Audio troubleshooting
Audio troubleshooting test instructions
Headphone outputs are single-ended type thus those must be measured against ground.
Internal loudspeakers outputs are measured using a current probe, if a special low-pass filter designed for
measuring digital amplifiers is not available.
Required equipment
The following equipment is needed for the tests:
• Oscilloscope
• Current probe (Internal handsfree DPMA output measurement)
• Low-pass filter designed for DPMA measurements
• Phoenix service software
• Battery voltage 3.7V
• Nokia HS-48 headset
• Sine signal generator
• Multimeter
Test procedure
Audios can be tested using the Phoenix audio routing options. Two different audio loop paths can be
activated:
• From internal microphone to headphone output (HP microphone in Ext earpiece out)
• From external microphone to headphone output (Ext microphone in Ext earpiece out)
These loops are basically meant for device’s internal microphone and headset’s microphone testing.
For internal loudspeakers and headphone output testing there is possibility to use test signals generated
inside of the device.
Note:
Sine test signals frequency and amplitude are fixed.
It’s possible to route the signal to the following outputs:
• Headphone left channel (Generated earpiece left out)
• Headphone right channel (Generated earpiece right out)
• Internal loudspeaker (Generated int handsfree out)
Each audio output configuration sets the internal test signal generator or microphone routing to the specified
output. Test signal path gains are fixed and they cannot be changed using Phoenix. Microphone is tested by
talking to the microphone and listening the output signal using headphones/headsets.
Correct measurement/test points for each test case are presented in a table below.
Phoenix audio loop tests and test results
The results presented in a table apply when no accessory is connected and the battery voltage is set to 3.7V.
Internal loudspeakers are in place during the measurements. Applying a headset or a headphone during
measurement causes a significant drop in measured quantities.
Output device
Output terminals
Output voltage (mVrms)
Headphone left
X4120 pin 5 and gnd
~43mVrms
RX-34
BB Troubleshooting and Manual Tuning Guide
Issue 2
COMPANY CONFIDENTIAL
Page 6 –37
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