Samsung LE26S81B randomly reboots

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  • Dannyx
    CertifiedAxhole
    • Aug 2016
    • 3912
    • Romania

    #1

    Samsung LE26S81B randomly reboots

    Good day folks. I thought I should ask for some tips on this TV which keeps turning off and restarting at random intervals. Browsing the internet didn't prove very helpful because apparently this is a strange model, unheard of outside Europe, so all I get are some random russian websites which don't actually provide any troubleshooting, so I thought perhaps someone who had this issue on a different model but with similar boards can provide their 2 cents.

    I know the issue can be very broad to diagnose, so let me narrow it down: I've replaced all "important" caps on the BN44-00191A PSU, both on the primary and the secondary, with the exception of the ones for the inverter, but the issue is still there so I doubt it's a PSU issue at this point. I get the correct voltages where they should be. Have a look at this motherboard, it's a BN41-00878a which I believe is used in other sets as well. CPU failure ? Bad caps on the main board ? The TV is almost 9 years old according to the guy and it's kept on almost continuously because it's used with a set-top box which they just turn off while and leave the TV on to turn off on its own when it's left without a signal for too long, so you can imagine it's had a tough life if it runs, say, 8 out of 10 hours every day....
    EDIT: it seems to be rebooting more and more often the longer I let it run and the hotter it gets....definitely something failing in there....
    Attached Files
    Last edited by Dannyx; 08-22-2017, 02:48 AM. Reason: Added Details
    Wattevah...
  • attainteddragon
    Badcaps Veteran
    • Apr 2013
    • 764
    • australia

    #2
    Re: Samsung LE26S81B randomly reboots

    is ps/on dropping out?

    does stby remain stable?

    will it stay on if you disconnect the button board?
    WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?

    Comment

    • Dannyx
      CertifiedAxhole
      • Aug 2016
      • 3912
      • Romania

      #3
      Re: Samsung LE26S81B randomly reboots

      I'm fairly sure it's not a button issue because the TV also comes back on. If it were a faulty button causing it to turn on, it would most likely remain off or at the very most turn back on and then off immediately (assuming the power key remained stuck).

      Haven't been able to measure the PS_ON signal since it happens at complete random and you have no control over it....to prove my point, right now it's been running for like 2 hours straight and it's been OK :|

      Another thing I noticed, though this might be pure coincidence is that it seems to reboot when there's a HDMI cable plugged in: I left it in service mode with nothing plugged in (just so it wouldn't shut down due to no signal) and it worked perfectly for 1 hour. I turned it off to exit service mode, plugged the HDMI back in and it's been running fine like that for about 20 minutes now. Things are also starting to become rather hot in the back (sounds wrong ), so perhaps there's a part that fails when it's cold and works fine when heats up. Caps usually do this, but with so many of them (solid state ones no less) it's impossible to guess which or IF one of them is indeed on its way out, that's why I was curious to see if somebody else fixed a similar board and is able to tell me "replace THIS and it should work".

      Off topic: I once fixed a Sammy which wouldn't come on at all and had that intermediary LVDS board between the main board and T-con and looking on the internet, there's a small 1uF cap on the edge of that board which had gone bad and everybody talked about replacing it and sure enough, it fired right up....hoping to have THAT sort of luck here as well
      Wattevah...

      Comment

      • attainteddragon
        Badcaps Veteran
        • Apr 2013
        • 764
        • australia

        #4
        Re: Samsung LE26S81B randomly reboots

        i am waiting for the day that i can say that i have x of a problem and have someone say, or find a search on, replace this and your all good!

        one day.

        i take it that pfc voltage is good and stable too.
        WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?

        Comment

        • Dannyx
          CertifiedAxhole
          • Aug 2016
          • 3912
          • Romania

          #5
          Re: Samsung LE26S81B randomly reboots

          Originally posted by attainteddragon
          i am waiting for the day that i can say that i have x of a problem and have someone say, or find a search on, replace this and your all good!
          Well it DID happen to me on a few occasions thanks to our wonderful guys here
          Yes, PFC is up at around 387v...a bit low for my taste, but does the job.
          Wattevah...

          Comment

          • Dannyx
            CertifiedAxhole
            • Aug 2016
            • 3912
            • Romania

            #6
            Re: Samsung LE26S81B randomly reboots

            Nearing the 2h mark now and the TV is STILL not complaining...going strong, although it's on HDMI2 this time, whereas the first time it was on 1. I know the thought of the HDMI interface causing this is just silly, but electronics can be tricky-dicky
            Wattevah...

            Comment

            • dskall
              Badcaps Legend
              • Oct 2016
              • 2905
              • usa

              #7
              Re: Samsung LE26S81B randomly reboots

              Try some heat to speed things up
              I assume no responsibility for any stupid suggestions I might post.

              Comment

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