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故障现象:刚开机时一切正常,5 min(分钟)后,彩色时而正常,时而呈深蓝或深黄色,且变换无规律。分析与检修:色彩异常一般是色解码电路出了问题,但将色解码电路通查一遍后,仍一无所获。检修一时陷入困境。由于行扫描电路故障率较高,所以决定测量行电路的几处关键点电压。参照图1所示,当测到行推动管Q402的 b 极时,发现该脚电压已上升至0.48 V(正常时应为0.27 V)。而其集电极电压也由正常的35 V 下
Symptoms: just boot everything is normal, 5 min (minutes), the color from time to time, sometimes dark blue or dark yellow, and no change in the law. Analysis and Maintenance: Color Abnormal Color decoding circuit is generally a problem, but the color decoding circuit check again, still nothing. Maintenance temporarily in trouble. Due to the high failure rate of the line scan circuit, it is decided to measure the voltage at several points of the row circuit. Referring to FIG. 1, when the b-pole of the push tube Q402 is measured, it is found that the voltage of the foot has risen to 0.48 V (0.27 V in the normal state). The collector voltage is also regulated by the normal 35V