Help a newbie with his first project

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  • jacobtc
    Badcaps Veteran
    • Apr 2016
    • 274
    • Denmark

    #1

    Help a newbie with his first project

    So, I recently acquired a Alienware 15 R1 (LA-B753P) as the guy told me it was completely dead, and I saw it as a fun project.

    I have done every ordinary thing, such as resetting CMOS and leaving the RTC battery out for a while. It is completely dead, no light, nothing. The powersupply outputs 19.5V and the DC plug measures fine. I have inspected the board, and nothing seems to be obviously damaged, no burn marks, and no apparent water damage. The next step is to check for shorts, however, how would I go about doing that? I don't have a bench powersupply, so it is difficult for me to inject voltage and check with alcohol evaporation etc.



    Anyone willing to give a bit of guidance?
  • caspian
    Badcaps Legend
    • Oct 2015
    • 1589
    • Laptop

    #2
    Re: Help a newbie with his first project

    is there any other voltages on the mainboard?

    Comment

    • jacobtc
      Badcaps Veteran
      • Apr 2016
      • 274
      • Denmark

      #3
      Re: Help a newbie with his first project

      Originally posted by caspian
      is there any other voltages on the mainboard?
      What do you mean? Plugged in to the DC adaptor?

      Comment

      • caspian
        Badcaps Legend
        • Oct 2015
        • 1589
        • Laptop

        #4
        Re: Help a newbie with his first project

        measure voltage on big coils and capacitors to see whether there are any voltages on the board other than the 19v.

        Comment

        • jacobtc
          Badcaps Veteran
          • Apr 2016
          • 274
          • Denmark

          #5
          Re: Help a newbie with his first project

          Originally posted by caspian
          measure voltage on big coils and capacitors to see whether there are any voltages on the board other than the 19v.
          Will do that later! Just got back from work... Thank you so much! Really hope I can get this working!

          Comment

          • jacobtc
            Badcaps Veteran
            • Apr 2016
            • 274
            • Denmark

            #6
            Re: Help a newbie with his first project

            So just got done meassuring some coils and caps. Where I have not written anything is due to also being 0V.

            https://i.imgur.com/40dINwh.jpg

            Also, nothing felt varm to the touch.

            UPDATE: I did not feel around the lower right corner, that gets really hot, around the two medium sized coils...
            Last edited by jacobtc; 04-26-2018, 08:50 AM.

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            • jacobtc
              Badcaps Veteran
              • Apr 2016
              • 274
              • Denmark

              #7
              Re: Help a newbie with his first project

              These get hot:
              https://i.imgur.com/ao3Unj3.jpg

              PL102
              PL101
              PC107
              PC108

              Comment

              • dspok
                Badcaps Veteran
                • Jan 2014
                • 553
                • Nepal

                #8
                Re: Help a newbie with his first project

                check resistance to ground on those coils. it looks like those coils are for ALW voltages, not sure though because I can't find schematics.

                Comment

                • jacobtc
                  Badcaps Veteran
                  • Apr 2016
                  • 274
                  • Denmark

                  #9
                  Re: Help a newbie with his first project

                  Also, on the back, the IC called PU100, is getting burning hot, I can't keep my finger on it...

                  Comment

                  • jacobtc
                    Badcaps Veteran
                    • Apr 2016
                    • 274
                    • Denmark

                    #10
                    Re: Help a newbie with his first project

                    Originally posted by dspok
                    check resistance to ground on those coils. it looks like those coils are for ALW voltages, not sure though because I can't find schematics.
                    PL102 resistance to ground is 0.5 kOhm and increasing constantly, PL101 resistance to ground is 2.8 kOhm and increasing. I guess they are getting more resistant, due to getting colder over time? If I plug in power, they go down to 5ohm on PL102 and around 96ohm on PL101 when they become slightly warm.


                    This is the IC on the back that gets way to hot to touch: https://i.imgur.com/hJbHhtS.jpg
                    Last edited by jacobtc; 04-27-2018, 02:45 AM.

                    Comment

                    • jacobtc
                      Badcaps Veteran
                      • Apr 2016
                      • 274
                      • Denmark

                      #11
                      Re: Help a newbie with his first project

                      Anyone?

                      Comment

                      • caspian
                        Badcaps Legend
                        • Oct 2015
                        • 1589
                        • Laptop

                        #12
                        Re: Help a newbie with his first project

                        Now, you should read what is marked on top of the IC to identify it.

                        Comment

                        • jacobtc
                          Badcaps Veteran
                          • Apr 2016
                          • 274
                          • Denmark

                          #13
                          Re: Help a newbie with his first project

                          Originally posted by caspian
                          Now, you should read what is marked on top of the IC to identify it.
                          The IC has the following written on it: 3h=2b q2b

                          Now, I've searched for the PU100 IC, and another forum says that it is a TPS51285BRUKR...

                          Comment

                          • caspian
                            Badcaps Legend
                            • Oct 2015
                            • 1589
                            • Laptop

                            #14
                            Re: Help a newbie with his first project

                            it does not seem to be TPS51285BRUKR. or maybe it is. I do not know. I hope someone help identify it.
                            Last edited by caspian; 04-27-2018, 02:19 PM.

                            Comment

                            • jacobtc
                              Badcaps Veteran
                              • Apr 2016
                              • 274
                              • Denmark

                              #15
                              Re: Help a newbie with his first project

                              Originally posted by caspian
                              it does not seem to be TPS51285BRUKR. or maybe it is. I do not know. I hope someone help identify it.
                              This guy identified it as TPS51285BRUKR

                              https://ascnb1.ru/forma1/viewtopic.php?f=31&t=130165

                              Comment

                              • vinceroger69
                                Badcaps Legend
                                • Mar 2012
                                • 6714
                                • uk

                                #16
                                Re: Help a newbie with his first project

                                Originally posted by jacobtc
                                This guy identified it as TPS51285BRUKR

                                https://ascnb1.ru/forma1/viewtopic.php?f=31&t=130165
                                data sheet
                                Attached Files

                                Comment

                                • jacobtc
                                  Badcaps Veteran
                                  • Apr 2016
                                  • 274
                                  • Denmark

                                  #17
                                  Re: Help a newbie with his first project

                                  Originally posted by vinceroger69
                                  data sheet
                                  The package looks different to what is in the data sheet, this one has five pins on four sides, the one on the data sheet has only pins on two sides.

                                  Comment

                                  • Johndill
                                    Badcaps Veteran
                                    • Aug 2015
                                    • 314
                                    • Australia

                                    #18
                                    Re: Help a newbie with his first project

                                    Originally posted by jacobtc
                                    The IC has the following written on it: 3h=2b q2b

                                    Now, I've searched for the PU100 IC, and another forum says that it is a TPS51285BRUKR...
                                    Is this the correct schematics for your board?

                                    PU100 page 60.
                                    Last edited by Johndill; 04-27-2018, 08:44 PM.

                                    Comment

                                    • JaroTech
                                      Badcaps Veteran
                                      • Mar 2015
                                      • 351
                                      • Canada

                                      #19
                                      Re: Help a newbie with his first project

                                      Hi, the code '3H =' comes from Richtek, the chip is a RT6585B, it is compatible with the chip TPS51285B.

                                      Comment

                                      • jacobtc
                                        Badcaps Veteran
                                        • Apr 2016
                                        • 274
                                        • Denmark

                                        #20
                                        Re: Help a newbie with his first project

                                        Originally posted by Johndill
                                        Is this the correct schematics for your board?

                                        PU100 page 60.
                                        Looks like it, thanks!

                                        Comment

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