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Packard Bell Easynote TE LA-7912p Rev 1.0

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    Packard Bell Easynote TE LA-7912p Rev 1.0

    Hi I have one of these for repair. Basically what happens is when I hook it up to bench supply Power Led comes on, fan spins then after it shuts down. If you press the power button again as many time it will not power up (PCH COLD). If I remove adapter from socket and re-apply it the laptop will switch on and then off again as before (PCH Very hot) . I have noticed the PCH gets very hot until you press the power button and the fan comes on it gets a bit cooler, and if you press the power button again and it does not switch on as before the PCH stays cold.

    The 3.3v and 5v stay ok throught all of this.

    Any ideas would be helpful. I have also tried different ram. is it possible CPU or Bios?

    #2
    Re: Packard Bell Easynote TE LA-7912p Rev 1.0

    Check voltage on pins 1,2,3 of U2006. Check if OK U2006. Check resistance on all pins of U2006.
    Check voltage and resistance on Q2006 and R197 (and if OK).
    Check resistance on C331.
    Check resistance on all coils.

    All this without pressing power button - resistance checking without power supply.

    Comment


      #3
      Re: Packard Bell Easynote TE LA-7912p Rev 1.0

      Originally posted by atsio View Post
      Check voltage on pins 1,2,3 of U2006. Check if OK U2006. Check resistance on all pins of U2006.
      Check voltage and resistance on Q2006 and R197 (and if OK).
      Check resistance on C331.
      Check resistance on all coils.

      All this without pressing power button - resistance checking without power supply.

      The only schematic I have for this is the Rev: 0.2 version but the board is Rev: 1.0 and Im having issues locating those components.

      Comment


        #4
        Re: Packard Bell Easynote TE LA-7912p Rev 1.0

        Check resistance on all coils.
        Do you mean check across them or check their resistance to Ground ?

        Comment


          #5
          Re: Packard Bell Easynote TE LA-7912p Rev 1.0

          Check resistance to ground.

          Comment


            #6
            Re: Packard Bell Easynote TE LA-7912p Rev 1.0

            Originally posted by atsio View Post
            Check resistance to ground.
            yeah I have done that on all the Coils I can find.

            The only ones that give a reading are PL14=18.7ohm, Pl20=11ohm,Pl21=10.9ohms, and Pl22=17.1ohms

            all the rest show OL on my meter.
            When the laptop is applied power and power button not pressed the laptop is drawing aroubt 1/4 of an amp and the PCh gets very warm even when not powered up. The 3.3v and 5 seem stable.

            Im looking for the LA-7912p Rev: 1.0 schematic as i cant find the components you listed.
            Thanks for you time also

            Comment


              #7
              Re: Packard Bell Easynote TE LA-7912p Rev 1.0

              check link out, https://www.badcaps.net/forum/showpo...17&postcount=2

              Comment


                #8
                Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                Originally posted by trebo View Post
                Thanks but its not quite the same issue I dont think.

                Comment


                  #9
                  Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                  Im not getting any +cpu_core voltage at all even if I take the CPU out.What should I be checking on PU13?

                  Any input appreciated

                  Comment


                    #10
                    Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                    Originally posted by Bisketti View Post
                    Thanks but its not quite the same issue I dont think.
                    it was the schematic that I was linking you to

                    Comment


                      #11
                      Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                      Originally posted by Bisketti View Post
                      Thanks but its not quite the same issue I dont think.
                      it was the schematic that I was linking you to, LA 7912P

                      Comment


                        #12
                        Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                        Originally posted by trebo View Post
                        it was the schematic that I was linking you to

                        Apologies. That schematic is ver: 02 I have it already plus version .3 the one I need i v1.0 but I dont know if theres much of a difference

                        Comment


                          #13
                          Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                          Supposing you have +3vs and +5vs the next important signal to enable the voltage regulator is VR_ON.

                          Comment


                            #14
                            Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                            Originally posted by atsio View Post
                            Supposing you have +3vs and +5vs the next important signal to enable the voltage regulator is VR_ON.

                            I have 5v and also 3.3v on vron but the +3VS is strange when its off I get 1.17v sometimes I get 3.3v and other times Im getting 0v on 1 side of PR147 and 3v onthe other side. I have checked the +3VALW to +3VS fet and its fine. If I remove the fet and pads 1-3 were reading 1.17 should be 0v.

                            Comment


                              #15
                              Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                              You must find which is the offending rail. I should first remove the solder from jumpers PJ4 and PJ5 and check if I still have 1.17 volts on pins 1-3.

                              Comment


                                #16
                                Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                                I removed PJ4 and Pj5 and no change. I replaced the bridges and removed Pj7 and PJ8 as they were the only ones exhibiting any voltage in the standby state (other than 3.3v/5v).
                                so now unit still turns off and pch gets really hot 1/2A in stand by but the spurious 1.17 voltage on u21 is gone and the laptop can be powered up again by the powerbutton a second and third time. This was not happening before as I would have to remove power completely before it would power up.

                                Comment


                                  #17
                                  Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                                  I see that you decided to replace PU9. How is that?

                                  Comment


                                    #18
                                    Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                                    I was not getting the 3vs to the chip so I removed it and the 3vs was present on the pad of pin 1 shortly after that I was measuring the 3v supply to the pch and I got a short on th b+ line and it turned out pq29 had become short circuit which was strange as pu9 is still out of circuit. This is becoming an ordeal

                                    Comment


                                      #19
                                      Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                                      Repalced pq29 and pq30 and put PU9 back in circuit so now it back to powering up (fan spin) sometimes when it does Im getting the 1.05v back but still unit powers down

                                      Comment


                                        #20
                                        Re: Packard Bell Easynote TE LA-7912p Rev 1.0

                                        Originally posted by trebo View Post
                                        it was the schematic that I was linking you to
                                        schematic.
                                        Attached Files

                                        Comment

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