8 - 4
8.3 Operation Panel (CMD-745)
CD1 through CD3 are 7 segment type LED indicators. The control
signals from the CPU are held in IC5 to IC8, and IC1 to IC4 drive the
LED's. CD8 and CD5 are send/receive indicators. SW1 through SW12
are numeric switches. S13 switch is used for switching between remote
and local modes. CD4,CD6,CD7 and CD9 are alarm indicators. They
are illuminated according displays signals from the CPU.
8.4
Control (CDE-885)
The CDE-885 Control has the control circuit for the unit and amplifier
circuit for audio signals.
8.4.1 Audio Amplifier Circuit (CDE-885)
The audio amplifier circuit consists of the microphone amplifier circuit
and speaker amplifier circuit. In transmission in local mode, voice signal
from the microphone connected to the panel is amplified by IC39-1, and
voice signal input in remote mode is buffer amplified by IC40-2. These
voice signals are selected by IC42-1. The level of selected voice signal
is adjusted according to whether it is simplex or duplex, and sent to the
transmitter section PLL circuit. In reception, the level of voice signal
detected by the receiver section is adjusted by RV4, and amplified by
IC38. To drive the speaker, this voice signal passes through IC38, and
is sent to the drive amplifier circuit consisting of IC38. For remote device,
the sound signal is output from IC40-2 through T3.
8.4.2 Control Circuit (CDE-885)
The control circuit includes the PLL circuits for transmission and
reception, PA circuit, panel switch circuit, and microprocessor (IC1), which
control the remote control circuit. The microprocessor has a data bus,
address bus, and control bus. To those bus lines, connected are ROM
(IC11), EEPROM (IC9), RAM (IC10), out ports (IC12, IC14, IC16, IC18,
IC20, IC21, IC23 and IC24), in ports(IC22, IC25, IC26, IC27, IC28 and
IC29) and timer (IC32). This control circuit operates according to the
RMT
LCL
DUP
SIMP
EXT AF out
MICROPHONE
EXT AF in
SPEAKER
RX
Circuit
TX
Circuit
LCL
RMT
Fig. 8.2 Audio amplifier Block diagram
