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Lenovo 500-15isk LA-C851P without CPU voltage

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    Lenovo 500-15isk LA-C851P without CPU voltage

    Lenovo 500-15isk
    LA-C851P

    i measured all voltage, only cpu dont work
    there is NCP81208 chip for three rail voltage :
    VCC_core VCC_GT and VCC_sa
    only one of three voltage working .ist 1volt
    two voltage ist null . i replaced 81208 chip ,but dont change. also i chnaged two NCP81253 together, one have voltage another ist null. also dont change
    So i think 81208 and 81253 not defect and problem ist another place.
    i can see three pin Communication (SOC_SVID_CLK ,SOC_SVID_DAT,SOC_SVID_ALERT) that connected direct to cpu .
    any person have idea for my problem ?
    How one of three voltage rail working , because all enable pin ist same but with seperate PWM ?

    i dont found datasheet for 81208 but i thinks ist similar NCP81243
    Attached Files
    Last edited by kokono; 12-07-2018, 02:19 PM.

    #2
    Re: Lenovo without CPU voltage

    Chek all your pgood pins

    Comment


      #3
      Re: Lenovo without CPU voltage

      i checked
      i am sure that +VCC_SA(one of three Rail voltage for NCP81208) ist ok ,plus VR_PWRGD
      Also i think +VCCIO is good.
      Have an idea?
      i reprogram Bios with this file.maybe my problem ist Bios ???
      please check my bios
      Attached Files
      Last edited by SMDFlea; 05-28-2022, 07:14 AM.

      Comment


        #4
        Re: Lenovo without CPU voltage

        No one can help?

        Comment


          #5
          Re: Lenovo without CPU voltage

          I got your PM. Try this bios.If it doesn`t work keep testing .
          Last edited by SMDFlea; 05-28-2022, 07:14 AM. Reason: bios removed
          All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

          Comment


            #6
            Re: Lenovo without CPU voltage

            Looks a lot like 2015! So an absurdly short life before a failure!
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            Comment


              #7
              Re: Lenovo without CPU voltage

              Originally posted by SMDFlea View Post
              I got your PM. Try this bios.If it doesn`t work keep testing .
              thx for reply
              i reprogram, now i have VCC_core(1 Volt clear) without VCC_GT.
              i think my problem ist Bios
              in addition, my Bios chip isn't 25Q64 . ist 25Q064A13. maybe ist important

              Comment


                #8
                Re: Lenovo without CPU voltage

                Originally posted by SMDFlea View Post
                I got your PM. Try this bios.If it doesn`t work keep testing .
                Do you can modifying my bios program ?
                with your Bios ,VCC_Core working only VCC_GT dont worked
                i am sure that dont have hardware problem

                Comment


                  #9
                  Re: Lenovo without CPU voltage

                  VCC_GT here refers to GFX Core ?? If so , it can be missing coz of many reasons like Bad bios, Bad ram stick or slot, PCH, Vcore ic(i rule it out as you have already replaced it) and missing DRAMRST# signal.

                  I'll suggest to check DRAMRST# signal on pin30 of Ram Slot. It should be 1.3V approx.

                  Comment


                    #10
                    Re: Lenovo without CPU voltage

                    Originally posted by mcplslg123 View Post
                    VCC_GT here refers to GFX Core ??.
                    i thinks No, because i have GFX voltage

                    Comment


                      #11
                      Re: Lenovo without CPU voltage

                      Originally posted by kokono View Post
                      i thinks No, because i have GFX voltage
                      ok. I didnt looked at the diagram. Just thought of it. Thanks for correcting.

                      Comment


                        #12
                        Re: Lenovo without CPU voltage

                        Update :
                        today i checked again, i can see when press start button,The LCD turns on and gets darker but without backlight
                        can i connect "VCC_Core" Enable pin to "VCC_GT" Enable ?

                        Comment


                          #13
                          Re: Lenovo without CPU voltage

                          did you solve the issue?

                          Comment


                            #14
                            Re: Lenovo without CPU voltage

                            Yes,After reprogram Bios,and without VCC_GT, i changed a lcd cable and working

                            Comment


                              #15
                              Re: Lenovo without CPU voltage

                              Originally posted by kokono View Post
                              Yes,After reprogram Bios,and without VCC_GT, i changed a lcd cable and working
                              If I am getting it correctly a bad LVDS cable was causing VCCGT to be missing?

                              Comment


                                #16
                                Re: Lenovo without CPU voltage

                                https://logi.wiki/index.php/User:Pie..._I_solve_it.3F
                                OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                                Comment

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