Since I joined the appliance repair forum on March 31st, I've been completely hooked. In my free time, I don't play games anymore—I spend almost all my days and nights there. I've even been working on repairs for a few days straight, and it feels like I've forgotten that I'm actually a professional in home appliance repair.
One afternoon, a customer called and said his TV had no sound or image and needed help immediately. I was so deep into the forum that I told him to come back tomorrow. But then he mentioned there were two other TVs to fix as well, and we could go together the next day to save on gas.
The customer was clearly upset, saying he wanted to watch an amazing TV series and didn’t want to miss any of the plot. He used some kind words, and since I’ve been running the shop for years, he respects me a lot. I didn’t want to hurt his feelings, so I reluctantly agreed to go to his house.
When I arrived, the homeowner was very polite. After a short conversation, I noticed the TV had a black screen but still had sound—something we often see due to a loose solder joint. The model was Konka P25SK071. I opened the back cover, removed the board, turned on the power, checked the key voltages, and suddenly the raster appeared! I connected the antenna, and both the image and sound were normal. I assumed it was a common issue with a cold solder joint, so I re-soldered the main chip OM8373 and others. After reinstalling, the screen was gray and black again, so I went back home right away and didn’t visit the other two customers. It wasn’t too late, and I rushed back to the forum—truth be told, I was already addicted.
After two more days, I finally fixed the other two TVs. Then, a few days later, the Konka owner called again, saying the TV had no response at all. I couldn’t ignore it, so I immediately went to his house. My rule is always: prioritize rework, and if necessary, do everything possible to fix it.
This time, the TV had no power at all—the indicator light wasn’t even on. Even though the owner remained polite, I could sense some doubt in his expression. I thought to myself, maybe he was thinking, “This machine was already fixed by you.â€
I opened the cover and started checking. I removed the backlight tube, connected a dummy load, and turned the power on. The indicator light came on, and the +B voltage was normal. The reverse path capacitance was fine, and there was no obvious short circuit. Since the previous repair had already addressed the virtual soldering issue, I didn’t check further. I replaced the tube and the crystal, and the boot image was normal. After about half an hour, when I touched the tube’s heat sink, it felt slightly warm. I assumed the tube had failed accidentally and installed it again.
As the student left, the homeowner handed me 20 yuan for the cost, but I refused to take it. He thanked me repeatedly.
Things went smoothly for a while, but I kept thinking about the machine. A few days ago, after lunch, the phone rang. It was the Konka owner's mobile number. The situation wasn’t good, so I answered immediately. He said the TV had no image again.
I quickly went to his house and got straight into repair mode. This time, I didn’t have the heart to observe his face. I powered on the TV, and the sound was normal, but the line output stage wasn’t working. The voltage at the tube was only 1.1 volts. I checked the primary coil of the transformer and found copper-green mold in the deep pins. The owner mentioned that before the problem occurred, there was a vertical bright band in the middle of the screen. Now I knew the real cause—it was the transformer's primary coil that had gone open. I replaced the transformer, and everything worked perfectly again.
Before leaving, the owner insisted on paying 50 yuan for the second repair, but I only accepted 20.
Summary: The two black screens were caused by the transformer’s push coil. Because the primary coil was open, it would work normally when the switch was on, but when it wasn’t, it would result in a black screen, leading to the initial diagnosis of a cold solder joint. The burned tube was also due to the lack of incentives for the line to push the mold.
Chinese Tier 1 brand Solar Panel (Longi, Jinko, Trina, Canadian, Ja etc.)
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TIER 1 brand include
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quality warranty
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grade
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power range
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