Motorola Moto X Pure Edition Troubleshooting Manuals page 75

Bottom Speaker Circuit
- Inspect the physical placement of U6454 and its related components on main PCB.
(See schematic in previous slides)
- Inspect the "Loudspeaker/Earpiece (Bottom)" components on the main PCB. (See
schematic in the previous slides)
- Verify that B_PLUS voltage is present on the LS_BOOST node, the junction of C6471
and C6474.
- Connect an 8Ω speaker to contacts M4681 and M4682 with short, thick wires. While
playing audio at normal to high volume, use an oscilloscope to verify that the voltage
on the VBST_AUD_AMP_R node, the junction of C6473 and C6475, alternates
between B_PLUS voltage and approximately 9 V, depending on the audio content.
- 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.
MOTOROLA CONFIDENTIAL
Moto X Pure Edition/Moto X Style
Baseband TROUBLESHOOTING GUIDES