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pls help HP 250 G4 NO POWER .

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    #1

    pls help HP 250 G4 NO POWER .

    Hi everyone
    hp 250 g4 LA-C701P is dead
    when i plug in the charger the power led is on but when i press the power button nothing happen

    when i press the power button the ic PU2 (RT8243AZQW 3/5V) becomes hot ; i change it with new one but same problem
    EC_ON , MAINPWON signal are exist and LDO3 AND LDO5 Exist too
    VIN voltage exist
    everything is ok and no short on output pins
    but i don't know why the ic becomes hot .
    Last edited by mo000; 07-08-2020, 10:27 AM.
    Tags: None
    #2
    Re: pls help HP 250 G4 NO POWER .

    any ideas .

    Comment

      #3
      Re: pls help HP 250 G4 NO POWER .

      Check boost capacitor and feedback rasistor

      Comment

        #4
        Re: pls help HP 250 G4 NO POWER .

        What is the voltage on pin 13 of PU2 when you turn it on?? Impedance on coil PL8/PL9 in diode mode?? Resistance in Ohms mode??

        Comment

          #5
          Re: pls help HP 250 G4 NO POWER .

          Originally posted by mcplslg123 View Post
          What is the voltage on pin 13 of PU2 when you turn it on?? Impedance on coil PL8/PL9 in diode mode?? Resistance in Ohms mode??
          pin13=3.3

          PL9 1014ohms
          but pl8 360ohms sometimes becomes 30ohms .
          Last edited by mo000; 07-09-2020, 12:22 AM.

          Comment

            #6
            Re: pls help HP 250 G4 NO POWER .

            Originally posted by qayyum786 View Post
            Check boost capacitor and feedback rasistor
            can you specific pls .
            Attached Files
            Last edited by mo000; 07-09-2020, 04:29 AM.

            Comment

              #7
              Re: pls help HP 250 G4 NO POWER .

              someone help pls .

              Comment

                #8
                Re: pls help HP 250 G4 NO POWER .

                i desolder the jumber PJP3 but same problem i think the whole problem in 5VALW side .
                Attached Files

                Comment

                  #9
                  Re: pls help HP 250 G4 NO POWER .

                  Remove jumper PJP2 also and check again whether PU2 is still getting hot. may be bad KBC.

                  Comment

                    #10
                    Re: pls help HP 250 G4 NO POWER .

                    Originally posted by mcplslg123 View Post
                    Remove jumper PJP2 also and check again whether PU2 is still getting hot. may be bad KBC.
                    I do but PU2 still getting hot .

                    Comment

                      #11
                      Re: pls help HP 250 G4 NO POWER .

                      Measure resistance on all pins of PU2 and voltage on each pin. Are you sure you soldered a new PU2 or pulled from scrap mb??

                      Comment

                        #12
                        Re: pls help HP 250 G4 NO POWER .

                        Originally posted by mcplslg123 View Post
                        Measure resistance on all pins of PU2 and voltage on each pin. Are you sure you soldered a new PU2 or pulled from scrap mb??
                        op said i change it with new one but same problem.

                        something is shorting pu2.. if you done desoldering the jpj2 jpj3. and still the ic overheat.. maybe its a bad ic batch... can you picture the pu2 for us.. tnx..
                        Last edited by Duranitron; 07-11-2020, 07:56 AM.
                        Never stop LEARNING because life never stops TEACHING!

                        Comment

                          #13
                          Re: pls help HP 250 G4 NO POWER .

                          Originally posted by mcplslg123 View Post
                          Measure resistance on all pins of PU2 and voltage on each pin. Are you sure you soldered a new PU2 or pulled from scrap mb??
                          i pulled from working motherboard , i'm sure .
                          Last edited by mo000; 07-11-2020, 08:01 AM.

                          Comment

                            #14
                            Re: pls help HP 250 G4 NO POWER .

                            Originally posted by Duranitron View Post
                            op said i change it with new one but same problem.

                            something is shorting pu2.. if you done desoldering the jpj2 jpj3. and still the ic overheat.. maybe its a bad ic batch... can you picture the pu2 for us.. tnx..
                            yes i desolder jpj2 and jpj3 and i also desolder pl8 but pu2 still overheating without output .

                            Comment

                              #15
                              Re: pls help HP 250 G4 NO POWER .

                              unfortunately the client take back his laptop , thnx mcplslg123 and duration for help .

                              Comment

                                #16
                                Re: pls help HP 250 G4 NO POWER .

                                Originally posted by mo000 View Post
                                i pulled from working motherboard , i'm sure .
                                I'll still bat for this ic being bad or badly soldered. However, its useless now since its no more with you.

                                Comment

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