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[例1]故障现象 一台如意牌SGC-4703E彩电,以前使用中经常出现无光、无伴音现象,每次开机后,能收看的时间长短不等。故障出现后,有时关机后隔一会儿再开,机器又恢复正常。可最近一次出故障后同以前不一样,先是光栅缩小、变暗,后突然声光全无。 分析与检修 拆机检查,发现行输出管2SD1427击穿,更换新管后,声光全无仍无规律出现。仔细聆听,出故障时机器发出“突—突”的声音,说明电源保护电路动作。断开电源115V负载,接一个220V、50W灯泡,开机灯泡发光正常(亮度约是220V电压值时的1/3左右),测115V及其它各端输出电压均正常。由于该机采用并联脉冲
[Example 1] Symptoms A wishful licensing SGC-4703E color TV, often used in the past no matte, no sound, after each boot, can watch the length of time. After the failure occurs, sometimes after the shutdown and then open again, the machine returned to normal. Can be the last time after the failure is not the same as before, the first grating narrowing, darkening, suddenly no sound and light. Analysis and troubleshooting disassemble inspection and found that the line output tube 2SD1427 breakdown, replacement of the new tube, no sound and light still no law appears. Listen carefully, when the failure of the machine issued a “sudden - sudden” sound, indicating the power protection circuit action. Turn off the power supply 115V load, then a 220V, 50W bulb, boot light glow normal (brightness is about 1/3 voltage when the voltage is about 220V), measured 115V and other output voltage of each terminal are normal. As the machine uses parallel pulse