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Hitachi LE55A6R9A - No backlight

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    #21
    Re: Hitachi LE55A6R9A - No backlight

    I'll make the orders soon, but I may have to wait a few weeks with the holidays and all.

    In the meantime, a question. The LED tester can be used to test the strips prior to opening the chassis and messing with them, yes?

    I'm not super hung up on saving this TV, more interested in practice, so I'm not opposed to opening it up. Still, if this particular unit can be salvaged without risking damage that's a plus. And I can, of course, practice that on a different TV in the future.
    Last edited by PorkfriedPanda; 11-26-2016, 05:15 AM.

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      #22
      Re: Hitachi LE55A6R9A - No backlight

      Bought the LED tester, confirmed that bottom LED strip works, top LED strip doesn't.

      Exploring options from here, watching vids, etc.

      Thanks for all the info guys

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        #23
        Re: Hitachi LE55A6R9A - No backlight

        The led tester will allow you to test each led strip or individual leds to verify which leds are faulty or show up any led strip connection problem. However it does mean removing the led panel carefully.
        Willing to help but I'm no expert.

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          #24
          Re: Hitachi LE55A6R9A - No backlight

          And don't forget to test your meter !

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            #25
            Re: Hitachi LE55A6R9A - No backlight

            Originally posted by dick_barton View Post
            The led tester will allow you to test each led strip or individual leds to verify which leds are faulty or show up any led strip connection problem. However it does mean removing the led panel carefully.
            Of course, that's what I'm studying up to do.

            I'm considering buying the little dedicated ShopJimmy gizmo to detach the single LED, and maybe some LEDs and diffusion covers so I can do this again if I have to.

            Originally posted by mmartell View Post
            And don't forget to test your meter !
            Definitely. I keep forgetting to do that, next time I've got a little spare time I'll unhook a car battery and check it.

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              #26
              Re: Hitachi LE55A6R9A - No backlight

              Car battery ? How about a simple 9v or AA even.

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                #27
                Re: Hitachi LE55A6R9A - No backlight

                I'm bot sure what the thread etiquette is on this forum so if I have breached it with this post, I apologize in advance. I'm bot sure if I can even start threads yet.

                Anyway, I have the same tv as the OP of this thread. As far as I can tell (watching youtube vids), all 3 of the main boards in my tv are good.
                It has sounds but no video.

                The flashlight test shows me images very light when I hit the menu button.

                I now find myself still unsure how to proceed. It sounds like my 2 potential issues are:
                Led inverter board or
                Led strips themselves

                So, do I just buy both and go with it? I prefer to be a cheap-a$$ when possible.

                Also, is it an absolute must to buy specific led strip "kits" specific to each model tv, or can I just sub in some led strips I picked up on ebay for $10. These particular ones run off of 12vdc I believe.

                A little about me, I am a competent arcade monitor (crt) repair guy, and overall good at repairs on arcade games and pinball machines.

                I certainly encourage input, and will not be offended easily.

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                  #28
                  Re: Hitachi LE55A6R9A - No backlight

                  Have you read through the thread and carried out any of the tests suggested earlier in the thread?
                  Willing to help but I'm no expert.

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                    #29
                    Re: Hitachi LE55A6R9A - No backlight

                    Originally posted by dick_barton View Post
                    Have you read through the thread and carried out any of the tests suggested earlier in the thread?

                    It seems like most of the thread is attempting to determine if his meter works. ��

                    If i remember correctly, the positions CN202 and CN203 , i was getting something like 270vdc out of 1, and a few vdc from the other.

                    I'm have not purchased an led tester (and probably won't).
                    I do believe, based on watching shopjimmy video(s) , that the power, t-con, and main board are all good.
                    Last edited by Tron guy; 03-19-2017, 09:00 AM.

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                      #30
                      Re: Hitachi LE55A6R9A - No backlight

                      If you believe that you have 270V at the led connector of which they appear to be wired in series then I believe that you may well have an open circuit led.
                      Last edited by dick_barton; 03-19-2017, 08:14 AM.
                      Willing to help but I'm no expert.

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                        #31
                        Re: Hitachi LE55A6R9A - No backlight

                        Originally posted by dick_barton View Post
                        If you believe that you have 270V at the led connector of which they appear to be wired in series then I believe that you may well have an open circuit led.
                        I definitely had 270vdc at CN 202.

                        So when you say "open circuit led"

                        are you saying a single LED or strip is bad?

                        Or is my voltage so high that a diode or transistor went out on the power board?

                        Again when watching a few videos I determined I had +12vdc at all of the points listed between the boards, +5vdc as well where it was supposed to be.
                        Shining a flashlight on the screen when powered on, got me some image in menu mode.
                        I am an absolute newbie at led/lcd tv repair (first attempt here).

                        thank you for replying

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                          #32
                          Re: Hitachi LE55A6R9A - No backlight

                          i believe it works like this....If you have a very high voltage spike going to leds then that is a very strong indication there is an open led because it won't turn on to draw that power to put a load on it and draw to normal voltage ranges approx 1XX volts. When power supply detects this over spike high voltage it goes into protect mode and shuts it down due to open (blown) leds.

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                            #33
                            Re: Hitachi LE55A6R9A - No backlight

                            The leds are connected in series, a little like old fashioned fairy lights, and when one goes open then no current can flow in the circuit to light the leds.

                            On the other hand it could be that a connection on the led strips inside the panel has gone open and that would cause the same fault condition. This has been the case in other threads here on the Forum where wire has been soldered across the connection to bridge the fault out.
                            Willing to help but I'm no expert.

                            Comment


                              #34
                              Re: Hitachi LE55A6R9A - No backlight

                              Originally posted by dick_barton View Post
                              The leds are connected in series, a little like old fashioned fairy lights, and when one goes open then no current can flow in the circuit to light the leds.

                              On the other hand it could be that a connection on the led strips inside the panel has gone open and that would cause the same fault condition. This has been the case in other threads here on the Forum where wire has been soldered across the connection to bridge the fault out.
                              So I could pull the panel open and look for continuity from the begging of the wiring to the end of the led strips? Somewhere in the middle there may be a loss of connection?

                              Or do I just buy the led strips (when they become available again from shopjimmy, unless someone knows elsewhere to buy them), and change them?

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                                #35
                                Re: Hitachi LE55A6R9A - No backlight

                                It's a large screen so I would search the forum for information on hints and tips for lifting away such a large lcd panel without breaking it.
                                There are also "Youtube video's" which could aid you. There are also a lot of useful tips for testing the leds.
                                Willing to help but I'm no expert.

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                                  #36
                                  Re: Hitachi LE55A6R9A - No backlight

                                  Thanks gentlemen.

                                  I think I replied earlier without reading all of recent replies to this thread.

                                  Looks like I should learn how to carefully open this thing up and pull out my meter and look for a break in continuity.

                                  It sounds like maybe I should do it with the power on as well and see if the voltage stops somewhere along the line?

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                                    #37
                                    Re: Hitachi LE55A6R9A - No backlight

                                    Well just following up on this one. Shopjimmy just got the led strips back in stock, so now I have them.

                                    This is my first lcd/led tv repair, I've done hundreds of crt's. I have to say, this reflector shield or whatever they call it is a joke. It's paper thin and it's held down with double sided tape. I will report back with how much damage I do to it and also if changing the led strips fix my problem.

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                                      #38
                                      Re: Hitachi LE55A6R9A - No backlight

                                      well I got everything apart , started to install the new led strips and the busted at the connection between the 2 pieces.

                                      I call shopjimmy and they said "yeah, manufacturing defect"

                                      This thing is apart and at work and in the way. So in the trash it goes. oh well

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                                        #39
                                        Re: Hitachi LE55A6R9A - No backlight

                                        Just bridge the connections
                                        I assume no responsibility for any stupid suggestions I might post.

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                                          #40
                                          Re: Hitachi LE55A6R9A - No backlight

                                          Originally posted by dskall View Post
                                          Just bridge the connections
                                          yeah if that had even a 1% chance of working I'd do it.

                                          I am at work not at home where I have complete access to my work bench and all of my tools. I've done some pretty intricate soldering before and I don't believe I could pull this off if I had my tools at my disposal.

                                          I love this site and I appreciate the insight, I probably won't be back because I don't intend to work on this type of tv ever again.

                                          thanks guys

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