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检修一台北京8303型彩电,故障现象为:伴音正常,图像上部出现几条回扫线,长短不一,有的台明显,有的台不明显,有些台根本没有。像这样的故障以前遇到不少,一般换掉OTL场输出电路的自举电路或行逆程脉冲整流、滤波电容即可将故障排除。而对本例故障,采取上述措施却无济于事。测场输出电路中点A电压基本正常,试换Q306、Q307、C316、D310等元件仍不奏效,维修陷入困境。静下心来,逐本翻阅几年来订阅的《家电检修技术》杂志,终于在1999年第5期黎崇山老师的《一种故障现象(圆扫线)两种处理方法》一文中找到了答案,悟出了道理:原来故障的根本原因是由于行、场振荡集成电路TA7609内部场振荡不良,使
Overhaul of a Beijing 8303 color TV, the fault phenomenon is: normal sound, the upper part of the image appears several retract lines, the length of different, some stations obviously, some stations are not obvious, and some Taiwan did not. Such failures encountered a lot of before, generally replace OTL field output circuit bootstrap circuit or line reverse pulse rectification, filter capacitor can be troubleshooting. In the case of failure, to take the above measures will not help. A point of the output voltage of the test circuit is normal, try Q306, Q307, C316, D310 and other components still not work, maintenance in trouble. Quietly, by the book read several years subscription “Appliance Maintenance Technology” magazine, finally in 1999 No. 5 Li Chongshan teacher “a phenomenon of failure (circular sweep line two processing methods” one article found the answer, enlightenment Out of reason: the root cause of the original fault is due to line, field oscillation IC TA7609 internal field oscillation poor