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Sharp 70' LEDs Spike 260v at start up?

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    #1

    Sharp 70' LEDs Spike 260v at start up?

    Hi all. This is my second thread. Have a bunch of questions.

    I got my hands on a 70 inch Sharp Aquos LC70EQ10U. Not working when I found it.

    I replaced the power board (found in eBay) and the TV finally produced an image. Reset it had image and sound.. Went from 2 slow and 2 fast blinks as a fault code to 1 slow 1 fast fault. Lamps or inverters according to the manual. TV is one now, at this moment (looks great w/ ZERO dark spots on screen) but it powering up and producing an image is unpredictable. 3 out of 10 times.

    There are 3 leads to the LEDs. On start up with a DMM I was getting a spike up to 260v measured with DMM. TV would cycle up then shut itself down due to power spikes....?

    With LED tester (if I'm doing it right) tv off, plug discon and back probing into red, blue and black and its white counterpart,,, I get R = 196 Bl = 196 and B = 190... All 3 LED strips light up, I can see them in the back of the TV...

    Voltages on these leads when the TV is playing varies but they are usually around 160 to 170v

    I have a "new" main board on the way.

    I don't know what's going on or what I'm seeing.
    What causes the spikes and what part of the TV controls the amount of voltage provided to the LEDs and when.

    I kinda am hoping for a basic TV anatomy lesson.
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    #2
    Re: Sharp 70' LEDs Spike 260v at start up?

    The reason the voltage is high is that it sees an open circuit, so one or more led's are likely going open.

    Comment

      #3
      Re: Sharp 70' LEDs Spike 260v at start up?

      What is a "normal" voltage one would expect?

      Comment

        #4
        Re: Sharp 70' LEDs Spike 260v at start up?

        Originally posted by JayPoorJay View Post
        What is a "normal" voltage one would expect?
        Likely what you measured when the tv was working, around 170 v

        This is the V+LED supplied to all three strips, then the - return side of each strip is current controlled. This current is closely monitored and will shut down the controller if the current draw is out of spec.
        Also remember that the led tester only supplies about 10~30 ma of current. the leds draw a lot more under normal operating conditions and that's when they can fail.

        Comment

          #5
          Re: Sharp 70' LEDs Spike 260v at start up?

          Good Morning, RJ. Thank you.

          Super interesting, and I have a LOT to learn... X10

          So does that ONLY leave the LEDs, or can it it be the main board not monitoring what's going on correctly, or both? Where does that leave me?

          The prospect of removing a 70inch display to replace individual leds as my first go around with something like this freaks me out a bit, lol. But, I did rescue a early 2000s something jaguar that had gone under water! Yeah, I'm nutts like that.

          Are there suitable replacement LEDs that can be found and, is it just a matter of time before more fail considering age and the punishment they've dealt with, etc?

          Someone had suggested running/wiring a "table lamp" in series with the LED strips...? Is that a thing?

          What would you do here? When operating, the darn thing looks perfect!

          I have a used main board in the way.
          Is this board what monitors this? Could I be as lucky?

          At this point I'm into this for 100bucks. Willing to spend more. The "poor" in my user name IS saying something and a new 70inch tv, well, that's lots of pennies in the piggy bank. And, I like to rescue and repair.

          What now?
          Sorry, I'm all questions...

          Comment

            #6
            Re: Sharp 70' LEDs Spike 260v at start up?

            This is a edge lit set x2 strips i think, if you have the back of the tv there should be a white sticker on the metal chassis telling us what lcd is used in this set

            Comment

              #7
              Re: Sharp 70' LEDs Spike 260v at start up?

              Originally posted by vinceroger69 View Post
              This is a edge lit set x2 strips i think, if you have the back of the tv there should be a white sticker on the metal chassis telling us what lcd is used in this set
              Nice. Thank you. After work I'll have a look.
              Is replacing LEDs in my future, ya think?
              Couldn't possibly be the "main board"?

              Comment

                #8
                Re: Sharp 70' LEDs Spike 260v at start up?

                my guess leds failing thats all im seeing lately repair wise, i have never attempted a 70in screen bigest i have done is 46in so larger screen size more risk of damage.
                led strips i buy from ali express and replace all in one go.

                Comment

                  #9
                  Re: Sharp 70' LEDs Spike 260v at start up?

                  Ok, reread it, with those high spikes, must be a problem in the backlights as mentioned, borderline led/s.
                  Last edited by nomoresonys; 02-02-2022, 07:45 AM.

                  Comment

                    #10
                    Re: Sharp 70' LEDs Spike 260v at start up?

                    Looks like you gotta do the dirty and remove the panel/screen.

                    Comment

                      #11
                      Re: Sharp 70' LEDs Spike 260v at start up?

                      Daaaaaaaaaaamn!
                      I'm in over my head I think, but willing to take the dive...

                      I'll try the board first? Should I?
                      It'll be here today or tomorrow.

                      I'll be looking to y'all...!

                      Comment

                        #12
                        Re: Sharp 70' LEDs Spike 260v at start up?

                        Originally posted by JayPoorJay View Post
                        Daaaaaaaaaaamn!
                        I'm in over my head I think, but willing to take the dive...

                        I'll try the board first? Should I?
                        It'll be here today or tomorrow.

                        I'll be looking to y'all...!
                        no harm in trying your new board.

                        Comment

                          #13
                          Re: Sharp 70' LEDs Spike 260v at start up?

                          Sorry. Also, what I've read from posts and threads dated many years ago is the there were no replacement LED strips available for this particular SHARP product... Does that mean replacing LEDs one by one in the OEM strips or, a substitute with similar specs and requirements? Just wondering.

                          Comment

                            #14
                            Re: Sharp 70' LEDs Spike 260v at start up?

                            your set may have led strips in like this
                            https://www.ebay.com/itm/284481358447
                            i certainly would never buy a used set but gives you a idea of possible leds used but you have too get a exact match ie colour mah voltage etc etc

                            Comment

                              #15
                              Re: Sharp 70' LEDs Spike 260v at start up?

                              Got ya. Perfect... Thank you!

                              I'm looking at a hot plate...?
                              What say you?

                              Comment

                                #16
                                Re: Sharp 70' LEDs Spike 260v at start up?

                                So, chatting with Shop Jimmy...
                                They dont (and I don't think ever have) a replacement strip for this particular 70inch TV.

                                I'm thinking I might try, literally give it a shot, at soldering on individual LEDs... At least after I'll have spares.

                                First,,, the main board was delivered.
                                Will give her the ol college try after work.

                                Open to pointers? Should I attempt a reset right out of the gate?

                                Comment

                                  #17
                                  Re: Sharp 70' LEDs Spike 260v at start up?

                                  first time LED LCD came to the market, they design the Firmware to boot 90 to 100% power the LED backlight.. early they call it LED BL start test if they fail the firmware will give blinking Red at front.... but after years they found this is wrong and can kill the LEDs at startup. they change it to 60% and some brands just let individual LEDs at the middle of the screen lit on. so your coming MB will have same level spike.

                                  Comment

                                    #18
                                    Re: Sharp 70' LEDs Spike 260v at start up?

                                    Originally posted by Diah View Post
                                    first time LED LCD came to the market, they design the Firmware to boot 90 to 100% power the LED backlight.. early they call it LED BL start test if they fail the firmware will give blinking Red at front.... but after years they found this is wrong and can kill the LEDs at startup. they change it to 60% and some brands just let individual LEDs at the middle of the screen lit on. so your coming MB will have same level spike.
                                    Is there something that can be done about this?
                                    You mentioned (in my first thread about Power Board) putting a "table lamp in series" but I didn't /don't understand this and would really need some clear instructions. I'm willing to try anything before COMPLETELY opening this TV. Please tell me what to do.

                                    Comment

                                      #19
                                      Re: Sharp 70' LEDs Spike 260v at start up?

                                      show me what kind of filament table lamp you have and how many watt the bulb of it

                                      Comment

                                        #20
                                        Re: Sharp 70' LEDs Spike 260v at start up?

                                        Hey Man, Hi...

                                        It's a standard US table lamp,,, I can put whatever size and style bulb in it that you suggest. I'm in the USA,,, so it's 110/120V, around. Having a clear understanding of the wiring is what I mean. And an assurance that this is something that will actually work... Never heard of such a thing.

                                        What's the reason that putting a filament bulb in series works?
                                        How does it work?



                                        On another note - got the MB in the mail, installed it, and it APPEARS to be a dud... No matter how I tried to boot up the TV I was unable to get the screen,,, light or dark,,, to display anything that would allow me to reset the TV, see the menus, or start it up in the special K screen where the "Industry Init" option is displayed,,,, well, anyways. The power light on the front of the TV came on and stayed on nicely. Just NO kinda image what so ever. Replaced the OLD board and things went back to "normal". A normal broken tv, lol.

                                        Any suggestions, new main board initial setup? I'm all ears. Or, I'll return it tomorrow or Friday AM.

                                        Again. That's to you all. I really really y'all sharing your hard worked for wisdom, knowledge and experience.

                                        Peace

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