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例1 故障现象:刚开机时一切正常,但开机后常有一条水平亮线,有时在开机几小时后出现,有时几天后才出现,只有重新开机才能消除。分析检修:从现象看,系场电路故障。在机器正常时用手拨动场振荡电路各元件未见异常。当用手拨动场输出电路IC681时故障出现,怀疑IC681有虚焊,重新焊过后,故障依旧。这时测IC681第⑩脚无电压,而测各脚电压却有明显的变化。怀疑LA7801集成电路问题,将其更换,结果故障依旧。又在故障出现时,测量
Example 1 Symptom: Just boot everything is normal, but often have a horizontal bright line after boot, and sometimes appear a few hours after boot, and sometimes only appeared after a few days, only to reboot to be eliminated. Analysis and maintenance: From the phenomenon of view, Department of circuit failure. When the machine is in normal use, the components of the field oscillation circuit are not abnormal. When the hand dial field output circuit IC681 failure occurs, suspected IC681 Weld, re-welding, the fault still. At this time IC681 measured ⑩ feet no voltage, while measuring the voltage of the foot there is a clear change. Suspected LA7801 integrated circuit problems, the replacement, the result of the malfunction remains. Again when the fault occurs, measure