Announcement

Collapse
No announcement yet.

SHARP LC-70UQ17U standby but no backlight or video =(

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    SHARP LC-70UQ17U standby but no backlight or video =(

    Hi all,

    I had posted about this a while ago but ended up getting side tracked. Now, before I dump it I decided to give it one more shot.

    No matter what I do I can't get any backlight or picture on the screen.

    I have the dreaded 2-5 blink code. I unplug 2 tcon ribbon connectors, or all of them no difference.

    I unplugged the ribbon connectors on each bottom left/right that plug into the driver boards and no difference.

    I tested the board OUT of the TV just to make sure using this video as a reference: https://www.youtube.com/watch?v=DCXHNN8nrws and the voltages seem to match up. I also tried different main board and power supply board but no luck.

    I feel like maybe when the board is connected to the TV/panel theres a short somewhere... I am just not sure how or where to look.

    Here are the voltages I was getting the last time I checked the board while it was plugged into the TV under load. (this is my first attempt at fixing a TV so please forgive me for my noobishness):

    Pin 1, PNL_12V: 11.91v
    Pin 2, PNL_12V: 11.94v
    Pin 3, GROUND: 0.28v
    Pin 4, GROUND: 0.27v (although ground, just posting my meter reading)
    Pin 5, UR13.2v: 13.35v
    PIN 6, UR13.2v: 13v
    PIN 7, UR13.2v: 13.35v
    PIN 8, UR13.2v: 13v
    PIN 9, GROUND: 02.4v (again, just posting my auto range meter reading)
    PIN 10, GROUND: 02.3v
    PIN 11, GROUND: 02.3v
    PIN 12, GROUND: 0.23v
    PIN 13, AC_DET: 3.3v
    PIN 14, PS_ON: 3.3v
    PIN 15, BU5v: 5.04v
    PIN 16, PNL_POW: 5v
    PIN 17, PWM1: 13.3v
    PIN 18, NC: 13.4v
    PIN 19, DIMMER: 13.4v
    PIN 20, ?: 13.6v
    PIN 21, OFL: 3.4v
    PIN 22, ERROR: This pin I tested a few times goes up and down 3v, 5v, 7v in no order. Basically bounces around.
    PIN 23, PWM2 / NC?: 9.5v
    PIN 24, STB: 9.5v

    Appreciate all of your help.

    #2
    Re: SHARP LC-70UQ17U standby but no backlight or video =(

    "PIN 22, ERROR: This pin I tested a few times goes up and down 3v, 5v, 7v in no order. Basically bounces around" I believe this is the backlight error pin, looks like it's a backlight issue.

    Comment


      #3
      Re: SHARP LC-70UQ17U standby but no backlight or video =(

      Originally posted by nomoresonys View Post
      "PIN 22, ERROR: This pin I tested a few times goes up and down 3v, 5v, 7v in no order. Basically bounces around" I believe this is the backlight error pin, looks like it's a backlight issue.
      That's the thing though, I tried to check the screen with a flash light but I don't see anything at all.

      Comment


        #4
        Re: SHARP LC-70UQ17U standby but no backlight or video =(

        Good point, some tvs will not show a display in this condition, can't remember if this model is one of them, because the memory...at least mine was the first thing to go, lol.

        Comment


          #5
          Re: SHARP LC-70UQ17U standby but no backlight or video =(

          Originally posted by nomoresonys View Post
          Good point, some tvs will not show a display in this condition, can't remember if this model is one of them, because the memory...at least mine was the first thing to go, lol.
          Lol, i understand. Also, do you know where i can find the proper way to reset the codes on this unit? I see quite a few different methods so I am not sure which one works. Do I have to reset the codes EVERY time I remove a ribbon cable or is unplugging it enough?

          Furthermore, I just checked one set of pins where I believe the backlight is plugged into.... when I power on the TV I get 85v on some pins, some have no voltage and another has 45v. Once the error kicks in and the standby light starts to blink I stop getting voltage on all pins. I don't know if this could help narrow it down?


          Comment


            #6
            Re: SHARP LC-70UQ17U standby but no backlight or video =(

            I added photos, not sure what happened.

            Side note, I notice when the error codes kick in I slowly lose voltage from the pins showing 85v, 45v, etc. It slowly goes lower and lower voltage. Just trying to document everything to see if we can pin point the issue. @budm and @budwich were a big help the last time before I ended up being sidetracked. If you guys could chime in I'd really appreciate it!

            Comment


              #7
              Re: SHARP LC-70UQ17U standby but no backlight or video =(

              Try that to access service menu, you MUST be very careful what you do in there, it's easy to brick a tv in there, check for lamp or backlight errors ant try to clear them:

              Let's start with turning off your tv...
              Afterward, unplug the TV from the power source.
              Now press and hold together the Input button and Vol - button on your TV.
              While holding the buttons plug the TV back into power.
              When the screen turns on you can release the buttons.

              Comment


                #8
                Re: SHARP LC-70UQ17U standby but no backlight or video =(

                The above may not work if you can't get a display.

                Comment


                  #9
                  Re: SHARP LC-70UQ17U standby but no backlight or video =(

                  For code reset maybe try but not exactly sure some combo of, tv off hold both volume plus channel - turn tv on while holding those two or hold those two while plugging tv in.

                  Comment


                    #10
                    Re: SHARP LC-70UQ17U standby but no backlight or video =(

                    Originally posted by nomoresonys View Post
                    Try that to access service menu, you MUST be very careful what you do in there, it's easy to brick a tv in there, check for lamp or backlight errors ant try to clear them:

                    Let's start with turning off your tv...
                    Afterward, unplug the TV from the power source.
                    Now press and hold together the Input button and Vol - button on your TV.
                    While holding the buttons plug the TV back into power.
                    When the screen turns on you can release the buttons.
                    Nope, doesn't work. Can't get any display. Is there any other way of getting it to bypass the errors and power on the backlights?

                    Do you know where I could find a schematic with the voltages, etc?

                    The inp + vol - does nothing either... the thing is I don't know for sure if/how to clear out the codes, no matter what combination I use the blinking doesn't go away.

                    Also, as far as 85v, 45v, on some of the LED pins, is that normal? The pins are LED+ etc. Im guessing this is what powers the actual LED? As I mentioned I get the voltage but once the blinking starts it slowly starts to drop.

                    I would go ahead and try to cut the tabs off but I am afraid I damage the TV for sure . The problem is no matter what I do I am unable to get a backlight or even any picture for that matter. I'm starting to feel like my issues isn't likst most where the tabs are bad... I might have a different issue which I am having trouble finding =(

                    Comment


                      #11
                      Re: SHARP LC-70UQ17U standby but no backlight or video =(

                      Post #1:
                      Pin 1, PNL_12V: 11.91v
                      Pin 2, PNL_12V: 11.94v
                      Pin 3, GROUND: 0.28v
                      Pin 4, GROUND: 0.27v (although ground, just posting my meter reading)

                      Pin 5, UR13.2v: 13.35v
                      PIN 6, UR13.2v: 13v
                      PIN 7, UR13.2v: 13.35v
                      PIN 8, UR13.2v: 13v
                      PIN 9, GROUND: 02.4v (again, just posting my auto range meter reading)
                      PIN 10, GROUND: 02.3v
                      PIN 11, GROUND: 02.3v
                      PIN 12, GROUND: 0.23v

                      PIN 13, AC_DET: 3.3v
                      PIN 14, PS_ON: 3.3v
                      PIN 15, BU5v: 5.04v
                      PIN 16, PNL_POW: 5v
                      PIN 17, PWM1: 13.3v
                      PIN 18, NC: 13.4v
                      PIN 19, DIMMER: 13.4v

                      PIN 20, ?: 13.6v
                      PIN 21, OFL: 3.4v
                      PIN 22, ERROR: This pin I tested a few times goes up and down 3v, 5v, 7v in no order. Basically bounces around.
                      PIN 23, PWM2 / NC?: 9.5v

                      PIN 24, STB: 9.5v

                      You need to recheck those Voltages, must be error in testing. What did you use for the meter ground? Did you count the pins correctly? It cannot be right to have Ground pin Voltage like that and the command pins Voltage higher than 5V.
                      Please attach good clear straight shots pictures of the board using GO ADVANCED.
                      Last edited by budm; 01-13-2021, 09:36 PM.
                      Never stop learning
                      Basic LCD TV and Monitor troubleshooting guides.
                      http://www.badcaps.net/forum/showthr...956#post305956

                      Voltage Regulator (LDO) testing:
                      http://www.badcaps.net/forum/showthr...999#post300999

                      Inverter testing using old CFL:
                      http://www.badcaps.net/forum/showthr...er+testing+cfl

                      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                      http://s807.photobucket.com/user/budm/library/

                      TV Factory reset codes listing:
                      http://www.badcaps.net/forum/showthread.php?t=24809

                      Comment


                        #12
                        Re: SHARP LC-70UQ17U standby but no backlight or video =(

                        Yep, something wrong with those readings for sure.

                        Comment


                          #13
                          Re: SHARP LC-70UQ17U standby but no backlight or video =(

                          Leaning towards a backlight issue, did you check the voltage between the legs on the big capacitors? probably labeled c7800, with tv powered on, BE VERY CAREFUL, those 450 volt caps can KILL, be careful not to touch them with anything but the meter ends, set meter at 200 vdc, neg probe on negative - leg, pos probe on positive + leg, thinking it should be around 400 with tv on and around 160 with tv in standby.

                          Comment


                            #14
                            Re: SHARP LC-70UQ17U standby but no backlight or video =(

                            Some simple testing there: https://www.youtube.com/watch?v=4RzuLiRTzJg

                            Comment


                              #15
                              Re: SHARP LC-70UQ17U standby but no backlight or video =(

                              Originally posted by nomoresonys View Post
                              Leaning towards a backlight issue, did you check the voltage between the legs on the big capacitors? probably labeled c7800, with tv powered on, BE VERY CAREFUL, those 450 volt caps can KILL, be careful not to touch them with anything but the meter ends, set meter at 200 vdc, neg probe on negative - leg, pos probe on positive + leg, thinking it should be around 400 with tv on and around 160 with tv in standby.
                              If you're referring to the 3 big black caps , I did test that the other night with the bird OUT of the Tv, I had the 160v and then jumpers two pins together (14 and 15, IIRC) and got the 400v. I followed a YouTube video.

                              I will try to test again while tv is plugged in. I guess on power up I should get a reading but once errors kick in voltage will drop.

                              Thank you for the warning, I didn't realize they were THAT danger, I'll be even more cautious now.
                              Will report back in a bit.

                              Comment


                                #16
                                Re: SHARP LC-70UQ17U standby but no backlight or video =(

                                Originally posted by nomoresonys View Post
                                I have one of those backlight led testers.. is there a way to use this and connect directly to the backlight cable to see if the backlight turns on? Basically by passing everything and trying to light the leds manually.

                                Comment


                                  #17
                                  Re: SHARP LC-70UQ17U standby but no backlight or video =(

                                  Ok, with bird connected to tv... the capacitors show 400v.. once the error codes kick in it slowly starts to drop in voltage.

                                  Comment


                                    #18
                                    Re: SHARP LC-70UQ17U standby but no backlight or video =(

                                    When I hold the power button and plug the tv in I get a slow pulsing on the standby light but still no backlight or video.

                                    Comment


                                      #19
                                      Re: SHARP LC-70UQ17U standby but no backlight or video =(

                                      What's the model number of your led tester?

                                      Comment


                                        #20
                                        Re: SHARP LC-70UQ17U standby but no backlight or video =(

                                        I had this one originally:

                                        https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

                                        And I just ordered this one which should be delivered tomorrow:

                                        https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

                                        I'm not sure what the difference is, but the new one I ordered said "no disassembly required"

                                        Are they both the same thing? Also, I am not exactly which pins I need to test and does the TV have to be powered on while doing this?

                                        Comment

                                        Working...
                                        X