I recently worked on a Skyworth 32L01HM LCD TV that had no power. The user mentioned that none of the lights were working, so I decided to take it apart and do a thorough check. After disassembling, I tested the main filter capacitor and found that the 380V voltage was normal. However, the power board only provided 3.5V for the standby power supply instead of the expected 5V, and all other output voltages were zero. Pressing the channel buttons or using the remote control had no effect.
Since the main power supply is controlled by the standby power and the motherboard, I first checked the standby power supply. Upon removing the heat sink from the power board, I noticed a swollen electrolytic capacitor. I then examined the 5V output filter capacitor on the power supply circuit. It was rated at 10V 680µF, but after replacing it with a 35V 1000µF capacitor, the voltage returned to normal, and the standby red light turned on. When I pressed the channel key, the TV started up normally and displayed the logo.
Next, I connected a DVD signal, and the image appeared fine. However, the sound was very loud and seemed to come from only one speaker, while the other side was normal. Even when I unplugged the audio cable and only used the video line, there was still noise in the channel. The TDA8932BT amplifier was powered on correctly, and the voltages on its pins were mostly normal. However, the power amplifier block felt extremely hot when touched, which made me suspect it might be damaged.
After checking online and comparing data, I found that the sound adjustment circuit in this model is prone to failure. It consists of an L358 IC (U45) and surrounding RC components. Replacing the L385 chip didn't help, but upon further inspection, I discovered that resistor R455 was open. Its nominal value was 33K, but I found two regular resistors in series, which were likely causing the issue. Replacing them fixed the problem completely.
The faulty resistors were R455 and R459, both of which were open-circuited. This repair restored full functionality to the TV, including clear sound from both speakers without any distortion.
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