Changhong plasma TV 3D50A3000IV repair Y board case sharing - Home Appliances

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

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Two days ago, in the afternoon, a customer brought in a Changhong TV for repair. The model is shown above. When I turned it on, the panel showed a red light. After pressing the power button, the indicator blinked a few times and then shut down. My first thought was that the Y board might be damaged.

I started by checking the voltage on the power board. The VS voltage was 0V, which raised some concerns. Then I removed the Y board and connected the test bulb to the VS and ground on the power board. When I powered it up, the bulb lit up, and the logic board's indicator also turned on. I could hear the TV startup sound, which suggested the power board was working fine. So the issue was likely with the Y board or the sustain board.

I tested the resistance between VS and ground on the sustain board and found no short circuits. Then I checked the Y board. The resistance between the VS terminal and ground was 0 ohms, confirming that the Y board was indeed shorted.

The Y board, also known as the scan driver board, plays a crucial role. It takes the scan control signal from the logic board and converts it into a scan drive waveform using FETs. This signal is then passed to the buffer board, which sends the scanning waveform to the panel's electrodes through integrated circuits. The buffer board is usually split into upper and lower sections.

If the Y board is faulty, common symptoms include a completely black screen, partial black areas, or a distorted image. In some cases, the buffer boards can also get burned out.

Knowing this, I proceeded carefully. I first inspected the small ceramic capacitors on the Y board and found C419 (331/1KV) had a burn mark. I replaced it with a 471/2KV capacitor. Next, I checked the FETs but didn’t find any issues. However, I discovered that Q410 (RJP30E2) was fully shorted and burned out. On the other side of the board, Q409 (SMK1360) and Q407/Q408 (FGPF4536) were also damaged. Additionally, D416 (20F40HF) was partially failed. Other components appeared normal.

After sourcing the original parts online, I installed them one by one. I was a bit nervous before powering it on again. A small mistake could cost me a lot. But I decided to take the risk. As soon as I pressed the power button, I heard the TV start up. I looked at the screen—only a white screen. What happened? Did I miss something?

I put the TV down and took a closer look. Oh my god! I had forgotten to connect the plug wire to the driver board. That was a silly mistake! I immediately powered it off, reconnected the cable, and powered it on again. This time, everything worked perfectly. The screen displayed normally, and the picture was clear.

It’s amazing how a small oversight can lead to confusion. But after fixing it, the TV was back to its normal function. Here are some photos of the process:

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