How to Repair LED TV Screen Panel with Display Rolling Problem?
This is an LED panel repair article. This LED TV screen with rolling problem is causing by the Panel STV signal line abnormal. Photo below is the LED TV screen problem:
The LED screen problem is rolling vertically. But the TV screen contains the characters and display normally just rolling only. Usually, if the tv screen rolling vertically is causing by their Gate driving side (supply/signals line). If you’re not sure about that, please refer to my new ebook “LED/LCD T-CON & Panel Repair Guide” for more details. To isolate the TV display problem, actually we can use the LVDS panel tester or another similar tool to testing it. So that you can confirm the problem is in T-con (Panel) or the Mainboard easily. But make sure you know how to use the tools correctly. Or you can also use different methods to isolate the display problem (for example: Oscilloscope), it depends on your skills and testers you have, too. From the above photo, this TV panel can showing their contents/characters normally, but just rolling only. That’s mean their supply lines VGH & VGL are normal. So, concentrate to check the Gate driving signal lines from T-CON to Gate COF there.
Below is the voltages check on this TV Panel Source board (built-in T-con section): VGH= 18V~33V VGL= -5V ~ -10V VDD= 3.3V VCOM= 5V~10V OE= 0.6V ~1.2V CPV= 1.5V ~ 2.2V STV= 0V (divided to STV-IN & STV-OUT) GND= Ground The above voltages values on T-con board is quite normal. So next step is checking their Panel Gate COF (this panel Gate driver have external COFs) voltage points. While measure the Gate COF voltage points, and found one of the point when meter probe touching it, the panel screen stop rolling and display perfectly! Refer to the COF BoardView in ebook and found this point is STV point. So suspect their line in between Source board STV to COF STV is broken or abnormal. Use the COF Bypass Modification method, use a wire connect the STV point on Source board and another wire side connect to the COF STV point too. Refer to the photo below:
Finally, this LED TV panel problem solved, and it can be display perfectly. Actually, this LED TV Panel was gave up by another TV repair shop, where they said this TV panel is beyond repair.
Notes: If the T-con board/section you can’t find the STV point, you can refer to “GSP” marking. Actually, both are the same thing, just different manufacturer using different word only.
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