Model: LC55FT68AC
Screen model: LTA550HF02
Symptoms: Vertical ghosting during boot screen. After turning on, the screen works fine for the first 5 seconds, then starts to crawl upwards slowly and stabilizes after 30 seconds, showing about 50 lines. Even after turning off the power, the vertical ghosting remains. After 24 hours of power-off, it works again for 5 seconds before the same issue occurs.
LCD TV repair is not my main expertise, so I did a lot of research online, including Baidu and forums. Initially, I thought it was a vertical drive failure, possibly due to a faulty component. I suspected a leaking capacitor or an issue with the motherboard RAM or logic board connection to the screen.
Since it's a ghost image, I didn't think the power board was the main issue. I started by opening the motherboard, but without proper schematics, it was risky. I tried replacing the motherboard with a known good one from a local store, but the problem remained. It felt like hitting a wall.
Next, I tested the logic board. Voltage readings were normal—12V and 3.3V were both stable. Still, the issue persisted. I decided to replace the board again, but that also didn’t solve the problem.
At this point, I was pretty sure the issue was with the screen itself. I had already spent a lot of time and effort, and giving up wasn’t an option. So I went ahead and removed the screen.
After disassembling, I was shocked. The screen was fully integrated, with the column driver external and the line driver embedded. That meant no standard repair could fix it. I still had nothing left to lose, so I disconnected the right board’s cable and noticed that the left half of the image was normal, while the right half or the entire frame showed ghosting.
Using an oscilloscope, I checked the CKV1-3 and CKVB1-3 signals. The waveforms were symmetrical, inverted, and each was 120° apart. Since the left side was working, I realized the internal dual-line driver chip might have a fault.
I considered using the remaining functional chips to drive the entire screen, but that wasn’t feasible. I had to make a risky move. I used a sharp blade to cut the CKV1-3 lines and connected them to CKVB1-3 instead.
After powering on, the screen worked after 3 seconds! It was a big relief.
I took a photo of the repaired screen and ran a 4-hour test without any issues.
Summary: Due to limited experience and lack of technical resources, I made several wrong turns, which led to wasted time and effort. The root cause was likely a misalignment or damage in the built-in driver chip caused by thermal expansion and contraction. Since the chip is embedded, it can’t be replaced easily. This kind of repair is more of a workaround than a permanent fix, but it saved the screen from being scrapped.
Although not 100% reliable, the success rate is around 85%, which is quite good compared to just throwing it away. I apologize for not being able to upload more images due to space limitations.
That’s all. I’m ready to continue my work. Thanks for your support!
A battery connection cable are the type of wire used to connect a battery to an electronic device. The are usually made of conductive material, such as copper or aluminum, and has a pair of connectors that connect one end to the positive end of the battery and the other end to the negative end of the battery.
The main function of the battery connection cable are to transmit current and electrical energy. They direct the current from the positive end of the battery through the positive connector, and then transmits it to the electronic device through the cable. At the same time, the negative connector directs the current from the electronic device back to the negative end of the battery, forming a circuit closure.
Battery connection cables are usually of a certain length and flexibility in order to provide a flexible connection between the electronic device and the battery. It may also have a protective housing to protect the cable from damage or wear.
When choosing a battery connection cable, you need to consider factors such as current transmission requirements, battery and device connector types, and cable length and material. Proper selection and use of battery connection cables can ensure a reliable connection and power transfer between the battery and the device.
Battery Connection Cable,Car Battery Wire Harness,Black Connection Cable,Battery Connection Wire Harness
Suzhou Yonghao Cable Co.,Ltd. , https://www.yonghaocable.com