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 either single-ended or differential.
Required equipment
The following equipment is needed for the tests:
•
Oscilloscope
•
Function generator (sine waveform)
•
'Active speaker' or 'speaker and power amplifier'
•
Sound level meter
•
Current probe
•
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 a table in the following section.
Phoenix audio loop tests and test results
The results presented in this 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.
The gain values presented in the table apply for a differential output vs. single-ended/differential input.
Loop test
Input
terminal
Output
terminal
Path
gain [dB]
Input
voltage
[mVpp]
Output
voltage
[mVpp]
Output
DC level
[V]
Output
current
[mA]
External Mic to
External Earpiece
XMICP and
GND
HSEAR R
and GND
16.7
100
680
1.2
NA
HSEAR L
and GND
External Mic to
Internal Earpiece
XMICP and
GND
EarP and
GND
10.9
100
353
1.2
NA
EarN and
GND
External Mic to
Internal
handsfree
XMICP and
GND
E2121 and
E2123 pads
28.1
100
2540
0
112mA
(calc.)
RM-598; RM-604
BB Troubleshooting and Manual Tuning Guide
Page 3 –38
COMPANY CONFIDENTIAL
Issue 1
Copyright © 2009 Nokia. All rights reserved.
