LG 42CS570 TV turns off and on and off and on and...

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  • JT2
    New Member
    • Mar 2022
    • 4
    • USA

    #1

    LG 42CS570 TV turns off and on and off and on and...

    Hi,
    I have an LG 42CS570, LCD TV.

    Does this problem sound familiar to anyone?

    When the TV is on and is not getting any signal, everything seems fine. Light is on. Controls work. Screensaver does its thing. I can turn it on and off as desired. There's absolutely no problem with the image.

    When the TV is getting a signal, it turns itself off and on and off and on and off and on and off.... I have to unplug it to make it stop. (It never spontaneously turns itself on out of the blue.)

    This originally started as an occasional problem with an Apple TV plugged into it and it's gotten progressively worse over the last year. It would turn off and then on, and a little while later, it would turn off and then on, and so on. It would happen in the same place in the program if I started it over, so I thought it might be a buffering problem. This is not a smart TV, so the menu options that I found online for fixing buffering problems don't exist.

    The problem became more frequent. Then the cycle became more immediate, so it no longer worked for a while between off-on's. Once it started it was just off-on-off-on-etc.

    Then it started doing it with the blu-ray player, too. That's how I know it's not the Apple TV.

    Then the problem started almost immediately upon turning on any input, so it doesn't work at all for any length of time while there's an input. (It's still totally fine on its own.)

    I tried leaving it unplugged overnight with no effect. I tried leaving it unplugged for a couple months, and it was ok for maybe half an hour.

    I tried putting new batteries in the remote. I tried taking the batteries out of the remote.

    I tried all the hints about turning off the TV's timers, energy savings, and simplink (HDMI-CEC) settings. I reset every setting.

    I tried every combination I could think of with different inputs, swapping HDMI ports, swapping cables.

    I tried it plugged into the wall, in different outlets, and plugged into the power strip.

    LG said to do a hard reset and gave me instructions. Unplug for a while, hold the power button down. This worked for a couple of days, and now it's back to being entirely non-functional whenever there's an input. That worked once.

    Hard reset no longer has any effect.

    At that point I called my brother to look at it (he fixes computers). He didn't see anything obviously wrong on any of the boards, but said the power supply was making a noise. He said he checked the wires and connections, too.

    He thinks the power supply is going bad and it can't handle the extra draw when the control board is trying to do more than the minimum of being on and displaying menus. So the power cuts out or drops momentarily, or maybe the power it gives isn't enough, and the control board says "oh! I lost power, I'll turn off...but here it is again, I'll turn on..."

    The light up power button on the front is always either blue-on or red-off, so it's not like a powerout. It's like turning off on purpose then turning on on purpose, and so on.

    My brother said I should replace the power supply first. Then if that doesn't solve the problem, I should replace the control board.

    So. Have any of you seen a TV do this before? Does it sound like the power supply? It's only the initial resemblance to buffering that makes me wonder. But perhaps a power issue was making it do that?

    Many thanks.
  • Diah
    Badcaps Legend
    • Feb 2013
    • 6343
    • Germany

    #2
    Re: LG 42CS570 TV turns off and on and off and on and...

    if the PCB cant handle pull up currents with full operation and this is not the case as i think... you can bring the lamp light down and see if it remain long on..

    but my first thought went to software problem.. thought long time of working years age of ithe firmware to handle apple TV or any other new platform devices.. so i suggest to make hard reset by in_stop command or by inter service menu initial the eeprom chip , then after the hard reset turn off function of CEC & Auto Off/Auto Sleep .

    Comment

    • nomoresonys
      Badcaps Legend
      • Jan 2013
      • 12076
      • U.S.

      #3
      Re: LG 42CS570 TV turns off and on and off and on and...

      maybe also check the solder joints on powerboard, just to be sure they are all good, can google images of bad joints if needed.

      Comment

      • JT2
        New Member
        • Mar 2022
        • 4
        • USA

        #4
        Re: LG 42CS570 TV turns off and on and off and on and...

        Diah:

        So you think it may stay on longer before the problem starts if I turn the power setting down all the way? I can try that.

        The sleep and CEC settings are both off.

        The Apple TV is the same vintage as the TV. Perhaps I can reset that to factory settings, though I think it might auto update right back to where it is. I'll take a look.

        Comment

        • JT2
          New Member
          • Mar 2022
          • 4
          • USA

          #5
          Re: LG 42CS570 TV turns off and on and off and on and...

          nomoresonys:

          My brother said he took the boards off and checked both sides and didn't see anything obviously damaged.

          Comment

          • dskall
            Badcaps Legend
            • Oct 2016
            • 2905
            • usa

            #6
            Re: LG 42CS570 TV turns off and on and off and on and...

            Is this just with hdmi? How about other inputs or over the air stations?.
            I assume no responsibility for any stupid suggestions I might post.

            Comment

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