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RM-272; RM-273
BB Troubleshooting and Manual Tuning Guide
Audio troubleshooting
Introduction to acoustics troubleshooting
Note:
Always make sure all openings are clean and all contact pads are intact and make contact. If
audio still does not work, please continue to the electronic audio troubleshooting (2nd diagram
where applicable).
Acoustics design ensures that the sound is detected correctly with a microphone and properly radiated to
the outside of the device by speaker(s). The acoustics of the phone includes three basic systems: earpiece,
Integrated Hands Free (IHF) and microphone.
The sound reproduced from the earpiece readiates through a single hole on the front cover (A-cover). The
sound reproduced from the IHF speaker radiates from a single sound hole located 3 cm below the power key.
The microphone is located at the hinge, next to the system connector.
For a correct functionality of the phone, all sound holes must be always open. When the phone is used, care
must be taken not to close any of those holes with a hand or fingers. The phone should be dry and clean,
and no objects must be located in such a way that they close any of the holes.
Audio troubleshooting test instructions
Differential internal earpiece outputs can be measured either with a single-ended or a differential probe.
When measuring with a single-ended probe each output is measured against the ground.
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, the input signal
frequency must be set to 2kHz.
The input signal for each loop test can be single-ended.
Required equipment
The following equipment is needed for the tests:
• Oscilloscope
• Function generator (sine waveform)
• Current probe (Internal handsfree PWM output measurement)
• Phoenix service software
• Battery voltage 3.7V
Test procedure
Audio can be tested using the Phoenix audio routings option. Three different audio loop paths can be
activated:
• External microphone to Internal earpiece
• External microphone to Internal handsfree speaker
• Internal microphone to External earpiece
Each audio loop sets routing from the specified input to the specified output enabling a quick in-out test.
Loop path gains are fixed and they cannot be changed using Phoenix. Correct pins and signals for each test
are presented in the following table.
Phoenix audio loop tests and test results
The results presented in the table apply when no accessory is connected and battery voltage is set to 3.7V.
Earpiece, internal microphone and speaker are in place during measurement. Applying a headset accessory
during measurement causes a significant drop in measured quantities.
Issue 1
COMPANY CONFIDENTIAL
Copyright © 2007 Nokia. All rights reserved.
Page 3 –25
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