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Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

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    Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

    Hello all ~

    I picked up this nice Sharp Aquos 80" television the other day but when I plugged it in nothing happened. And I mean nothing. No picture, no sound, no logo, no LED lights on the front panel. Nothing.

    So, I opened it up and the only thing I could detect using my multimeter was the fact that it was receiving and passing along the 120 AC volts from the plug and I was also able to determine that the glass fuse that's near the plug-in appeared good and it was registering 45.4 AC volts. Not sure if that number indicates that the fuse is good or not.

    Beyond that, no voltages were detectable on the 3 connectors that come off the power supply board or (then, as expected) no voltages were present on either of the other two boards (main and logic).

    I took some pics of it all which I will post shortly. Hoping someone has run into this "absence of voltages" problem before and can provide some starting point insight.

    Note: I believe this particular power supply generates the typical voltages a PSU would and also controls the LED inverter operation(s).

    ~ kca

    #2
    Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

    Originally posted by kca View Post
    Hello all ~

    I picked up this nice Sharp Aquos 80" television the other day but when I plugged it in nothing happened. And I mean nothing. No picture, no sound, no logo, no LED lights on the front panel. Nothing.

    So, I opened it up and the only thing I could detect using my multimeter was the fact that it was receiving and passing along the 120 AC volts from the plug and I was also able to determine that the glass fuse that's near the plug-in appeared good and it was registering 45.4 AC volts. Not sure if that number indicates that the fuse is good or not.

    Beyond that, no voltages were detectable on the 3 connectors that come off the power supply board or (then, as expected) no voltages were present on either of the other two boards (main and logic).

    I took some pics of it all which I will post shortly. Hoping someone has run into this "absence of voltages" problem before and can provide some starting point insight.

    Note: I believe this particular power supply generates the typical voltages a PSU would and also controls the LED inverter operation(s).

    ~ kca
    1) How did you go about measuring 45.4VAC at the fuse? Where did you put the two probes of the meter?

    2) What is the resistance reading when you measure between the two ends of the fuse?
    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


      #3
      Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

      Hello budm ~

      1) I put the black probe on the tv chassis and the red probe on one end of the fuse and got the 45.4. Did the same thing on the other end of the fuse and got the same reading.

      2) I didn't get the resistance reading on the fuse before buttoning up the set for the night but will do so tomorrow. I put the DMM on the continuity mode setting and it emitted the audible beeping sound when I put the two probes on the two ends of the fuse. So, it appeared good. Although, it wasn't the strongest beep I have ever heard off of a fuse. Kind of slightly intermittent but not enough to make me think the fuse was automatically bad.

      Comment


        #4
        Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

        1) You are checking the AC input so do not use chassis for your meter, to measure incoming AC you put one probe on Neutral, another probe on the one end of the fuse at time.

        2) Meter continuity mode will beep with resistance as high as 50 Ohms, you need to look at the display to see how many Ohms it shows on your meter, it should show the same reading when you touch the meter probes together.

        3) You can use chassis when making measurement in the cold side of the circuit.
        Last edited by budm; 08-26-2020, 10:30 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


          #5
          Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

          Hello again budm or others ~

          I got this tv back out again and did a closer check on the ceramic fuse. It zeros out on the DMM (reads 000) after about a second. It will initially jump up to 7 or 13 or something of the like but that is only momentary until the triple zeros appear onscreen. And, it is beeping the entire time when in the continuity mode. I also took the power supply board off the tv and tested this same fuse (and also the encased fuse on the lower left-hand side of the board) at their back side solder points and they both read 000 while beeping. So, unfortunately, I don't think either one of these fuses is the cause of the trouble.

          I'm still trying to figure out what else would cause absolutely no voltages going out of the 3 connectors on this power supply board. Could it be that the backlights are denying all power to the set because they are defective? The power supply board is tied directly into the LED array via one of those three connectors I just mentioned.

          Will get pics up now.

          Comment


            #6
            Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

            Originally posted by kca View Post
            Hello again budm or others ~

            I got this tv back out again and did a closer check on the ceramic fuse. It zeros out on the DMM (reads 000) after about a second. It will initially jump up to 7 or 13 or something of the like but that is only momentary until the triple zeros appear onscreen. And, it is beeping the entire time when in the continuity mode. I also took the power supply board off the tv and tested this same fuse (and also the encased fuse on the lower left-hand side of the board) at their back side solder points and they both read 000 while beeping. So, unfortunately, I don't think either one of these fuses is the cause of the trouble.

            I'm still trying to figure out what else would cause absolutely no voltages going out of the 3 connectors on this power supply board. Could it be that the backlights are denying all power to the set because they are defective? The power supply board is tied directly into the LED array via one of those three connectors I just mentioned.

            Will get pics up now.
            It should not be doing that, it should show the same when you touch the meter probes together, you will see 000 reading right away and no any rising when you touch the two probes together, just take the fuse out and test it again..
            Last edited by budm; 08-31-2020, 05:11 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


              #7
              Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

              Here are pics of the entire set and some up close of the front of the PSU itself. Will post images of the back of the PSU next.
              Attached Files

              Comment


                #8
                Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                Images 3 through 8 above posted themselves upside-down.

                Comment


                  #9
                  Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                  That fuse is soldered in, budm, so I can unsolder and measure it but I don't think it's the fuse at this point based on the following:

                  1) It shows the randomly rising numbers (for example, 330, 17, then 000, or 152, 12, then 000) every time I touch the DMM probes to it. Different #'s every time, but it always goes to 000 within 1 second.

                  2) The same exact thing that I just described above also happens when I touch the two probes of the DMM together.

                  and

                  3) I pulled a very similar looking, ceramic fuse from a different set and it also behaves the exact same way then the black and red probes are applied to it.

                  Comment


                    #10
                    Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                    Originally posted by kca View Post
                    That fuse is soldered in, budm, so I can unsolder and measure it but I don't think it's the fuse at this point based on the following:

                    1) It shows the randomly rising numbers (for example, 330, 17, then 000, or 152, 12, then 000) every time I touch the DMM probes to it. Different #'s every time, but it always goes to 000 within 1 second.

                    2) The same exact thing that I just described above also happens when I touch the two probes of the DMM together.


                    and

                    3) I pulled a very similar looking, ceramic fuse from a different set and it also behaves the exact same way then the black and red probes are applied to it.
                    1) That is not normal for the meter to behave like that since resistance of the probe does not change, just think about it, if the probe leads have 1 Ohm resistance then how can the meter be showing more than 1 Ohm. I do not want to be troubleshooting the circuit if the meter is not behaving correctly. Why do you not use Ohm mode instead?

                    2) So what AC Voltage do you have when measure between AC incoming Neutral against each end of the fuse? You reported as 45.4VAC in your post #1 which is not correct.
                    Last edited by budm; 08-31-2020, 07:32 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


                      #11
                      Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                      post a picture of the meter showing your attempt at a reading of the fuse.... it will likely clear up a few things.

                      Comment


                        #12
                        Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                        Thanks for your patience, budm. In the past, I have always just put the DMM into Continuity Mode and tested fuses by checking to see if the beeping sound registered. It always seemed to "tell the truth", but I now know based on your earlier post that that is not the best, most exact way to do it.

                        I'll answer your question (Question #2 above) about the AC Voltage when I test the incoming neutral and each end of the fuse. I got between 121.4 and 121.6 on both ends of the soldered in fuse. So, I think that probably proves that the fuse is good. Correct me if I am wrong on that.

                        As far as Question #1 above goes, I wasn't using the Ohm setting because the only reading I could get on that is a 00.3 or 00.2 reading on the 200 setting and the rest of the Ohm settings did not register anything. I know those fluctuations where it rises momentarily and then drops and then drops again to 000 are probably unusual, but I think my DMM has pretty much always operated that way.

                        I will post the following sequential pics:

                        1) The 121.4 reading I got between incoming neutral and either (both) ends of that initial ceramic fuse.

                        2) The 00.2 reading I got when I had the DMM set on 200 Ohms

                        and

                        3) Three sequential pics I snapped in rapid fashion. I got lucky and captured all three of the "initial rise, then rapid down and rapid down again to 000 sequence".

                        Let me know how these images help and what I can do next. I tried every combination of the the Power Supply connectors (connected/disconnected) I could think of and nothing changes the fact that not a single voltage appears on any of them. That includes disconnecting all three and still no voltage readings to any of the many pins.

                        Also, I am going to include one more set of pics. I probably should have mentioned this earlier, but there is something a bit odd I thought with the AC incoming plug itself. It has the "traditional" quasi-pentagonal shape to it found on almost all of the larger tv's I've ever worked on, but instead of having a ground prong it only calls for and accepts the other two prongs. You'll see in the pictures what I mean. Now, I looked but could not find a pentagonal shaped cord in my collection that only has two prongs. So, I have been using the one you will see in the pics that has the three female points of connection. So, it fits perfectly into the pentagonal opening on the tv itself, but it only connects with those two existing prongs on the tv and the ground is simply unutilized. Could that, in and of itself, be causing some of these problems to exist? I didn't think so, but could be wrong.


                        ~ kca

                        Comment


                          #13
                          Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                          So, the last two pictures document the pentagonal shaped housing on the tv's incoming AC port, and the fact that there are only two prongs and no larger, cylinder-shaped ground prong. I thought it very odd that an 80” tv that must consume a considerable amount of power had no need for a ground on the AC. Is that unusual? If I have to, I can go about finding a cord that has only two prongs yet also has the pentagonal shape. I picked this tv off of a curb and kind of assumed the owner had the OEM cord that fit the bill but the tv failed not because of the cord and has some other issue(s). Unfortunately, that cord was not out on the curb along with the tv set itself.

                          ~ kca
                          Attached Files

                          Comment


                            #14
                            Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                            The three "sequential pics" images (#3, #4, and #5 above) are a bit hard to see, but they read 018, 001, and then 000 respectively. Again, all of that happens in about 1 second or less when I try to measure the fuse in Continuity Mode. It was beeping the entire time. Couple that with the 121.4 reading when incoming neutral was paired with each fuse end and it looks like that fuse is not the culprit. Correct?

                            Comment


                              #15
                              Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                              Originally posted by kca View Post
                              The three "sequential pics" images (#3, #4, and #5 above) are a bit hard to see, but they read 018, 001, and then 000 respectively. Again, all of that happens in about 1 second or less when I try to measure the fuse in Continuity Mode. It was beeping the entire time. Couple that with the 121.4 reading when incoming neutral was paired with each fuse end and it looks like that fuse is not the culprit. Correct?
                              Good so you do have 120 at the fuse, not 43V as report in post # 1.
                              I do not know what is going on with your meter at this why it is showing the the resistance going up and down.
                              I use Ohm mode for checking the resistance of the fuse.
                              Last edited by budm; 08-31-2020, 09:54 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


                                #16
                                Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                                1) So when you power up the TV and turn it on, do you hear the power relay on the power supply board click on?

                                2) What DCV do you have when measure right between the two legs of the main filter caps (47uF 450VDC) when TV is off and when power switch is activated?
                                Last edited by budm; 08-31-2020, 10:00 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


                                  #17
                                  Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                                  There is no relay clicking sound at all. There in no sound either when I plug it in nor when I try to then hit the power button on the side. (Don't have the remote to it, as that was not on the curb either). Sorry, I really should have mentioned that lack of a clicking sound before.

                                  And, I get a DC Voltage reading that fluctuates mildly between 163 and 164 on all three of the 47 uf 450 VDC caps. All three give the exact same reading.

                                  Comment


                                    #18
                                    Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                                    Originally posted by kca View Post
                                    There is no relay clicking sound at all. There in no sound either when I plug it in nor when I try to then hit the power button on the side. (Don't have the remote to it, as that was not on the curb either). Sorry, I really should have mentioned that lack of a clicking sound before.

                                    And, I get a DC Voltage reading that fluctuates mildly between 163 and 164 on all three of the 47 uf 450 VDC caps. All three give the exact same reading.
                                    So it does have 160VDC for the standby power supply to run.

                                    https://www.badcaps.net/forum/attach...3&d=1598919712
                                    With all connectors in place, you will need to make DCV measurement on the pins of the PD connector.
                                    You can see that there is pins chart printed close to PD connector.
                                    The exposed pins you see on the top side of the board are ODD number pin, you can also see pin 1 marking, to measure the EVEN number pins you will need skinny probe to probe the pins from the wire entrance side.
                                    You MUST report the reading for each pin in the format as shown below so we can easily see what each pin has or does not have when TV is plugged in and when power switch is activated.

                                    Pin 1: Name of the pin, TV OFF = xxx V, TV ON = xxV.
                                    Pin 2: Name of the pin, TV OFF = xxx V, TV ON = xxV.
                                    Pin 3:......
                                    Pin 4:.......

                                    BTW: https://www.badcaps.net/forum/attach...7&d=1598930270
                                    That setting is in Diode/continuity test so it will not show the resistance reading, it will show Voltage reading of diode junction in Volt.
                                    Last edited by budm; 08-31-2020, 10:48 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


                                      #19
                                      Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                                      Okay. I will get those readings in the morning on the PD Connector. Have to close shop for the night.

                                      Thanks for all of your help, budm.

                                      Comment


                                        #20
                                        Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

                                        Originally posted by kca View Post
                                        The three "sequential pics" images (#3, #4, and #5 above) are a bit hard to see, but they read 018, 001, and then 000 respectively. Again, all of that happens in about 1 second or less when I try to measure the fuse in Continuity Mode. It was beeping the entire time. Couple that with the 121.4 reading when incoming neutral was paired with each fuse end and it looks like that fuse is not the culprit. Correct?
                                        of course, you are doing ALL continuity tests with NO powering (ie. cord disconnected). Resistance measurements of any kind should not be done under power as that may cause an instrument problem and / or measurement issue since the powering may "contribute" to the meter thinking it has received more current than it "provided" to do the measurement.

                                        Comment

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