Ericsson R320s Working Instruction page 29

4.3 Microphone out of order
Open the phone and check for liquid damage.
Remove the microphone rubber and microphone, check the microphone contacts and replace
the complete system connector if necessary. Replace the microphone rubber and microphone.
Assemble the phone and test the microphone again.
If the fault remains open the phone and check for liquid damage.
Measure the resistances of R814 (0 ohms), R812, R817, R819 (1 kohm) and R818 (22
kohms).
If all the resistances are correct, replace C818 and C819.
If the fault remains, send the unit on according to the local company directives.
4.4 Handsfree microphone out of order
The fault arises when the audio path is interrupted somewhere between the handsfree
microphone (connected through the system connector) and the input of N800. The audio path
is shown in fig. 4.1.
Open the phone and check for liquid damage, especially around the system connector.
Make sure that the system connector is not damaged or incorrectly soldered.
Make sure that all the components in fig. 4.1 (R814, R825, R802, R803, R805, R850, C810,
C812, C817, C835 and C850) are mounted on the circuit board.
Measure the resistances of C810 (>60 kohms), C812 (>1 Mohm ), C817 (>1 Mohm), R802
(3.9 kohms), R805 (15 kohms), R803 (1 kohm ), R814 (0 ohms), R850 (47 kohms) and C850
(>90 kohms ). Replace if incorrect.
If the fault remains, send the unit on according to the local company directives.
4/00021-2/FEA 209 544/21 B
Fig. 4.1
Trouble Shooting Guide, Standard
13(26)