Operation Manual

4-8 Technical Description
4.2.7 Electronically Controlled Volume
The receiver's sound volume on the handset is controlled by the M62429FP
(IC706).
4.2.8 Off-Hook Detection Relay
The reed relay ORD213 (RL701) detects the On/Off Hook State of the
handset.
4.3 External Speaker Circuit
4.3.1 Outline
The cradle relays signals between and the handset and the rest of the
equipment, makes a sound upon receiving a call, and monitors the calling
voice signal.
4.3.2 Power Supply System
+13.6 VDC is supplied as the main input source. The following voltages
are supplied for the internal components:
• +13.6 VDC for the speaker amplifier
• +5 VDC from the voltage regulator (IC804) for controlling the analog
switch
• +2.5 VDC (VTH) for operating bias-voltage for voice signals
4.3.3 Monitor Speaker Amplifier
A 5W/4Ω output TDA1905 (IC802) is used for the speaker amplifier to
implement an output of 2W/4Ω.
4.3.4 Sound Volume Control
Sound volume is adjusted by the Volume Controller (VR801).
Upon receiving a DSC (Digital Selective Calling), a sound is produced at
the maximum level regardless of the sound volume value set by the volume
controller (VR801).
RAY230_sect4.p65 7/13/2001, 1:43 PM8