1. No display on the display
(1) The internal battery connection is disconnected or the battery contact is not good: Solder the connection and replace the battery contact piece. (2) Damaged battery: replace the battery.
2. The measurement reading is obviously low or the calibration is less than 94.0dB.
(1) The microphone sensitivity is too low or damaged: replace the microphone and recalibrate.
(2) The contacts of the preamplifier are not in good contact with the microphone: clean the contacts.
(3) The plug of the preamplifier is not in good contact with the socket of the host: replace the plug and socket.
3. The reading is too high during low sound level measurement, and the ground wire of the preamplifier is in poor contact: tighten the outer sleeve.
