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故障现象:一台长城公司生产的GW500型彩色显示器,当主机RESET后,显示器无显示,但电源指示灯还亮,关机一段时间后再开机,显示器恢复正常。 分析检修:从故障现象可断定是高压保护电路起动。GW500型高压保护电路设置的目的是防止高压过高时显像管辐射X射线。但正常的机器在出厂时已调好高压值,不会因为有一高压脉冲而发生保护现象。这种故障往往是某元器件变质或失效引起的。GW500型彩显的高压保护电路如附图所示。当高压过高时,行输出变压器第7脚的脉冲信号增大,经D407、C427整流
Symptom: GW500-type color monitor produced by a Great Wall Company, when the host RESET, the monitor no display, but the power light is still on, turn off the power after a period of time, the monitor back to normal. Analysis and maintenance: fault phenomenon can be concluded that the high voltage protection circuit start. GW500 high-voltage protection circuit is set to prevent the high voltage tube X-ray radiation. However, the normal machine has been adjusted high pressure value at the factory, will not be protected because of a high voltage pulse protection. This failure is often caused by deterioration of a component or failure. GW500-type color display of high voltage protection circuit as shown in the figure. When the high voltage is too high, the line output transformer pin 7 pulse signal increases, the D407, C427 rectifier