Audio troubleshooting
Audio troubleshooting test instructions
Single-ended external earpiece and 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 2 kHz.
The input signal for each loop test can be either single-ended or differential. Exception to this is a digital
microphone which needs input signal from an external sound source (laptop speaker) to playback, eg. 1 kHz
sine wave from 5 cm distance.
Required equipment
The following equipment is needed for the tests:
•
Oscilloscope
•
Function generator (sine waveform)
•
Current probe (Internal handsfree DPMA output measurement)
•
Service software
•
Battery voltage 3.7V
•
Sound source (laptop speaker or B&K type 4231 calibrator)
Test procedure
Audio can be tested using the application in NWP. Three different audio loop paths can be activated:
•
XMIC to XEAR (L) and (R)
•
MIC1 to EAR
•
MIC1 to IHF
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 the application.
RM-824; RM-825; RM-826
BB Troubleshooting Guide
Issue 2 NOKIA INTERNAL USE ONLY Page 3 – 33
Copyright © 2012 Nokia. All rights reserved.
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