First, the microphone switch is not opened, or the internal contact of the switch is poor, you can try to open and close several times.
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The second is that the microphone cable plug is not inserted, you can remove the plug and wipe it clean before inserting it into the socket, be sure to plug it into the end.
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Third, the volume adjustment of the microphone on the power amplifier is not adjusted well, and the volume of the microphone should be turned up clockwise.
Fault cause and troubleshooting:
First check whether the charger has output voltage, if there is a good contact in the check microphone plug, contact is not bright, you must find a professional to repair. It usually takes 2 to 3 hours for the microphone to be fully charged, and it can be used for 6 to 8 hours after being fully charged