Lenovo G480(LG4858L 11326) Power problem

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  • YourLocalGeek
    Member
    • Feb 2015
    • 43
    • Philippines

    #1

    Lenovo G480(LG4858L 11326) Power problem

    hi guys

    lenovo g480
    MB CODE: LG4858L MB 11326-1

    laptop turns on (automatically) only if cmos battery has been reseated.
    after shutdown, laptop does NOT turn on using power switch
    cmos battery has to be reseated again for it to turn on.


    any ideas?
    thanks in advance

    attached are the schematics
    please help
    Attached Files
  • ktmmotocross
    Boardkiller
    • Feb 2014
    • 3580
    • slovakia

    #2
    Re: Lenovo G480(LG4858L 11326) Power problem

    check if u can start the board without attached power switch board. looks like your power button is not working

    Comment

    • YourLocalGeek
      Member
      • Feb 2015
      • 43
      • Philippines

      #3
      Re: Lenovo G480(LG4858L 11326) Power problem

      thanks for the reply ktm
      but sorry board still wont turn on without power switch i tried switching it on by shorting pin 2(kbc_pwrbtn) to ground of btncn1 (power switch board port) or am i doing it wrong?

      Comment

      • ktmmotocross
        Boardkiller
        • Feb 2014
        • 3580
        • slovakia

        #4
        Re: Lenovo G480(LG4858L 11326) Power problem

        try to short KBC_PWRBTN_EC# on C2717 and check voltage on it

        Comment

        • YourLocalGeek
          Member
          • Feb 2015
          • 43
          • Philippines

          #5
          Re: Lenovo G480(LG4858L 11326) Power problem

          same results boss still wont turn on
          voltage on c2717 is 1.11v

          is the kbc faulty?

          Comment

          • ktmmotocross
            Boardkiller
            • Feb 2014
            • 3580
            • slovakia

            #6
            Re: Lenovo G480(LG4858L 11326) Power problem

            check both sides of R2703 and R2704 for voltage

            Comment

            • YourLocalGeek
              Member
              • Feb 2015
              • 43
              • Philippines

              #7
              Re: Lenovo G480(LG4858L 11326) Power problem

              R2703 1.11V both sides
              R2704 1.11v & 3.3v other side
              is that good?
              again thanks for the time ktm

              Comment

              • ktmmotocross
                Boardkiller
                • Feb 2014
                • 3580
                • slovakia

                #8
                Re: Lenovo G480(LG4858L 11326) Power problem

                1.1V is low. it must be 3V. check resistance of R2774 and R2704

                when nothing try to remove EL8204.

                all this things do with powerswitch board removed
                Last edited by ktmmotocross; 02-25-2015, 01:45 AM.

                Comment

                • YourLocalGeek
                  Member
                  • Feb 2015
                  • 43
                  • Philippines

                  #9
                  Re: Lenovo G480(LG4858L 11326) Power problem

                  in circuit resistance
                  R2704: 9k
                  R2774: 13k

                  and then i removed el8204
                  same resistance but voltage changed from 1.1v to 3v

                  tested it out of circuit
                  r2704: 10k
                  r2774: 99.6k

                  Comment

                  • ktmmotocross
                    Boardkiller
                    • Feb 2014
                    • 3580
                    • slovakia

                    #10
                    Re: Lenovo G480(LG4858L 11326) Power problem

                    ok,, u have 3V. so now try to start it by shorting KBC_PWRBTN_EC# on C2717 to ground

                    Comment

                    • YourLocalGeek
                      Member
                      • Feb 2015
                      • 43
                      • Philippines

                      #11
                      Re: Lenovo G480(LG4858L 11326) Power problem

                      tried shorting c2717 to ground
                      mboard turned on for 1 sec then turns off?
                      it looks like i can switch it on now but now it turns off after 1 sec

                      tried it without cmos battery and i turned it off (after it automatically turned on) and tried switching it on again, it turns on and off after 1 sec
                      but for the 5th time mboard stays on

                      Comment

                      • ktmmotocross
                        Boardkiller
                        • Feb 2014
                        • 3580
                        • slovakia

                        #12
                        Re: Lenovo G480(LG4858L 11326) Power problem

                        ok. so leave removed that coil and try to switch on with powerswitch board.

                        for that 1s switching check power sequence at the end of schematic

                        Comment

                        • YourLocalGeek
                          Member
                          • Feb 2015
                          • 43
                          • Philippines

                          #13
                          Re: Lenovo G480(LG4858L 11326) Power problem

                          thank you ktmmotocross for your time and guidance
                          laptop works great now

                          for the 1s switching, i just assembled the laptop (i think its because there was no cpu before) and it worked with just 1 press to turn it on.

                          thanks again boss
                          more power to badcaps and to ktmmotocross

                          Comment

                          • mcoytzhi27
                            Mr
                            • Nov 2015
                            • 43
                            • philippines

                            #14
                            Re: Lenovo G480(LG4858L 11326) Power problem

                            any dump files for this unit.. thanks...

                            Comment

                            • andrew25
                              Badcaps Veteran
                              • Feb 2016
                              • 221
                              • Malawi

                              #15
                              Re: Lenovo G480(LG4858L 11326) Power problem

                              need bios dump too for it

                              Comment

                              • andrew25
                                Badcaps Veteran
                                • Feb 2016
                                • 221
                                • Malawi

                                #16
                                Re: Lenovo G480(LG4858L 11326) Power problem

                                need bios dump too for it

                                Comment

                                • Homero
                                  New Member
                                  • May 2018
                                  • 1
                                  • Pery

                                  #17
                                  Re: Lenovo G480(LG4858L 11326) Power problem

                                  Originally posted by YourLocalGeek
                                  hi guys

                                  lenovo g480
                                  MB CODE: LG4858L MB 11326-1

                                  laptop turns on (automatically) only if cmos battery has been reseated.
                                  after shutdown, laptop does NOT turn on using power switch
                                  cmos battery has to be reseated again for it to turn on.


                                  any ideas?
                                  thanks in advance

                                  attached are the schematics
                                  please help

                                  try reprogramming the BIOS. I leave the link here:
                                  https://mega.nz/#!2R9CnSLL!PJJugfreu...tgyi83gBmvNds0

                                  Comment

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