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TCL color TV HID29276PB boot smoke problem repair - android - Phones Developers
During the viewing process, a TCL color TV model HID29276PB suddenly emitted an unusual noise and smoke from inside. After removing the main circuit board, I discovered that resistor R419 was burned. Checking the data, I found that R419 is a 1K (0.125W) resistor, which serves as the ABL output resistor in the high-voltage section.
Overhaul Process:
1. I replaced R419 with a 1K (0.5W) resistor. After installation, when the TV's high voltage started to operate, it smoked again. Upon inspection, not only was R419 burnt, but also R425 and R426 were damaged.
2. After replacing those three resistors, I rechecked the line tube drive circuit and power supply voltage. No abnormalities were found, but the three resistors burned again. This made me puzzled.
3. When I couldn't find the cause, I turned to online forums for help and posted a detailed message. With the assistance of other technicians, I re-examined the row tube drive circuit and the video panel’s ABL control circuit. During this check, I found that resistor RN425 on the video panel was also burnt.
4. I ordered a new high-voltage module (model: BSC29-0185V) and a video board (model: 40-29206P-DIA4X) online, which cost a total of 64 yuan.
5. I received the parts this morning. After installing them, I powered on the TV. It had sound, but the screen remained black. The three resistors were no longer burnt, which confused me. I was about to turn it off and remove the board when I noticed three adjustable potentiometers on the high-voltage module. Using a small screwdriver, I adjusted the SCR potentiometer and found that the TV displayed an image. Then I adjusted the SCR and FUS potentiometers. After fine-tuning, the image became stable and worked properly.
6. The entire unit was reassembled, and after a final power test, the TV functioned normally.
Maintenance Summary:
The original issue with this TV was likely caused by a faulty high-voltage module, leading to abnormal ABL voltage output and subsequent burning of R419. Later, replacing R419 without addressing the root cause led to additional damage to R425, R426, and RN425. Therefore, if you encounter a similar situation, avoid replacing R419 without thoroughly checking the high-voltage section first. Doing so could expand the fault and lead to more damage.