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    #1

    Dell SP2008WFPt no picture

    I have a used Dell SP2008WFPt 20 inches monitor with USB hub and webcam that doesn't work anymore.

    When I plug it in, the power button light blinks blue, but pressing it doesn't do anything.

    I disassembled it and took pictures of the two boards. I tested the power supply board (yellow-ish one) with my multimeter and the +5V points do indeed output 5 volts when the power cable is plugged in.

    On the other board, I haven't tested the points because I don't know what any of it does. I did look at all the capacitors and they all seem fine to me.

    Tools I have access to: soldering iron, digital multimeter


    I've attached a few pictures. If they are unclear or if close shots of particular areas are required, I can add some more. I do have access to a flatbed scanner, but since there are some fairly high components, I don't think the picture would be any good.

    I uploaded the full resolution pictures on imgur: http://imgur.com/a/CUTze
    Attached Files
    Tags: None
    #2
    Re: Dell SP2008WFPt no picture

    Originally posted by kynax View Post
    When I plug it in, the power button light blinks blue, but pressing it doesn't do anything.
    If you hookup a working computer with your favourite wall paper, do you see it by shining a flashlight on the lcd?
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      #3
      Re: Dell SP2008WFPt no picture

      There are voltage regulators on the logic board. I have circled them in yellow.

      Use a ground screw on the logic board for the black probe. Put your multimeter on 20V DC (if manual).

      1) What are the part numbers of each regulator?

      2) What is the DC voltage of each pin?
      Attached Files
      Last edited by retiredcaps; 03-07-2011, 11:08 PM.
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        #4
        Re: Dell SP2008WFPt no picture

        Is there a legend silk screened next to the wiring harness on the power board identifying voltages, ena, on/off, etc?

        Comment

          #5
          Re: Dell SP2008WFPt no picture

          Originally posted by jetadm123 View Post
          Is there a legend silk screened next to the wiring harness on the power board identifying voltages, ena, on/off, etc?
          Yes, you can see it in the 6th picture. If you check the imgur files, the resolution is high enough to see it.

          The picture is upside-down, but the order is:

          OFF | BRI | ON-OFF | A-EN | A-DET | GND (4) | +5V- RTN | 5V (4)


          I already checked that the 4 5V pins do have 5V compared to the 4 GND pins.

          Comment

            #6
            Re: Dell SP2008WFPt no picture

            Originally posted by retiredcaps View Post
            If you hookup a working computer with your favourite wall paper, do you see it by shining a flashlight on the lcd?
            No, nothing at all.

            Comment

              #7
              Re: Dell SP2008WFPt no picture

              Originally posted by retiredcaps View Post
              There are voltage regulators on the logic board. I have circled them in yellow.

              Use a ground screw on the logic board for the black probe. Put your multimeter on 20V DC (if manual).

              1) What are the part numbers of each regulator?

              2) What is the DC voltage of each pin?
              Here are the readings I get:
              Attached Files

              Comment

                #8
                Re: Dell SP2008WFPt no picture

                Originally posted by kynax View Post
                Here are the readings I get:
                Those readings look good.

                I missed one voltage regulator. Report and measure I317 (just above chip labeled 3B72).

                For the future, one good clear focused picture top down view of each board is sufficient. Having the logic board chopped up in 4 quadrants is difficult to view.
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                  #9
                  Re: Dell SP2008WFPt no picture

                  Originally posted by kynax View Post
                  Yes, you can see it in the 6th picture. If you check the imgur files, the resolution is high enough to see it.

                  The picture is upside-down, but the order is:

                  OFF | BRI | ON-OFF | A-EN | A-DET | GND (4) | +5V- RTN | 5V (4)


                  I already checked that the 4 5V pins do have 5V compared to the 4 GND pins.

                  Many members here avoid (myself included) photos posted on external sites for fear of catching a virus on their computer.

                  Can you please measure the voltages of BRI,ON-OFF,A-EN and A-DET?

                  Also, it looks like you missed a voltage reg (circled in yellow). Measure and report the voltages and part number. There seems to be a number of fuses (circled in red). Check them for continuity. Check around the board for additional fuses. They are generally marked FXXX (XXX=number).
                  Attached Files

                  Comment

                    #10
                    Re: Dell SP2008WFPt no picture

                    Originally posted by retiredcaps View Post
                    Those readings look good.

                    I missed one voltage regulator. Report and measure I317 (just above chip labeled 3B72).

                    For the future, one good clear focused picture top down view of each board is sufficient. Having the logic board chopped up in 4 quadrants is difficult to view.
                    I don't get anything on any of the pins.
                    It's a 17-33L like the other one.


                    One thing I did notice with the VGA cable plugged into my laptop is that Windows does recognize the monitor:
                    Attached Files

                    Comment

                      #11
                      Re: Dell SP2008WFPt no picture

                      Originally posted by jetadm123 View Post
                      Can you please measure the voltages of BRI,ON-OFF,A-EN and A-DET?
                      BRI: oscillates between 0 and 2.7V every 0.5 seconds
                      ON-OFF: 0.12V
                      A-EN: 0.12V
                      A-DET: 0V

                      Comment

                        #12
                        Re: Dell SP2008WFPt no picture

                        Originally posted by kynax View Post
                        BRI: oscillates between 0 and 2.7V every 0.5 seconds
                        ON-OFF: 0.12V
                        A-EN: 0.12V
                        A-DET: 0V


                        What about the fuses I asked you to check?

                        Comment

                          #13
                          Re: Dell SP2008WFPt no picture

                          Originally posted by jetadm123 View Post
                          There seems to be a number of fuses (circled in red). Check them for continuity. Check around the board for additional fuses. They are generally marked FXXX (XXX=number).
                          I tested all I could find (over 15) and they all worked fine (continuity).

                          Comment

                            #14
                            Re: Dell SP2008WFPt no picture

                            Originally posted by kynax View Post
                            I don't get anything on any of the pins.
                            It's a 17-33L like the other one.
                            Assuming the fuses around that component are all working, then this voltage regulator is bad. You should get some DC voltage readings on the pins.
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                              #15
                              Re: Dell SP2008WFPt no picture

                              Originally posted by kynax View Post
                              I don't get anything on any of the pins.
                              It's a 17-33L like the other one.


                              One thing I did notice with the VGA cable plugged into my laptop is that Windows does recognize the monitor:

                              You should have at least 5V on one of the pins. I would have suspected a bad fuse.

                              Comment

                                #16
                                Re: Dell SP2008WFPt no picture

                                Originally posted by retiredcaps View Post
                                Assuming the fuses around that component are all working, then this voltage regulator is bad. You should get some DC voltage readings on the pins.
                                Is this a component that fails fairly often? As in, is there a good chance that this is the problem?

                                I'm pretty sure I can buy a replacement locally and change it.

                                Comment

                                  #17
                                  Re: Dell SP2008WFPt no picture

                                  Regardless of whether it's bad or not, you should still measure the 5V input.

                                  Comment

                                    #18
                                    Re: Dell SP2008WFPt no picture

                                    Originally posted by kynax View Post
                                    Is this a component that fails fairly often?
                                    Voltage regulators do fail. How often? I don't know.

                                    You can look for replacements on junk boards and reuse the old ones.

                                    PS. You should retest it one more time.
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                                    Comment

                                      #19
                                      Re: Dell SP2008WFPt no picture

                                      Originally posted by jetadm123 View Post
                                      Regardless of whether it's bad or not, you should still measure the 5V input.
                                      Indeed, I misread your previous post.

                                      Which one is the input pin?

                                      Comment

                                        #20
                                        Re: Dell SP2008WFPt no picture

                                        Originally posted by retiredcaps View Post

                                        PS. You should retest it one more time.
                                        That's also what I though.

                                        I still get 0V on all pins.

                                        I compared with the other regulator and that one is still working.


                                        EDIT: Is is possible that this regulator is there for the USB hub, in which nothing is plugged right now, explaining the lack of voltage in there?

                                        Comment

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