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    3 seconds usage on Hyundai N91W

    Hello there,

    This is my first post, so please feel free to let me know where there are bits of information I haven't covered (or tell me that I haven't done enough work yet to be asking questions!)

    I have a Hyundai N91W monitor which will operate for only 3 or 4 seconds at a time. The monitor powers up, displays a perfectly good image, then immediately switches to standby. The monitor will happily start-up again, simply by pressing the front-panel power button, but almost always switches off after a few seconds. Once in a while, it is possible to get the monitor to stay switched on (normally after about 40 power cycles - I'm persistent if nothing else). It will then stay on without problems until it is powered down (this includes screen-restarts when changing resolutions, or the PC going to sleep). It is then once again a matter of perseverance to get the monitor into a usable state.

    From the information I've read on the internet I think that there are possibly bad capacitors on the power inverter. I've taken the monitor apart and had a good look at all the components. Using this guide I have identified 3 capacitors (2 x 680microfarad 25V and 1 x 470microfarad 25V) on the power inverter which don't appear to be charging.

    I should mention that there are no signs on any of the component boards (that I can see) of any burst/swollen caps, heat damage or anything else which looks out of place.

    The monitor is out of warranty, so I'm happy to play around with the innards, but I only have the most basic equipment (multimeter - without ability to test capacitance, screwdrivers, soldering iron, etc).

    Having looked on this forum, I can only see one thread that mentions the N91W in a related problem, and the poster says they replaced a large number of capacitors on their power inverter.

    I would like to ask the forum if, given the symptoms described, my current course of action seems appropriate, and if they would recommend any other steps I could take to try and track down the problem.

    Many thanks in advance.

    #2
    Re: 3 seconds usage on Hyundai N91W

    What brands of caps are currently in the monitor? Some (Sam Young) are 'replace on sight', some (Capxon, Elite) are notorious for failing, some (Panasonic, Nichicon, others) are noted for reliability. If your monitor has known crap brands the best approach is to replace the full set of electrolytic caps. If you are in the US and order from Digikey it will cost about $10.00

    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


      #3
      Re: 3 seconds usage on Hyundai N91W

      is it pink/reddish on cold start?
      its caps or in the case of pink bad lamps.

      Comment


        #4
        Re: 3 seconds usage on Hyundai N91W

        Originally posted by PlainBill View Post
        What brands of caps are currently in the monitor? Some (Sam Young) are 'replace on sight', some (Capxon, Elite) are notorious for failing, some (Panasonic, Nichicon, others) are noted for reliability. If your monitor has known crap brands the best approach is to replace the full set of electrolytic caps. If you are in the US and order from Digikey it will cost about $10.00

        PlainBill
        Thanks for the reply PlainBill.

        The caps seem to be "Xunda". I'll include an image here, and just for reference I've indicated the three that I suspect are faulty (though they don't look any different from the rest).
        Attached Files

        Comment


          #5
          Re: 3 seconds usage on Hyundai N91W

          Originally posted by kc8adu View Post
          is it pink/reddish on cold start?
          its caps or in the case of pink bad lamps.
          Thanks for the reply.

          I used to have the fault you're referencing here, but a trip back to Hyundai whilst under warranty fixed that, thank goodness.

          The problem is very simple, really, in that everything on the monitor works absolutely fine, but the monitor won't stay on for more than a few seconds. Every once in a while, it will stay on, but I can't work out why this might be.

          Comment


            #6
            Re: 3 seconds usage on Hyundai N91W

            replace all xunda.pure crap.

            Comment


              #7
              Re: 3 seconds usage on Hyundai N91W

              Originally posted by maverickprowls View Post
              Once in a while, it is possible to get the monitor to stay switched on (normally after about 40 power cycles - I'm persistent if nothing else). It will then stay on without problems until it is powered down (this includes screen-restarts when changing resolutions, or the PC going to sleep).
              What you describe sounds like capacitors with high ESR (ohms). When the caps get warm, the ESR drops which allows the lcd to operate properly. When the caps are "cold", they have high ESR.

              There are a couple of ways you can check for high ESR.

              1) The most obvious is to use an ESR meter. These meters are designed to measure ESR, but unfortunately cost between $65 and $300. For a one time lcd fix, it is not economical to buy one.

              2) Use a hair dryer and carefully warm up the capacitors only and see if the lcd powers up and stay on.

              As others have mentioned, you want to use high quality low ESR replacements. A list can be found at

              https://www.badcaps.net/forum/showthread.php?t=2280

              Members here advise replacing all the electrolytic capacitors except the largest one which rarely, but not never, fails.

              BEFORE ordering the caps, you might also want to check the inverter transformer secondaries to make sure they are okay. Details can be found at posts 13 and 14 at

              https://www.badcaps.net/forum/showthread.php?t=10419
              Last edited by retiredcaps; 03-06-2011, 02:30 PM.
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                #8
                Re: 3 seconds usage on Hyundai N91W

                Xunda,were used in a lot of Proview Monitors, and failed on a regular basis.Although your photo does not show the whole board from the top,I see that there are 2 of those caps near the Inverter transformers,and they may well be the cause,HOWEVER change them all as already advised.

                Comment


                  #9
                  Re: 3 seconds usage on Hyundai N91W

                  Xunda = replace on sight. all of them.
                  my mom's old LCD (17" Medion) had them. bulging after about 8months.. total crap..

                  Comment


                    #10
                    Re: 3 seconds usage on Hyundai N91W

                    Originally posted by Rtech View Post
                    Xunda,were used in a lot of Proview Monitors, and failed on a regular basis.Although your photo does not show the whole board from the top,I see that there are 2 of those caps near the Inverter transformers,and they may well be the cause,HOWEVER change them all as already advised.
                    Thanks for the advice!

                    The inverter board is marked as Proview, as are several of the other boards, actually. I have some Nichicon caps on order, so hopefully they'll do the trick.

                    I will update with my progress once I've replaced all the Xunda caps.

                    Thanks to everyone who's sent advice.

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