TCL color TV screen only blue green color alone lacks red strange fault sharing - android - Phones Developers

0805 side blue

Recently, the misty rain in Shantou, South China, has been quite similar to the "West Lake March Day" scene, with temperatures ranging from 12 to 18°C. The light drizzle carries the fragrance of flowers and plants outside the window, creating a gentle symphony of nature. Sipping a rich cup of Kung Fu tea while chatting with a friend over a sea otter is a perfect way to spend a quiet afternoon. Then, the phone rings — it's the CEO of a cosmetics company calling. He says his home TV is broken, and it's the mental support of his father. He asks me to come over for a check-up. According to the appointment, a 34-inch TCL high-definition TV was playing something. The image was mostly blue-green, with red appearing purple, but the sound was fine. The boss said he rarely repairs appliances these days and didn't want to ask me directly. Instead, he called two maintenance experts, both of whom gave the same response: “Like the ancients!” He originally wanted to replace the LCD panel, but his father insisted that the old CRT TV was still good, saying it wasn’t bright enough and even joked about Yao Ming being a dwarf. The father believed the color was still very good, so they decided to fix it instead of replacing it. The boss also knows a bit about electronics, and since the TV is less than five years old, there was no reason to throw it away. After disassembling the TV, I checked the three-color outputs. R was at 175V, G at 152V, and B was almost the same as G. Rechecking the RGB excitation showed a balance of around 2.3V, so it wasn’t a color difference output issue. The fault was narrowed down to the output board. Further analysis suggested that if the R output were cut off, the voltage should be around 200V, but it was only 175V, which is relatively high. Could the emission capability of the R gun have dropped? We all know that voltage and current are inversely related. Since the R output wasn’t fully cut off, this indicated a possible reduction in the emission capacity of the R gun. However, the father mentioned that it had been working fine a few days ago. In my experience, an X-ray tube doesn’t just “die” overnight. It’s more like a cordless phone transformer — if it’s 7.5V, it works fine. Checking the three guns, everything looked normal, so the tube itself still seemed healthy. I replaced the output IC, checked all the bypass capacitors and clamp circuits, including ABl, but found nothing wrong. This situation was really strange — like an ancient mystery! Haha, after over 20 years in the repair business, can you really stump me? As I smoked a cigarette and sipped some tea, a smile played on my lips. High-definition video tubes are special, and sometimes the problem lies not in the circuit, but in the internal components — like the tube socket. I removed the tube seat and saw the truth: the connection for FOUS2 had completely broken! Quickly replacing the socket, the image came back to life, vibrant and clear. The boss’s father smiled, showing his teeth, though he was still holding an unfinished cigarette. He told his son, “Look, this TV is still good.” The boss was speechless... The TV was fixed, and the praise flowed freely. But one question remains: why did the loss of voltage in FOUS2 cause a drop in the R output current while G and B remained normal? I hope the experts here can shed some light on this. Tip: Due to the unique nature of high-definition video tubes, some faults differ from traditional CRTs. So, when circuits appear normal but strange issues persist, don’t forget to consider the tube socket — it might be the key to solving the puzzle!