论文部分内容阅读
例1 机型:8000A—25PP(5720机芯) 故障现象:开机约10 min(分钟)场幅由顶部慢慢向中部卷边,再过几分钟场幅由上下两侧向内压缩十多厘米变成水平亮带。分析与检修:该现象说明故障在场扫描部分,测IC301(TA842)供电28 V正常,IC301②脚输出脚14 V正常,其余各脚也正常。用手摸散热片感觉场块发烫,但更换后故障依旧,继续检查场反馈电路,当测量解码块TB1240各脚电压时发现,(28)脚行电源只有6.7 V(正常值应为9.1 V),该脚电压由开关电源+12V经IC200(LA7809)供给.测其输入端+12 V正常值
Example 1 Model: 8000A-25PP (5720 movement) Symptom: start-up about 10 min (minutes) field slowly from the top to the middle curling, and a few minutes away from the top and bottom of the field inward compression of more than 10 cm Into a bright band. Analysis and Overhaul: This phenomenon shows the presence of fault scanning section, measuring IC301 (TA842) power supply 28 V normal, IC301 ② foot output pin 14 V normal, the rest of the feet are also normal. Feel the heat of the field by hand touching the hot plate, but after the replacement of the fault remains the same, continue to check the field feedback circuit, when measuring the voltage of the decoding block TB1240 feet found that (28) feet only 6.7 V power supply (normal value should be 9.1 V ), The voltage of this pin is supplied by switching power supply + 12V by IC200 (LA7809). Measure its input +12 V normal value