Service Manual

MM-E 2072-09333-00
2-42
2-7. INTERCONNECTION MODULE
Refer to Figure A-4.
Figure 2-20 shows the functional block diagram of the INTERCONNECTION module.
P2
Amplifier
U1
P1
TX_AUDIO
To
Control
Head
13V8_RADIO_TRUNK
Voltage
Regulator
Q1, U2
To Internal Circuits
13V8_DC_RADIO
ON_OFF_CONT_PNL
Line
Receiver
U5
PTT
Line Driver
U4
Line
Receiver
U3
CH_RXD
CH_TXD
PTT_MIC
RX_UART0
TX_UART0
To
LORD
MIC_IN
Figure 2-20. INTERCONNECTION Module, Functional Block Diagram
a. The TX_AUDIO_P, TX_AUDIO_N balanced signal is converted to a single-ended signal,
MIC_IN, by the audio amplifier U1.
b. The RS-485 balanced PTT signal is converted to a single-ended signal, PTT_MIC, by the
RS-485 line receiver U5.
c. The RS-485 balanced CH_TXD signal is converted to a single-ended signal, TX_UART0, by
the RS-485 line receiver U3.
d. The RX_UART0 signal is converted to a RS-485 balanced signal, CH_TXD, by the RS-485 line
driver U4.
e. The 13V8_DC_RADIO supply voltage received from the LORD module is connected to the
voltage regulator built around U2 and Q1.
Q1 connects the supply voltage to the 13V8_RADIO_TRUNK line supply voltage, which
powers the control head assembly through the interconnection cable.
In addition, the 13V8_RADIO_TRUNK line supply voltage is used to provide power to the
amplifier U1. Another amplifier in U1 provides the AUDIO_BIAS reference voltage for the
audio amplifier.
2-8. FAN CONTROL MODULE
Refer to Figure A-5.
The cooling tray includes the FAN CONTROL module. This module provides the connections
between the radio side connector, J2, and the user’s side connector, J3. In addition, it includes a
voltage regulator comprising U1 and Q2, which provides +12VDC to the fan installed in the tray. The
voltage regulator starts providing the voltage when a high level is applied on the DSO/FAN_ON_OFF
line: this turns Q1 on, and enables U1.