Fault phenomenon: After the second boot, the screen shows a raster, but it automatically shuts down before fully loading. Pressing the standby button again causes the power to turn off temporarily, and the fault reappears.
Repair process: At startup, voltages such as B1 (130V), filament voltage, video discharge voltage, +8V, +5V, ±14V are all normal. However, during the second boot and standby mode, the third pin (field protection input) of the 8879CSBNG6K02 chip measures 4.7V. Normally, this pin should be high in standby. After the second boot, it drops to 0V, indicating that the TV has entered a protective state.
Further inspection was conducted on Q015 (TC144E), which is connected to the third leg of the 8879CSBNG6K02. Components connected to the B terminal were checked, and it was found that R030 (18K1/8W) was open. It was replaced with a 20K1/4W resistor. After testing, the issue was resolved. R030 is connected to the deflection yoke through C025 (10uF 50V).
The following circuit diagram was drawn based on the board:
wrist watch accessories,watch parts,custom watch accessories,watch parts customize Dongguan Yingxin Technology Co., Ltd. , https://www.dgyingxintech.com