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Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

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    #21
    Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

    Originally posted by tucocaps View Post
    Oh, one thing I forgot. I remember reading something when googling this fault about the LED array causing it. Unfortunately, the post was short and rather vague that I had found. All I remember is that the suggestion was that there could be a short in the LED array, and in some cases that could somehow be repaired. I'm not sure if that is even correct, or if it is, feasible to be able to take apart the panel and fix.

    If you do try this, make sure to post back and let us know!
    I rather doubt that the led array is an issue since with two tcon cables on, the screen fully lights and looks fine... of course, the only visible display are a group of vertical lines on both half since the two outer cables are disconnected.

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      #22
      Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

      Originally posted by budwich View Post
      I rather doubt that the led array is an issue since with two tcon cables on, the screen fully lights and looks fine... of course, the only visible display are a group of vertical lines on both half since the two outer cables are disconnected.
      Yeah, but I think I remember reading something about a single LED being shorted. Like I said, I have no idea on that. I'm not even sure what it takes to disassemble to get to the LEDs on these.

      Comment


        #23
        Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

        It looks significant. Still not sure how the led string can impact the 12v panel power in any form since the led string is fed from the inverter "domain" with no direct "paths" to 12v unless they are pulling down the whole power supply which I doubt.

        Thanks for the suggestions / ideas. I am still trying figure out how to "pin probe" the "det_pnl 12v" lines without damaging / contacting nearby circuits / pins.

        Comment


          #24
          Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

          OK... now I got some head scratching.

          first, the short story. My neighbor indicated that when the estimator came over to look at the set, during that whole time with both the back on and off, doing some measurements, with the tcon cables both on and totally off, my neighbor never saw the perimeter lights come on. Strange but true I guess. My first few times of powering, I too never saw the perimeter lights come on. Then when I was doing some measurements after taking the right most tcon cable off, the perimeter lights suddenly turn on and the panel appear to act "normal"... albeit just one side (but the whole panel is lit). Then after playing with the left side tcon cable (causing the "picture" to move to the right side, we reconnected all the cables, and got back the flashing 2-5. Couldn't get out of it until following tucocaps suggestions about removing both cables. That got me back to panel lighting up, perimeter lights on, basically the panel running with just the two inner cables (out of the 4) connected. Put back the left most cable. Flashing 2-5 came back and panel and perimeter lighting never go on... :-( Take the left side off, flashing goes away and perimeter lights light up along with panel lighting with vertical lines. Scratching head. Still pondering about how to monitor the "det_pnl 12v" pin. For the heck of it, I get a cotton swab and alcohol and swab the left ribbon, dry it and reconnect it. Re-power the set... SURPRISE!!!, the perimeter lights come on along with the panel and I can read the menu on that side of the screen. WWWHHHHHAAAATTTT! So that panel appears to work, then not, then works. I don't think the board can be shorted because how does the short "fix" itself.

          I guess I wondering if perhaps swabbing the cable is potentially shorting any "capacitance charge" and maybe resetting what ever that charge is associated with????

          comments???

          PS. I can now readily get a "run result" with 3 out of 4 cables connected at the tcon. Either the right or left most one connected, set "runs". Add the additional cable and it fails to light perimeter lighting and soon flashes 2-5 there after. What am I missing here?
          Last edited by budwich; 08-31-2015, 01:46 PM.

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            #25
            Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

            not sure I followed that. Did you get the set to power on without the 5 blinks with ALL the ribbons connected?

            FWIW, I had a few that I swore turned on after sitting for a day or so, but after a minute or two shut down to 5 blinks. Since I sold off every part I could, and only got stung with returns on the mains I was actually able to test (typical ebay con artists), I know the boards were all OK. Point is, that just leaves the panel.

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              #26
              Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

              Originally posted by budwich View Post
              PS. I can now readily get a "run result" with 3 out of 4 cables connected at the tcon. Either the right or left most one connected, set "runs". Add the additional cable and it fails to light perimeter lighting and soon flashes 2-5 there after. What am I missing here?
              I don't think you are missing anything. If you can't get'r going without ALL of the ribbons connected, then you clearly have a panel issue. That's my take on it anyway after slaving away on a bunch of these sets.

              Comment


                #27
                Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                Put another way, I have not seen or heard of 5 blinks tying back to anything other than a panel issue, but if you manage to find something else, please let me know

                Comment


                  #28
                  Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                  thanks... :-( I guess what I don't understand is if you cable up one side and it works and cable up the other, it works, then basically the "root sanity" of both sides is "checked" / "good". To me, the only thing different from there, with both sides going is the load on the drivers and what is feeding them. This points either at the TCON board or the PD board. That's what I don't understand. Further, just measuring voltage isn't telling you much about the powering being delivered if for some reason, current is being limited or is insufficient.

                  Comment


                    #29
                    Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                    well this morning, I removed the two inner cables (64 pin I think) with the two outters (80 pin) attached, powered up, no perimeter lighting, shortly there after 2-5 flashing... prior to this, with either one of the outter cable attached (ie. 3 out of 4 attached), the set "runs" (ie. perimeter lighting, no flashing codes, etc).

                    Strange but true is about to happen. Cleaned the two inner cables with alcohol and swab. Replaced them and just one of the outter cables, to get the set back to the "run" mode that seems now easy to obtain. Set does come back to "run". OK! So for fun, I decided to attach the remain outter cable (right most in this case), power up the set and SURPRISE, perimeter light comes up, no code flashing, and basically the set is "operating".... WWWWHHHHHHAAAAAAATTTTTTT!!!!!!!!!

                    So now I have the set basically operating with all cables attached. It is lying face down on a "bench" with some over hang so I can some of the screen but not all. The issue that I see now, is there is like a "strobing" effect... kind of like when you have a move camera taking a picture of a tv in the "old days" and the resulting movie is got the "strobe" lines rolling across the screen. Is this maybe because the set is lying face down?

                    I definitely have my fingers crossed that the panel is NOT a problem but that there is some sort of connectivity issue.

                    Comment


                      #30
                      Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                      So... in time it took to write the preceeding post and the set was left "running", I went back (from upstair to basement work area), the set reverted to the 2-5 flash... :-( However, using the remote and hitting the power button twice (once for "off" I guess and then to turn it "on"), the set came back up, running again like it did before, perimeter lighting, menu screen seen (strobing effect), etc.
                      I am wondering about the strobing as I have no input so perhaps an input my help stabilize the video output... ?

                      Anyways, some progress but not there yet.
                      Ideas on what to do. My guess is that I may try getting access to the other ends of the ribbon cables at the panel connects and cleaning those.

                      Comment


                        #31
                        Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                        Seem to have "lost" being able to have all tcon cables attached after it had shut down in 2-5 error again. Now can only run every time with 3 cables, either right or left unplugged, gets the set up into "run" without code 2-5 happening. I "ventured" into trying to clean the other ends of the two cable in question... they are attached to boards on the rim of the panel. Might have been a mistake as they are hard to get at without disassembling the bottom portion of the panel (don't really want to go there). Anyways cleaning didn't help and further it appears to have added a "line" across the screen. When the left cable is off, before there was a prefect set of vertical lines on that side of the screen. Now, the same vertical lines are there BUT there is a small (one or two pixel wide) line horizontally thru those lines. That "horizontal error" wasn't there before I had attempted the cleaning of the opposite end. Attached is a couple of picture of the vertical lines (and error) along with a picture of a "Menu screen" when the oppose cable is removed. The menu screen shows larger portions of "horizontal errors". I am not sure if those were there earlier because I never looked that close because of the "surprise" that the set even turned on.... but I suspect they weren't.

                        I feel that some of this reflects the potential of poor connections between the tcon board and panel but not sure what is "normal" display for an lcd panel when one cable is detached. I know from some reads that people "trouble shooting" other lcd screens have suggested reseating cables XY ???? or otherwise to remove lines and such. Is this appropriate in this case... just poor seating / alignment / connectivity?

                        The picture of the tcon board and cabling shows the disconnected left ribbon cable and with a portion the lower plastic panel frame removed to access the other cable end. To get full access to the panel end, is significant work removing metal frame members.

                        Another question, is there a technique for cleaning the contacts on the clamp down ribbon connector without damaging them or the board?
                        Attached Files
                        Last edited by budwich; 09-01-2015, 11:13 AM.

                        Comment


                          #32
                          Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                          Not much progress. Basically, I am stuck at "3 out of 4 " cables connected... :-(

                          One thing that I have noticed, when the set fails the "power up", the Tcon board is quiet. When it does power up (in 3 out of 4 cables mode), there is a "pitched" noise emanating from the Tcon much like that of a rectifier power supply noise... but not as loud. Not sure why there would be that kind of "chopper" noise associated with that card. The main card which houses the main processor is quiet or at least the noise isn't in my audible range. The PD board is quiet at all times.

                          Is this a sign that perhaps there is some sort of "unstable" condition in the Tcon? Anyone every listen to their Tcon? :-)

                          PS. Searching thru the forum, I see that a "noisy" Tcon is just the vertical refresh cycle that is audible in some form.... :-( Those same discussion certainly appear to put credence to the high likelihood that the panel drivers are bad in some form... :-(
                          Last edited by budwich; 09-02-2015, 03:49 PM.

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                            #33
                            Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                            I think this is a lot of wishful thinking on your part, that there isn't a problem with the panel. Based on the sets I have taken apart, I don't believe there is any particular design defect in the ribbons or connections. If I were you, I'd part this set out and move on. You have enough to show all the boards are good....

                            Comment


                              #34
                              Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                              Its more of a learning exercise now although hope is still in the background.
                              I took off the lower support rail to access where the Tcon cable connect in the boards around the edge of the set. There are four boards about 10in long by about 1 in wide. Two tcon cable connect to one board and the other two connect to the other board. The outlying two other board are interconnected to the those with removable "flex cables" (I think that what they are referred to as). The four boards have "bonded" flex cables that leave the boards in various place to connect to the panel. I found that if I brushed my finger across one of those cables, I could cause a set of vertical lines to appear on that side of the screen. ???? Doing the same to all the other flex cables does nothing to the screen. I don't know enough about how the buffers move the data towards the driver to cause "pixels" but it seems strange that one particular "bonded" cable can cause that effect. I can't see any direct issue with the "bonding" or the cable itself.

                              Comment


                                #35
                                Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                                I don't know much about "fixing" panels or the tab bonds. I have a small old rca set I'm trying to mess with on that right now.

                                However, I think the challenge you'll face with that and the sharp is this fault circuit. Since you won't be able to see immediate feedback when messing with a cable or bond, and instead just a flashing light, I would think it would be impossible to "fix".

                                Comment


                                  #36
                                  Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                                  Originally posted by budwich View Post
                                  Its more of a learning exercise now although hope is still in the background.
                                  I took off the lower support rail to access where the Tcon cable connect in the boards around the edge of the set. There are four boards about 10in long by about 1 in wide. Two tcon cable connect to one board and the other two connect to the other board. The outlying two other board are interconnected to the those with removable "flex cables" (I think that what they are referred to as). The four boards have "bonded" flex cables that leave the boards in various place to connect to the panel. I found that if I brushed my finger across one of those cables, I could cause a set of vertical lines to appear on that side of the screen. ???? Doing the same to all the other flex cables does nothing to the screen. I don't know enough about how the buffers move the data towards the driver to cause "pixels" but it seems strange that one particular "bonded" cable can cause that effect. I can't see any direct issue with the "bonding" or the cable itself.
                                  Now that you've been messing with that obviously faulty tab plug all tcon ribbons in and see if the set starts normally. That bond may be your problem or maybe just ANOTHER problem the set has or was going to have had it not quit when it did.

                                  Comment


                                    #37
                                    Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                                    No luck. :-(
                                    I cry "uncle".

                                    Thanks for the info and ideas everyone. I learned quite a bit on this journey. Hopefully, it won't be needed directly in my immediate future. I have also provided info on some other threads dealing with other issues so it has been a bit of a "share and contribute" venture.

                                    Comment


                                      #38
                                      Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                                      Hold on!... the cry now is "AUNT".

                                      Last week, after re-assembling the lower half of the framing and mechanicals there abouts to get access to the various bonded cables and other "frame boards" (ie. boards around the frame edge) and connectors, I tried various power ups (ie. 2, 3 , and 4 tcon cables). Basically, I couldn't get any further than 3 cables connected which gave me a "run" set but of course, missing half of the screen. When ever the 4th cable was connected, I ended up in a 2-5 code ... :-(

                                      Fast forward to the post holiday weekend (hope people had a good one), I was going to start putting the full back on but thought I would power up the unit one more time. There were just 3 cables connected so I was expecting it to "run", it did. No surprise. I used the remote to power it off (not unplugging the main power). I then decided to plug in the 4th cable because I didn't want the cable freely dangling once the back was replaced. Plugged it in and then decided to try one more power up. IT DID. So now I have it powered up and feeding it an SD video and audio signal from a dvd player.


                                      The attached picture is a still of the screen. The video display is still kin of doing a "scrolling" type effect, almost liking a ground loop hum type screen or like an old set that has lost one of its hold (vertical?) but the picture isn't flipping just a "rolling pulse" of "brightness" moving vertically across the screen.

                                      There are some groups of horizontal lines in the middle and lower portion of the screen.
                                      What is the cause of these? Is it something that is repairable or still a sign (good or bad) that the panel is not operating properly? Is it possible that the long "rest" is a sign that perhaps the power supply is marginal and that once some components were unpowered for a bit, that it is running "better" for the time being? Other reasons? My hopes are a little higher again. I am not turning the tv off... :-)
                                      Thanks again for any further guidance.

                                      PS. went back down to the basement to see how things were doing... they weren't :-( flashing 2-5 came back.... some time of about 20 minutes, the set reverts back to the code flashing. I tried to restart it with all cables attached. No dice. Unplugging one, gets me back to a form of run. An additional observation was that the horizontal lines and scrolling are only on the right side of the screen, the left of the screen is good (no lines, no "scrolling") but note this observation is only with 3 cables as I didn't look at the left hand side with the 4 cables attached as I thought the lines and scrolling went across the screen (the complete screen not easily viewable because it is flat on a work area with some over hang on the ends). Is the lines / scrolling on one half of the screen possibly a symptom of issues with the tcon as opposed to the panel... maybe?... hoping :-)
                                      Attached Files
                                      Last edited by budwich; 09-08-2015, 07:51 AM. Reason: messed up where the edits went in the text box

                                      Comment


                                        #39
                                        Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                                        I thought since things are kind of "broke", I probably can't make them worse... right... :-)

                                        Anyways, with the set powered up and running with 3 tcon cables connected, I "carefully" plugged in the 4th (left most on the back), the set is staying in "run mode" now for over 1.5 hours, The picture has the "scrolling" along with the horizontal lines in the middle and lower section. The "scrolling" and lines are across the screen as I have now looked at both halves. So somehow during a startup, there is some process / check that isn't satisfied but once past, the set seems to be able to get around the 2-5 code / failure and run. Any ideas as to what the system is looking at / to during that initial process?
                                        Last edited by budwich; 09-08-2015, 09:56 AM.

                                        Comment


                                          #40
                                          Re: Sharp LC-70LE757U Flashing 2-5 :-( can it be saved economically?

                                          well, the plugging in of the tcon cables while powered doesn't work any more. As soon as the 4th one is plugged in, the set shutoff and flashes 2-5 codes... :-(

                                          I continued to play with things and found some more things out. By unplugging the corner ribbon cable on the left backside, which connects the edge boards on that side to the bottom edge boards (that are ultimately connected to the tcon board / cables), I can now start that tv with all 4 tcon cables connected. The resulting picture appears to be relatively "stable" except for "two lines" mid / lower screen (right half viewed from the front). The lines do go out on black picture backgrounds (ie. for pictures less than full res, ie. dvd). They also are not horizontally across the entire screen, but disappear about 2/3 of the way across. Also appear to have some sort of "pixel data" as they do "change" color elements with the picture, just seem to be out of "time".

                                          Not knowing enough about the overall tv operation in terms of the side boards, does any one know what the right side edge boards control? The picture seems "OK" outside of the lines (which are there with or without the corner cable attached). Further, doing a similar test of removing the corresponding connector on the other side, results in the set not turning on and flashing 2-5.

                                          Progress? Comments?
                                          Attached Files

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