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Dell Dimension 4700 - Bad United Chemi-Con

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    Dell Dimension 4700 - Bad United Chemi-Con

    I was hired to troubleshoot a Dell Dimension 4700 PC that kept having random keyboard errors. I checked the BIOS log and noticed it had multiple errors with not only the keyboard but also with the memory, mouse, fan, etc.

    I opened the cover to clean it figuring the heavy dust buildup was causing the CPU to overheat and generating these random errors. After blowing the dust out I found two United Chemi-Con caps leaking oil and with bulging tops.

    The only two caps one each of the KZG, and KZJ series on the whole motherboard were bad. All other caps by United Chemi-Con are of the KZE series and are good.

    New caps ordered will update when I install them.

    2200uF 6.3vdc KZJ 105C, and 3300uF 6.3vdc KZG 105C
    Last edited by enduser; 12-29-2010, 05:25 PM.

    #2
    Re: Dell Dimension 4700 - Bad United Chemi-Con

    Check the fan direction. Dell installed the case/cpu fan to blow IN. According to Dell, this is deliberate and correct. They even have a page dedicated to the issue warning you not to change it:
    http://support.dell.com/support/topi...&isLegacy=true

    However, in my experience, every 4700 I've worked on runs cooler with the fan blowing out in the traditional direction. Take from that what you will.

    Comment


      #3
      Re: Dell Dimension 4700 - Bad United Chemi-Con

      An inwards blowing fan was standard with old AT power supplies... till they figured out it gathers WAY too much dust this way. So i second the recommendation to flip it around.
      Originally posted by PeteS in CA
      Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
      A working TV? How boring!

      Comment


        #4
        Re: Dell Dimension 4700 - Bad United Chemi-Con

        It's one of those cases where DELL = Doesn't Ever Last Long
        I love putting bad caps and flat batteries in fire and watching them explode!!

        No wonder it doesn't work! You installed the jumper wires backwards

        Main PC: Core i7 3770K 3.5GHz, Gigabyte GA-Z77M-D3H-MVP, 8GB Kingston HyperX DDR3 1600, 240GB Intel 335 Series SSD, 750GB WD HDD, Sony Optiarc DVD RW, Palit nVidia GTX660 Ti, CoolerMaster N200 Case, Delta DPS-600MB 600W PSU, Hauppauge TV Tuner, Windows 7 Home Premium

        Office PC: HP ProLiant ML150 G3, 2x Xeon E5335 2GHz, 4GB DDR2 RAM, 120GB Intel 530 SSD, 2x 250GB HDD, 2x 450GB 15K SAS HDD in RAID 1, 1x 2TB HDD, nVidia 8400GS, Delta DPS-650BB 650W PSU, Windows 7 Pro

        Comment


          #5
          Re: Dell Dimension 4700 - Bad United Chemi-Con

          Originally posted by c_hegge View Post
          it's one of those cases where dell = doesn't ever last long
          My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.

          Comment


            #6
            Re: Dell Dimension 4700 - Bad United Chemi-Con

            Enduser, there is a transistor just to the left of the power supply socket by an inductor, Q5H1. Can you tell me the number of that? Took it out then lost it before I got the number. Thanks.

            Comment


              #7
              Re: Dell Dimension 4700 - Bad United Chemi-Con

              Originally posted by styxbound View Post
              Enduser, there is a transistor just to the left of the power supply socket by an inductor, Q5H1. Can you tell me the number of that? Took it out then lost it before I got the number. Thanks.
              It is made by ON semiconductor the numbers on it are shown as follows:

              441 ON
              T
              11ON2

              Comment


                #8
                Re: Dell Dimension 4700 - Bad United Chemi-Con

                Mmm, isn't that 110N2 and Infineon? http://www.alldatasheet.com/view.jsp?Searchword=110N2
                Originally posted by PeteS in CA
                Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                A working TV? How boring!

                Comment


                  #9
                  Re: Dell Dimension 4700 - Bad United Chemi-Con

                  Hey thanks, guys. Thought I was going to have to wait until I run across another of these things.

                  Comment


                    #10
                    Re: Dell Dimension 4700 - Bad United Chemi-Con

                    Just like to update and confirm that replacing the mentioned caps fixed this motherboard. I replaced those caps with the Panasonic low-esr series

                    Comment


                      #11
                      Re: Dell Dimension 4700 - Bad United Chemi-Con

                      Originally posted by Th3_uN1Qu3 View Post
                      Mmm, isn't that 110N2 and Infineon? http://www.alldatasheet.com/view.jsp?Searchword=110N2
                      Thanks for the correction, I was not aware of this brand.

                      Comment


                        #12
                        Re: Dell Dimension 4700 - Bad United Chemi-Con

                        Infineon makes A LOT of motherboard mosfets. Some memory chips too.
                        Originally posted by PeteS in CA
                        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                        A working TV? How boring!

                        Comment


                          #13
                          Re: Dell Dimension 4700 - Bad United Chemi-Con

                          Originally posted by enduser View Post
                          I was hired to troubleshoot a Dell Dimension 4700 PC that kept having random keyboard errors. I checked the BIOS log and noticed it had multiple errors with not only the keyboard but also with the memory, mouse, fan, etc.

                          I opened the cover to clean it figuring the heavy dust buildup was causing the CPU to overheat and generating these random errors. After blowing the dust out I found two United Chemi-Con caps leaking oil and with bulging tops.

                          The only two caps one each of the KZG, and KZJ series on the whole motherboard were bad. All other caps by United Chemi-Con are of the KZE series and are good.

                          New caps ordered will update when I install them.

                          2200uF 6.3vdc KZJ 105C, and 3300uF 6.3vdc KZG 105C

                          Hey enduser. I'm working on a friend's a Dell Dimension 4700 that has at least one bulging capacitor and the same symptoms you've described. I've removed all the motherboard retaining screws but the motherboard isn't releasing. It seem to be held near the CPU. Do you remember there being a hidden screw under the CPU heatsink? I didn't want to remove and re-seat the heatsink unless necessary.

                          Comment


                            #14
                            Re: Dell Dimension 4700 - Bad United Chemi-Con

                            Yes, almost all Dell Socket 775 CPU brackets screw to the case chassis. You're going to need to pull the heatsink. Under that there are 4 screws holding on the plastic retention bracket. Remove those and the motherboard should come out.

                            Comment


                              #15
                              Re: Dell Dimension 4700 - Bad United Chemi-Con

                              Replacing the 2200uF 6.3v KZJ located by the RAM slots solved the rebooting/stability problem with my friend's Dimension 4700. Works like a charm now!!

                              Comment

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