between Pin 4 of R7050 and Pin 2 of R7052. On my donor boards these test as connected. Presume I can just run a wire to fix this? Is this likely to be the issue?

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              • #22
                Yes, fix the trace.

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                • #23
                  Cheers, will do in the morning.

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                  • #24
                    FIXED! Thanks to everyone that helped. Especially you, Jason. Much appreciated! That final post lead me right to the cause. I have learnt loads from this. Importantly, I have proved to myself that my soldering and hot air skills are up to the job.

                    I still don't get any reading from testing between those pins on the ISL, not that it matters now but still a mystery that I'd like to solve. Perhaps my multi meter is a bit crap? Works for everything else though.... Will see if I can borrow a more expensive one to test that theory before shelling out on a more expensive one.

                    Just need to tidy up the wire and all the other bits and pieces I have touched and then need to decide what ultrasonic to buy over here in the UK. Any suggestions?

                    https://www.youtube.com/watch?v=ZkdU5QsGlSg

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