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Dell 1800FP, not powering up.

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    #1

    Dell 1800FP, not powering up.

    I recently started working on two Dell 1800FP screens. One of them powered up and just had what looked to be a video issue, it was flickering and the picture kept scrolling up. I was able to find a fix on this thread https://www.badcaps.net/forum/showpo...0&postcount=12 . I replaced the SMD caps C739 and C207 on the input board with http://search.digikey.com/us/en/prod...42-1-ND/757603 (sorry I don't remember if direct linking is allowed) and the video problem went away. I also recapped the power board and re-soldered the 3 transistors around the main group of caps on the power board, as suggested on another thread, because of some bad solder joints. That monitor is now working fine, but its brother is not doing so well.

    When I plugged in the monitor and tried to turn it on it did nothing. It didn't flicker on the screen, the led didn't light up so I thought it was the power board. Since I had a working model it was very easy to diagnose. After switching parts around, I found out that it was the input logic board. I then proceeded to search for a solution and after trying a couple I didn't find anything that worked. First I tried switching the caps like I did on the first monitor, and that didn't fix anything, still nothing coming up. I tried replacing the c817 capacitor (the one next to the larger through hole brown caps,) because some others have had an issue with it, but that didn't help. One other problem, I don't own an ESR meter, so I can't test caps effectively (it's on a list of things to buy.) Everything in this monitor is working, I simply put the working logic board in it and tested it, so I know its this board. Thanks in advance for any and all help.

    Brink

    p.s. The picture of the power board is from the first link I posted, if you need a picture of mine, I can do that easily.

    p.p.s. The caps I used on the power board are Panasonic Fm or Fc series, and rated at the correct voltage and farad.
    Attached Files
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    #2
    Re: Dell 1800FP, not powering up.

    U704, U801, and U803 are voltage regulators.

    A voltage regulator may have a part number like AS1117-33 where the suffix (-33) denotes the output voltage (3.3 V DC).

    We want the DC V measurements of all 3 pins (including the cut ones) with respect to ground (use a ground screw on the logic board). So report it like

    U704 - part # AS1117-33 - pin 1 = 0V, pin 2 = 5.01 V, pin 3 = 3.32 V

    Voltage regulators are spec'd to +/- 1%. So a good regulator should be within

    3.3 x 1.01 = 3.333 V
    3.3 x 0.99 = 3.267 V
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      #3
      Re: Dell 1800FP, not powering up.

      The two main problems on the signal/logic board for this monitor are the caps you mentioned and a corrupted eeprom (U201). It should be a ATMEL AT49F001.

      Comment

        #4
        Re: Dell 1800FP, not powering up.

        Ok so here is what I got:

        U704 Part#: KA78M05R, Pin 1: 12.07v, Pin 2: 0v, Pin 3: 5.05v

        U801 Part#: BA033, Pin 1: 4.65, Pin 2: 0v, Pin 3: 3.32v

        U803 Part#: CQ32 or 1725, Pin 1: 0v, Pin 2: 2.48v, Pin 3: 3.62v

        Those look right to me. But if it is the eeprom how can I go about testing. Should I try to pull it off of the other logic board, it has the same part number of Atmel AT49RF001n, like this board. They have the same Model number and manufacturing date, but they do have different power regulators and slightly different "small components". Thanks for the help guys, I included pics of the regulators just in case I got the part #'s wrong (you might have to zoom out sorry.).

        Brink

        P.S. Heres a link from atmel for that eeprom:
        Attached Files

        Comment

          #5
          Re: Dell 1800FP, not powering up.

          Originally posted by jplt View Post
          Ok so here is what I got:

          U704 Part#: KA78M05R, Pin 1: 12.07v, Pin 2: 0v, Pin 3: 5.05v

          U801 Part#: BA033, Pin 1: 4.65, Pin 2: 0v, Pin 3: 3.32v

          U803 Part#: CQ32 or 1725, Pin 1: 0v, Pin 2: 2.48v, Pin 3: 3.62v

          Those look right to me.
          Agreed. U803 just makes the cut at 2.48V, but it could be low due to the accuracy of your multimeter?

          But if it is the eeprom how can I go about testing.
          I'll defer to jetadm123 since he knows more about this monitor.

          PS. Great close up pics. Most people wouldn't go through the trouble, but I'm glad you did. It helps a lot.
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          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.

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          Comment

            #6
            Re: Dell 1800FP, not powering up.

            There used to be a company that sold replacement eeproms. However, I think they went out of business. I'm afraid you might be stuck having to purchase another logic board. There are a few on Ebay, but they are rather pricey.

            Comment

              #7
              Re: Dell 1800FP, not powering up.

              Originally posted by jetadm123 View Post
              TThere are a few on Ebay, but they are rather pricey.
              The cheapest one I saw was $25. Too much money for a 7 year 18 inch monitor. You can keep the monitor for spare parts or part it out and sell the working stuff on ebay.

              I missed out on this one local deal today because I was getting clarification from the seller, but one guy was selling two working 22 inch wide screen monitors for $20 each.

              Normally, I would repair old broken ones, but I would pay for the above deal. He said he was flooded with requests and eventually sold them.

              I didn't NEED them, but I figure I could sell a recapped 20 inch 4:3 ratio monitor quite easily for $40 to even out the money situation.
              --- 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

                #8
                Re: Dell 1800FP, not powering up.

                Originally posted by retiredcaps View Post
                The cheapest one I saw was $25. Too much money for a 7 year 18 inch monitor. You can keep the monitor for spare parts or part it out and sell the working stuff on ebay.

                I missed out on this one local deal today because I was getting clarification from the seller, but one guy was selling two working 22 inch wide screen monitors for $20 each.

                Normally, I would repair old broken ones, but I would pay for the above deal. He said he was flooded with requests and eventually sold them.

                I didn't NEED them, but I figure I could sell a recapped 20 inch 4:3 ratio monitor quite easily for $40 to even out the money situation.
                I was also eyeballing a 22 inch monitor that I saw on craigslist today. The seller says that it failed after only one year of service! He was also asking $20 for it, but he's a ways out and I'm not sure it's worth the time and gas.....

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