编辑同志:我在修理几块带有机玻璃面壳的万用电表(如 MF30型、U-20型等)时,发现一种奇特现象:即盖上电表面壳时,指针会出现偏转,将面壳用布类擦过后,表针偏转幅度更大,甚至可达中心点。用标准 D030-B 型数字武三用表校验仪作检定时,被校表未加面壳,一切正常。加上面盖后,表针处于惯性状态,即延时上升和下 Editor’s Comrade: When I was repairing a few multimeters (such as MF30, U-20, etc.) with a plexiglass shell, I found a peculiar phenomenon: the pointer would deflect when covered with an electric surface shell, After the surface shell is rubbed with cloth, the gauge needle deflection is even larger, even up to the center point. With the standard D030-B digital martial meter calibrator for verification, the school table is not added shell, all normal. Coupled with the cover, the hands in the inertia state, that is delayed rise and fall