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    Dell U2413 turning off

    I recently bought a used Dell U2413 monitor. All is going well until after a few days, the monitor started to shut down on its own. This would happen 30mins to an hour after turning it on -- the behavior is like it's pulled from the AC plug -- no power LED, and pressing the power button does not work. It would then take a few minutes for it to turn back on on its own. Sometimes, it would shut off again within 5mins after turning back on. I noticed that the room temperatt
    ure contributes to the issue. When used in a cold room/environment, the monitor works fine. Also, the monitor has four usb ports, with power coming form the main power supply circuit, and one of the ports outputs "1.5Amax" and "supports BC 1.2 compliance charging devices" as stated form the manual. As part of my trouble shooting, once the monitor turns off, I plug a usb device on each port to check for power. All three ports have power, even with the monitos' power LED out, but when I plug a device to the "1.5A" usb port, the monitor somehow turns back on, and shuts off as soon as I unplug the usb device from the said port.

    I've taken a look at the power supply board and no visible signs of burnt components, bad solder joints, or bulging capacitors. Though, I've read that some caps may still be going bad even without showing physical symptoms.

    Do you guys have an idea what component could be at fault here? I'm slowly leaning towards replacing all caps, but I'm still having doubts as I don't have concrete proof yet.

    #2
    Re: Dell U2413 turning off

    Took a couple of images of the disassembly and board, for those looking for references, or who might encounter the same issues:

    The caps are a mixture of CapXon, Sus'con, and Elite caps, not sure if they're reliable though.
    Attached Files

    Comment


      #3
      Re: Dell U2413 turning off

      I also uploaded a video to show the issue:
      https://youtu.be/rC2FBfbaFmI

      (I can't seem to edit my previous posts)

      Comment


        #4
        Re: Dell U2413 turning off

        Try again after disconnecting the USB daughter board.
        Also if possible, measure voltage on all pins of the power supply connector while the monitor is off, while it is on, and after it has shut down by itself.

        I don't think there is any service manual/schematics available for this one and I don't see any labelling on the power supply connector so you'll have to compare between working and non-working state.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment


          #5
          Re: Dell U2413 turning off

          Originally posted by piernov View Post
          Try again after disconnecting the USB daughter board.
          Also if possible, measure voltage on all pins of the power supply connector while the monitor is off, while it is on, and after it has shut down by itself.

          I don't think there is any service manual/schematics available for this one and I don't see any labelling on the power supply connector so you'll have to compare between working and non-working state.
          I tried disconnecting the side usb board -- no luck. I've yet to check the power supply pins, though it sucks that there's no labelling on the board.

          Comment


            #6
            Re: Dell U2413 turning off

            Can we see good clear straight shot high res pictures of the whole top and bottom side of the power supply board?
            Never stop learning
            Basic LCD TV and Monitor troubleshooting guides.
            http://www.badcaps.net/forum/showthr...956#post305956

            Voltage Regulator (LDO) testing:
            http://www.badcaps.net/forum/showthr...999#post300999

            Inverter testing using old CFL:
            http://www.badcaps.net/forum/showthr...er+testing+cfl

            Tear down pictures : Hit the ">" Show Albums and stories" on the left side
            http://s807.photobucket.com/user/budm/library/

            TV Factory reset codes listing:
            http://www.badcaps.net/forum/showthread.php?t=24809

            Comment


              #7
              Re: Dell U2413 turning off

              Originally posted by budm View Post
              Can we see good clear straight shot high res pictures of the whole top and bottom side of the power supply board?
              You can check the images I've attached below. Hope this helps
              Attached Files

              Comment


                #8
                Re: Dell U2413 turning off

                Check the Voltages when missing and when it does not work, see marked pictures.
                The DC Voltage measured between the two legs of the main filter cap in the host side should be around 380 ~ 400VDC when monitor is turned on.
                Attached Files
                Never stop learning
                Basic LCD TV and Monitor troubleshooting guides.
                http://www.badcaps.net/forum/showthr...956#post305956

                Voltage Regulator (LDO) testing:
                http://www.badcaps.net/forum/showthr...999#post300999

                Inverter testing using old CFL:
                http://www.badcaps.net/forum/showthr...er+testing+cfl

                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                http://s807.photobucket.com/user/budm/library/

                TV Factory reset codes listing:
                http://www.badcaps.net/forum/showthread.php?t=24809

                Comment


                  #9
                  Re: Dell U2413 turning off

                  So I powered up the LCD with its guts open, plugged in to a video source -- been waiting for it to turn itself off to check voltages, but it's been an hour and a half and it's still running fine. Man, this thing won't let me troubleshoot.

                  @budm -- voltage from the main filter cap was steady at 427VDC
                  Last edited by dcdcc; 04-26-2018, 08:35 PM.

                  Comment


                    #10
                    Re: Dell U2413 turning off

                    427V DC, that is on the high side, may be you should check the batteries of your meter to make sure they are OK. I would expect the OVP circuit to kick in at that high PFC Voltage.
                    You measure right between the two legs, not from chassis GND, correct?
                    Last edited by budm; 04-26-2018, 09:39 PM.
                    Never stop learning
                    Basic LCD TV and Monitor troubleshooting guides.
                    http://www.badcaps.net/forum/showthr...956#post305956

                    Voltage Regulator (LDO) testing:
                    http://www.badcaps.net/forum/showthr...999#post300999

                    Inverter testing using old CFL:
                    http://www.badcaps.net/forum/showthr...er+testing+cfl

                    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                    http://s807.photobucket.com/user/budm/library/

                    TV Factory reset codes listing:
                    http://www.badcaps.net/forum/showthread.php?t=24809

                    Comment


                      #11
                      Re: Dell U2413 turning off

                      Originally posted by budm View Post
                      427V DC, that is on the high side, may be you should check the batteries of your meter to make sure they are OK. I would expect the OVP circuit to kick in at that high PFC Voltage.
                      You measure right between the two legs, not from chassis GND, correct?

                      Yes, between the two cap legs.

                      PS. What do you mean by OVP circuit? Thanks
                      Last edited by dcdcc; 04-26-2018, 09:56 PM.

                      Comment


                        #12
                        Re: Dell U2413 turning off

                        'OVP' = Over Voltage Protection.
                        Most PFC will have Low and High Voltage protection.
                        So at this points you need to test all those Voltages I already marked for you in the pictures. I hope you did take the Voltage readings on those points I made for you when it is working as I suggested.
                        Never stop learning
                        Basic LCD TV and Monitor troubleshooting guides.
                        http://www.badcaps.net/forum/showthr...956#post305956

                        Voltage Regulator (LDO) testing:
                        http://www.badcaps.net/forum/showthr...999#post300999

                        Inverter testing using old CFL:
                        http://www.badcaps.net/forum/showthr...er+testing+cfl

                        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                        http://s807.photobucket.com/user/budm/library/

                        TV Factory reset codes listing:
                        http://www.badcaps.net/forum/showthread.php?t=24809

                        Comment


                          #13
                          Re: Dell U2413 turning off

                          Update: After it turned off, I immediately put on a fan pointed towards an SB20100 (Schottky Diode, according to its datasheet, within the "main switched power supply" circuit, with its own heatsink) and just after a few seconds, the monitor turned back on.
                          Last edited by dcdcc; 04-26-2018, 11:05 PM.

                          Comment


                            #14
                            Re: Dell U2413 turning off

                            PS1 is stable at 5.37VDC. I can't get an accurate reading for PS2 (was hovering around 2.9mV) and PS3 (hovering around 1.5mV), and now the LCD panel is not working, but the buttons do light up, and the output of the main filter cap is now only at 348VDC.
                            Last edited by dcdcc; 04-27-2018, 12:41 AM.

                            Comment


                              #15
                              Re: Dell U2413 turning off

                              PS1 is the standby power supply, it is working that is why you are getting the button to light up.
                              PS2, PS3 are the main switched power supplies that require the PFC Voltage to run, but since the PFC Boosted Voltage is low so PS2/3 stay in the shutdown mode.
                              At this point we need to verify if the PS-ON is present or not or we can verify to see the PFC Controller IC is getting the switched Vcc to run or not.
                              If you look at the picture of the top side, I marked the PFC IC, we need to the P/N as printed on the top of the IC, report what ALL the prints on top of the IC, so we can look up the spec. sheet for it.
                              Never stop learning
                              Basic LCD TV and Monitor troubleshooting guides.
                              http://www.badcaps.net/forum/showthr...956#post305956

                              Voltage Regulator (LDO) testing:
                              http://www.badcaps.net/forum/showthr...999#post300999

                              Inverter testing using old CFL:
                              http://www.badcaps.net/forum/showthr...er+testing+cfl

                              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                              http://s807.photobucket.com/user/budm/library/

                              TV Factory reset codes listing:
                              http://www.badcaps.net/forum/showthread.php?t=24809

                              Comment


                                #16
                                Re: Dell U2413 turning off

                                It's K15A60U

                                Comment


                                  #17
                                  Re: Dell U2413 turning off

                                  Originally posted by dcdcc View Post
                                  It's K15A60U
                                  That is not it.
                                  It is the black kind of square device with 8 pins on it.
                                  https://www.badcaps.net/forum/attach...8&d=1524771853
                                  Never stop learning
                                  Basic LCD TV and Monitor troubleshooting guides.
                                  http://www.badcaps.net/forum/showthr...956#post305956

                                  Voltage Regulator (LDO) testing:
                                  http://www.badcaps.net/forum/showthr...999#post300999

                                  Inverter testing using old CFL:
                                  http://www.badcaps.net/forum/showthr...er+testing+cfl

                                  Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                  http://s807.photobucket.com/user/budm/library/

                                  TV Factory reset codes listing:
                                  http://www.badcaps.net/forum/showthread.php?t=24809

                                  Comment


                                    #18
                                    Re: Dell U2413 turning off

                                    Originally posted by budm View Post
                                    That is not it.
                                    It is the black kind of square device with 8 pins on it.
                                    https://www.badcaps.net/forum/attach...8&d=1524771853
                                    apologies for the late response. Been caught up at work..

                                    The IC says:
                                    1608B
                                    PRCM

                                    Comment


                                      #19
                                      Re: Dell U2413 turning off

                                      Hi

                                      I have the same problem.

                                      did you solve it?

                                      Thank you

                                      Comment


                                        #20
                                        Re: Dell U2413 turning off

                                        It has been running for two days without turning off. I put new thermal paste on the K15A60U and I attached a radiator to the LD7904jgp7

                                        Comment

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