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LBI-31869
S3 Radio Engaged
Closes when radio is
properly inserted into
charging insert and ap-
plies power to DS1, RA-
DIO
E NGAGED
indicator.
S1 Repeater OFF-ON
ON: Enables Vehicular
Repeater function if ra-
dio is not inserted into
charging compartment.
OFF: Vehicular Repeater
System is disabled.
OPERATION
Temperature characteristics of nickel-cadmium batter-
ies, prevent a full charge at temperature extremes. For maxi-
mum charge, recharge the battery pack at ambient room
temperature or between 65° and 85°F.
WARNING
The General Electric Vehicular Charger is designed
to recharge the GE standard high capacity battery
pack and the extra high capacity battery pack. At-
tempting to recharge any other battery pack or bat-
teries may result in damage to equipment, leakage,
or explosion.
CHARGER/REPEATER OPERATION
NOTE
When the portable radio unit is placed in the charg-
ing insert, set the REPEATER OFF-ON switch to
ON so the Vehicular Repeater System will be en-
abled automatically when the portable radio is re-
moved from the charger.
The following procedures describe the recharging of the
portable radio battery pack and the operation of the Vehicular
Repeater System.
1. The power switch on the radio battery pack may be
in the ON or OFF position.
2
2. Insert radio unit into charging compartment with its
speaker facing forward (see Figure 2.).
TM
3. Slide the POSILATCH
toward the portable radio
unit until you feel it engage and the red RADIO
ENGAGED indicator lights.
4. Place the REPEATER ON OFF switch to the ON
position. The red repeater ON indicator will not light
until the portable radio is removed from the charging
compartment.
NOTE
The Vehicular Repeater System will be disabled as
long as the portable radio unit is in the charging
compartment or the REPEATER OFF-ON switch is
in the OFF position.
5. The red CHARGE indicator will light and remain lit
until the portable radio unit is removed or until the
vehicular repeater/charger unit circuits sense that the
battery pack has reached total charge capacity. At this
time the green READY indicator will also light,
indicating that the charger has switched to the trickle
charge rate.
6. To remove the portable radio from the charging
compartment, depress the blue push-button release
on the POSILATCH and slide the latch completely
away from the portable radio unit. The red RADIO
ENGAGED indicator will turn off and the portable
radio unit can be removed from the charging com-
partment (see Figure 2).
CAUTION
DO NOT use the antenna to remove the portable
radio from the charging compartment.
7. Removing the portable radio unit will automatically
enable the Vehicular Repeater System and the red
REPEATER ON indicator will light.
NOTE
The REPEATER OFF-ON switch must be in the
ON position for the Vehicular Repeater System to
function.
Figure 2 - Inserting and Removing Portable Radio Unit
CIRCUIT ANALYSIS
The Vehicular Charger is comprised of a Charger board,
LED board, Display Repeater board, and a UDC board.
CHARGER BOARD
The Charger board contains the charging circuit, with
voltage and temperature cut-off circuits.
CHARGING CIRCUIT
When power is first applied to the charger, the voltage at
pin 5 of Comparator A7 is higher than at pin 6 of A7 due to the
charging time of C18. The higher voltage causes the output at
pin 7 of A7 to go high, keeping A13 turned off. This allows the
battery to start charging. A block diagram of the Vehicular
Charger is shown in Figure 3.
Charging current flows through series connected resistors
R21 and R22 to regulator transistor Q3. The output of Q3 is
connected to the positive charging contact of the battery. Test
Point TP2 provides a convenient
LBI-31869
place to monitor the positive battery contact. A portion of the
charging current is routed through resistor R24 and transistor
Q2 to turn on CHARGE LED DS3 on the LED board and to
provide a trickle charge when Q2 turns off. The series con-
nected charge circuit determines the high charge rate and is
controlled by the temperature controlled cut-off circuit.
CHARGER CONTROL CIRCUIT
The Charger Control circuit consists of a temperature
controlled cut-off circuit and battery charged memory circuit.
The temperature controlled cut-off circuit consists of inte-
grated circuit A13, a bridge circuit comprised of R29, R30,
R33, thermistors RT1 and RT (BATT), and associated circuitry.
Temperature cut-off IC A13 monitors the temperature of the
charging insert through thermistor RT1 and the temperature of
the battery pack through internal thermistor RT (BATT). It also
controls transistors Q3 and Q4, turns the "READY" indicator
on when the battery pack is fully charged, and provides mem-
ory to prevent the same battery pack from being recharged at
the high rate.
Thermistors RT1 and RT (BATT) are connected with R29,
R30, and R33 to form a bridge circuit (see Figure 4). The output
of the bridge circuit is connected to terminals 13 and 14 of A13.
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