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国庆长假期间,河南网友寄来一台DM529要求帮忙给予维修,机主描述的故障现象是接收机无法收到水平极化节目,初步估计是极化切换电路出现问题造成的。收到机器后笔者马上将其接上自用的中星6B天线,通电试机果然如此。测量LNB输出端电压始终为14.1V,打开机器,发现该机的极化切换电路是以LM317T为核心组成的电路,如图1所示,为便于检修实绘出相关原理图,见图2所示,工作原理大致是这样的:来自
During the National Day holiday, Henan users send a DM529 request for help to provide maintenance, the owner describes the failure phenomenon is the receiver can not receive horizontal polarization program, the initial estimate is caused by the polarization switching circuit problems. After receiving the machine I immediately connected to their own use of satellite 6B antenna, power test machine Sure enough. Measuring LNB output voltage is always 14.1V, open the machine and found that the machine’s polarization switching circuit LM317T as the core of the circuit, shown in Figure 1, in order to facilitate the maintenance of real-drawn plot, see Figure 2 Show, the working principle is roughly like this: from