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Trouble Shooting Guide, Advanced
21.2 How to find the fault
The trouble shooting part assumes that the microphone, with the elastome, and the earphone are
faultless and correctly mounted.
Start the phone (assembled) in the test program.
Go to Audio / Audio Fig. 21.2.
Test the five different audio paths.
An appropriate signal for the audio signal generator is 1 kHz and 100 mVrms or 280mVp-p
sinus.
At the test "ATMS – Earphone" you should hear the chosen input signal (1 kHz) in the
earphone.
It is needed to set the Speaker/ Mic gain in the Gain control for each measurement,
adjustable between 00 to 3C. Fig. 21.2.
Apply the signal with a zero ohm probe at J602: 2.
Fig.21.2
At the test "Mic – AFMS" a whistle in the microphone should be seen as a sinus shaped curve at
the oscilloscope.
At "ATMS – PCM – AFMS" the chosen input signal should be seen at the oscilloscope
(input signal 1 kHz, 100 mVrms or 280mVp-p sinus gives an output signal of 120mVrms or
340mVp-p).
Apply the signal with a zero ohm probe at J602: 2.
Measure it with a standard probe at J602: 1.
4/00021-3/FEA 209 544/18 B
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