Universal TAB repair. - AVS Forum
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post #1 of 5 Old 05-19-2011, 06:00 PM - Thread Starter
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Here's what we know:

LCD panels use TABs to connect to the driver boards. TABs are (tape automated bonding.
------[COPY FROM WIKI]--------
Tape automated bonding (TAB) faults
A TAB fault is caused by a connection failure from the TAB that connects the transparent electrode layers to the video driver board of an LCD.
TAB is one of several methods employed in the LCD display manufacturing process to electrically connect hundreds of signal paths going to the rows and columns of electrodes in layer 6 (the transparent electrode layer) in the LCD display to the video ICs on the driver board that drive these electrodes.
If an LCD display is subjected to physical shock, this could cause one or more TAB connections to fail inside the display. This failure is often caused by horizontally flexing the chassis (e.g., while wall mounting or transporting a display face up/down) or simple failure of the adhesive holding the TAB against the glass. TAB faults require replacement of the LCD display module itself. If these connections were to fail, the effect would be that an entire row or column of pixels would fail to activate. This causes a horizontal or vertical black line to appear on the display while the rest of the display would appear normal. The horizontal failure runs from edge to edge; the vertical failure runs from top to bottom.
-------------------------------
It uses Anistropic tape as the bonding agent. This stuff is REALLY REALLY expensive. 35' goes for about $200. Not to mention that you have to have very special (and very expensive) equipment to rework it. (Sorry, no easy repair.)

HERE is what THEY DON'T TELL you.

LCD panels use newer technology in between the physical panel and the driver. It's called FFC/FPC. FFC is flexible flat cable, whereas FPC is flexible printed cable. This is very similar to the old school ribbon cables used in computers. There is actually a FPC between the panel and the driver board. THIS IS WHAT IS COMMONLY REFERRED TO AS THE TABs. The logic by using anistropic tape is that each panel is directly paired to the driver board, so no need to make available for individual replacement. It is kind of like a hamburger bun, you can't just buy the top half of the bun. It comes as one unit.

How to fix it?

FFC and FPC are essentially the same, the only difference is that FPC is more specific routing patterns and FFC is essentially a newer and smaller ribbon. Using skilled technique, replace this bonding with a fpc recepticle from molnex (or some other supplier). This is not the exact part but it is the kind that you are looking for. I dont have the exact specifics for each tv so you would need to find out how many pins and the pitch.

http://www.newark.com/jsp/search/pro...FC-GB100000001

Basically you need a low insertion force connector that is one sided (bottom surface) and has a side entry with locking mechanism. This is just like the connector that has the FFC ribbon between the tcon and the lcd driver board.

Techniques to solder it would be one of two ways. The first is beading each individual pin kind of like how you would a chip before soldering it to a board. Using a small heat gun to heat up the solder and seat it to the pins on the lcd driver board. It would be wise to mark on the board which are the starting and ending pins covered by the lcd's FPC. The second technique is to use a lot of flux and solder each pin individually. Don't worry about them bridging b/c you will go back with a wick and clean it up. Here are some video's demonstrating the techniques.

http://www.youtube.com/watch?v=EqJN1CTCOQs

http://www.youtube.com/watch?v=wMKXZ...97CBCCFA3C550D

http://www.youtube.com/watch?v=IhDsN...=17&playnext=2

http://www.youtube.com/watch?v=e5qYG...eature=related

If you need help, youtube some videos on SMT (surface mount technique) or Fine Pitch Soldering, etc. etc.

WARNING: I DO NOT RECOMMEND THIS UNLESS YOU TRUELY HAVE TO DO SO. IF YOUR TAB IS JUST SLIGHTLY AFFECTED, TRY SOME SORT OF LOW HEAT TECHNIQUES (SUCH AS A CLOTHES IRON ON THE 1-3 SETTING FIRST, IF YOU NEED TO GO HIGHER, MAKE SURE THERE IS NO WATER IN IT AND IT IS SET TO DRY HEAT ONLY!!!!) I AM NOT RESPONSIBLE IF YOU RUIN YOUR TV.


NOW GO LEARN HOW TO SOLDER, AND FIX YOUR TV THE RIGHT WAY!!!!
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post #2 of 5 Old 11-02-2012, 11:37 AM
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Great post!! The one and only of it's kind! I know it's been nearly a year... maybe you're still monitoring this thread?

Just traded an extra monitor I had lying around +$10 for a 52" Bravia with this TAB fault issue.

The symptoms match perfectly with this particular problem. (darkening of screen on side, trippy/ghosting of one side)

Pushing on the bezel does nothing, and I have yet to take it apart to attempt other pressure checks... so my TAB may be long gone in terms of it's adherence to the panel.
I wanted to be sure I had every option available to me before I pulled it apart, because I only want to do it once!!

If a standard electrical tape strip wont fix it, or a spacer/bumper won't either, I am going to attempt this.

Obviously, I need to get inside the TV and visually follow what you've suggested before I tinker around.

Is this a repair you've conducted?

Any suggestions for possible problems while taking on the repair?? Did it work well??

I'm excited that there seems to be a logical way to fix these problems more permanently than electrical tape....
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post #3 of 5 Old 01-26-2013, 01:17 AM
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I picked up a NEC LCD5220 with what I believe is this same fault. I had it tested by a local TV repair shop and they told me the only thing wrong with it is the LCD panel itself and that it would need to be replaced. I'm only having issues with one side of the panel. Here's a video of what it's doing on YouTube:

NEC LCD5220 Display Problems

As you can see, about 1:15 into the video the whole left side goes vertical lines. When I move the unit around the picture usually returns. Lately, when I just turn the unit on the whole left side has vertical lines until I move it around a bit.

I'm not exactly sure what's wrong but I'm going to take it apart at some point and see if I might be able to do some sort of repair to get it fully working again - at least for a few months.

slinkybeats, how did your repair go?

urgodfather, any more info? I know it's been over a year and a half since you first posted, but any more thoughts?

To anyone else, you're thoughts would be appreciated!
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post #4 of 5 Old 09-04-2013, 04:07 PM
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Watch this video i found on You Tube.
http://www.youtube.com/watch?v=xHst6pKLtTE

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post #5 of 5 Old 09-04-2013, 05:08 PM
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Quote:
Originally Posted by tubetwister View Post

Watch this video i found on You Tube.
http://www.youtube.com/watch?v=xHst6pKLtTE

Interesting video. I have actually performed a similar "repair", although I would call it more of a "band-aid". Because it's not a permanent fix, though it may be effective.

My LG 65LW 6500 developed a red/purple vertical line near the right side. At first it was only after the TV heated up, but it became more or less permanent. Like the guy in the video, I removed the back and the bezel of the TV. On the LG, the ribbon cables are lined up across the bottom of the panel. I could make the vertical line go away with slight pressure on the rightmost ribbon cable. Looking more closely, I could see that the ribbon had a slight crease in it a fraction of an inch from the panel. The ribbon also looked slightly longer than the others. So I surmised that the bezel was too tightly fitting and caused the crease when the TV (and tape) heated up.

My fix differs from the video in that: I simply rolled up some electrical tape to make a pad and placed it *behind* the ribbon tape in the slight recess just below the panel. Right behind the crease. (I suppose latex surgical tubing would have worked also). This was to keep the bezel from exacerbating the already present crease in the ribbon tape. The pad keeps the tape flat at that point and any movement due to heat expansion occurs further back the length of the ribbon tape.

At any rate, the TV has been fine since February this year and it's on several hours each day.
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