Motorola Moto Z Play Troubleshooting Manual page 91

Secondary Microphone Circuit
MK5750 2nd MIC part
If the secondary MIC is not functioning,
- Check MIC bias at C5753 or C5757 or C5758. Measured level should be almost 1.8V when the microphone is being enabled.
- Check the microphone output at C5750 or C5751. The AC amplitude should be increased (Output DC bias should be around
0.7V), when audio is present.
- If there is no AC amplitude, MIC part should be reworked.
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