Skyworth LCD TV LED46E70RD indication is not bright, sometimes can be turned on - android - Phones Developers

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Recently, I had a tricky repair on a Skyworth LCD TV model LED46E70RD. The issue was that the indicator light wasn’t lighting up consistently, and sometimes it would turn on briefly but then go out. When the user first called, they mentioned that the screen had no power, but after checking the voltage levels—380V, 24V, 12V, 5V, STB high level, and P-ON/OF voltage were all normal—it still didn’t work properly. After unplugging and plugging the screen cable, the TV turned on again with the blue light on, backlight working, and background sound coming through. But after some time, the problem returned, and I suspected a logic board issue.

The next day, the user called again, saying the TV was not working again. I went back to check and found the same symptoms: voltages were stable, but the screen wouldn't stay on. After multiple attempts of plugging and unplugging the screen cable, the TV worked temporarily, but the issue persisted. I started suspecting a faulty mainboard or possibly a loose connection. I checked the power board for any solder issues but found nothing wrong. Then I focused on the motherboard, noticing that the main chip was getting extremely hot during boot-up.

After repeated testing, I realized that pressing the main chip slightly after booting could temporarily fix the issue. However, the screen would still go black, and the speaker would make a strange noise like an old TV. I discussed this with the user and explained the situation honestly. I told them I’d do the first repair for free, and if it didn’t fix the problem, we could consider replacing the board. The user appreciated my honesty and agreed to proceed.

Here’s what I did step by step: First, I used a heat gun to warm the heat sink on the chip for a few minutes, keeping the temperature under 280°C. Then, I carefully removed the heat sink using tweezers. I used a scalpel to cut around the edges of the chip and covered the surrounding small components with aluminum foil to protect them. Next, I applied BGA solder paste to the bottom of the chip with a heat gun and placed it back on the machine. I heated the chip until it started to smoke slightly, then added more solder paste while gently touching the chip with tweezers. Once the temperature reached 240°C, I continued heating and adding solder until the chip was fully reflowed.

After cooling down, I tested the motherboard for several hours, repeatedly pressing the chip to ensure stability. Everything worked perfectly after that. The user was happy with the repair and thanked me for being honest and helpful. This kind of customer interaction makes the job much more rewarding.