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故障现象:冷机能收看节目30～60分钟,然后自动关机。关断电源,稍候再开机,能工作5～10分钟又自动关机。分析与检修:从故障现象分析,判定为保护电路动作。实测保护电路可控硅Q_(751)的G极有0.6V电压,表明判断正确。该机有过流、过压、X射线过量等多种保护。为了确定是何种保护,试在行管c极供电回路中串联一只500mA电流表,再在+B(112V)与地之间并联一只电压表,观察电流表、电压表在关机时的摆动情况。结果表明,在自动关机瞬间,两表均无增大指示,且荧屏亮度、光栅尺寸也无异常。从而证明不是真保护,故障在保护电路本身。从故障现象看,属于元件热稳定
Symptoms: cold machine can watch the program 30 to 60 minutes, and then automatically shut down. Turn off the power, turn on again later, can work 5 to 10 minutes and automatically shut down. Analysis and Maintenance: From the failure phenomenon analysis, determine the protection circuit action. Measured protection circuit silicon Q_ (751) G very 0.6V voltage, indicating that the judgment is correct. The machine has over-current, over-voltage, X-ray and other over-protection. In order to determine what kind of protection, try in the tube c pole power supply circuit in series with a 500mA ammeter, and then + B (112V) and ground in parallel with a voltmeter to observe the ammeter, voltmeter in the shutdown when the swing . The results show that in the automatic shutdown moment, no increase in the two instructions, and screen brightness, grating size is no exception. Prove that is not true protection, breakdown in protecting the circuit itself. From the phenomenon of failure, belonging to the thermal stability components