一台熊猫牌3405型44cm(17英寸)黑白电视机出现有光栅无图像、有满幅回扫线、亮度失控、伴音中有“嗡”声故障。检测显像管各极电压,发现阴极与栅极均有25V左右电压,且栅极电压时有波动,阴极电压不可调,其他各极电压正常,因而怀疑阴极与栅极相碰,于是卸下高压帽,拔下管座测量脚电压恢复正常,由此证明判断正确。这种故障的检修,笔者采用改变显像管各 A panda brand 3405 44cm (17 inches) black and white TV there is no image raster, there is a full recovery line, the brightness out of control, accompanied by a sound “Om” sound failure. Detection of the cathode voltage tube, found that the cathode and the gate are about 25V voltage, and the gate voltage fluctuations, the cathode voltage is not adjustable, the other pole voltage is normal, so suspected cathode and gate collision, then remove the high pressure cap , Unplug the tube base voltage measurement returned to normal, which proved to judge correctly. Maintenance of this failure, I used to change the picture tube