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

LED light-emitting diode

Last night, a customer brought in a Sanyo 32-inch LED TV with the issue of "three no": no power, no display, and no sound. The indicator light wasn't lighting up either. Upon inspection, I noticed that the case had been opened, and there was a phone number stuck on the back, which suggested it might have been previously repaired or at least attempted to be fixed by someone else. The user mentioned that he had asked around and was told the mainboard was faulty, with a replacement costing 550 yuan. He decided not to go ahead with the repair. I took a closer look at the board and found it was a three-in-one board. When I tried to power it on, the power supply didn’t output any voltage. I informed the customer that the red-brown color (a common term for a specific type of fault) needed fixing. He agreed to proceed, left his contact number, and asked me to call him once the repair was done. Today, I did a power check and found that the 300V input was normal. However, when the power was turned off, the voltage dropped immediately, indicating the power supply could start but had issues with the secondary outputs. Checking further, I found that the 12V rail only had 2V, and the 24V rail had 0V. A continuity test revealed a short to ground on the 24V output. Further inspection showed that one of the rectifier diodes had failed. It was a Schottky diode, SR3200 (3A - 200V). I replaced it with an MBR5200 (5A - 200V), which solved the problem. The TV now powers on normally and works as expected. I've attached some photos of the faulty component and the repair process for reference.