TM9100 Installation Guide
Installing the Radio
19
© Tait Electronics Limited
August 2005
2.5
Connecting the Power Cable to the Power Source
This section provides information on connecting the power cable to the
power source.
Power Connector
The power connector is the interface to the vehicle battery and an optional
external remote speaker. Connecting a remote speaker is described in
“Connecting a Remote Speaker” on page 21
.
Important
This radio is designed to operate from a nominal 12V
negative ground supply and may draw up to 15A of current.
The radio will tolerate a supply voltage range of 10.8V to
16.0 V at the radio.
Selecting the Power
Source
In passenger vehicles, the radio is always connected directly to the battery
using the power cable provided.
In trucks, where direct connection to the battery is often not possible, the
radio can be connected to a suitable terminal inside the fuse box that is
connected directly to the battery.
24V-to-12V
Converter
In vehicles with a supply voltage larger than 16.0V, such as many trucks, it
is essential to provide a suitably rated 24 V-to-12V converter. This will
isolate the radio from excessive battery voltage and provide the correct DC
operating conditions. Note that most 24 V-to-12 V converters already fitted
are not rated sufficiently.
Standby Current
When connecting the radio to the battery without using the ignition signal
as described
on page 23
, the standby current is approximately 50mA.
When using the ignition signal to turn off the radio, the standby current is
reduced to <3mA.
Tip
To reduce the standby current from 50mA to <3 mA without using
the ignition signal, connect pin 4 (AUX GPI3) and pin 15 (GND)
of the auxiliary connector.
Table 2.1
Power connector (radio)— pins and signals
Pinout
Pin
Signal name
Description
Signal type
1
AGND
Earth return for radio body power source Ground
2
SPK–
External speaker output. Balanced load
configuration
Analog
3
SPK+
External speaker output. Balanced load
configuration
Analog
4
13V8 BATT
DC power input for radio body and
control head
Power
rear view
40W/50W radio
1
2
3
4
rear view
25W radio
