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例1、故障现象 一台菲利普二十英寸彩色电视机在加装遥控器时,接上行、场同步信号、复合同步信号及R、G、B、BLANKING信号后,开机检查字符显示是否正常,这时屏幕出现消隐框内的无色字符,并巳出现随着图像内容的变化,该字符的颜色发生变化的故障。 分析与检修 最初误判为该红外遥控器主板故障,认真检查该主板上电脑芯片PCF84C640字符信号输出引脚及周围相关元件、插排都未发现问题,于是又替换一新的该红外遥控器主板,该彩色电视机故障依旧。问厂家答复未加装过此类机子,此时又怀疑该彩色电视机的色解码集成电路TDA3561及周围R、G、B、BLANKING信号输入电路有问题,经检查和替换TDA3561故障仍不变,只有继续改装,当改装好该彩色电视机调谐选台及频道控制电路后,再开机字符显示及图像、伴音皆正常。
Example 1, Fault Phenomenon A Philip 20-inch color TV set up the remote control, connected to the line, field sync signal, composite sync signal and R, G, B, BLANKING signal, the boot check character display is normal, which When the screen appears colorless character blanking box, and has emerged as the image content changes, the characters of the color change fault. Analysis and maintenance of the initial misjudgment of the infrared remote control motherboard failure, carefully check the motherboard PCF84C640 character signal output pin and related components, plug row did not find any problems, so they replaced a new infrared remote control motherboard The color TV malfunction still. Asked the manufacturer did not reply to such machines, at this time they also suspect the color television color decoding IC TDA3561 and around R, G, B, BLANKING signal input circuit problems, after inspection and replacement TDA3561 failure remains unchanged, Only continue to refit, when the tuning of the color TV tuning channel selection and channel control circuit, and then start the character display and images, sound are normal.