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 (Internal handsfree DPMA 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 right Internal handsfree speaker
•
External microphone to left Internal handsfree speaker
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
XMICN and
GND
HSEAR R
and GND
HSEAR L
and GND
RM-627
BB Troubleshooting and Manual Tuning Guide
Issue 1
COMPANY CONFIDENTIAL
Page 3 – 39
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