Trouble Shooting Guide, Advanced
4/00021-3/FEA 209 544/25 C
Ericsson Mobile Communications AB
64(78)
17.10 All audio paths are working in EFRA, but both the
microphone and the earphone is out of order during a
connected call
If the signal CFMS is too low (short circuit against ground), the phone thinks there is a
handsfree unit connected and switches the audio paths to the system connector instead of the
microphone and earphone of phone. This is only valid during a connected call with signal
program in the phone. At this type of fault all audio paths will work with test program in
EFRA.
Open the phone and check for liquid damage.
No further action should be taken for a liquid damaged unit, send it on according to the
local company directives.
The signals are active low, i.e. a connected hands-free unit is simulated if the
signal is connected to GND.
Power up the board and start it in EFRA with the test program.
Measure the voltage at X800: 5/ 2.75 V
DC
.
If the voltage is incorrect, check the signal between D800 and D600, measure at X804 (the
test-point close to V850).
If the signal is correct at X804 it probably is D800 that is faulty, if it is incorrect it is D600
that occurs the fault.
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