SOS!!!知道三社焊机维修方面的大师请指点!!!

本人遇到一台三社200可控硅二保焊机,目前出现的问题就是按住手把开关送丝速度很快,送丝电压24V左右,焊机输出电压40V,不轮机控或外控都调不下去,有关电路板上控制送丝相关电路的器件基本检查都正常,但是就调不下送丝第一次遇上这么纳手的事情,现在就是不知道主板上有个黑色陶瓷封住的立板WH-018A是不是坏了请各位大师,高手赐教!!!谢谢!!!
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