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[例1]TCLLCD37K73M61R液晶彩电,接收电视信号无图像。分析与检修:AV状态下图像正常,在接收TV信号时没有图像,有雪花,说明高频头的5V供电正常。如果高频头没有5V供电,高频头不工作时,屏幕上无雪花,只有字符。测试其他信号都正常。故障在TV信号处理通道。首先检查高频头的工作条件,5V正常、30V调谐也正常、I2C总线电压4.8V正常、AGC电压3V正常,说明高频头大致正常。进一步检查解码集成电路U9,发现U9輵訛輩脚没有电压(正常机器輵訛輩脚电压大约为
[Example 1] TCLLCD37K73M61R LCD TV, receiving TV signal No picture. Analysis and Overhaul: The image is normal in the AV state, there is no image when receiving the TV signal, there is snowflake, indicating that the 5V power supply of the tuner is normal. If the tuner does not have 5V power supply, the tuner does not work, there is no snow on the screen, only the characters. Test other signals are normal. Fault in TV signal processing channel. First check the working conditions of the tuner, 5V normal, 30V tuning is normal, the I2C bus voltage 4.8V normal, AGC voltage 3V normal, indicating tuner roughly normal. Further examination of the decoding integrated circuit U9, found that U9 輵 false generation of foot voltage (normal machine 輵 false generation voltage is about