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Audio troubleshooting
Audio troubleshooting test instructions
Single ended external earpiece and differential internal earpiece/IHF outputs can be measured either with a
single ended or a differential probe.
When measuring single ended, each output is measured against ground.
Note:
Do not connect ground of single ended probe to 2nd signal of differential lines.
Internal handsfree output is measured using a current probe, if a special low-pass filter designed for measuring
a digital amplifier is not available. Note also, that when using a current probe, input signal frequency must be set
to 2kHz.
The signal for input is single ended.
Required equipment
The following equipment is needed for the tests:
Oscilloscope
Function generator (sine waveform)
Current probe (Internal handsfree PWM output measurement)
service software, Nokia L3 PST Fx.xx
Power supply 3.7V
Test procedure
Audio can be tested using MIT (*#648#). Four different audio loop paths can be activated:
• Receiver test
• Microphone test
• Speaker test
• Headset test
Correct pins an signals for each test see following table.
Audio loop tests and test results
The results presented in the table apply, when no accessory is connected. Earpiece, internal mic and speaker are
in place during measurement. Applying a headset accessory during measurement causes a significant drop in
measured levels.
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Baseband Troubleshooting
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