Hisense plasma TPW32V68 power supply repair - Home Appliances

DFN1006 TP-RCLAMP3321P ESD Diode Low Capacitance

A customer sent a Hisense 32-inch plasma TV for repair. He mentioned that the screen had some issues, but it wasn't fully broken. I thought that if the YZ board was burned, no matter which part was damaged, it wouldn’t be completely functional. So I didn’t want to spend too much time on it. However, today I decided to take a closer look. The first thing I noticed was the LG PDP32F1 screen, which looked more promising compared to the previous two repairs where Samsung screens were partially dead. The power supply board appeared to be in good condition. I checked the ground resistance of VA and VS, and they were fine. The two fuses on the Z board were intact as well. When I powered up the unit, there was no response—no power at all. I measured 5V and found nothing. After removing the power board, I checked it thoroughly and found only one issue: R1513A00SMT was 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 properly, so I tried powering it again. But when I turned it on, the power supply immediately collapsed. I double-checked the power supply circuit. When I removed Q151, the transistor was soft-punched. Testing it with a 1K resistor showed normal results, but with a 10K resistor, there was leakage at the SD level. After replacing Q151, the boot image appeared, and the DVD playback worked, although the power supply still made a loud noise. Next, I tested C151 (102), C154 (10UF), and C156 (47UF). All were within normal range. R158 had a low resistance, indicating it was okay. On the flip board, I found a Schottky diode SB140A connected in parallel with R158, but it was shorted. Since I didn’t have that specific part, I used a 1A 40V Schottky diode from a previously purchased Xiaohong 6456 power supply module. After replacing it, the TV worked perfectly—both picture and sound were clear.