Ericsson T18s Trouble-Shooting Instruction page 24

T18s, T18sc Standard Electrical Repairs
4.3 Microphone out of order.
Open the phone and check for liquid damages.
Clean the system and microphone connector pads if needed.
Most of the microphone faults are mechanical.
Make sure C815 and C820 (both of class A, fig. 4.2) are mounted at the circuit
board. They easily fall of when removing the system connector.
Fig. 4.2
Make sure the sound channel gasket is free from dust and correctly mounted.
Replace the system connector and the microphone to a pair you know work. Assem-
ble the phone and check if the microphone works.
Measure the resistance of C850 and C851 (fig. 4.2, both of class A and >100
kohms).
Measure the resistance of R817, R814 (both of class A and ~1 kohms, fig. 4.2) and
R818 (19 kohms, class A, fig. 4.2).
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