Announcement

Collapse
No announcement yet.

Dell 2007WFP Won't Power On

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #41
    Re: Dell 2007WFP Won't Power On

    @peterfares (if you still are watching this post): One thing you might want to fix (and I don't know if you did or not) is to resolder the plug in. I picked up this monitor for free on craigslist and replaced all the capacitors and it somewhat worked, I noticed that this was completely coming undone and resolder it and it now works 100%!. And yours looks like it might be starting to do that as well.



    @core2kid: Make sure to check for cold soldering, as now I've seen 3 different monitors have this issue. (On top of what retiredcaps/PlainBill said)

    Comment


      #42
      Re: Dell 2007WFP Won't Power On

      Are there any specific areas I should be checking for cold solders?

      I don't have any idea where to start to even look for the voltage regulators. I have an idea of where the diodes are though (Are they the two by the 12v power connector?

      How do I check them with a digital multimeter?

      Here's some pics of my board. Do you all need better pics or pics of the back? If so, I'll be able to post better pics that I can take in daylight.





      Comment


        #43
        Re: Dell 2007WFP Won't Power On

        Yes, we'd like to see both sides of the board and in better light, keep in mind we're looking at rather small parts through the computer. So make sure the whole board takes up the picture.

        Comment


          #44
          Re: Dell 2007WFP Won't Power On

          Sure thing, I'll do it tomorrow afternoon after college. Thanks again for helping me out!

          Comment


            #45
            Re: Dell 2007WFP Won't Power On

            Originally posted by core2kid View Post
            I don't have any idea where to start to even look for the voltage regulators.

            How do I check them with a digital multimeter?

            Here's some pics of my board.
            1) Voltage regulators (U designation) can be bad. They can be shorted or output the incorrect voltage. The test described below only tests the former.

            If you have a manual range multimeter, set it to 200 ohms (two hundred). You can test voltage regulators "in circuit" for shorts by (power off and unplugged)

            a) black on pin 1- red on pin 2 - record ohms
            b) black on pin 1- red on pin 3 - record ohms
            c) black on pin 2- red on pin 3 - record ohms

            If any ohm reading is less than 30 ohm you might have shorted voltage regulator. Remove from circuit and repeat the tests to verify.

            2) To test a diode in circuit,

            a) put your multimeter in diode test mode
            b) put your black lead on one side and the red lead on the other - record reading
            c) reverse the leads - recording reading

            A good diode should read 0.4V to 0.7V in one direction and 0L in the other. If you get a reading in both directions, you will have to desolder one leg and retest to verify.

            3) PLEASE follow the instructions in PlainBill's signature on how to post pictures so they are posted here and please don't post inline.
            --- begin sig file ---

            If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

            We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

            Please do not post inline and offsite as they slow down the loading of pages.

            --- end sig file ---

            Comment


              #46
              Re: Dell 2007WFP Won't Power On

              Sorry for the delay all, I'm still waiting for a good sunny day when I can take pics. I've been hit by the east coast storm and I haven't had a good sunny day yet, just dull days :/
              I'm hoping to have pics for you tomorrow.

              Comment


                #47
                Re: Dell 2007WFP Won't Power On

                Here are some pictures of the board.
                Attached Files

                Comment


                  #48
                  Re: Dell 2007WFP Won't Power On

                  Not that this is the fix, but is that some cold soldiering on the upper left picture of the back side of the power board?

                  Comment


                    #49
                    Re: Dell 2007WFP Won't Power On

                    I tried to reheat most of the solder points, maybe I missed that one. I'll try it tonight and post back.

                    I can however say that occasionally it'll power on for 2 seconds and then start flashing.

                    Comment


                      #50
                      Re: Dell 2007WFP Won't Power On

                      I resoldered that and it didn't work. Any other suggestions?

                      Comment


                        #51
                        Re: Dell 2007WFP Won't Power On

                        Originally posted by core2kid View Post
                        I resoldered that and it didn't work. Any other suggestions?
                        Try checking the fuses circled below. With power off and your meter set to resistance, place your probes across each fuse. Reading should be around 0 ohms.
                        Attached Files

                        Comment


                          #52
                          Re: Dell 2007WFP Won't Power On

                          All the fuses read .00 to .02 Ohms, they also show continuity. Could one of the capacitors have failed?

                          Comment


                            #53
                            Re: Dell 2007WFP Won't Power On

                            Sorry to bring this old thread back to life but I'm still trying to get this monitor back up. I'm using a CRT for now. Any ideas on what may have failed of the USB board?

                            Comment


                              #54
                              Re: Dell 2007WFP Won't Power On

                              See post 45 to test the voltage regulators and diodes.

                              Are you saying that if you hookup a working computer with your favourite wallpaper that the computer shows the wallpaper for 2 seconds and then go to black?

                              If yes, you could have

                              a) bad capacitors
                              b) bad inverter transformer
                              3) bad ccfl
                              4) bad ccfl wiring/soldering

                              For the all of above, see starting with post #13

                              https://www.badcaps.net/forum/showthread.php?t=10419
                              --- begin sig file ---

                              If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                              We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                              Please do not post inline and offsite as they slow down the loading of pages.

                              --- end sig file ---

                              Comment


                                #55
                                Re: Dell 2007WFP Won't Power On

                                I have 2 of these monitors, one is my dads and this one was mine. Basically when it went out, I replaced the USB board with one from a known working monitor and it worked fine. That rules out #3 and #4.

                                About it working, occasionally it'll work but it'll only go as far as to turn on the backlight for a second and then it'll go off. This happens about 5% of the time.

                                All capacitors aren't bulged out or leaking. Could they still be bad?
                                What's the inverter transformer?

                                Comment


                                  #56
                                  Re: Dell 2007WFP Won't Power On

                                  One thing you could try is measuring the voltages at the power connector of the usb board. It looks like the pins are labeled 1-6 and 7-12. Try measuring the voltages with the "good" board installed and again with the "bad" one installed. Also, measure voltages while pushing the on/off button on the front panel. Compare the voltage output of the two boards. If you find a major difference, then try to trace what that pin is connected to.


                                  Yes, a cap can be bad. However, since you have no way of testing them, you'd be replacing them based on a "hunch".

                                  Comment


                                    #57
                                    Re: Dell 2007WFP Won't Power On

                                    Okay, i'll work on replacing the caps first. Can I test a cap with a multimeter?

                                    I don't want to take apart the other monitor at the moment, my dad needs it every day and if something goes wrong, I'm dead...

                                    Comment


                                      #58
                                      Re: Dell 2007WFP Won't Power On

                                      Other than a dead short, you will not be able to test cap with a DMM. Replace with good quality caps like panasonic FC or FM series from digikey.com.

                                      Comment


                                        #59
                                        Re: Dell 2007WFP Won't Power On

                                        Hi there! I´m also trying to repair a 2007wfp dell monitor, had replaced a shorted J598 mosfet, and the two diodes S4 62A (with similar FU4007: 1000V, 1A, 75ns) (one of the S4 diodes was shorted) and also the 3A fuse.
                                        But the result is that I still get a short and is caused by the ZD701 (very little zener diode, the only one on the pcb)
                                        Does anybody know of a proper replacement? I can´t get to figure wich voltage is it suposed to work with, guessing for the size that it´s a 1/4W diode.
                                        Thanks for your wisdom!
                                        Chad
                                        PW: I think pcb voltages are 19V and 5V for the usb, but do not know if there´s another/s.

                                        Comment


                                          #60
                                          Re: Dell 2007WFP Won't Power On

                                          Originally posted by chad720 View Post
                                          Hi there! I´m also trying to repair a 2007wfp dell monitor, had replaced a shorted J598 mosfet, and the two diodes S4 62A (with similar FU4007: 1000V, 1A, 75ns) (one of the S4 diodes was shorted) and also the 3A fuse.
                                          But the result is that I still get a short and is caused by the ZD701 (very little zener diode, the only one on the pcb)
                                          Does anybody know of a proper replacement? I can´t get to figure wich voltage is it suposed to work with, guessing for the size that it´s a 1/4W diode.
                                          Thanks for your wisdom!
                                          Chad
                                          PW: I think pcb voltages are 19V and 5V for the usb, but do not know if there´s another/s.
                                          Earlier today I saw this thread. The gentleman provided a good description of the problem, just like you did. He ALSO provided pictures and a datasheet. This changed a 10 or 20 post problem into a simple analysis.

                                          The best solution to your problem is to identify the zener diode. Many SMD components have a two or three character marking code on the device. With that information, identifying it becomes easy.

                                          PlainBill
                                          For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                          Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                          Comment

                                          Working...
                                          X