HP w1907 Powers On Then Doesn't Detect Signal.

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  • zylcho
    Padawan Learner
    • May 2010
    • 52
    • USA

    #1

    HP w1907 Powers On Then Doesn't Detect Signal.

    Powers up fine, shows bios and refreshes to desktop for about 10 seconds then flashes "Input signal not detected" and shuts off. This happens in both VGA and DVI.

    On dissection I see nothing visually that would be a possible suspect. Some minor oxidation of a few joints.

    Video board "appears" to ok.

    Any assistance in this would be greatly appreciated. Thank you in advance.
    Attached Files
  • delaware74b
    Badcaps Veteran
    • Apr 2009
    • 628
    • USA

    #2
    Re: HP w1907 Powers On Then Doesn't Detect Signal.

    What brand and series caps on the power supply board? That board has lead-free solder and usually doesn't look good when compared to the old 60/40 lead/tin solder. I'd reheat those connections that don't look good and apply some 60/40 solder (if you're in the US).
    Stupidity should be a crime, especially for drivers. I have NO patience for them.

    Comment

    • zylcho
      Padawan Learner
      • May 2010
      • 52
      • USA

      #3
      Re: HP w1907 Powers On Then Doesn't Detect Signal.

      Couple different brand of caps, suscon, samxon, teapo and a symbol that looks like Leton. Sorry not quite following you as far as series?

      Can you mix the 2 solders? Or do I have to remove all existing? As I have plenty of 60/40.

      Yes I am in the US. Thank you for the assist.

      Comment

      • retiredcaps
        Badcaps Legend
        • Apr 2010
        • 9271

        #4
        Re: HP w1907 Powers On Then Doesn't Detect Signal.

        One cap series might say HM(M). It is a two or three letter code.

        The 0405 (4 digit number) indicates year (2004) and the week (5th week) of when the cap was made.

        I think that is Lelon.

        Re the 10 seconds, try turning down the brightness and contrast down to say 25/100 and see if you get more than 10 seconds of operation.

        Originally posted by zylcho
        Couple different brand of caps, suscon, samxon, teapo and a symbol that looks like Leton. Sorry not quite following you as far as series?

        Can you mix the 2 solders? Or do I have to remove all existing? As I have plenty of 60/40.

        Yes I am in the US. Thank you for the assist.
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        Comment

        • zylcho
          Padawan Learner
          • May 2010
          • 52
          • USA

          #5
          Re: HP w1907 Powers On Then Doesn't Detect Signal.

          OK powered on with Marlboro and plastic insulators to run while dissembled. The damn thing started working!

          Of course passed all brightness tests as it is now working.

          Been over 10 hours without power save and still good to go....

          Did I wiggle something to cause this to function?
          Attached Files

          Comment

          • zylcho
            Padawan Learner
            • May 2010
            • 52
            • USA

            #6
            Re: HP w1907 Powers On Then Doesn't Detect Signal.

            Crap! Reassembled and back to original problem.... What I did notice now is that the blue power indicator (led) is now turning yellow (power save mode?)when the screen is not on.

            So is not displaying "Signal not detected" anymore.

            Screen turning off after 5 seconds and instantly turning power light yellow.

            Could this be a problem with the video board?
            Last edited by zylcho; 05-30-2010, 12:21 PM.

            Comment

            • retiredcaps
              Badcaps Legend
              • Apr 2010
              • 9271

              #7
              Re: HP w1907 Powers On Then Doesn't Detect Signal.

              Try the configuration where you had it working for 10 hours again and see if it works. If it works, maybe check the cable connectors?

              Also try gently rocking the caps back and forth to see if you have a loose solder joint. I found one cap on a Benq PCB board that looked good from the backside, but it was obviously loose when I rocked it back and forth on the frontside.

              Originally posted by zylcho
              Crap! Reassembled and back to original problem.... ?
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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

              • zylcho
                Padawan Learner
                • May 2010
                • 52
                • USA

                #8
                Re: HP w1907 Powers On Then Doesn't Detect Signal.

                Well it was dissembled when it worked for 10 hours, took apart again and same crap, no work.

                I have stuck, measured, wiggled and inspected every "movable" part on both boards.
                Will try some heat on the joints and see what that gets. Thanks for the reply.

                Comment

                • delaware74b
                  Badcaps Veteran
                  • Apr 2009
                  • 628
                  • USA

                  #9
                  Re: HP w1907 Powers On Then Doesn't Detect Signal.

                  zylcho, I try to remove as much of the lead-free solder as possible, but sometimes I have to add some 60/40 to the existing solder connection before I can remove the old solder or component. I'm willing to bet you have a cracked solder connectionon that board. It also sounds like the backlight circuit could be shutting down due to overload condition in either the inverter or you have a backlight starting to fail.
                  Stupidity should be a crime, especially for drivers. I have NO patience for them.

                  Comment

                  • mathog
                    Badcaps Legend
                    • Mar 2010
                    • 2655

                    #10
                    Re: HP w1907 Powers On Then Doesn't Detect Signal.

                    Originally posted by zylcho
                    Powers up fine, shows bios and refreshes to desktop for about 10 seconds then flashes "Input signal not detected" and shuts off. This happens in both VGA and DVI.
                    I had a display where the VGA socket was slightly dirty inside. The DVI might have been too, don't know, didn't have a DVI cable to plug into it. Scraped out the inside of each VGA socket "tube" with a paper clip, which happened to be just the right size, and then a VGA cable was able to make a decent connection to the socket, and it saw signal. The display was still broken though in other ways. Apparently, the remaining failure had put it out of action originally, and then it sat around a long time with nothing plugged into the VGA port, so by the time I saw it VGA cables were not making an adequate electrical contact with the socket.

                    If you see the no signal symptom and there was no cable plugged into it when you first obtained the monitor suspect dirt in the video socket.

                    Comment

                    • zylcho
                      Padawan Learner
                      • May 2010
                      • 52
                      • USA

                      #11
                      Re: HP w1907 Powers On Then Doesn't Detect Signal.

                      Definitely not a dirty VGA socket. But thanks for the tip.

                      I took an iron to some of those oxidized joints and now monitor wont even attempt to power on. Not giving up just gets frustrating.

                      Thanks everyone for the assist. Will fiddle with later on.

                      Comment

                      • alexanna
                        Member
                        • Mar 2010
                        • 1346

                        #12
                        Re: HP w1907 Powers On Then Doesn't Detect Signal.

                        I have a very similar problem with several monitors. [ 2 sec off] I can not rembember the exact status of the power led, but running them on bench lcd out of case laying flat I could not get them to fail by wiggiling wires taping on screen they worked perfect. I have not run them for 10 hours, if they worked I put them back together,Then they would start their 2sec out problem. What I have found is poor or over heated wiring on the return side of the UPPER ccfls. Not sure why they work out of case laying flat other than added heat when they are assembled, an that heat rises.
                        Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

                        Comment

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