Information and Communication Products Communication Devices 5.4Repair Documentation
5.4.1Description of procedure:
5.4.1.1Diagnosis
The 18µH coil is used in the step up converter which is generating a 5.4 V supply voltage for the power amplifier out of the 2.8V battery voltage. If the coil is mechanically damaged (broken) it produces heavy interference with the acoustical elements of the C25 resulting in a loud humming noise in the earpiece. A broken coil can easily be diagnosed by trying to move it with two fingers. If it moves, the core is broken and the coil has to be replaced.
5.4.1.2Repair by component change
Use hot air to remove defective coil. Avoid excessive heat! Watch surrounding components!! Resolder new coil afterwards
5.4.1.3Repair by SW-Booting
Not possible!
5.4.1.4Test
Retest handset after repair by checking the audio quality with the echo loop of the testprogram.
