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

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Fault phenomenon: A TCL LCD TV was struck by lightning and now shows three no signs of power. After opening the casing, I disconnected the power supply board and motherboard for inspection. The power supply board model is 40-E061C3. Upon checking, I found that the copper foil between points A and B had burned out, along with a blown R116 resistor. The power management IC 6754 showed visible cracks. After removing the IC, I noticed that the copper trace between points A and B was actually a hot ground line. Due to its thinness, it couldn't carry the current effectively. So, I connected points C and D as a temporary fix. Then I replaced the 6754 and R116, checked the voltage sampling, and powered on the unit. The 24V output was normal, but there was no 3.3V output.

This TV uses a small board to convert 12V to 3.3V. I checked the input voltage on the small board and confirmed it was normal. There was no short circuit on the output side. Therefore, I concluded the small board was faulty. Since I didn’t have a replacement, I decided to use an LM2596 module instead. I connected the module to a 12V DC power source and adjusted the potentiometer to get a stable 3.3V output. Then I tested it with 24V and 6V inputs and confirmed the output remained at 3.3V accurately. This proved the substitution was successful.

The module board was slightly larger than the original, so I had to find a suitable mounting space inside the TV. Once installed, I reconnected everything and did a final test. The system worked well, and the 3.3V output was stable. It’s always important to carefully analyze the issue before making replacements, especially when dealing with sensitive components like power management ICs and voltage regulators. Sometimes, a simple fix or a substitute component can solve the problem without needing to buy a new part.