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十二、灵敏度低故障的检修灵敏度低的特征是只能收到强信号电台或收台数目减少,但音量没有明显减小,该故障的毛病多出在变频、中放或检波电路。根据各单元电路原理分析,检波电路造成的灵敏度降低,主要是因检波二级管反向电阻减小,检波效率降低所致。此时常伴有杂音增大和强信号时失真;中放电路造成的灵敏度降低主要原因是第一中放工作电流偏小(小于0.25mA),常伴有音量减小。从前几节的电路介绍中看出,输入回路和变频电
Second, the low sensitivity of the fault detection of low sensitivity characteristics can only receive a strong signal radio station or reduce the number of reception, but the volume was not significantly reduced, the failure of the fault more in the inverter, the release or detector circuit. According to the analysis of the principle of each unit circuit, the sensitivity caused by the detection circuit is reduced mainly because the reverse resistance of the detection diode decreases and the detection efficiency decreases. This time often accompanied by increased noise and strong signal distortion; in the release of the circuit caused by reduced sensitivity is mainly due to the first operating amplifier current is small (less than 0.25mA), often accompanied by a decrease of volume. From the previous sections of the circuit description shows that the input circuit and inverter