Xian Qingxin has good skills. According to relevant information, the technology has reached the level of not picking brands, repairing 10~20 units per capita and opening stores at chip level. The frequency converter maintenance training course taught by Mr. Xian Qingxin at home has been successfully taught for three periods and has been widely praised by the students. Linyi Xianqingxin Electronic Technology Service Center was established on 20 19-09-06, and its legal representative is Xianqingxin. Its registered place is located in Shi Qiaocun, East of Fangcheng Town, Lanshan, Linyi City, Shandong Province, and its business scope is frequency converter, servo driver and technical consultation for industrial circuit maintenance.