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故障现象:电视图像随不同画面内容有时能稳定,大部分时间不停地抖动,无法观看。分析与检修:该机属A3机芯,场输出电路由LA7837完成。查该集成块各脚电压无异常,因画面有时能长时间稳定(如播放测试圆及蓝屏静噪时),图像系统随画面内容的不同而抖动,基本可以排除LA7837出现故障的可能,分析故障应在中放电路或同步分离电路,为电源滤波不良或其他干扰引起。查220V市电整流、滤波后得的310 V正常,B1—B6各电压也基本正常,仅(30)、(31)、(35)、(41)脚在发生场抖动时电压有微小的波动,试在各电源滤波电容上并接好电容试机无效,电源供电滤波不良引起干扰的设想被排除。
Symptom: TV images with different picture content can sometimes be stable, most of the time constantly shaking, unable to watch. Analysis and maintenance: The aircraft is A3 movement, field output circuit completed by the LA7837. Check the integrated block voltage of each foot no exception, because the picture can sometimes be stable for a long time (such as playing the test circle and blue screen noise), the image system with different screen content and jitter, LA7837 basically ruled out the possibility of failure, failure analysis Should be in the discharge circuit or synchronous separation circuit for the power supply filter or other interference caused by poor. Check the 220V mains rectifier, the filtered 310 V is normal, B1-B6 the voltage is basically normal, only (30), (31), (35), (41) feet in the event of field jitter voltage fluctuations slightly , Try the power filter capacitor and then connect the capacitor test machine is invalid, the power supply filter is not ideal to interfere with the idea was ruled out.