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故障现象:“三无”,但电源指示灯亮。分析与检修:指示灯亮说明该机处于预备状态,反复按动预备开关或遥控开机均无法启动。该类故障牵涉面较广,当电源电路、微处理器及保护电路的某一部位工作失常,均会造成此现象。根据遥控彩电的特点故先检查微处理器IC601(M50436—560SP)的工作状态,有关电路见附图。查得IC601的(52)脚供电正常,(29)脚时钟振荡1.7V也正常;而控制开机⑨脚的电位为0V(正常值为4.9V),进一步检查复位控制电位,发现该值比正常值4.7V低很多,说明该电路已不能正确复位,故使V_(610)无正偏而截止,因此光电耦合器TLP621受高电位控制,电源无法
Symptom: “three no”, but the power indicator light. Analysis and Overhaul: The indicator light indicates that the aircraft is in a ready state and can not be started by repeatedly pressing the preparatory switch or the remote control. This type of fault involves a wide range, when the power circuit, microprocessor and protection circuit of a part of the work of abnormal, will cause this phenomenon. According to the characteristics of remote control TV first check the working state of the microprocessor IC601 (M50436-560SP), see the attached circuit. Check IC601 (52) feet normal power supply, (29) foot clock oscillation 1.7V is normal; and control the boot ⑨ feet potential of 0V (normal value of 4.9V), further check the reset control potential and found that the value than normal The value of 4.7V is much lower, indicating that the circuit can not be properly reset, so the V_ (610) no positive and off, so optocoupler TLP621 high potential control, the power can not