32-inch Sanyo LED LCD TV three fault-free maintenance examples - appliance repair - Huaqiang electronic network

LED light-emitting diode

Yesterday night, a customer brought in a Sanyo 32-inch LED TV. The main issue was that the TV didn't turn on at all, and the indicator light wasn't lighting up. Upon inspection, I noticed that the screws had already been removed, and there was a phone number stuck on the back of the unit. It looked like someone else had tried to fix it before. When I asked, he mentioned that he had consulted someone who said the mainboard was damaged and suggested replacing it for 550 yuan. He decided not to proceed with the repair. I took a closer look at the board and found that it was a three-in-one board, which means the power supply, main board, and other components were integrated. After checking, the power supply wasn't outputting any voltage. I informed the customer that the red-brown color (a common term used in repair shops to indicate a specific type of fault) was the issue, and he agreed to proceed with the repair. He left his phone number and asked me to call him once it was fixed. Today, I did a power check and found that the 300V rail was normal, but after turning off the power, the voltage disappeared immediately, indicating that the power supply could start but wasn't functioning properly. I checked the secondary outputs and found that the 12V rail was only around 2V, while the 24V rail was completely dead. Further testing revealed that the 24V output was shorted to ground. After inspecting the circuit, I discovered that one of the Schottky rectifier diodes had failed. The original part was an SR3200 (3A–200V), so I replaced it with an MBR5200 (5A–200V), which resolved the issue. Here are some photos from the repair process:

This repair involved identifying a faulty component in the power supply section and replacing it with a suitable alternative. It's always important to double-check all connections and test voltages carefully to ensure the problem is fully resolved before returning the device to the customer.