故障现象：刚一开机，显示屏一亮一暗闪动。有时用手轻敲机壳，荧光屏显示正常。但过一会儿则整个荧光屏发白，此时，直角坐标消失，探头深度不能调节，整个前面板控制钮失灵。故障分析：开始以为是亮度或对比度失灵，在故障出现时，本人调节亮或对比度旋钮，均不起作用，测量? Symptoms: Just after booting, the display is bright and dark. Sometimes the cabinet is tapped by hand and the screen shows normal. However, after a while, the entire screen is whitish. At this time, the rectangular coordinates disappear, the probe depth cannot be adjusted, and the entire front panel control button malfunctions. Failure analysis: At first thought it was a failure of brightness or contrast. When the failure occurred, I adjusted the brightness or contrast knob, and it did not work. Measurement?