How to determine whether belt switch adjustable encoder broken?

Adjustable encoder with switch is on the encoder switch devices are attached. Coaxial switch and encoder, switch and control mode is divided into rotary and push-pull type two kinds. With switch adjustable encoder USES: used in black and white television for more volume control and power switch. Small rotary switch, the encoder is mainly used for transistor radio or other small electronic products for the volume control ( Or current and voltage regulation) And the power switch. So how do we determine with adjustable encoder switch is broken? Check before, should be twisted or push-pull encoder handle, along with the switch 'disconnect' and 'on', should have good touch feeling, can also hear the thrum of the switch contact bounce. Use multimeter R× first; 1 k block, a pens and '4' side, the other pens and '5' end, rotary encoder shaft, make the switch to 'open' & rarr; 'closed', at the same time, observe whether multimeter pointer is' pass 'or' off '( Should be 'open' and 'closed' many times, and observe whether responded well every time) 。 Under normal circumstances, when the switch, the measured value should be zero or near zero. When the switch is off, the measured value shall be the infinity. If the switch to double type, then the two switch shall comply with the above requirements. If the switch in the 'open' position, value is not zero, then internal bad touch switch contacts; If the switch is in the 'off' position, resistance to infinity, explain the internal switch is out of control.