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本文就7A7193P组成的色解码器常见故障进行分析.图1为其原理图,图2为解码器输入1.3伏_(峰峰)标准彩条信号,且处在正常工作时各脚的波形图. 故障现象1黑白图象正常,但无彩色首先,用示波器测TP_(501)的波形,如无输出或输出较图2中(15)小很多,则测TP_(301)直流电压.如直流电压大大低于8.1伏,可能是ZD_(302)击穿或C_(501)击穿短路.如果直流电压正常,且波形为1.3伏_(峰峰)的彩色全电视信号,则问题出在带通滤波器和C_(502),检查上述各元件并检查T_(501)的磁芯使TP_(501)的波形如图2中(15)的波形.
This article analyzes the common faults of the color decoder composed of 7A7193P.Figure 1 shows the principle diagram, and Figure 2 shows the waveform of the standard color bar signal of 1.3 volts_ (peak-to-peak) input by the decoder and the normal operation of each pin. Symptom 1 Black and white image is normal, but no color First, use the oscilloscope to measure the waveform of TP_ (501), if no output or output is much smaller than (15) in Figure 2, then measure TP_ (301) DC voltage, Well below 8.1 volts, it could be a ZD 302 breakdown or a C 501 break-in. If the DC voltage is normal and the color is a full-color TV signal with a 1.3 V peak, the problem is that the bandpass Filter and C_ (502), examine the above elements and examine the core of T_ (501) so that the waveform of TP_ (501) is the waveform of (15) in FIG. 2.