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故障现象:开机三无,调整加速极电压,出现满幅加扫线的光栅。 分析与检修:由故障现象可知,该机具有加速极电压,说明开关电源、行扫描电路已启动工作,所以应重点检查亮度控制电路:按动遥控器键和本机键的亮度控制键,主控微机块PC A84C640的亮度控制输出端③脚电压无变化;按动开关机键,主控微机块(41)脚输出的控制电压有高低电平变化;按动亮度、色度、音量键中某一键时,屏显模拟量交替变化,而主控微机块相应的输出端控
Symptoms: boot three no, adjust the acceleration pole voltage, there is full plus scan line grating. Analysis and Overhaul: From the phenomenon of the malfunction, the machine has an accelerating pole voltage, indicating that the switching power supply, the line scanning circuit has been started, so should focus on checking the brightness control circuit: press the remote control button and the local key brightness control keys, the main Control microcomputer block PC A84C640 brightness control output ③ pin voltage no change; press the switch button, the main control microcomputer block (41) pin output control voltage level change; press the brightness, color, volume keys A certain key, the screen display the amount of alternating changes, while the main control output corresponding computer block control