Ericsson T28S Troubleshooting Manual page 15

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 ohm), R850 (47 kohms) and C850
(>90 kohms). Replace if incorrect.
If the fault remains, send the unit on according to the local company directives.
4.5 Hands free speaker out of order
The fault arises when the audio path is interrupted somewhere between the output of N800
and the hands free microphone (connected through the system connector). The audio path is
shown in Fig. 4.2.
Open the phone and check for liquid damage, especially around the system connector.
Make sure the system connector is not damaged or incorrectly soldered.
Measure the resistances of R804 (100 kohms), R640 (10 ohms) and C813 (>1 Mohm).
Replace if incorrect.
Measure the resistance from C813, the pin close to C835, to pin 10 of J602 (10 ohms).
If the resistance is incorrect, replace R640.
If the fault remains, send the unit on according to the local company directives.
4.6 The hands free microphone and speaker out of order
Replace J602.
If the fault remains, send the unit on according to the local company directives.
4/00021-2/FEA 209 544/19 E
Fig. 4.2
Trouble Shooting Guide, Standard
15(29)