Peer sent a Hisense 32-inch plasma TV for inspection. He mentioned that the screen was not fully damaged, and I thought that if the YZ board was burned, no matter which part was affected, it would still be non-functional. So I didn't want to keep it for a few days. Today, I decided to take a look. First, I checked the screen model LG PDP32F1. It looked more practical compared to the previous two repairs, which were both Samsung TVs with faulty screens.
The power supply board appeared to be in good condition. The VA and VS lines had proper ground resistance, and the two fuses on the Z board were intact. When I powered up the unit, there was no response. I tested the 5V line and found no voltage. After removing the power board, I found that the only issue was R1513A00SMT being open. According to the specifications, this should be a fuse resistor. I replaced it with a 2A fuse and reinstalled it. The 450V filter capacitor charged normally, but when I plugged the unit back in, it immediately shut down upon turning on.
I rechecked the power supply circuit. When I removed Q151, I found the transistor was soft-burned. Testing with a 1K resistor showed normal results, but with a 10K resistor, there was a leakage at the SD level. After replacing Q151, the boot image appeared, and the DVD video and audio played without issues. However, the power supply made a loud noise during operation.
I then checked capacitors C151 (102), C154 (10UF), and C156 (47UF), all of which were functioning properly. The resistance of R158 was low, indicating it was fine. On the flip board, I found a Schottky diode SB140A connected in parallel with R158. Upon testing, it was found to be shorted. Since there was no such diode available, I used a 1A 40V Schottky diode from an old Xiaohong 6456 power supply unit as a replacement. After installation, the TV worked perfectly with clear picture and sound.
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