故障现象:开机只在显示屏中间出现一断续竖亮条,其它位置无显示。分析检修:轻触面板功能键,显示屏亮条纵向位置及长短有改变。判断控制电路信号传输电路正常,场扫描电路亦正常,故障出在行扫描电路,行扫描电路示意图如下。开机在线量Ｐ31(1):+5Ｖ、Ｐ31(2):-42Ｖ电压正常;ＳＷＢ Symptom: The power-on only shows an intermittent vertical bar in the middle of the display. No other position is displayed. Analyze and repair: Touch the panel function key, and the vertical position and length of the display bar are changed. It is judged that the signal transmission circuit of the control circuit is normal, the field scan circuit is normal, and the fault is in the row scan circuit. The schematic diagram of the row scan circuit is as follows. Online power P31(1): +5V, P31(2): -42V normal voltage; SWB