TCL LCD TV power supply lightning strike three trouble-free repair - android - Phones Developers

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Fault phenomenon: After a lightning strike, the TCL LCD TV shows no power, no display, and no sound. After opening the cover, I disconnected the power supply board and the motherboard. The power supply board model is 40-E061C3. Upon inspection, the copper foil between points A and B was burned out, and resistor R116 was also damaged. The power management IC 6754 showed visible cracks. Removing the 6754, I found that the copper trace between points A and B was acting as a hot ground wire. Due to its thinness, it couldn’t be reconnected through the original path, so I connected points C and D instead. I replaced the 6754 and R116, checked the sampling circuit, and everything looked normal. When powering on the unit, the 24V output was normal, but there was no 3.3V voltage. This particular 3.3V is generated by a small board that converts 12V to 3.3V. The input voltage to this small board was fine, and there were no short circuits on the output side. Therefore, I concluded that the small board was faulty. Since I didn’t have a replacement available, I decided to use an LM2596 module board as a substitute. I connected the module board to a 12V DC power source and adjusted the potentiometer to set the output to exactly 3.3V. Then I tested the module by applying 24V and 6V inputs and measured the output again. It maintained 3.3V accurately, confirming that the substitution worked properly. However, the module board was larger than the original small board, so I had to find a suitable mounting space inside the TV. Once installed, I reconnected the power board and performed a final test. The unit powered on normally, and the 3.3V output was stable. The repair was successful.