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HP LP2065 Buzzing noise / other issues

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    #1

    HP LP2065 Buzzing noise / other issues

    Hi everyone.

    I had opportunity to get one HP LP2065 for free from our company's IT department. I quickly took a look that monitor showed picture and took it home. After switching on monitor at home everything seemed to be ok...

    ...however monitor wasn't ok. After it had warmed up a buzzing noise started to strengthen. After fully warmed up that buzzing is annoying and cannot be normal behaviour. Picture is fine, no flashing or anything else. Power-up is instant.

    Then i took some time googling for possible solution and i found badcaps.net and issues with other monitor that had bad capacitor problem. Ok... i disassembled power-supply card out from the monitor and thought big caps would be the problem and replaced them first.

    https://www.dropbox.com/s/1adp624rr54itvj/IMG_1398.JPG
    https://www.dropbox.com/s/c6d2xpzdct2u4ip/IMG_1399.JPG

    That was the starting stage. However replacing those Samxon caps did nothing good, in fact monitor started to shut down after it had warmed up. Time to order all the remaining smaller caps.

    https://www.dropbox.com/s/welllpq180q1b65/IMG_1587.JPG
    https://www.dropbox.com/s/rmy1of30w7mnr6q/IMG_1588.JPG
    https://www.dropbox.com/s/o3vpigxfxppg73p/IMG_1589.JPG
    https://www.dropbox.com/s/9i9j3vghohimb6t/IMG_1590.JPG

    Today i changed all those smaller c(r?)apxion caps to rubycon ones...

    Powered up monitor and complete silence. Ahhh... Would that solve my problem? After a 15min i had answer. No! That buzzing noise is still there. Picture is fine as it was in the beginning...

    What's up next?

    I've read that sometimes that big yellow transformer between AC and DC sides of circuit board may fail. It also looks like it have had some heat. Protective coating seems to be melted sometime and is in some places a bit brownish. Could that be the problem source? All other components are looking good, however i haven't tested all components separately.

    Can someone help me finding that transformer or any information or specifications concerning it? Thank you all for your help in advance! All help is respected!
    Tags: None
    #2
    Re: HP LP2065 Buzzing noise / other issues

    I took my time trying to look for some information of that transformer but i got stuck again.

    However i tried to adjust brightness and contrast from OSD and when i turned brightness to 100% buzzing noise (it begins after ~10min) disappeared almost completely. Small "humming" is still audible, but that is not as annoying as the loud one. If i turn brightness from 100% to 97% (from OSD) buzzing comes back getting louder every step from 100 to 97.

    As i mentioned earlier, picture is fine. I found some information from OSD. Power on time is about 34700h and backlight time about 5870h. Are those numbers so big that i should try to look new ccfl lamps for example?

    Comment

      #3
      Re: HP LP2065 Buzzing noise / other issues

      Hi again...

      I uploaded pictures of circuit board. I also measured resistances of those inverter CCFL transformers. Here are the measurements from upper left to lower right:

      1: 8.89Mohm, 8.89Mohm, 0.89komh
      2: 8.89Mohm, 8.92Mohm, 0.892kohm
      3: 8.99Mohm, 9.01Mohm, 0.882kohm

      4: 0.874kohm, 9,01Mohm, 9,27Mohm
      5: 0.875kohm, 8.75Mohm, 8.85Mohm *
      6: 0.894kohm, 8.92Mohm, 8.92Mohm *

      Sometimes two transformers marked with * showed ~200-300kohm instead of 8...10Mohm. Small tap to circuit board changed readings. Are those broken? If so, where can i find spare parts? Google didn't help me with those SPI 8TP00011 transformers.
      Attached Files
      Last edited by ConD; 07-14-2012, 02:59 AM.

      Comment

        #4
        Re: HP LP2065 Buzzing noise / other issues

        Because the transformers are fitted differently,then the secondaries on Your 1,2 and 3 are 0.89K,0.892K,0.882K,whereas the secondaries on your 4,5 and 6 are 0.874K,0.875K and 0.894K...they all look fine,suspect they are not your problem.

        Comment

          #5
          Re: HP LP2065 Buzzing noise / other issues

          Thank you for your answer.

          Something wrong there are in those two transformers. I just made very simple microphone-headphones test with monitor interiors visible. When buzzing noise began, two of the inverter-side transformers were making much more noise than other four. After i gently tap those transformers with microphone, buzzing noise disappeared.

          Do i have to start hitting my monitor every time buzzing begins?

          The real problem is however, where can i get replacement transformers since i don't believe that those are repairable.

          Comment

            #6
            Re: HP LP2065 Buzzing noise / other issues

            Originally posted by ConD View Post
            The real problem is however, where can i get replacement transformers since i don't believe that those are repairable.
            The last digit is off, but it may not matter?

            http://www.lcdparts.net/TransformerD...ProductID=3355
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            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.

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            Comment

              #7
              Re: HP LP2065 Buzzing noise / other issues

              What you could try is give them a good soaking in Varnish,and seen if that stops them vibrating, if that is what they are doing .

              Comment

                #8
                Re: HP LP2065 Buzzing noise / other issues

                Originally posted by Rtech View Post
                What you could try is give them a good soaking in Varnish,and seen if that stops them vibrating, if that is what they are doing .
                I have to try that. Small, hardly audible buzzing is still there, but that loud one is still gone after 1 hours from that gentle tap with mic. Looks like it begins somehow after it reaches some critical temperature point.

                I have to ask more accurate dimensions to that 8TP00010 since it looks a bit smaller than my ...11 versions. Still 13$ isn't bad if it will fix that buzzing.

                Comment

                  #9
                  Re: HP LP2065 Buzzing noise / other issues

                  Hi - You could also try de soldering and putting a small packing piece under
                  then resolder so the transformer is under some tension.
                  Size wise this site has a picture of a ...10 against a rule.
                  http://tda2000.ru/catalog/passiw_tra...ACL-TSM/61122/

                  Click on the image to make it bigger
                  Last edited by selldoor; 07-14-2012, 03:39 PM.
                  Please upload pictures using attachment function when ask for help on the repair
                  http://www.badcaps.net/forum/showthread.php?t=39740

                  Comment

                    #10
                    Re: HP LP2065 Buzzing noise / other issues

                    May be the switching power supply is running at the wrong frequency, due the cap for frequency control is drifting in value after warm up.
                    Never stop learning
                    Basic LCD TV and Monitor troubleshooting guides.
                    http://www.badcaps.net/forum/showthr...956#post305956

                    Voltage Regulator (LDO) testing:
                    http://www.badcaps.net/forum/showthr...999#post300999

                    Inverter testing using old CFL:
                    http://www.badcaps.net/forum/showthr...er+testing+cfl

                    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                    http://s807.photobucket.com/user/budm/library/

                    TV Factory reset codes listing:
                    http://www.badcaps.net/forum/showthread.php?t=24809

                    Comment

                      #11
                      Re: HP LP2065 Buzzing noise / other issues

                      Originally posted by ConD View Post
                      I have to try that. Small, hardly audible buzzing is still there, but that loud one is still gone after 1 hours from that gentle tap with mic. Looks like it begins somehow after it reaches some critical temperature point.

                      I have to ask more accurate dimensions to that 8TP00010 since it looks a bit smaller than my ...11 versions. Still 13$ isn't bad if it will fix that buzzing.
                      Loose coils or a cracked core can make that sound. I'd also recommend the varnish soak.

                      Comment

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