Check the back panel of various electrical devices, such as contacts connect a voltmeter, ammeter, lights, buttons are secure, if loose, must be tightened
Check that the contact connection series of various electrical devices on the back of the panel, such as the voltmeter, current meter, indicator, button, is secure and reliable, and if it is loose, it must be tightened.
Check whether the contact wires of various electrical devices on the back of the panel, such as voltmeter, ammeter, indicator light and button, are firm and reliable. If they are loose, they must be tightened<br>