Sharp LC-55LE643U, bad gate drivers?

[wagivem657]

Just received a busted Sharp 55" Aquos (LC-55LE643U) from a coworker. He tried swapping all three boards (power, main, TCON) to fix the problem, but it had the same issue. He was kind enough to give me the TV and both sets of boards for free, so I can try to get it working for myself.

Unfortunately, I think I may have made the problem (much) worse, but I'm interested to see if the original problem was fixable at all regardless...

Pictures show the issues:

1. shows what happens when you first turn the TV on. Well, kinda, the white column wasn't there at first - that must be my fault. I guess I knocked out a source driver?
   
2. shows a closeup so you can see what's going on better. Some of the rows of pixels are working fine, but others are black, except where the white color of the text has "smeared" into them. The text smears out over a period of a few seconds before it gets as bad as what's pictured. This made me think it was a gate driver issue.
   
3. Based on my understanding from this youtube repair video (I found this super helpful for understanding how the source/gate drivers interact), I decided to see if I could isolate the issues to one side. This picture shows what happens when you remove the right side TCON ribbon cable - behavior is exactly the same as before
   
4. shows what happens when you remove the left side ribbon cable. It's definitely not any better! There's similar horizonal striping up high on the screen, which works fine whenever the right TCON cable is plugged in.
   
5. is a closer view near the top-right corner of the white portion of 4. You can see that there's striping in that middle section (vertically middle) with the striping. The whole lower portion of the screen actually doesn't have any striping at all - it starts out black, and then a white color smoothly takes it over. It's splotchy and doesn't look like the pixels are doing anything at all. This even happens for the permanently white column - though that portion turns white more quickly and gets brighter.

So is this a gate driver issue? Due I need to pull tabs/cover TCON pins with tape? Posts in this thread on bad sharp gate drivers suggest it will be one or the other - but how do I know if my TV has side tabs? I don't see any, but I haven't disassembled the panel yet.

And did I permanently ruin this TV by blowing a source driver? Or could that white band be something else (I've already swapped the TCON and main boards, since I have 2 sets - no change)? Or is it fixable somehow?

At least all I have in this TV is a little bit of time...

Thanks guys!

[neilc6]

Re: Sharp LC-55LE643U, bad gate drivers?

The vertical bands correspond to the flex cables tab bonded to the panel. Bad connection or failed chip on film (COF) in that section. Possibly other panel damage as well. Not repairable.

If you are curious, you can inspect the panel board and flex cables. The one corresponding to the white band may be totally disconnected.

Sony Tcon training manual https://dokumen.tips/documents/sony-...ng-manual.html

[budwich]

Re: Sharp LC-55LE643U, bad gate drivers?

You want to take a closer look at the ends of the cables that are connecting between the tcon and panel. Depending on how they were "played with", they maybe damaged. The "history story" might help as to what the first person saw, then what he saw after his effort and finally what you saw when you first started... of course, you have posted your current situation which does not look good. Further check the cabling from the tcon to the main board for damage AND proper connection seating. Use your glasses to ensure that you are seating cabling correctly and with the proper procedure... hoping you are not just pulling and pushing them without first "unclamping" the holders.

[wagivem657]

Re: Sharp LC-55LE643U, bad gate drivers?

The vertical bands correspond to the flex cables tab bonded to the panel. Bad connection or failed chip on film (COF) in that section. Possibly other panel damage as well. Not repairable.

If you are curious, you can inspect the panel board and flex cables. The one corresponding to the white band may be totally disconnected.

Yep, that's along the lines of what I was thinking. The tab feels like it's still securely connected, but I'll have to take the bezel off to get a better look at the IC and the panel and see if I can tell why it went out.

You want to take a closer look at the ends of the cables that are connecting between the tcon and panel. Depending on how they were "played with", they maybe damaged... Further check the cabling from the tcon to the main board for damage AND proper connection seating. Use your glasses to ensure that you are seating cabling correctly and with the proper procedure... hoping you are not just pulling and pushing them without first "unclamping" the holders.

I'm definitely "unclamping" the holders before pulling anything out. Also, I swapped the TCON board and all ribbon cables after the white bar first appeared. I did not swap the main board, though I do have a spare. Still, it's worth double checking to make sure there's no obvious damage to any of the connectors, including the ones to the tab boards... I'll take a look.

The "history story" might help as to what the first person saw, then what he saw after his effort and finally what you saw when you first started...

I don't think I have a great history prior to when I saw it.

• My coworker mentioned something about a purplish hue appearing on the bottom, and then it got worse, possibly over time. There may have been a time when it would "warm up" and fix itself - he wasn't very clear.
• He described the issue when he gave it to me as "half of the TV showing white". He must have been referring to the bottom half.
• When I got it and plugged it in, the first image in my post was what I saw (without the white bar - that column was originally working). I think if you played video on this, the bottom half would probably wind up looking white, like my coworker said - I haven't tried anything other than the menus though.
• I disconnected the first side from the TCON board and it looked just like image 3 in my first post.
• At this point I started gently tapping/putting pressure on connectors to see if there would be any change in the image. Nothing improved the image.
• I disconnected the first side from the TCON board again, and again it looked just like image 3 in my first post.
• I disconnected the second side from the TCON board, and saw the 4th image in my first post, extra white bar and all
• The image has been consistently what is shown in my first post since then.

-----

I managed to find schematics for the actual LCD panel itself (T550HVN06.0). They show that this TV has 8 bottom source tabs - so it definitely looks like one of them is knocked out; the white bar is exactly 1/8th of the image*. Also, there appear to be no side tabs/gate driver tabs.

I guess that would make any gate issues (which I think it has, in addition to the obvious source tab that's out) on this model a candidate for a tape fix. Unfortunately, the schematic includes the TCON board, meaning I only get the pinout for the LVDS - the ribbon cables from the TCON to the tab board are "internal" and the pinouts aren't given. That's hampering any attempt to figure out which signals I might block to deal with the gate driver issues. The TCON board is 55t16-c04, but I haven't had any luck finding a schematic or pinout for that.

*Please desregard the fact that 1900 does not divide by 8 evenly.