Nokia RM-779 Service Manual page 79

RM-779
BB Troubleshooting and Manual Tuning Guide
Required equipment
The following equipment is needed for the tests:
• Oscilloscope
• Function generator (sine waveform)
• Current probe (Internal handsfree DPMA output measurement)
• Phoenix service software
• Battery voltage 3.7V
• Sound source (laptop speaker or B&K type 4231 calibrator)
Test procedure
Audio can be tested using the Phoenix audio routings option. Three different audio loop paths can be
activated:
• External headset mic to earpiece
• External headset mic to IHF mono
• Internal digital microphone to headset
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.
The gain values presented in the table apply for a differential output vs. single-ended/differential input.
Loop test Input
terminal
External HS_MIC & GND
headset
mic to
earpiece
External HS_MIC & GND
headset
mic to IHF
mono
Internal Acoustical
digital Input, 1kHz
microphon sine wave
e to
headset
Issue 1
Output Path gain
terminal [dB]
(fixed)
EAR 1 & GND 0
EAR 0 & GND
L4855 & 10
L4856
L4857 &
L4858
HS_L & GND NA
HS_R & GND
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Input Output DC
voltage level [V]
[mVp-p]
300 1.35
200
94 dBSPL
Output
voltage
[mVp-p]
300
630
70
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