Changhong LCD TV LED50C2000 model had a "three no" fault. After disassembling and testing the power board, the primary voltage was normal, but there was no 12V output on the secondary side. When I unplugged the motherboard's 12V connector, the power board output returned to normal. Further testing revealed that the motherboard's 12V line was shorted to ground.
After further investigation, it was confirmed that the issue was a low-voltage 12V short to ground. The next step was to disconnect the 12V power supply and replace the 4803A component with a known good one for testing.
The sound was still very quiet, and it wasn't directly connected to the input port. It seemed like the audio block might be causing the problem. So, I decided to remove it.
Re-soldering the original audio block was quite challenging. At the C827 position, a 0.1 microfarad capacitor was installed, and after testing, the sound quality improved significantly. The TPA3110 chip still performed well, delivering strong audio output.
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