HP W1907 powers off cffl after 3 seconds

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  • ndoggfromhell
    Member
    • May 2010
    • 24
    #1

    HP W1907 powers off cffl after 3 seconds

    I've got an HP W1907. It would power on and display an image fine. Shows the resolution and input information, then suddenly nothing. I took the back off and found some su scon caps which i've read our notoriously bad. I ordered replacements from Mouser (3 caps total) and replaced them on the board. One was a big 100uF 450V (replaced with Nichicon), another was a 1000uF 25V replaced with a panasonic, and lastly was a 1000uF 10V replaced with a panasonic. There are other capacitors on the board SAMXON branded. when i put the monitor back together, it would power up for a minute but then turn off again (power button still lights up). If i left it cool down, it would work again for another minute shot... but they go out. Now, i've taken it apart and without being in the case it powers off again after just a couple of seconds. i was hoping to use a laser temp meter to findout the part overheating... but now it won't stay on long enough.

    Suggestions?
    Tags: None
    • Dgtech
      E. Technician
      • Apr 2009
      • 1462
      • Steeler
      #2
      Re: HP W1907 powers off cffl after 3 seconds

      You may have a bad lamp (CCFL). Some of the more experienced techs may know a good way to test this theory. I'm somewhat new on LCD's but I have had an IBM LCD with that symptom. I took it all the way appart to get the lamps out and once out and one out of the four was visually bad. The only problem with this is, most units I have seen so far are almost shot by time you get far enough to get to the lamps not to mention it may be hard to get the exact replacements.
      The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

        Comment

        • ndoggfromhell
          Member
          • May 2010
          • 24
          #3
          Re: HP W1907 powers off cffl after 3 seconds

          Ok, checked the order of the CFFL's and I think they went blue pink pink blue, so i switched them to that way and it was working again for over an hour. Then my genius friend turned it off and on real quick and now it's not working right again. Only powers the backlight for a couple seconds then turns off. Speakers are still playing and the image is still moving... just no backlight. Ideas? Something obviously got hot and didn't fail until there was a power interuption.

            Comment

            • ndoggfromhell
              Member
              • May 2010
              • 24
              #4
              Re: HP W1907 powers off cffl after 3 seconds

              I let it sit about 10 minutes, turned it back on and it's working now. Gonna leave it on the rest of the day and see if it turns off by itself.

                Comment

                • Dgtech
                  E. Technician
                  • Apr 2009
                  • 1462
                  • Steeler
                  #5
                  Re: HP W1907 powers off cffl after 3 seconds

                  I think what is happening is either one of these scenerio's:

                  1. One lamp may be goind bad and you just switched it to a circuit that is more tolerant to the lamp's changed characteristics, OR

                  2. The characteristics of the inverter circuit has changed not sensing the lamps correctly and when you switched it, the lamp was a better match for the circuit.

                  Like I said, I'm not the best at this so ... It's just a guess.
                  Others have better tricks and methods to help you out.
                  The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

                    Comment

                    • retiredcaps
                      Badcaps Legend
                      • Apr 2010
                      • 9271
                      #6
                      Re: HP W1907 powers off cffl after 3 seconds

                      Check out this video. It talks about a LG monitor overheating due to bad solder connection.

                      http://www.youtube.com/watch?v=rePrm...eature=related

                      Originally posted by ndoggfromhell
                      i was hoping to use a laser temp meter to findout the part overheating... but now it won't stay on long enough.

                      Suggestions?
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                        Comment

                        • ndoggfromhell
                          Member
                          • May 2010
                          • 24
                          #7
                          Re: HP W1907 powers off cffl after 3 seconds

                          Originally posted by retiredcaps
                          Check out this video. It talks about a LG monitor overheating due to bad solder connection.

                          http://www.youtube.com/watch?v=rePrm...eature=related
                          Found no discoloration on the board. I wonder if baking the power board would work for the solder problem? I did it to a Nvidia 8800 and it brought it back to life.

                            Comment

                            • retiredcaps
                              Badcaps Legend
                              • Apr 2010
                              • 9271
                              #8
                              Re: HP W1907 powers off cffl after 3 seconds

                              I would not recommend baking the entire board like some of those youtube videos. Take a magnifying glass or jewelers loupe to look at your solder joints.

                              Originally posted by ndoggfromhell
                              Found no discoloration on the board. I wonder if baking the power board would work for the solder problem? I did it to a Nvidia 8800 and it brought it back to life.
                              --- 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.

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                                Comment

                                • ndoggfromhell
                                  Member
                                  • May 2010
                                  • 24
                                  #9
                                  Re: HP W1907 powers off cffl after 3 seconds

                                  I'm sure I didn't solder something right when I was replacing capacitors. I'll take the board out and redo it tomorrow. I'll keep the oven out of the mix. Thanks for the advice.

                                  Originally posted by retiredcaps
                                  I would not recommend baking the entire board like some of those youtube videos. Take a magnifying glass or jewelers loupe to look at your solder joints.

                                    Comment

                                    • retiredcaps
                                      Badcaps Legend
                                      • Apr 2010
                                      • 9271
                                      #10
                                      Re: HP W1907 powers off cffl after 3 seconds

                                      When I first started soldering, I'm sure it was really bad. Now that I have had more practice, it is getting better.

                                      I found this video helpful.

                                      http://www.youtube.com/watch?v=I_NU2ruzyc4

                                      PS. Having a clean and hot tip helps a lot.

                                      Originally posted by ndoggfromhell
                                      I'm sure I didn't solder something right when I was replacing capacitors. I'll take the board out and redo it tomorrow. I'll keep the oven out of the mix. Thanks for the advice.
                                      --- 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.

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