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故障现象:该机操作正常,但射频无输出信号。分析检修:为了判断故障部位,首先用AV输出看是否有图像和伴音,如有,则故障在射频调制器,如无法进一步检查。经查AV无输出,RF输入端电压与另一完好机器差别很大(见表1)。由AV无输出可判断,故障可能在通道电路,而且Y/C通道和伴音都有问题。这往往与工作电压有关,检查IC果然无9V工作电压,该电压为受控电压,主要供音频电路和Y/C电路中的IC工作。测PG1第④脚电压为0,查开关电源
Symptom: The aircraft is operating normally, but no RF output signal. Analysis and maintenance: In order to determine the fault location, first use the AV output to see if there are images and sound, if so, the fault in the RF modulator, such as further examination. The investigation of AV no output, RF input voltage and the other intact machines vary greatly (see Table 1). No output by the AV can be judged, the fault may be in the channel circuit, but also Y / C channel and sound problems. This is often related to the operating voltage, check the IC really no 9V operating voltage, the voltage for the controlled voltage, mainly for audio circuits and Y / C circuit IC work. Test PG1 ④ pin voltage is 0, check the switching power supply