Figure 11-12 shows the detection of a dual-channel earphone.

    When detecting the headset, the multimeter chooses R×1 or R×10 stop, first connect the black watch pen to the public conductive section of the headset plug, the red watch pen intermittently contacts the L conductive section, listen to the left channel headset has no sound, there is a "scratch" sound in the normal headset, when the red and black watch pen contact the two guide rings do not move, the resistance value of the left channel headset coil should be several ohms to several hundred ohms. As shown in Figure 11-12, if the resistance value is 0 or infinity, the left channel earphone coil is short or open. Then the black watch pen does not move, and the red watch pen touches the R conductive section intermittently to detect whether the right channel earphone is normal.