Ericsson R310s Troubleshooting Manual page 13

Trouble Shooting Guide, Standard
Fig. 4.2
Open the phone and check for liquid damage, especially around the system connector.
Make sure that the system connector is not damaged.
Measure the resistance of R804 (100 kohms), R640 (82 ohms) and C813 (>1 Mohm). Replace
the corresponding component if it is incorrect.
Measure the resistance from C640 to pin 10 of J602 (0 ohms).
If the resistance is incorrect, the foil is damaged. Send the unit on according to the local
company directives.
If the fault remains, send the unit on according to the local company directives.
4.6 Neither the handsfree microphone nor the handsfree
speaker works
Replace J602.
If the fault remains, send the unit on according to the local company directives.
4/00021-2/FEA 209 544/31 B 13(23)