Removal and Replacement of Control, Radio Set C-7088/ARC-131 (FM Control Head)

TM 11-5821-285-12-1

5-12. Removal and Replacement of 8-Day Clock

5-8. Removal and Replacement of Control, Radio

and Clock Bracket

Set C-7088/ARC-131 (FM Control Head)

a Removal.

a. Removal.

(1) Rotate four Dzus fasteners one-quarter turn

(1) Loosen fasteners on each side of the clock

counterclockwise.

bracket.

(2) Pull the FM control head out far enough to

(2) Lift off the clock bracket.

reach the electrical connector on the rear of the unit.

(3) Remove the 8-day clock.

b. Replacement.

(3) Release the electrical connector (twistlock

connector) from the FM control head.

(1) Reinstall the 8-day clock.

b. Replacement.

(2) Reinstall the clock bracket.

(1) Plug the electrical connector into the rear of

(3) Secure the clock bracket in place with the

the FM control head and secure it.

fasteners located on each side. 5-13. Removal and

(2) Reinstall the FM control head in its mounting

Replacement of Antenna AS-1703/ARC (FM Whip

in the console.

Antenna) Elements Unscrew the antenna element from

(3) Rotate the four Dzus fasteners one-quarter

the coupler. Screw the replacement antenna element

turn clockwise.

into the coupler. When replacing the FM-1 or FM-2 an-

tenna element, make sure that the AS-1703/AR is

5-9. Removal and Replacement of Receiver-

inserted through the grommet on the standoff mounted

Transmitter, Radio RT-8231ARC-131 (FM

on the side of the aircraft.

Radio)

5-14. Removal and Replacement of Computer,

a. Removal

Voice Security TSEC/KY-28 (KY-28 Crypto

(1) Release the locking handle catch from its

Box)

secured (down) position and pull the locking handle

outward and downward.

NOTE

(2) Pull out firmly on the locking handle to extract

TSEC/KY-28 may be installed for use

the FM radio from the mounting.

with any one FM radio or all three FM

b. Replacement.

radios.

(1) Set the FM radio on the mounting and slide it

a. Removal.

back carefully; make sure the guide pins at the rear

(1) Disconnect the cables from the KY-28 crypto

properly engage the guide pin receptacles.

box.

(2) Lift the locking handle, press inward, and

(2) Connect the cables to plugs P1 and P2 on

secure with the locking handle catch.

the associated security bypass adapter.

(3) Loosen the screw type fasteners on the KY-

28 crypto box mounting bracket or adapter bracket

5-10. Removal and Replacement of Cable

assembly and lift off the KY-28 crypto box.

Assemblies

b. Replacement.

(1) Secure the KY-28 crypto box on the

WARNING

associated receiver-transmitter mounting bracket

Always disconnect primary power prior

assembly (FM-3) or adapter bracket assembly (FM-1 or

to removing any cable assembly. All

FM-2).

major cable assemblies that require

(2) Remove the two cables from P1 and P2 on

removal

and

replacement

the associated security bypass adapter plate.

organizational maintenance level use

(3) Connect the cables removed in (2) above to

standard connecting devices.

the mating connectors on the KY-28 crypto box.

special techniques or tools are required

for removal and replacement of these

5-15. Removal and Replacement of Control Indicator

cables.

C-8157/ARC (KY-28 Control Head)

a. Removal

5-11. Removal and Replacement of Indicator

(1) Disengage the six Dzus fasteners that hold

Lamps

the KY-28 control head in the console and pull gently.

a. Removal

(1) Remove the lens cover from the applicable

indicator lamp assembly.

(2) Disengage lamp from the assembly.

b. Replacement.

(1) Insert a new lamp in the assembly.

(2) Reinstall the lens cover.

5-4