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Dell Ultrasharp 1800 no power

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    #1

    Dell Ultrasharp 1800 no power

    Hi, I have a dell ultrasharp 1800 that i am trying to fix.

    Note: I have read numerous posts on this type of monitor failing due to the ICE2AS01 chip failing. Apparently from VCC to GND there is a short of about 13ohms. For THIS monitor the GND to VCC reading is in the MEG-ohms so my first reaction is the ICE2AS01 chip is ok.

    Symptoms of this monitor:
    1-WHen i plug in the power......nothing happens. The LED light does not come on.

    2-I did measure the voltages at the connectors 1 and 2 (CN1 and CN2 respectively) see enclosed pics.

    For CN1: (DC voltages)
    Pin1: 5.09V
    Pin2: 0V
    Pin3: 0.24V
    Pin4: 0.26V
    Pin5: 5.08V
    Pin6: 5.08V


    For CN2: (DC voltages)
    Pin1: 12.09V
    Pin2: 12.09V
    Pin3: 0V
    Pin4: 0V
    Pin5: 5.09V
    Pin6: 5.09V
    Pin7: 0V
    Pin8: 0V


    3-I also measured the DC voltage across the big cap: I measured 167.9V

    I have no idea as to what to try next. If its the logic board that is "bad" then i dont think its worth replacing.....but i dont even know how to determine this.

    Can someone help? Any ideas on what to try would be appreciated.
    Attached Files
    Tags: None
    #2
    Re: Dell Ultrasharp 1800 no power

    Originally posted by Welchs101 View Post
    Symptoms of this monitor:
    1-WHen i plug in the power......nothing happens. The LED light does not come on.

    I have no idea as to what to try next. If its the logic board that is "bad" then i dont think its worth replacing.....but i dont even know how to determine this.
    On the logic board, I think I see 3 voltage regulators (just left of the big chip in the middle).

    They may be marked AL1117-33 indicating a voltage regulator with 3.3V DC output.

    List the part numbers and see if the voltages match the chip designation. See post #5 at

    https://www.badcaps.net/forum/showth...ghlight=daytek

    for examples.
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    Comment

      #3
      Re: Dell Ultrasharp 1800 no power

      The 3 voltage regulators are
      1) 1117S25
      2) BA033
      3) KA78M05R

      (see enclosed pic)

      I plugged in the power cord and measured the voltages at the respective pins.

      1) 1117S25
      Pin1: 0V
      Pin2: 0V
      Pin3: 0.162V

      2) BA033
      Pin1: 0.162V
      Pin2: 0.001V
      Pin3: 0V

      3) KA78M05R
      Pin1: 12.09V
      Pin2: 0V
      Pin3: 5.09V



      So it appears that (1) and (2) either are "bad" or just dont have the correct voltage input. My guess is they dont have the correct voltage input.......what does this mean?
      Attached Files

      Comment

        #4
        Re: Dell Ultrasharp 1800 no power

        Originally posted by Welchs101 View Post
        The 3 voltage regulators are
        1) 1117S25
        2) BA033
        3) KA78M05R

        (see enclosed pic)

        I plugged in the power cord and measured the voltages at the respective pins.

        1) 1117S25
        Pin1: 0V
        Pin2: 0V
        Pin3: 0.162V

        2) BA033
        Pin1: 0.162V
        Pin2: 0.001V
        Pin3: 0V

        3) KA78M05R
        Pin1: 12.09V
        Pin2: 0V
        Pin3: 5.09V



        So it appears that (1) and (2) either are "bad" or just dont have the correct voltage input. My guess is they dont have the correct voltage input.......what does this mean?
        Open fuse, open inductor, bad solder joint, or shorted load.

        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

          #5
          Re: Dell Ultrasharp 1800 no power

          Originally posted by Welchs101 View Post
          1) 1117S25
          Pin3: 0.162V

          2) BA033
          Pin1: 0.162V
          Wiht power off and LCD unplugged, I suggest tracing/ohming out the above VIN pins "backwards" to the components that feed the voltage. Make a quick diagram. Then, with power on, see where the Voltage disappears?
          Last edited by retiredcaps; 11-08-2010, 12:40 PM. Reason: edit: clarifications
          --- 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

            #6
            Re: Dell Ultrasharp 1800 no power

            Things moving a little slow. I am trying the suggested things......just moving slow.

            I did have a question. I found a post online somewhere that indicated that the chip U501 had problems. The Part U501 is a motorola chip with part number MC68HC908BD48IB.

            I have enclosed what i think is the data sheet for this part. But i have no clue as to how to determine if this chip is working ok or not.

            Attached Files

            Comment

              #7
              Re: Dell Ultrasharp 1800 no power

              have a look at page 30 and 31 then check if you have power in or out

              Comment

                #8
                Re: Dell Ultrasharp 1800 no power

                I have power on pin5 but i am not sure what pin to look at to determine if i have "stuff coming out".........

                Comment

                  #9
                  Re: Dell Ultrasharp 1800 no power

                  pin 5 is Power supply input to the MCU.
                  pin 2 is 3.3V regulated output from the MCU.
                  pin 9 is reset

                  Comment

                    #10
                    Re: Dell Ultrasharp 1800 no power

                    Pin2: 3.39V dc
                    Pin5: 5.08V dc
                    Pin9: 5.08V dc

                    Does this mean the chip is ok?

                    Comment

                      #11
                      Re: Dell Ultrasharp 1800 no power

                      were does pin 2 and pin 9 go to?

                      Comment

                        #12
                        Re: Dell Ultrasharp 1800 no power

                        ok.....i am not making much progress.

                        I was wondering if someone help guide me on what i should do next to try and narrow down the problem.

                        Comment

                          #13
                          Re: Dell Ultrasharp 1800 no power

                          Any ideas on what to check to figure out whats going on? Please help? I will do my best to get back to you in a reasonable time.

                          Comment

                            #14
                            Re: Dell Ultrasharp 1800 no power

                            have you traced to see were pin 2 and pin 9 go to ?

                            Comment

                              #15
                              Re: Dell Ultrasharp 1800 no power

                              Originally posted by Welchs101 View Post
                              Any ideas on what to check to figure out whats going on? Please help? I will do my best to get back to you in a reasonable time.
                              The best thing to do is put it on the shelf and hope a working logic board comes along. Pin 9 is active low - that means the processor should be operating. But something isn't working, and your capability of identifying the defective part is limited. Just as a guess, I would say the most likely candidate is U501. However, that contains a custom ROM, and the proper part is no longer available.

                              Looking at the board, it uses 6 chips to perform the functions usually accomplished by 1 chip. That screams 'old design'.

                              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

                                #16
                                Re: Dell Ultrasharp 1800 no power

                                Sorry for not responding until now.........in-laws were in town.

                                Bill, thanks for the advice.

                                Comment

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