故障现象：平床普通摄影、断层摄影、滤线器摄影均mA减半，而诊视床透视及点片正常。检修与分析：一般情况下，X光机mA减半的现象有四种故障可能：（1）高压发生器内四个高压整流管中某一个出现开路性故障；（2）高压初级两个反并联主可控硅在曝光时其一未导通；（3）指示mA的 Symptoms: Normal flat bed photography, tomography, and filter halving are all half of the mA, while the bed and perspective are normal. Maintenance and Analysis: Under normal circumstances, there are four kinds of faults in the phenomenon of halving the mA of the X-ray machine: (1) An open-circuit fault occurs in one of the four high-voltage rectifiers in the high-voltage generator; Parallel main thyristor is not turned on during exposure; (3) indicates mA