70LE660U dark cloud or black screen with sound.

[Rozp]

Hello Everyone,

This is my first post so I will try to be as precise as possible without making this post too long winded. Unfortunately I don't have pictures of the original problem but I included images of the TV internals.

I have a Sharp 70LE660U. The problem started a few months ago with the bottom row looking out of sync and was dark on the left side and then fading to transparent on the right side. Shortly after, a dark cloud appeared in the center of the screen. The dark cloud started small and shaded but the image was visible. It also affected the menu area. If I left the TV on for about 30 min, the dark cloud would go way only leaving an overall clear picture with the bottom row still out of whack. With time the dark cloud got larger and darker and even after 30 min would not go away.

Then the opposite happened. If I unplugged the TV power for 24 to 48 hours, on the first power up, the TV would display a clear picture except for the bottom row still out of whack. After about 30 min of the screen displaying properly, it would flash a few times and then the dark cloud would appear again. After the first power up, every other attempt of turning the TV On/OFF (without unplugging it), it would instantly display the dark cloud, always in the center. During all of this, I never had the TV opened and or never tried to work on the internals.
After reading all the posts in this forum, I was convinced it was the tabs that needed pulling (i.e. tab surgery). My dilemma was that the dark cloud was in the center of the screen so I couldn't figure out if the left or right tabs were the issue. Also, as I understood it, the tabs (as described in the posts) are supposed to be located on the left and or right edge of the screen. The tabs on my TV are located on the bottom edge of the TV. I also have what looks like single tabs on the left and right edge of the TV but the do not look the same as the ones that connect to the t-con board. They are smaller.
Before pulling the tabs, I decided to purchased a new t-con board to make sure that was not the issue. I changed the board and still had the same problem. I then disconnected the ribbon cables from the t-con board, first the left then the right and in each scenario I would get the white screen on one side and a dark cloud image on the other side. So again I couldn't tell which side is problematic.
I then disconnected the ribbon cables that connected to the tabs section (see image t-con-ribbon-cables.jpg). It didn't help, but a new symptom showed up. Not sure if it was because I reconnected the cables incorrectly or it was coincidence, but now on power up, after about 15 secs, the backlight will flash and turn off. I still have sound and there are no error codes. I tried the flashlight test and could not see any image.
So at this point I have a TV that turns on, no image, no error codes, with sound and any input I try is the same. I opened up the frame to expose the tabs and they do not have any discoloration as if they are burnt (please see attached images).
Not sure where to go from here. I ordered a new power supply/led driver board and a new t-con board. I would have ordered a new main board, but they are not existent.

I have included a few images. I only included one image of the tab chip (tab-chip.jpg) but they all look the same (i.e. no burnt ribbon). I also added an image of the side tabs located on the left and right edge of the tv (side-tabs.jpg) as well as a single image of the chip state on the side tabs (single-side-chip.jpg). Again they all look the same and no visible burnt marks.

Any help or advice at this point will be very much appreciated.

Regards to all.
Roz

[nomoresonys]

Re: 70LE660U dark cloud or black screen with sound.

You probably already tried just putting a little pressure on the tab bonds, with your finger, one at a time wile it's on and see if there's a change in display.

[nomoresonys]

Re: 70LE660U dark cloud or black screen with sound.

Another simple test, check the little mlc capacitors on the panel driver boards for shorts or very low ohms.

[Rozp]

Re: 70LE660U dark cloud or black screen with sound.

Thanks for the reply. Yes I tried the putting pressure on the tabs as well as all the other connections, no change. Other than a visual inspection I did not test the capacitors. None of them looked liked there were bubbling.

[nomoresonys]

Re: 70LE660U dark cloud or black screen with sound.

I'm referring to the boards you have a hold of in picture #6, the little tan colored ceramic capacitors.

[Rozp]

Re: 70LE660U dark cloud or black screen with sound.

As best as I could measure, some were very tiny, using a digital multimeter, none appeared to be shorted or resulting in low ohms. Most were in the 1.4 to 3 mega ohms range others were on the 200 kilo ohms range. Does that make sense?

[nomoresonys]

Re: 70LE660U dark cloud or black screen with sound.

Yes that seems ok. So there is only one chip on each side? The last sharp I dealt with had 4 or 5 chips on each side. Most of the time when I had a dark growing or rolling cloud it was a tab bond not getting good connection, maybe check all the usual voltages on the tcon, can check youtube for tcon troubleshooting, one there and many more: https://www.youtube.com/watch?v=FexX7TGRzDc

[Rozp]

Re: 70LE660U dark cloud or black screen with sound.

There are what looks like 5 individual tabs with a chip on it on both the left and right sides of the TV. Then on the bottom edge of the tv, there are 6 ribbon cables, each with a chip on it, connected to the long PCB strip on either side of the t-con. That makes 12 on the bottom of the TV. Please see attached for better explanation.

[nomoresonys]

Re: 70LE660U dark cloud or black screen with sound.

Ok, that makes much more sense, you want to inspect the side ones closely, you should also be able to carefully look on the reverse side of those chips for damage of any kind, usually if it is a bad side cof, it shows which one in the one connected at a time tcon ribbon test, do any of them get a lot hotter than the others?

[nomoresonys]

Re: 70LE660U dark cloud or black screen with sound.

There's a really good thread that covers the bad side cof situation, tho not sure if that IS your issue, that was started by Freakafter8, check it out, it covers that whole gamut.

[nomoresonys]

Re: 70LE660U dark cloud or black screen with sound.

It's this vizio thread, same principal: https://www.badcaps.net/forum/showth...ht=freakafter8

[Rozp]

Hello Everyone,

Sorry I have not updated this thread in a while, I had put aside my troubleshooting due to some personal issues.

To pick up where I left off, where I was getting no video at all just audio, I finally made some progress. To make a long story short, I ended up changing the t-con board again. The one I purchased previously, although it was "new", was over heating the power supply and not displaying any video at all, nor were the backlights turning on. I was only getting audio.

After changing it, I started getting some video, mainly strips vertically on the screen. I re-seated all the ribbon cables and finally got to the point where I started which is having a black bar across the bottom of the screen and once in a while I get the black cloud in the middle of the screen (please see attached images). FYI, you can ignore the rib effect on the color bars, the image is generated from my laptop, so they only appear in the image.

If I let the TV cool down for a couple of hours and turn it back on, the TV will work perfectly for about 1-1.5 hours, then the screen starts to flash randomly and then the black bar appears on the bottom. Eventually the black cloud start to appear randomly as well. I have a spare main board and power supply, but I don't think it is related. Since the black cloud appears in the center I don't know if it is related to the famous tabs on the sides of the screen and if it is which side?

Not sure where to go from here. Any advice is much appreciated.

[Davi.p]

Don't ever rip off tabs.. this is a butcher technique.., you have two possible issues for me , one or both, oxidizing a the tcon and at the tabs.. if you want, start to study at these two inputs, you can for semplicity get another tcon *only* from working recently cracked panel, and you can be safe with luck, for the rest i cannot help much you... bye..

[Davi.p]

LC-70LE660U

[Rozp]

Thanks for the advice. FYI I have already tried 4 different t-con boards. 2 of them seem to be defective out of the box (even though they were sold as "new" (i.e. from cracked screen)) and the other 2 gave me the exact same results as in the last images posted. I will re-check the tabs for oxidization. Just curious, if it was oxidization, why would the TV work properly for the first hour?

[Davi.p]

What do you mean for "seem defective out of the box"? Be more precise, i suspect there are some mafia listings of broken parts sold as new or good.. for your question, it's a simple question of resistivity, the more the set stays on, the more it heats, at a certain point i'm thinking crertain gate drivers fails to work because them receives too few current, but they doesn't break.. this is my new theory, until two months ago i always said bad gate drivers circuits.. the culprit here is the BGA on the tcon i suspect.. i'm trying to improve my reflows capacity, to have a proof of what i think.. with this supposing mafia of the spare parts, i go nowhere.

PS: some gate drivers circuits can maybe suffer more than others the scarceness of signal, not all the drivers are 100% identical.. maybe..

[Rozp]

I have 4 t-con boards. At the time I purchased the first 2 t-con boards, I thought I did my due diligence and tried to stay away potential scammers. I live in Canada so I purchased them all from a site in Canada. I am confident the site I used is reputable. For the last t-con board I purchased they even called me after I placed the order to confirm it would work with my TV so I don't think it is a scam but you never know.

The original t-con that came with the TV and the last t-con board I purchased have the exact same symptoms as the last images I posted with the color bars above (i.e. works for about an hour but later the black bar and cloud appear on the screen.) The other 2 t-con boards I believe to be defective because they both behave the same, i.e. the TV has no video, the LED backlights do not turn on and the the power supply overheats to the point where you cannot touch the heat sinks but there is still audio available. I also tried changing the power supply and the main board but it didn't make a difference. So there must be an issue with those boards because if I disconnect it from the power supply, the power supply no longer overheats.

I also changed the t-con ribbon cables. The other thing I found was when I first plugged in the 4th t-con board I only got vertical lines on the screen. By disconnecting the right side on the strip of the bottom mounted ribbon cables I got the image in the first pic attached. As I re-seated all the ribbon connections I got different results ( i.e. different combination of vertical lines on the screen over the displayed image). I was able to get it to a stable point where the TV works properly for the first hour or so until the black cloud appears, which is the original problem when it all started.

Thanks for your feedback.

[Davi.p]

). I was able to get it to a stable point where the TV works properly for the first hour or so until the black cloud appears, which is the original problem when it all started.

How do you.do it? It does automatically?
From the tests on my tv i have unfortunately bad feedback and bad feel or confusion.. i need to think on a bit more..

[Rozp]

I don't do anything. it does it on its own. I don't know if it is related to cooling or just waiting for capacitors to discharge. I just have to wait for an undetermined period of time, anywhere from a couple of hours to a day.

[Diah]

I don't do anything. it does it on its own. I don't know if it is related to cooling or just waiting for capacitors to discharge. I just have to wait for an undetermined period of time, anywhere from a couple of hours to a day.

yours all 4 t_CON... are useless.... just put please the original one.... the issue are Panel driver SW.... i will search i may find it but you need to search too for firmware to downgrade first..