LA-G07JP led power shortly and goes off

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  • ziko07
    Senior Member
    • Jun 2021
    • 93
    • Somewhere

    #1

    LA-G07JP led power shortly and goes off

    Hi, sch is from LA-G07DP but looks similiar. Problem is that 3/5 v ALW comes when bring power short (1-2 sec)
    From image all marked GREEN is same, 1-2 sec has power

    SPOK colmes 3v3 for short time
    en2= 9v4, its normal and is stady voltage
    en1= 3v3/5v short same as SPOK
    LDO 3v/5V only present short as SPOK
    Pin 11 of IC has stady 9.4v but LDO output also goes iff after 1-2 sec
    EC_ON on pin112 comes also short time and goes low
    Small ic drivers for 3 and 5v alw are SY8286A
    Any help please?
    Attached Files
  • mon2
    Badcaps Legend
    • Dec 2019
    • 14022
    • Canada

    #2
    Remove all power. Meter in resistance mode. Measure the resistance to ground of each and every inductor. Checking for a lower than normal resistance which indicates a shorted part on the board.

    Power adapter is suitable to run this board?

    Comment

    • ziko07
      Senior Member
      • Jun 2021
      • 93
      • Somewhere

      #3
      Not seen suspicious resistance, I use to see current consumption bemch lab power but same probl with ori power adapter
      when 35v present than board without battery tajes 450mA and there us oresent cou voltage 1.1v 2 ohases,1.0v, 1 2 to ran, fan spinning but after 3 sec all stops, i noticed if I bend pcb (i connected wire to 5v alw coil) than voltsge comes, like some bad soldering or maybe vias on pcb

      Comment

      • mon2
        Badcaps Legend
        • Dec 2019
        • 14022
        • Canada

        #4
        when 35v present than board
        ?? 35v is too high for the logic board. This will nuke at least the dcin MOSFETS.

        Comment

        • ziko07
          Senior Member
          • Jun 2021
          • 93
          • Somewhere

          #5
          I'm sure you get point that I meant 3v/5v
          Too much syntax errors on my gsm tastature, sorry

          Comment

          • mon2
            Badcaps Legend
            • Dec 2019
            • 14022
            • Canada

            #6
            Actually no, that is why I asked.

            Remove all power. Meter in resistance mode. Measure the resistance between ACP / ACN pins 1&2 directly on the charger IC. Need to confirm the current sense loop resistance is matching the schematic values.

            Touch your meter probes together, this same measurement should be matching the ACP/ACP resistance.

            Comment

            • ziko07
              Senior Member
              • Jun 2021
              • 93
              • Somewhere

              #7
              Resistance ACP/ACN is 0.004R, on probe direct 0.001R and drops to 0.000R
              Here is image with coil resistance with GND
              BQ chip write on it BQ25A...
              Attached Files

              Comment

              • mon2
                Badcaps Legend
                • Dec 2019
                • 14022
                • Canada

                #8
                Full datasheet for the charger IC is posted here:

                https://www.ti.com/lit/ds/symlink/bq...=1736098219535

                Can you confirm if ACDRV is with ~25v at all times or also shutting off after 1-2 seconds?

                Voltage to ground of:

                ACOK
                ACDET
                VCC



                Backup your original EC rom and consider to reflash the same - see post # 40 here:

                https://www.badcaps.net/forum/troubl...ios-dump/page2
                Last edited by mon2; 01-06-2025, 07:26 AM.

                Comment

                • ziko07
                  Senior Member
                  • Jun 2021
                  • 93
                  • Somewhere

                  #9
                  Will check voltages tommorow, also will put your bios even servicer before me tried ,but strange when I bent, press board on ram connectors missing voltage comes again and after 2 sec goes away again. Like some bad solder or pcb

                  Comment

                  • SMDFlea
                    Super Moderator
                    • Jan 2018
                    • 20698
                    • UK

                    #10
                    Originally posted by ziko07
                    Will check voltages tommorow, also will put your bios even servicer before me tried ,but strange when I bent, press board on ram connectors missing voltage comes again and after 2 sec goes away again. Like some bad solder or pcb
                    Loose ram slot pins, check them all
                    All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

                    Comment

                    • ziko07
                      Senior Member
                      • Jun 2021
                      • 93
                      • Somewhere

                      #11
                      I couldn't see on microscope, also tried ram in other slot
                      will double check

                      Comment

                      • ziko07
                        Senior Member
                        • Jun 2021
                        • 93
                        • Somewhere

                        #12
                        Originally posted by mon2
                        Full datasheet for the charger IC is posted here:

                        https://www.ti.com/lit/ds/symlink/bq...=1736098219535

                        Can you confirm if ACDRV is with ~25v at all times or also shutting off after 1-2 seconds?

                        Voltage to ground of:

                        ACOK
                        ACDET
                        VCC



                        Backup your original EC rom and consider to reflash the same - see post # 40 here:

                        https://www.badcaps.net/forum/troubl...ios-dump/page2
                        Your bin file is 128kB, ori on board is 64kB, its 25X05CL
                        In attachment my ori dump, the big one bios 16Mb servicer already tried 2-3 dumps
                        Attached Files

                        Comment

                        • ziko07
                          Senior Member
                          • Jun 2021
                          • 93
                          • Somewhere

                          #13
                          I give up when bend pcb or press power button all voltages present and goes away after 2 sec
                          tnx for trying help

                          Comment

                          • mon2
                            Badcaps Legend
                            • Dec 2019
                            • 14022
                            • Canada

                            #14
                            Sounds like a PCB break and/or solder joint dry solder that mates with the flexing. Either way, a tough one to hunt down.

                            Comment

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