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Lenovo z51 : no display, fan spin and stop looping

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    Lenovo z51 : no display, fan spin and stop looping

    hello,

    i have an issue with a lenovo z51 laptop
    when plugged in leds are ok
    when pressing power button with only the battey : leds shine, the cpu starts spinning but no display and after 1 or 2 seconds, lights and fan go off.

    after 2 seconds, leds appear and fan start for 1 seconds and then and then

    no display

    i have tried bios reset : remove cmos battery, no fix
    i have tried start directly by bios button (novo button) : exactly the same cycle as power button
    i removed all the connectors except power button flex cable
    i try another ram

    no fix

    can anyone help me : this could be caused by short ??? thank you all !

    #2
    Re: Lenovo z51 : no display, fan spin and stop looping

    Check if you have CPU VCore.
    Clean the RAM slot with some contact cleaner.
    Try the motherboard outside the chassis.
    If everything good, next step is to try to flash the BIOS.
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment


      #3
      Re: Lenovo z51 : no display, fan spin and stop looping

      hello, thanks for help
      don't know exactly where to find all vcore lines but i have tested this ones :
      -laptop off plugged to ac power : 20V, 5V, 3.3V ok
      -when pressing power button : 1.4v 1.7v Ok
      i have none coil with 0V

      the lines that appears after pressing power button, disappear when the lights go off

      i have clean ram slots, try all slots with two different ram

      but the MB outside the chassis, the same

      how to flah bios if i can't access bios ?

      Visiblement tu es francais, ce sera plus simple.
      donc le pc affiche les differentes leds : batterie, allumage sans probleme.
      quand j'appui sur on, le bouton on s'eclaire, la led disque dur aussi, le ventilo cpu commence a tourner. puis au bout de 2 secondes, le ventilo ralenti, les leds s'eteignent et le ventilo s'arrete. puis sans que je fasse rien ca recommence en boucle.
      on attend le hdd s'amorcer mais comme le 5V se coupe, il s'arrete.
      j'ai bien essayé en retirant toutes les nappes de la MB , ca fait pareils.
      ce probleme est arrivé apres une periode de 15 jours sans s'en servir. pas de liquide, pas de surtension ou quoique ce soit
      merci a toi !!

      Comment


        #4
        Re: Lenovo z51 : no display, fan spin and stop looping

        up

        can i flash bios with usbkey ?
        i have only found .exe file, don't know how to extract .bin
        i search on myself

        Comment


          #5
          Re: Lenovo z51 : no display, fan spin and stop looping

          Il Faudra dissoudre le Pouce Bios et après le reprogrammer, Mais pour cela on a besoin d'un Programmer Bios. Cela ne coûte pas cher sur eBay

          Comment


            #6
            Re: Lenovo z51 : no display, fan spin and stop looping

            Originally posted by piernov View Post
            Check if you have CPU VCore.
            Clean the RAM slot with some contact cleaner.
            Try the motherboard outside the chassis.
            If everything good, next step is to try to flash the BIOS.
            (piernov]Check if you have CPU VCore)
            Prends une photo de la carte mère et dans la photo, marque la tension de chaque inducteur (Gray Coils) a côté de ceux-ci. Il y en aussi à côté du processeur.
            Last edited by Techtiger; 01-11-2019, 02:47 PM.

            Comment


              #7
              Re: Lenovo z51 : no display, fan spin and stop looping

              ok je ferai ca demain, merci

              ce que je peux dire deja c'est que pour les coils :
              -pres de la batterie : 0.228 ou 16v si la bat est branchée
              -pres des rams 1.3V que apres avoir appuyer sur power
              -pres du cpu : 1.7V que apres avoir appuyer sur power sinon 0V
              -entre les prises usb et les rams : 5V et 3.3V pc eteint ou pas
              -sur le bios : 3.3V toutes les pates

              il n'y a que ces 5 coils
              merci

              Comment


                #8
                Re: Lenovo z51 : no display, fan spin and stop looping

                Originally posted by disorder View Post
                ok je ferai ca demain, merci

                ce que je peux dire deja c'est que pour les coils :
                -pres de la batterie : 0.228 ou 16v si la bat est branchée
                -pres des rams 1.3V que apres avoir appuyer sur power
                -pres du cpu : 1.7V que apres avoir appuyer sur power sinon 0V
                -entre les prises usb et les rams : 5V et 3.3V pc eteint ou pas
                -sur le bios : 3.3V toutes les pates

                il n'y a que ces 5 coils
                merci
                is this you Mob & the PL Coils Voltages are correct ?
                Attached Files

                Comment


                  #9
                  Re: Lenovo z51 : no display, fan spin and stop looping

                  hello

                  yes this is the mob i have
                  and yes i have all this voltages, 1.3 and 1.7 are presents only when i push power button (i think it's normal : voltages for cpu and rams ?)
                  i have no shorts on coils
                  but when the laptop have done multiple loop, the coil of the cpu is a little hot.

                  new thing : once, when the laptop began to loop (when the light was on 1 second), i have touched the area near 3+5V cols , then the light stay on but fan was off , no display, no sign of life but this light.

                  i think i will buy a new chip bios and switch it.

                  Comment


                    #10
                    Re: Lenovo z51 : no display, fan spin and stop looping

                    Originally posted by disorder View Post
                    hello

                    yes this is the mob i have
                    and yes i have all this voltages, 1.3 and 1.7 are presents only when i push power button (i think it's normal : voltages for cpu and rams ?)
                    i have no shorts on coils
                    but when the laptop have done multiple loop, the coil of the cpu is a little hot.

                    new thing : once, when the laptop began to loop (when the light was on 1 second), i have touched the area near 3+5V cols , then the light stay on but fan was off , no display, no sign of life but this light.

                    i think i will buy a new chip bios and switch it.
                    If you have a hotair gun reheat PU401/PU402 and see if any changes
                    yes it' normal voltage in CPU & RAM those are not ALWS VIN only comes after presing the power button PL1102 getting hot or worm ?

                    Comment


                      #11
                      Re: Lenovo z51 : no display, fan spin and stop looping

                      ok, i have reflow pu401 and 402, it does the same
                      effectivly pl1102 is worm, not hot

                      Comment


                        #12
                        Re: Lenovo z51 : no display, fan spin and stop looping

                        hello,
                        some news...bad news
                        i have changed the bios chip with a programmed one
                        the laptop is always dead
                        exactly same symptoms : led on, fan spin and stop. no backligh no display.
                        the sequence repeats itself many times and always same issue

                        pl1102 is hot progressively, in diode mode it is at 136, don't know if it is a good value
                        with power supply, 1V2Amp, consumption on pl1102 is 7mamp, and consumption on pu803 0.50
                        i think it is a short somewhere no ??
                        does somebody knows wich line it is ?

                        and if it is normal to have consumption current ?

                        tjank you

                        Comment


                          #13
                          Re: Lenovo z51 : no display, fan spin and stop looping

                          need the Schematic to help you out give some time i made a reqest for the Schematic,
                          once you press the power button the sequence repeats itself many times ? send a snap of the motherboard both sides

                          Comment


                            #14
                            Re: Lenovo z51 : no display, fan spin and stop looping

                            hello, here some pictures, not enough time to do it before, thanx
                            Attached Files

                            Comment


                              #15
                              Re: Lenovo z51 : no display, fan spin and stop looping

                              this is your Schematic
                              Attached Files

                              Comment


                                #16
                                Re: Lenovo z51 : no display, fan spin and stop looping

                                test PJ501 PJ503 PJ602 PJ704 PJ801 PL902 PL903 PL1102 all voltages

                                Comment


                                  #17
                                  Re: Lenovo z51 : no display, fan spin and stop looping

                                  hello, there it is the mesures i could do.
                                  all are only present when power button is push
                                  PJ501 : 1.368
                                  PJ503 : .400 but sometimes 0.683, when the laptop boot loop this voltage rise to 0.683 and then 0v when the laptop switch off. when the laptop on and off without bootloop it only rise to 0.400 and the 0V
                                  PJ 704 : 1.500v
                                  PJ 801 : 1.04v but it is no soldered,
                                  PL 1102 : 1.701

                                  i don't find PJ602, PL902 and PL903.

                                  thank you for help

                                  Comment


                                    #18
                                    Re: Lenovo z51 : no display, fan spin and stop looping

                                    I had the same problem in the past and when I tried everything possible, I found short on lvds cable! So try to start the board up with no lvds cable connected, what if..

                                    Have you tried reprogramm KBC EC rom already?

                                    Comment


                                      #19
                                      Re: Lenovo z51 : no display, fan spin and stop looping

                                      find out if your Mob have U13 IC if so test pin 10 & 6 +5VS +3VS stable, test PJ802 PJ803 for Voltage ?

                                      Comment


                                        #20
                                        Re: Lenovo z51 : no display, fan spin and stop looping

                                        hello, i tried without any cable except power line and power button flex :
                                        U13 : pin 10 J5=5.050V ; pin 6 J4=3.358V stable
                                        pj 802 : 3.350V (laptop off) 3.347V on
                                        pj803 : 0.016V off, and 1.046V on

                                        thanks

                                        Comment

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