TV Repair Questions? Ask a TV Technician
Link to screen pictures: http://imgur.com/a/CwrOA#4
The LCD screen seems to be putting out more heat then normal, after it has warmed up for 20 min.
I assumed this was not a LCD panel, because there are several different problems in different location of the screen, which start working at different times during the 20 min warm up.
If this is a bad LCD panel, are there components of the LCD panel which can be replaced to fix this problems.
I tried this already and did not get any improvement. Once I take the TV apart, I will be able to press on the cables directly to test this out better. I assume the problem is not the cable problem, because the problem goes away after a short warm up. Also the low brightness problem is across the TV display, not just on the right 4" like all the other problems are. The different problems are fix at different times during the warm up.
It is gradual process.
Most of the problems clear up in the first 10 min. except the solid thin line on the right side of the screen from top to bottom, which clears up in another 10 min.
Hi,Ok, thanks.What you have here is a faulty LCD panel (the screen itself). More specifically, some of the TABs on the panel are faulty. "TAB" stands for "tape automated bond[ing]" which is part of the LCD panel's manufacturing process (TABs are permanent connections between the electrode layers of the panel and the panel's inputs).Sometimes a TAB will break, separate, or otherwise fail and cause a particular area of the screen to malfunction (there are horizontal and vertical TABs).Usually and as you noticed, turning the TV on for a while will remedy the issue because the heat generated will cause the panel to expand which will force the TABs to make contact (i.e., it "warms up"). This is what we tried to simulate by manipulating the screen.Eventually, even the thermal expansion won’t help… the TABs will fail completely. You might be at this stage already.The bad news here is that the only way to remedy this is to replace the panel itself (unless you have access to a $500,000 bonding machine), and a new panel would be far too expensive to be cost effective.This is actually a pretty common malfunction… I suggest you Google "LCD TAB bonding.” You’ll see lots of articles.I wish I had better news for you, but I hope this helps!If you need any clarification or have more questions for me, click "reply to expert" and let me know. If you're finished, please click the smiley face that best represents the service I've provided. If the system won't let you click a smiley face, please let me know because without your rating, I'm not compensated for my time here. Rating me will not close your question (you can get back to me, if you need to).Best,Dan
One of the problems I have "The brightness on the complete screen is low, mostly in the middle of the screen" affects the complete screen, so I do not think this would be a TAB problem. See the dark pictures I uploaded.
Have you see a TAB problem that affects the brightness of the complete screen?
The other problem that does not look like a TAB problem is the slow refresh rate; but since this problem is only located on the right 4" of the screen, it may be a TAB problem.
I also assume that it is not a TAB problem, because I have 4 different type of problems. Also the problems do not clear up all at the same time. I assume a TAB problem will not slowly fix itself over time, the connection is either their or not.
I also assume by having four different problems like I have; it would have to be mutable TABs that have gone bad at the same time, which seems unlikely.
Relist: Incomplete answer. The answer said I have a TAB problem. I do not think it is a TAB problem. The answer also said I absolutely have some defective bonds, and may also have other things going on. I think the chances that I have a TAB problem and a second problem at the same time, is very unlikely. Please assign this to a expert with more experience working on LCD TV. I asked what test I should preform to help diagnose this problem. I did not get any recommended troubleshot recommendations. Ask the expert to provide troubleshooting recommendations and answer the below questions. Is it feasible to troubleshoot this problem by spraying the boards with cold spray one at a time while the TV is working okay to see what board stops working when cold? Can I use the TV's Service Mode to troubleshoot this TV.
Could the 4 problems I listed be a bad T-Con board with a heat problem. How likely is it to be a bad T-Con which only starts working after the TV heats up. Most heat problems I have seen, start working when you cool down the problem board, not heat it up.
Well, I would FREEZE the boards when they are BAD.....But I honestly think DAN is correct....
The Banding....the sluggish picture.... if you grab the left and right side of the TV and Twist/Flex the panel in it's frame.....the picture goes nuts and either fixes it or worsens it.
The right 4" of the screen from top to bottom has a very slow refresh rate (5 sec). When you change channels this 4" of screen will show a background image of the channel
Out of all the information you gave, there is always a piece of information that is "conclusive"
I know you'd LOVE it to be the TCON....because it's cheap and fixable.
But....I may have an alternative to save your LCD panel.
I've tried it....it works but the success rate is dependent upon WHAT is damaged.
I will let you know the TCON creates some of the issues, but the sluggish picture is the one that pushed it towards the LCD panel.
And note that the LAST thing to disappear is actually that one single line....it you think about it, and the information in the above pictures, you can pretty much draw your own conclusion about the problem and where it is.
My conclusion -- LCD Tab ICs
Dan's - LCD Tab ICs
Yours -- TCON.
1 Twist and Flex the frame of the LCD and see if it reacts, and if it does the LCD is bad.
2 Freeze the TCON when it starts clearing up the picture. If its bad it should go bad
I honestly think you'll find flexing the frame is going to make it respond.
And if so....there might be a cheap fix for it.
I took the back off the TV to try some testing with a heat gun. I did not have any cold spray, so I used a heat gun instead. When I turn back on the TV, the only problem I had was the two thin lines on the right side of the screen. I tried heating each of the boards and the lines never went away and the other problems did not show up.
When I flex the TV screen, I can get one of the thin lines to go off and on, so this is a bad TAB bond. I can not get the other problems to change by flexing the TV.
When I put the back on the TV and turned it back on, I only have the thin line problem and none of the other problems I had before when the TV was cold.
After 45 min of watching TV the other problems all came back and the thin line was gone. So the problems have now reverse, most of the problems don't apper on cold and show up after the TV has warmed up for 45 min. Befoere I took the back off and on, most of the problems show up on a cold TV and go away after the TV warms up for 30.
Since cold and hot reversed, I am now thinking all the problems are bad TAB bonds.
One of the problems is the brightness of the screen gos down. It is mostly dark in the middle of the screen. It looks like the brightness affects the right 3/4 of the screen. The most left 1/4 screen does not seem to be affected by this brightness problem, put the complete screen does not look as sharp as it was when TV is working correctly. Does these symptoms indacate bad TAB bonds. I did not expect bad TAB bonds to affect the complete screen.
Please provide your fix for bad TAB bonds.
I tried downloading a service manual for this TV, but when I try to review the manual; I just keep getting error message "The Zeus engine cannot be located". I have download and installed a version of the Zeus Engine I found on the internet, but still could not bring up the document. I also downloaded and installed Autodesk Design Review 2013.
I wanted the service manual to get instructions on how to remove the front bezel so I could do the repairs on the TAB bonds. This will also allow me to put pressure on each of the TAB bonds to see if this fixes my problems.
Do you know where I can find a PDF version of the service manual orwhere can I find a copy of the ZEUS Engine version which will work?
Update 9/4/12 I found the PDF Service Manual. It does not show how to remove the front bezel, so I will take off the bezel without instructions.
Thanks for your help,
The most left 1/4 screen does not seem to be affected by this brightness problem, put the complete screen does not look as sharp as it was when TV is working correctly. Does these symptoms indacate bad TAB bonds.
There's actually a lot of different symptoms that show bad tab bonds.
Picture is sluggish, you get 4 or 5 horizontal sections of picture, you sometimes see the onscreen displays repeat themselves below the original one (even a small bit of it.
Sometimes half the screen turns white or has a milky picture....
A TV set with a rigid plastic frame can make it hard to get it to act up, but flexy frames they show up pretty easily rocking/flexing it back and forth.
I've seen tab bonds mostly go bad in the top corner of the frame especially on the top right corner. I'll flex the top /bottom on both sides, and if the TV isn't too wide I'll grab the top left/right corners and flex it back and forth.
The Zeus engine cannot be located". I have download and installed a version of the Zeus Engine
Don't feel bad....I couldn't get the Zeus engine to work and I know about half the Toshiba tech couldn't get it to work either.
I don't know what Toshiba was thinking when they didn't go with PDF files.
Pretty much, you have to go with common sense, like knowing the rear cover comes off, then the whole chassis -- LCD and boards come out the back. You disconnect the speakers, and the power/Infrared reciever boards from the TV's main board. Then you go around the edge of the LCD frame and remove screws, along with the screws holding the wall mount bars to the plastic frame and literally lift the whole chassis off of the front faceplate.
Here is that TAB IC video -- the guy is doing it to a Sony, but a lot of LCD panels are only manufactured by 3 companies, and the design is pretty much the same. Remove the metal frame and the ribbon cables are right under it.
Did you notice the black/white snow was sluggish until he pushed on the ribbon cable and then it speeded up? That's the sluggish picture I mentioned. And notice the picture faded to a bunch of white streaks too? It's a slow fade to white on his, and any TCON problems are usually a sharp edged failure right down the middle of the picture, or a repeating line color like these --
Thanks for your help