TM 55-1730-229-12
AG 320A0-OMM-000
TO 35C2-3-473-1
TM 1730-12/1
(5) The battery output (or com-
utility lamps DS103 through DS105, con-
bined battery and charger output if en-
trol panel indicator lamps 1DS1 through
gine is running) can be connected to the
1DS21, a steering diode for each indi-
AGPU dc output cable, or made available
cator lamp, voltage regulators 3VR1 and
to the propulsion system traction motor.
3VR2, and control panel switches (1S4,
This occurs when control panel DC POWER
1S6, and 1S7). DC power is available
switch 1S12 is OFF and BATTERY OUTPUT
whenever the MASTER switch and LIGHTS
switch 1S5 is ON, which activates bat-
circuit breaker 1CB1 are on.
tery output/traction motor contactor
(1) DC power is applied directly
K3.
to the panel lights (located above main
(6) Power diodes 3CR7 through 3CR9
control panel) when PANEL switch 1S6 is
Power is applied
prevent the GTE control circuits from
in the BRT position.
shutting down the engine because of a
to the panel lamps via 3VR1 when the
3VR1
generator dc output or battery charger
switch is in the DIM position.
failure.
If the generator dc output or
limits the panel lamp voltage to 14 vdc
to reduce lamp intensity.
charger 20 amp section fails, the 20
amp section output decays gradually.
Battery/charger transfer relay 3K3 does
(2) DC power is applied directly
not drop out until the potential across
to the utility lamps (fuel, engine, and
the relay coil drops to approximately 18
hydraulic) when UTILITY switch 1S7 is
vdc.
If diodes 3CR7 through 3CR9 were
Power is applied
in the BRT position.
not connected as shown, the GTE dc con-
to the utility lamps via 3VR2 when the
3VR2
trol power could drop to 18 vdc before
switch is in the DIM position.
relay 3K3 drops out and switches to bat-
limits the utility lamp voltage to 14
The GTE ECU (electronic
vdc.
tery power.
control unit) is designed to shut down
the engine if the GTE dc control power
(3) Some of the control panel in-
drops to approximately 18 vdc. For this
dicator lamps (IDS1, 1DS2, 1DS7, 1DS11,
reason, battery voltage is connected via
1DS13 through 1DS19, and 1DS21) are per-
diodes CR8 and CR9 to the GTE control
manently grounded. During operation the
circuits. The voltage drop across zener
associated control circuit applies a
diode 3CR8 (4.3v) and diode 3CR9 (0.7v)
voltage to the lamp positive terminal
reduces battery voltage (24 vdc) to 19
PRESS TO TEST
to illuminate the lamp.
vdc. The 19 vdc battery voltage is suf-
switch 1S4 (when pressed) applies dc
ficient to keep the engine running when
power via steering diodes to illuminate
the charger output drops below 19 vdc,
all of the permanently grounded lamps.
but is lower than the normal charger
The diodes prevent a voltage input to
output so that no GTE control power is
one lamp from illuminating other lamps.
drawn from the battery when the charger
is operating normally.
(4) The other control panel indi-
Steering diode
3CR9 prevents the charger normal output
cator lamps (1DS3 through 1DS6, 1DS8
(relay 3K3 activated) from seeking the
through 1DS10, 1DS12, and 1DS20) are
lower voltage level at the anode of
permanently connected to dc power (after
3CR8. Steering diode 3CR7 prevents the
MASTER SWITCH is turned on). During op-
19 vdc battery voltage from holding re-
eration, the associated indicator lamp
lay 3K3 on when the charger output drops
control provides a ground return at the
below the normal 18 vdc level required
lamp negative terminal to illuminate the
to keep the relay activated.
The PRESS TO TEST switch (when
lamp.
pressed) provides a ground return to
b. Lights Control System.
The diodes
(See
illuminate all the lamps.
prevent a voltage to one lamp from
includes panel lamps DS101 and DS102,
illuminating other lamps.
4-161
