Motorola Moto X Pure Edition Troubleshooting Manuals page 70

Earpiece (cont'd)
- Inspect the "Earpiece Support" and "Loudspeaker / Earpiece (Top)" components on the
main PCB. (See schematic in the previous slides)
- Connect an 8Ω speaker to the contacts on M4670 with short, thick wires. While playing
media audio at normal to high volume, use an oscilloscope measure the differential
voltage on the test speaker. A 384 kHz PWM waveform should be observed, similar to
the example shown on the previous slide. The waveform amplitude should vary between
2 x B_PLUS up to 18 V p-p depending on the audio content.
- Check the voltage on the VDD_SPK_BOOT node (R4697) and verify that it alternates
between B_PLUS voltage and approximately 9 V, depending on the audio content.
- Check the voltage on the VDD_SPK_5V_BOOT (R4699) and verify that it is 5 V DC.
- Check the differential voltage across R4692, it should be about 0 V.
- Probe the voltage at the SPKR_MODE_GATE node (R4698) and verify that it is a PWM
waveform that varies between about 8 V and 16 V.
- In the "Audio" menu of the CQA apk, select "Ear Speaker" and then "Play Harvard
speech pattern". The playback volume should be much lower than it was with media
playback. Probe the voltage at the SPKR_MODE_GATE node (R4698) and verify that it
is near 0 V.
MOTOROLA CONFIDENTIAL
Moto X Pure Edition/Moto X Style
Baseband TROUBLESHOOTING GUIDES