Specifications

5/2/2013 888-2500-001 4-11
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
DAX-1/DAX-3
components are damaged. Semiconductor fuses are employed to provide this protection
function.
4.4.2.5.2 Low Voltage Power Supply
The transmitter power supply system includes low voltage switching power supplies,
which provide power for the transmitters control circuitry, fans, and Binary PA’s. There
are two low voltage power supplies in the system, which provide three DC output
voltages: +/-12Vdc and +48Vdc. The table below shows the current requirements for
the low voltage power supplies.
The DC output voltages in the table above are fed from the switching power supplies to
the Power Supply Controller Board, where over-current protection is provided for each
DC output. The low voltage power supply voltages are then fed to the rest of the
transmitter system.
4.4.2.6 DC Discharge Circuit
A DC discharge circuit is used in the power supply in order to discharge the DC bus
voltage to a safe level when the power supply receives the “off” command from the
main controller. When the power supply receives the command to turn off or switch
secondary taps a FET switch connects a bleeder resistor to the DC bus, discharging the
DC voltage to approximately 40.5V in 2 seconds.
4.4.2.7 Power Supply System I/O
The power supply system is controlled and monitored via an I/O Data Buss. AC and DC
power I/O will be referred to as being on the Power Buss.
Table 4-1 Low Voltage Power Supplies’ Current Requirements
Output Voltage Current Load Over-Current
Protection
+12Vdc 6A 15A Slow Blow Fuse
-12Vdc 1.1A 2.5A PTC
+48Vdc 2A 7A Slow Blow Fuse