Nokia RM-824 Service Manual

Contents

Audio troubleshootingAudio troubleshooting test instructionsSingle-ended external earpiece and differential internal earpiece outputs can be measured either with asingle-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 formeasuring a digital amplifier is not available. Note also that when using a current probe, the input signalfrequency 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 digitalmicrophone which needs input signal from an external sound source (laptop speaker) to playback, eg. 1 kHzsine wave from 5 cm distance.Required equipmentThe 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 procedureAudio 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 IHFEach 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-826BB Troubleshooting GuideIssue 2 NOKIA INTERNAL USE ONLY Page 3 – 33Copyright © 2012 Nokia. All rights reserved.