Nokia NSE-3 SERIES, Service Manual

Page: 165 / 217

PAMS
Technical Documentation
CARK–91
Page 7
Original 11/97
Ignition Sense IGNS
The ignition sense feature prevents your car kit from draining the car bat-
tery by executing an auto power off in 20 seconds after the ignition key
has been turned off. The blue wire of the power cable is used for the igni-
tion sense feature. The use of ignition sense is recommended to prevent
accidental draining of the car’s battery. The wire is connected via a 1 A
fuse to a 12/24 volt potential that is controlled by the ignition key. Do not
connect it directly to the high voltage sections of the ignition circuit.
Car Radio Muting CRM
The car kit offers a feature that can mute the car radio automatically dur-
ing a conversation. This feature is convenient and provides for safer
handsfree operation. The car radio muting feature is based on a
grounded line, so it means that in standby, the yellow wire (XCRM) is not
grounded and car radio works normally, but during a call, line is grounded
and car radio is muted. Note that an auxiliary relay or muting unit must
be used when the car radio doesn’t have a mute feature available.
When a relay is used, connect of series with the car radio main supply. A
200 mA fuse should be used to protect the XCRM output in event of a
short circuit. Some radios have separate supplies for amplifiers and mo-
tors, and another for memory backup purposes. Very often these radios
also have a secret code system, which activates itself if a break in the
memory supply is detected. Be careful when installing the relay not to
break the memory supply (usually marked ACC or +MEM), but to install
the relay in the main supply feed.
CAR
RADIO
Bosch P/N 0–332–204–150
12 V, 30 A. SPDT
12 V d.c.
12 V d.c.
Supply for
car radio
Fuse 200 mA
(not supplied)
To XCRM line
(yellow wire)
85
87
87A
30
86
GND
Another possibility is to use a special muting unit, which mutes the radio
by connecting load resistors to the speaker lines of the car radio.