I'm not going to write this article myself, but you can check out "TV Cooling Maintenance Technology" after the dominance. Think about it or just write it down yourself (I don't want to write it because I didn’t take any pictures during the maintenance of two cases of this model, and I didn’t think too much about it). It's not about rushing to win a prize, just a technical exchange. If there are similarities, please forgive me!
I saw that some forum users mentioned that LG plastic screens have interference lines, and when turned on, the screen goes black after a few seconds (similar to backlight protection, where the screen isn’t completely black but very dark). Sometimes the image flickers, and sometimes the upper part of the screen is normal while the lower part is black. When these issues occur, the backlight works fine, and the sound is also normal.
The solution proposed by some users was to clean the screen’s gold fingers, use aluminum foil to cover the screen lines, wrap the logic board, and even wrap the back casing. Some interference could be resolved this way. However, if the interference is severe, wrapping with aluminum foil might not help. To be honest, they never found the real source of the interference. These two repaired Haixin TVs are used to demonstrate the solution.
Model: Hisense LCD TV TLM32H78 (0000)
Screen Model: LC320WXE (SB) (V2) (LG Plastic Screen)
Power Board: RSAG7.820.1731/ROH (two-in-one board)
Digital Version: RSAG7.820.4143/ROH
Case 1: The TV boots up with the Hisense logo, then turns black after about 3 seconds (the screen is dark, but the backlight is bright, and the sound is normal). The screen isn’t completely black—it’s very dark. After several days of testing without success, I thought the issue might be caused by the backlight tubes, which could lead to black screen protection. I explained the situation to the customer, informed them of the risks involved in removing the screen, and obtained their consent before proceeding.
This model uses an LG plastic screen with 10 EEFL tubes connected in parallel. Two tubes are placed on each side, connecting all 10 tubes in parallel. There are lines on both sides of the screen connected to the high-voltage board. When opening the screen, there are two key points to note:
- Before removing the screen, remove the small screws around the edges, take off the side strips, and lift the LCD panel using the high-pressure cap as a suction cup. Once moved, remove the suction cup and gently lift the left and right sides of the screen onto a flat surface.
- After removing the screen, there are self-locking plastic strips on both sides. Remove them to access the diffuser board, which has three layers—two thin ones and one thick one. Underneath, you’ll see 10 small parallel tubes.
Note 2: Each end of the lamp is fixed with five small flat-head screws. Remove four screws from each side, leaving only one in the middle. Then, remove the central plastic clip. Each lamp has a clip in the middle. Hold the clip and gently lift it upward, being careful not to apply too much force to avoid breaking the tube. After removing the clip, take off the remaining screws on both ends. With both metal strips in hand, slowly lift the lamp group downward.
Once the lamp is removed, there’s a light-shielding plastic piece under it. Beneath each tube, there is a 6 mm wide tin foil strip. Use a multimeter to check if the two ends of the strip are connected. In this case, 6 out of 10 were faulty, with 4 working normally. The broken strips showed local bulging, likely due to thermal expansion over time. I decided to replace them, even though it wasn’t worth much money. I bought aluminum foil paper about 48 mm wide, cut it to length, divided it into six pieces, each 8 mm wide, and installed them in the opposite direction of removal. After reassembly, the TV worked fine.
The first time I removed the EEFL lamp, I accidentally broke one of the clips in the middle, but I had a spare in stock.
Case 2: Same model, different symptoms. The TV turns on in cold state, and after 5 minutes, the image starts to flicker and dim, with occasional horizontal interference lines. Eventually, it turns black, but the backlight is still on, and the sound is normal.
Maintenance date: May 2016. The machine was purchased five years ago. All board voltages were normal. Following the previous experience, the process of removing the screen was the same as in the first case. After removing the screen, I directly measured the tin foil strips and found 3 breaks. Replacing all 10 strips took about 2 hours, and the TV worked fine for 2 hours afterward. Unfortunately, no photos were taken during the repair.
If there are any shortcomings in this explanation, please forgive me! This is just my personal experience shared for technical discussion purposes.
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