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    Hanns-G HG281D 'column shimmer' and start up problems

    Heya!

    Finally getting around to trying to fix this monitor that's having some issues. I had taken it apart initially after finding this forum last year. There were no visibly bad capacitors and to be honest I wasn't sure about checking the ESR because I wasn't too keen on the idea of working near an exposed power supply and didn't feel confident with that.

    I feel it important to note that this monitor was also sent in to Hanns-G for repair after a loud 'pop' it made and wouldn't come on. When it came back there was no documentation as to what they did but the controls were different and I actually had an option to choose from fit/full aspect ratio. The logic board I believe was replaced as it listed some revision 4 something on it and the HDMI port was tighter and easier to keep the cable plugged in.

    The screen worked fine for about a year and a half afterward.

    Here's what happens on the monitor now:

    Upon powering on, it would come on. Then about 5-10 seconds later or so (the time varies) the screen would go off, then come on, off again a second later, back on for a second, off for about 10 seconds, then on again. The pattern and interval of this is random and lasts anywhere between 30 seconds to around a minute at worst. If it helps there is no sort of 'clicking' sound with it that at one point happened with this screen when it would change resolution for example.

    After it goes through that fit it will stay on just fine and will do it again upon a cold start. The picture is as expected with this monitor with the exception of one detail. In seemingly random columns there is this 'shimmer' effect like random blocks of pixels along that column change color tones to something slightly brighter than the color in that area.

    It's hard to explain but it's hard to see overall but it catches your eye and is more apparent with certain colors. So it's like it's adapting to color but just those pixels go brighter or darker or something. I've attached a picture I snagged that shows it. It's a bit of large image which was needed so you can see what I'm talking about. Please pardon the spelling error in the pic. :P

    I've tried this on different computers, different video cards in the same systems with different HDMI cables that are known to work fine. So right now I'm at a loss. Any help would be appreciated.
    Attached Files
    Last edited by LexGoyle; 06-15-2013, 02:45 PM. Reason: fixing up the post to include details about the attachment.

    #2
    Re: Hanns-G HG281D 'column shimmer' and start up problems

    From the symptoms you describe I would suggest it is bad capacitors on the PSU causing this. Remember bad capacitors might not show any visual signs (indeed ones causing intermittent problems like this are more likely to be still working but on their way out). Your best bet is to test the voltages coming from each pin outputting from the PSU when it is on (be careful!) and reporting them here for the experts to see. But the black probe on a grounded screw and the red probe on each output pin and note the voltage. Take special note of any pins producing fluctuations in voltage. The artifacts could be from a voltage ripple to the a/v board and/or tcon.
    Last edited by leapius; 06-15-2013, 03:33 PM.

    Comment


      #3
      Re: Hanns-G HG281D 'column shimmer' and start up problems

      Originally posted by leapius View Post
      From the symptoms you describe I would suggest it is bad capacitors on the PSU causing this. Remember bad capacitors might not show any visual signs
      Correct, in fact in this monitor the small capacitors in the power supply tend to dry out with no signs of bulging.

      Hey Lex. If your power supply looks like this you need to replace the 3 caps circled in red on my attached photo.

      Then on the main board replace the 2 caps budm suggests in this photo.
      http://s807.beta.photobucket.com/use...62664929957295

      That should take care of both problems you are having. Fixed 4 of these. The problem was always the same 5 capacitors. 3 on the power supply and 2 on the main board.
      Attached Files

      Comment


        #4
        Re: Hanns-G HG281D 'column shimmer' and start up problems

        Originally posted by Lumberjack777 View Post
        Correct, in fact in this monitor the small capacitors in the power supply tend to dry out with no signs of bulging.

        Hey Lex. If your power supply looks like this you need to replace the 3 caps circled in red on my attached photo.

        Then on the main board replace the 2 caps budm suggests in this photo.
        http://s807.beta.photobucket.com/use...62664929957295

        That should take care of both problems you are having. Fixed 4 of these. The problem was always the same 5 capacitors. 3 on the power supply and 2 on the main board.


        I would also change caps in red under heatsink
        Attached Files

        Comment


          #5
          Re: Hanns-G HG281D 'column shimmer' and start up problems

          Originally posted by LexGoyle View Post
          Finally getting around to trying to fix this monitor that's having some issues. I had taken it apart initially after finding this forum last year. There were no visibly bad capacitors and to be honest I wasn't sure about checking the ESR because I wasn't too keen on the idea of working near an exposed power supply and didn't feel confident with that.

          I feel it important to note that this monitor was also sent in to Hanns-G for repair after a loud 'pop' it made and wouldn't come on. When it came back there was no documentation as to what they did but the controls were different and I actually had an option to choose from fit/full aspect ratio. The logic board I believe was replaced as it listed some revision 4 something on it and the HDMI port was tighter and easier to keep the cable plugged in.

          The screen worked fine for about a year and a half afterward.

          Here's what happens on the monitor now:

          Upon powering on, it would come on. Then about 5-10 seconds later or so (the time varies) the screen would go off, then come on, off again a second later, back on for a second, off for about 10 seconds, then on again. The pattern and interval of this is random and lasts anywhere between 30 seconds to around a minute at worst. If it helps there is no sort of 'clicking' sound with it that at one point happened with this screen when it would change resolution for example.
          Possible badcaps somewhere. Also check the inverter transformer section, especially the transformer...

          Originally posted by LexGoyle View Post
          After it goes through that fit it will stay on just fine and will do it again upon a cold start. The picture is as expected with this monitor with the exception of one detail. In seemingly random columns there is this 'shimmer' effect like random blocks of pixels along that column change color tones to something slightly brighter than the color in that area.

          It's hard to explain but it's hard to see overall but it catches your eye and is more apparent with certain colors. So it's like it's adapting to color but just those pixels go brighter or darker or something. I've attached a picture I snagged that shows it. It's a bit of large image which was needed so you can see what I'm talking about. Please pardon the spelling error in the pic. :P

          I've tried this on different computers, different video cards in the same systems with different HDMI cables that are known to work fine. So right now I'm at a loss. Any help would be appreciated.
          Seen this before. Besides possible badcaps, the most obvious source of this problem is the LVDS section. Try cleaning the FFC/FPC connectors (on both Tcon and Dscaler board side) and contacts on the LVDS cables first.

          Example of a severe dirty LVDS connection (see attachment). On areas with lots of identical colors, the effect is not apparent. The shimmers and noise becomes more apparent as they appear randomly and gets worse on lines/rows with more picture details (e.g. more color changes per pixel, fine lines, dithering patterns, etc). That's an old ancient Acer AL1717B, by the way...
          Attached Files
          Last edited by lexwalker; 06-15-2013, 10:56 PM.

          Comment


            #6
            Re: Hanns-G HG281D 'column shimmer' and start up problems

            The two caps on the main board when they are bad will get bad pictures with noise and lines running on the screen, when put on native resolution it will black out, turns itself off, but it will look normal and will stay on if you put it in lowest resolution. I would replace those two caps on the main board first.
            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


              #7
              Re: Hanns-G HG281D 'column shimmer' and start up problems

              Thanks for all the replies. My power supply appears to be a different model than the one pictured. I'll try doing a voltage test and get some caps ready to be ordered. I'll post an update and let you all know how it turns out.

              Comment


                #8
                Re: Hanns-G HG281D 'column shimmer' and start up problems

                Originally posted by budm View Post
                The two caps on the main board when they are bad will get bad pictures with noise and lines running on the screen, when put on native resolution it will black out, turns itself off, but it will look normal and will stay on if you put it in lowest resolution. I would replace those two caps on the main board first.
                Thanks again for the help everyone! I've replaced the two capacitors on the logic board as Budm suggested and the problem is gone. So far it's been running for 3 hours and still no 'shimmer' or troubles with the start up like before.

                On a side note desoldering.... pain in the butt. :P The wick I used I guess was too narrow or something because it didn't work out as easily as it showed in the videos online. Ah well. Saved the monitor for basically a few bucks and gained some experience.

                Comment


                  #9
                  Re: Hanns-G HG281D 'column shimmer' and start up problems

                  Glad to hear the problem is fixed, you may want to look into a set of caps for the power supply board next.
                  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

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