Operation - Benefon DELTA TDP-40-TN2 Service Manual

8.1.3 Operation

Operating voltage is fed to pin EXTVB/6. L001/C005 filters the power supply, and
D001 limits any voltage peaks. When the handportable is placed in its handset, a
voltage occurs at the BOX/3 pin which triggers Q101 and Q102 open.
The regulator I101 feeds 9V to the audio stage and PC/EXTHS pin, and I102 feeds
5V to other functions. External relay controls Q104 and and Q106 get their control
from the circuit I103.
The HF microphone gets its bias voltage throuh resistors R311 and R212. I304
serves as the microphone amplifier and I105 as a low-pass filter with a border fre-
quency of 3.3 kHz.
The analog switch I302 connects the HF microphone or external device microphone
signal to the EXTMIC-line.
The analog switch I307 connects the audio signal from the EXTERP-line to either
the external device HSERP line or to the audio stage I309.
Xo0314e4_fm5.fm
Product: CIU-40 (Carbox) /
28.1.1999
YO0314
4