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故障现象 满幅回扫线,光栅洁白,亮度调整失控。 分析与检修 彩电出现亮度失控并有回扫线的故障,其根本原因在于显像管电子束电流增大。显像管电子束电流增大的原因,一是栅极对阴极之间的电压增大;二是加速极电压升高。 检修时,首先调节加速极电压调整旋钮,荧光屏没有变化。再测量三只视放管集电极电压只有10V,而视放供电电压200V正常,见右图。静态测量视放管三极之间正反向阻值正常,集电极负载电阻正常,加电测量三只视放管基极(色差信
Full recovery line failure phenomenon, white grating, the brightness adjustment out of control. Analysis and Maintenance Color TV out of control brightness and the flyback line failure, the fundamental reason is that tube electron beam current increases. CRT tube electron beam current increases, one is the voltage between the gate and the cathode increases; the other is to accelerate the voltage increase. Overhaul, first adjust the acceleration voltage adjustment knob, no change in the screen. Re-measure the three tubes as the collector voltage is only 10V, while the visual power supply voltage 200V normal, see the right. Static measurement tube as the positive and negative resistance between the normal three-pole, collector load resistance normal, plus power measurement of three depending on the tube base (color difference signal