I can't resolve a problem [No Power to CPU]

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  • hazardus
    Senior Member
    • Apr 2014
    • 105
    • USA
    #1

    I can't resolve a problem [No Power to CPU]

    Hi guys,

    Ok, so this is my second motherboard (Dell vostro 3750) which came with no display. In both case I found the issue no power to CPU. I can't find the problem which causes the no power issue to the cpu. No short nothing.

    What do you guys think?
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    • pholix
      New Member
      • Nov 2013
      • 1
      • UK
      #2
      Re: I can't resolve a problem [No Power to CPU]

      2 new motherboards with the same fault, thats really quite rare. I know this is is stating the obvious, but on your PSU power supply unit there will be a square plug that fits directly into the motherboard, its usually within and inch or 2 of the the cpu housing - check this part of your power supply is working and connected correctly to the motherboard.

        Comment

        • hazardus
          Senior Member
          • Apr 2014
          • 105
          • USA
          #3
          Re: I can't resolve a problem [No Power to CPU]

          These are not new. These are here for repair.

            Comment

            • hazardus
              Senior Member
              • Apr 2014
              • 105
              • USA
              #4
              Re: I can't resolve a problem [No Power to CPU]

              I checked PU4 NPC6131:
              Pin1 - nothing
              Pin2 - 0.86V
              Pin3 - 1.03V
              Pin4 - 0.95V
              Pin5 - 0.73V
              Pin6 - 1.03V
              Pin7 - nothing
              Pin8 - nothing
              Pin9 - 3.35V
              Pin10 - 5.05V
              Pin11 - 1.96V
              Pin12 - nothing
              Pin13 - 0.87V

              These are on.

              When off
              just Pin38 and Pin39 are present.
              Pin38 and Pin39 - 0.44V after press the power button both goes high to 5.1V.
              Last edited by hazardus; 12-05-2014, 06:41 AM.

                Comment

                • dj_ricoh
                  Badcaps Legend
                  • Jan 2013
                  • 2073
                  • uk
                  #5
                  Re: I can't resolve a problem [No Power to CPU]

                  resolder PU4
                  Just cook it! It's already broken.

                    Comment

                    • hazardus
                      Senior Member
                      • Apr 2014
                      • 105
                      • USA
                      #6
                      Re: I can't resolve a problem [No Power to CPU]

                      I did that. I also put a new one I thought something wrong with it.
                      CPU has two phases and neither is working. Interesting isn't it?

                        Comment

                        • dj_ricoh
                          Badcaps Legend
                          • Jan 2013
                          • 2073
                          • uk
                          #7
                          Re: I can't resolve a problem [No Power to CPU]

                          so on page 41 you got all the voltages?
                          Just cook it! It's already broken.

                            Comment

                            • hazardus
                              Senior Member
                              • Apr 2014
                              • 105
                              • USA
                              #8
                              Re: I can't resolve a problem [No Power to CPU]

                              Yes, I've all the voltages.
                              Last edited by hazardus; 12-05-2014, 05:20 PM.

                                Comment

                                • dj_ricoh
                                  Badcaps Legend
                                  • Jan 2013
                                  • 2073
                                  • uk
                                  #9
                                  Re: I can't resolve a problem [No Power to CPU]

                                  PL5,PL4,PL6 and PL9 voltage.
                                  Just cook it! It's already broken.

                                    Comment

                                    • dj_ricoh
                                      Badcaps Legend
                                      • Jan 2013
                                      • 2073
                                      • uk
                                      #10
                                      Re: I can't resolve a problem [No Power to CPU]

                                      o lol did you test with another CPU?
                                      Just cook it! It's already broken.

                                        Comment

                                        • hazardus
                                          Senior Member
                                          • Apr 2014
                                          • 105
                                          • USA
                                          #11
                                          Re: I can't resolve a problem [No Power to CPU]

                                          Nothing on PL5,PL6, and PL9.
                                          PL4 is empty because CPU just uses two phases instead three.

                                          I tried with different CPU but didn't help.
                                          Last edited by hazardus; 12-07-2014, 11:52 AM.

                                            Comment

                                            • dj_ricoh
                                              Badcaps Legend
                                              • Jan 2013
                                              • 2073
                                              • uk
                                              #12
                                              Re: I can't resolve a problem [No Power to CPU]

                                              we need voltage from PU1,PU2 and PU3
                                              Last edited by dj_ricoh; 12-07-2014, 02:40 PM.
                                              Just cook it! It's already broken.

                                                Comment

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