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该机已加装了“三森牌”遥控系统。故障现象为“三无”,在排除了电源部分故障后,试机时发现该机在VHFL、VHFH两波段收看的节目相同,而UHF波段不能接收。针对上述现象,让电视机处于自动搜索状态,根据屏幕上的波段指示监测高频头波段转换控制各端子上的电压变化情况为:BV、BU随波段转换变化正常,而BS端子上的电压始终为30 V。该机所用高频头为TDQ—2类型,其正常接收电视节目时,波段转换各端子上所需电压真值表如表1所示,显然问题出在30
The aircraft has been installed, “Sen Sen card” remote control system. Fault phenomenon “three no”, ruled out the power part of the fault, the test machine found VHF, VHFH two bands to watch the same program, and UHF band can not receive. In response to the above phenomenon, the television is in an automatic search state, and the monitoring of the voltage changes on the terminals of the tuner according to the on-screen band indication is as follows: the BV and the BU change normally with the band conversion, and the voltage on the BS terminal is always Is 30 V. The machine used for high-frequency head for the TDQ-2 type, the normal reception of television programs, the band conversion terminal required voltage truth table shown in Table 1, obviously the problem is 30