Communications
Confidential 28 COM MD CC GRM T
J. Junggebauer
Version 1.0 July 2005
6.11 Microphone faulty
Affected unit: Handset
Diagnosis code IRIS:
73110 (ACOUSTICS / TRANSMITTING / MICROPHONE / NO FUNCTION)
73170 (ACOUSTICS / TRANSMITTING / MICROPHONE / LOW VOICE LEVEL)
Repair level: Level 2.5
Components: Microphone
Needed equipment: Soldering iron
Working material: Desolder wick, solder
Diagnosis:
The diaphragm of the microphone is affected by humidity or nicotine with increasing
age or the microphone could be electrically faulty. There will be a higher attenuation
when measuring SLR (sending loudness rating). In most cases the microphone is
defective.
Repair:
Remove the microphone by desoldering the 2 solder joints.
You can also heat up both pins simultaneously with a broad soldering iron tip and
turn the board upside down, letting the microphone fall out.
Clean pads with desoldering wick and replace it by a new component afterwards.
Attention: Avoid excessive heat (2 seconds maximum)!
Test:
Put the repaired board in a testhousing.
Make a sidetone check by blowing into the microphone and checking the volume
of the noise on the earphone.
If there is a telephone tester with acoustic testhead make a SLR-test and check
whether the attenuation is o.k..
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