NUMERIC DISPLAY, 1A9

TM 11-5820-917-13

out (opens) removing the battery load. Turning the AC line power to the 4028

back on automatically resets (closes) the relay and activates the battery charger

circuit to recharge the batteries. Depressing switch S1 forces the relay to drop

out when the batteries have normal charge and the AC line power is off. This

allows the batteries to be disconnected from any load for long term storage.

4-58. NUMERIC DISPLAY, 1A9

4-59. The numeric display is a 9-digit, 7-segment LED display consisting of two

groups of four digits (frequency and time) and one path digit. The first group

(LED 1 thru 4) displays program time elapsed in minutes and seconds and has a

fixed colon (CR1 and CR2, figure FO- 19) separating the minutes from the seconds.

The second block (LED 5 thru 8) displays frequency in megacycles to 10 kHz reso-

lution. The decimal point is permanent and is placed at the start of the third digit

(activated by R65 to ground). The path digit (LED 9) displays the actual path

being received, and is independent of the path selected for CRT display by the

CRT (memory) control pushbutton. When the mode select switch is in one of the

SET positions (i.e. , a path timer under manual control) , the path digit flashes.

The LED display is driven by nine BCD-to-7 segment decoder drivers ( figure

FO-19/2). The two blocks of four drivers accept positive true BCD time and

frequency information from the 3-path programmer (1A 4A 1) and receiver control

circuit ( 1A 4A2) , respectively, and translate it to 7-segment negative true outputs

for the common anode LED readouts. The lamp test line causes all LED display

segments to illuminate.

SUB PANEL CONTROL, 1A10

4-61. This assembly includes most of the control switches for the 6025 unit.

Operation of the switches is described in section 3. This module may be removed

from the chassis for troubleshooting bv first removing the five casting modules

from the unit. Mounting screws for the sub-panel are on the bottom of the unit

with additional nuts on both sides. Once removed from the chassis it is then

possible to remove the four socket-head screws on the front to access the

switches.

4-62. ENCLOSURE ASSEMBLY, 1A11

4-63. The enclosure consists of a chassis, front panel and rear panel assemblies.

Internal wiring and cabling are part of the front and rear panel assemblies. The

rear panel mounts the voltage regulators, (three terminal IC'S in T03 cases), a

cooling fan, and the input/output connectors. Interconnections of the unit are

defined in Section 2. Front panel controls are explained in Section 3. A schematic

diagram for the regulators and fan circuit is provided ( figure FO-21). The DC

voltages required by the 6025 (unit 1) are generated in the 4028 (unit 2) .

Voltages as input to the 6025 are unregulated. U1 through U5 are 5-volt, 3-

amp regulators. U6 through U10 are +12-volt, 1-amp regulators. U11 and U12 are

- 12-volt, 1-amp regulators.