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Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

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    #1

    Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

    Hi people,

    Ideapad 130-15IKB
    LA-G202P
    CPU: i5 8250U

    The laptop turns on without picture. All voltages are present except +VCCGT. Probably POST not starting because current stays around 300mA. I've checked resistance and voltages:

    PL602 - 28ohm - 1.0 VALWP - 1.04V present
    PL502 - 231ohm - 1.2VP - 1.2V
    PLA1 - 17ohm - VCCSA - 1.03V
    PLZ1 - 4ohm - VCCCORE - 0.84V
    PLZ2 - 4ohm - VCCCORE - 0.84V
    PLG1 - 7ohm - VCCGT - 0V

    The VCCGT comes from PUG1 (RT9610CGQW). Signals are:
    EN-5V,
    PHASE-0V,
    UGATE-0V,
    BOOT-4,7V,
    PWM-2.5V,
    LGATE-0V,
    VCC_GT-5V

    PWM signal comes from PUZ1 (RT3602AE). All mosfets are good. I have noticed that PWMs on PUZ2 and PUZ3 (responsible for VCCCORE) are 0.22V, and also comes from PUZ1.

    I have already replaced PUZ1, PUG1,reprogrammed BIOS and EC. No change and no ideas, what to do next. Oscillators 32kHz and 25MHz are working. The RSMRST is high so I assumed that EC is good.
    Tags: None
    #2
    Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

    Usually no point to troubleshoot +VCC_GT, since the voltage appears only under load, so the mess there was likely for nothing.

    Same for RSMRST# when the board reaches the late sequence.

    I'd stay at BIOS instead, and check whether PLT_RST# and DRAMRST# are present.

    You might want to restore all the firmware you have played with so far, to have a good start point.
    Last edited by Sephir0th; 03-07-2023, 08:36 AM.
    FairRepair on YouTube

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      #3
      Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

      Thanks Sephir0th for the answer.

      About bios: I used latest available from Lenovo website. After replacing ICs I have returned to original bios file.

      DRAMRST# is low all the time, about 76mV. PLTRST# is 3.3V. I hope I've found the right place to measure it (picture).
      Attached Files

      Comment

        #4
        Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

        Yeah, that's fine but also check at Y-Pin for sanity. DRAMRST# staying low is actually a bad thing. Please double-check.

        RAM is known good?
        FairRepair on YouTube

        Comment

          #5
          Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

          Y-pin is also 3.3v. RAM is onboard. But there is one DIMM slot. I used good RAM but no effect.

          I've checked DRAMRST# with oscilloscope. It stays low all the time.

          Comment

            #6
            Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

            If BIOS was ruled out for sure be sure, i'm afraid to share we're likely dealing with a dead CPU/PCH here.
            FairRepair on YouTube

            Comment

              #7
              Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

              OK, so I have another donor for my collection. Thanks for help.

              Does always low DRAMRST# mean faulty CPU/PCH? Could you explain it more?

              Comment

                #8
                Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

                Originally posted by theManieq View Post
                OK, so I have another donor for my collection. Thanks for help.

                Does always low DRAMRST# mean faulty CPU/PCH? Could you explain it more?
                it usually means that either your soc/cpu or the firmware is faulty (there are exceptions...). it's one of the last rails that starts in the power sequence (block diagram).

                Comment

                  #9
                  Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

                  I'll bet for a faulty onboard ram here. If you have access to schematic and boardview, disbale the onboard ram and put up a known good ram stick. Lenovo and asus are notorious for onbaord ram issues.

                  Comment

                    #10
                    Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

                    Originally posted by mcplslg123 View Post
                    I'll bet for a faulty onboard ram here. If you have access to schematic and boardview, disbale the onboard ram and put up a known good ram stick. Lenovo and asus are notorious for onbaord ram issues.
                    ah sure, there is soldered ram. this is the best advice! the amps read are a big clue for ram issue.

                    Comment

                      #11
                      Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

                      Hi, sorry for the absence. There is only schematic available, so finding those resistors is imposible for me.
                      Attached Files

                      Comment

                        #12
                        Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

                        Yes, no point trying to disable ram under darkness. Its impossible to do without boardview.

                        Comment

                          #13
                          Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

                          we can disable ram on board by bios modified.

                          Comment

                            #14
                            Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

                            Originally posted by fauzanmint View Post
                            we can disable ram on board by bios modified.
                            Could you guide me, how to do it?

                            Comment

                              #15
                              Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

                              Originally posted by theManieq View Post
                              Could you guide me, how to do it?
                              Serach on Google for "spd bios onboard memory removal"

                              Comment

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