744T User Guide and Technical Information
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v. 2.67
Features and specifications are subject to change. Visit www.sounddevices.com for the latest documentation.
External DC Input Wiring
Operation
pin-2 to negative (–)
pin-3 to positive (+)
operates the on-board Li-ion charger when the unit is both turned on and off. Use when
plugged into AC power
pin-1 to negative (–)
pin-4 to positive (+)
operates the on-board Li-ion charger only when the unit is turned on—there is no exter-
nal current draw when powered off. Use when connecting to an external battery pack
Regardless of whether pins-1 and -4 or pins-2 and -3 are used, the unit will always charge the Li-ion battery when the unit is
powered on.
Pin-1 and pin-2 of the external DC input are at the same ground potential as chassis and signal ground.
The voltage level of the source powering the unit is displayed on the main LCD screen in the up-
per left-hand corner (
). When the 744T senses a low voltage condition from an external
DC source the power LED and battery voltage display flashes, to alert the user. When the external
DC reaches 9 volts, the 744T will automatically switch over to the removable battery. If no battery is
installed the unit will shut down.
The included AC-to-DC power supply operates the unit and charges the removable batteries simul-
taneously. Pins-3 and -4 are wired to (+) and pins-1 and -2 are wired to (–).
When power is applied, the charging circuit evaluates the battery condition and supplies charg-
ing current, if necessary. When charging, the amber charge LED will flash. Once the battery is fully
charged, the charger will turn off and the amber charge LED will light solid, indicating a full charge.
Large capacity cells increase the charge time.
Charge LED Activity Description of Activity
Off
Charger disabled
On
Completed charge / battery fully charged
Blinking
Charger enabled / battery is charging
If the charge LED shows anything but a successful charge, the Li-ion battery may require replacement.
Time Code Clock Battery
The 744T has an internal NiMH LR6 (AA) battery to power to the time code generator circuitry and
time-of-day clock. This battery is charged simultaneously with the Li-ion battery. Additionally, the
AA is charged from the Li-ion battery when the unit is powered on.
With a fully charged AA battery, accurate time code is held for two hours after power down. The
744T can be powered down and the removable battery can be removed and replaced without worry
of time code jumps or inaccuracy. When the NiMH battery reaches a factory-set voltage, the time
code generator will shut off and the time-of-day clock will take over — holding time and date for up
to 60 days.
744T maintains accurate time code for 2 hours after power-down with a fully charged NiMH battery time
code AA battery, even with the Li-ion and external DC power sources removed.
Auto Functions with External Powering
The 744T can perform several functions when DC power is applied to and removed from the record-
er. Options available include:
Summary of Contents for 744T
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