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故障现象:用NSA4-300型直流手工钨极氩弧焊机小电流(20A)引弧,使用数分钟后突然变成大电流,调节焊机面板上焊接电流调节旋钮不起作用(即电流调节失控)。 分析检修:根据故障现象分析,可能是晶闸管电流调节器电路或ZXG7-300-1型弧焊整流器电路发生故障。首先检查晶闸管电流调节器电路板上所有元器件,均正常。然后用M-47型万用表500mA挡串接到磁饱和电抗器绕组与供电电源之间进行焊接试验,结果是万用表指示约为50mA,关断焊机总电源10s后再合闸,万用表指示可降为25mA,如此
Symptom: NSA4-300 type DC TIG welding machine small current (20A) arc, after a few minutes suddenly become a large current, adjust the welding machine welding current control knob on the panel does not work (that is, current regulation out of control). Analysis and maintenance: According to the analysis of the fault phenomenon, it may be thyristor current regulator circuit or ZXG7-300-1 arc welding rectifier circuit failure. First check the thyristor current regulator circuit board all the components are normal. Then use the M-47 multimeter 500mA block connected to the magnetic saturation reactor windings and the power supply between the welding test, the result is that the multimeter instructions about 50mA, turn off the welder total power 10s and then closed, multimeter instructions can be lowered For 25mA, so