At 7 PM tonight, a customer brought in a Skyworth LCD TV model 32E55HM for repair. The unit was as shown in the image. When I powered it on, the red light came on but kept flashing. It couldn't be turned on via the remote or the standby button. The customer asked about the repair cost. After hearing the price, he tried to negotiate. I refused and told him to call back if he wanted to proceed.
After opening the case, I started testing. The power supply filter capacitor voltage measured 350V, which was normal (this model doesn’t have a PFC circuit). The power chip used is TEA1733P. The voltage at pin 1 was 20V, while pin 5 only showed 2.3V. I wasn’t sure if that was normal, but something felt off. I checked the output voltages again: 24V was only 15V, 12V was 6V, and 5VSB was just 3.5V. The indicator light flashed because of the unstable 5V rail. This clearly prevented the TV from booting up properly.
Since there were no schematics available, it was hard to tell if the issue was in the power supply or the main board. To test, I disconnected the motherboard and used a bulb as a load. I connected the 24V and 12V lines to the bulb and forced the power on. The bulb didn’t light up, and I only heard a "beep" from the power supply. At this point, I suspected the power chip might be faulty.
I turned off the TV, discharged the power supply capacitors, and removed the TEA1733P. I replaced it with a new one, then powered it on again. This time, the bulb lit up! I reconnected the motherboard and powered it on. The indicator light stopped flashing, and I saw a green light. The backlight also turned on, and I could hear the splash screen sound. The signal line showed normal video and audio output.
After the repair, I downloaded the power supply schematic for this TV online and shared it with others. Here are some photos of the process and the schematic file:
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