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Dell 1703fps backlight problem

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    #1

    Dell 1703fps backlight problem

    I have a Dell 1703 fps where the backlight turns on for about a second. Turning the monitor off and on again causes the light to repeat the cycle.
    The monitor has a Lien Chang inverter board (LI-2070) and the power board is numbered BN41-00296B. I've replace 3 1000 mf 25v Capxon and 3 1000 mf 16v Capxon electrolytics on the power board. The caps showed no signs of bulging and also tested good with an esr meter. There are two other caps on the power board and one on the inverter board that check good (with esr meter) that I have not replaced.
    If I monitor pins 1 and 12 on the connector going to the inverter board (I'm pretty sure this is supposed to be the 12 volt line) I get 17.70 volts when plugged in but not turned on - after turning on and the backlight comes up the voltage is 15.26. The backlight goes off and the voltage increases to 19.47 volts.
    Seems like this backlight issue is common for this monitor - anyone have a fix for it?

    Thanks

    Mike
    Tags: None
    #2
    Re: Dell 1703fps backlight problem

    Originally posted by mu2
    I have a Dell 1703 fps where the backlight turns on for about a second. Turning the monitor off and on again causes the light to repeat the cycle.
    The monitor has a Lien Chang inverter board (LI-2070) and the power board is numbered BN41-00296B. I've replace 3 1000 mf 25v Capxon and 3 1000 mf 16v Capxon electrolytics on the power board. The caps showed no signs of bulging and also tested good with an esr meter. There are two other caps on the power board and one on the inverter board that check good (with esr meter) that I have not replaced.
    If I monitor pins 1 and 12 on the connector going to the inverter board (I'm pretty sure this is supposed to be the 12 volt line) I get 17.70 volts when plugged in but not turned on - after turning on and the backlight comes up the voltage is 15.26. The backlight goes off and the voltage increases to 19.47 volts.
    Seems like this backlight issue is common for this monitor - anyone have a fix for it?

    Thanks

    Mike
    Post good quality pictures of the boards. I'm not familiar with that monitor. The symptom you describe (often refered to as the 'two seconds to black' problem) has several causes. It can be a problem with either the inverter or the backlights (CCFLs).

    PlainBill
    Last edited by PlainBill; 10-30-2009, 10:04 AM.
    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

      #3
      Re: Dell 1703fps backlight problem

      I'll work on getting some photos over the weekend, if my digital camera is still working.
      Does the fact that the 12 volt input is high have any significance? Could the inverter be shutting down due to a too high voltage condition?

      Mike

      Comment

        #4
        Re: Dell 1703fps backlight problem

        Originally posted by mu2
        I'll work on getting some photos over the weekend, if my digital camera is still working.
        Does the fact that the 12 volt input is high have any significance? Could the inverter be shutting down due to a too high voltage condition?

        Mike
        It could be. Most inverter controllers monitor the output voltage and current and shut down if either go out of limits. But that raises other questions - what is the voltage supposed to be? (Not all inverters use a 12V supply). What is the voltage going to the logic board? Is it correct?

        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 1703fps backlight problem

          My information on the 12 volt input came from this link.
          http://www.lcdparts.net/InverterDeta...ProductID=2233
          My inverter board (the Lien Chang LI-2070) doesn't look like this one although the CCFL connectors, inverter transformers and input connector are the same.
          Since this is supposed to be a sub and 12 volts is mentioned as the input voltage, I figured my supply voltage was high. There is a KA431LZ which is supposed to be a programmable shunt regulator on the power board, but I haven't looked at the voltages in that area. Not sure if the 12 volts comes from there.

          Mike

          Comment

            #6
            Re: Dell 1703fps backlight problem

            Here is a photo of the power and inverter boards. I found that a connector on the power card is marked "14v" and "5v". My 5 volt supply is pretty close (5.1) but the 14 volt supply is high.

            Mike
            Attached Files

            Comment

              #7
              Re: Dell 1703fps backlight problem

              I just bought this same exact monitor and it has the same exact problem. The power board is the same as above. It had 3 X 1000uF 25V and 3 X1000uF 16V. Recapped to all six new 1000uF 25V caps. Same problem exists still. I have yet to go through the checklist of "2 seconds to black" procedure. Has anyone ever found a solution to this problem with this monitor?
              The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

              Comment

                #8
                Re: Dell 1703fps backlight problem

                Originally posted by Dgtech View Post
                I just bought this same exact monitor and it has the same exact problem.
                One case was traced to bad a CCFL post #16.

                https://www.badcaps.net/forum/showth...t=Dell+1703fps
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                Comment

                  #9
                  Re: Dell 1703fps backlight problem

                  I work on Dell 1703 fps the problem you had is Lien Chang inverter board (LI-2070), take close look on bottom hight volt transformer on both side on hight volt transformer is burn up need replace (one side had 6 legs & another had 2 legs got to backlight)
                  check is out website last time I paid $39.95 + shipping or send you inveter they can repair
                  http://www.lcdpart.com/Products/li2070.html

                  Comment

                    #10
                    Re: Dell 1703fps backlight problem

                    Here another website & cheap too
                    http://www.lcdrepair.us/1703fps-inverter.html

                    Comment

                      #11
                      Re: Dell 1703fps backlight problem

                      Wow, only $30? lol Just kidding. Thats way too much for a board that will repair a monitor that I bought for $20. I just went ahead and scrapped that monitor for a good pair of test CCFL's. Oh and other parts too.
                      The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

                      Comment

                        #12
                        Re: Dell 1703fps backlight problem

                        I sorry to hear that, last time I had to buy ist & only one website sale cheap. You can save the Lien Chang inverter board (LI-2070) for future use, because only one hightvolt transformer go bad (they had 2 hightvolt transformer) you can use good hightvolt transformer to replace another board on Dell 1703fps.

                        Comment

                          #13
                          Re: Dell 1703fps backlight problem

                          Or you can find inverter transformer on ebay, to replace bad one

                          Comment

                            #14
                            Re: Dell 1703fps backlight problem

                            I understand the same Inverter is also used in the following units,so perhaps some of them may yield you a spare transaformrt,if you can find a 'scrapper' monitor.
                            Compaq

                            TFT1701

                            17" TFT Panel


                            Dell

                            1703FPS

                            17" LCD Monitor


                            Dell

                            1703FP

                            17" LCD Monitor


                            Dell

                            1702FP

                            17" LCD Monitor


                            Dell

                            1701FP

                            17" LCD Monitor


                            Dell

                            1900FP

                            19" LCD Monitor


                            Dell

                            E171FP

                            17" LCD Monitor


                            IBM

                            6657-HG2

                            17" LCD Monitor


                            Samsung

                            SyncMaster 171P

                            17" LCD Monitor


                            Samsung

                            SyncMaster 171B

                            17" LCD Monitor


                            Samsung

                            SyncMaster 181T

                            18.1" LCD Monitor


                            Samsung

                            LTM170E04-L01

                            17" TFT Panel


                            Samsung

                            SyncMaster 192MP

                            19" LCD Monitor

                            Comment

                              #15
                              Re: Dell 1703fps backlight problem

                              have a same dell model and same problem.

                              Comment

                                #16
                                Re: Dell 1703fps backlight problem

                                Had this problem to but took an inverter transformer off a dell 172
                                difference being that these are thro hole and the 1703 uses surface mount
                                but trimmed right they do fit but a deft bit of soldering required unless you are lucky enough to have a hot air station
                                not the prettiest of jobs but works the only real greif is removing the black glue from the transformer (hard as concrete)

                                Comment

                                  #17
                                  Re: Dell 1703fps backlight problem

                                  I have two 1703FPs, 2 secs to black symptom, both of them have Li-2070, with a burned transformer on each, took out a SIC1803 inverter from a 1702FP, and did fix the problem.

                                  Those transformers have some tough plastic glue really difficult to disolder.
                                  Attached Files

                                  Comment

                                    #18
                                    Re: Dell 1703fps backlight problem

                                    Dude, very nice pics. Great job. That will indeed help people. As for myself, I now hate Dell monitors more than Samsung.
                                    The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

                                    Comment

                                      #19
                                      Re: Dell 1703fps backlight problem

                                      Strange that the transformer that has burnt out on the firt pic is the exact same one that i had to change be interesting to hear from others if the transformer is the one that has gone on theirs not that it probably makes a lot of difference but its the one closest to the psu board

                                      Comment

                                        #20
                                        Re: Dell 1703fps backlight problem

                                        i have the same monitor and same problem but don't know nothing about fixing eletronics where could i take it or send to get fixed thanks ron

                                        Comment

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