Section III. MAINTENANCE

TM 11-5895-1123-34

Section III. MAINTENANCE

NOTE

4-6.

General

In the next step it is extremely important

The following paragraphs contain those disassembly

to note the position of the pin on the

procedures necessary for troubleshooting and repairing

bottom of A3 that is protruding through

the -48 vdc power supply and 20-Hz ringing supply

an off-white bead at its base to ensure

assembly.

the replacement A3 module is inserted

back in the same way.

4-7.

Removal and Replacement of -48 Vdc Power

Supply Module A1

d. Pull straight down on the defective A3

a. Remove the four nuts and washers on the

ensuring not to change its position and note the relative

bottom of the power supply chassis which hold A1 to the

position of the pin that is protruding through an off-white

frame.

bead at its base.

Tag and unsolder the four wires connected

e. On the replacement A3 module, observe

to Al OUT -, +, and IN 1 and 2.

the position of the pin protruding through the off-white

c. Lift the power supply chassis off A1

bead at its base and be sure to align it in the same

d. Set the power supply chassis on the

position that it was in on the A3 module that was

replacement Al module.

defective.

e. Prepare the wires for soldering, and using

Set the replacement A3 module in place on

good soldering practices, solder the four wires back to Al

the power supply chassis and secure it in place with the

OUT, -, + and IN 1 and 2.

four mounting washers and nuts.

Remount the four washers and nuts on the

g. Prepare the wires for soldering and, using

mounting bolts protruding through the bottom of the

good soldering practices, solder the wires back to their

power supply chassis and tighten them to secure Al.

appropriate pins on the bottom of A3.

h. Slide the plastic insulating sleeve back over

4-8.

Removal and Replacement of -48 Vdc Power

the solder connections.

Supply Module A2

Replace the tie-wraps that were removed

a. Tag and unsolder the two wires connected

from the wires going into A3.

to A2 + and dc terminals on the bottom of power supply

chassis.

4-10. Removal and Replacement of --48 Vdc Power

b. Remove the four screws and washers from

Supply CR1

the bottom of the power supply chassis which hold A2 in

place and remove the defective A2.

Unsolder the two leads connected to the top

c. Hold the replacement A2 module in place

of CRI.

and secure it to the power supply chassis with the four

b. Remove the nut, two washers, and

washers and mounting screws.

insulating disk from the bottom of CR1 which holds it to

d. Prepare the two wires for soldering and

the power supply frame.

using good soldering practices solder them to A2 + and

c. Remove CR1 from the power supply

dc terminals.

chassis and remove the nylon insulating washer,

insulating disk, and the cathode washer from the

4-9.

Removal and Replacement of -48 Vdc Power

mounting stud.

Supply Module A3

d. Assemble the cathode washer, insulating

disk, and nylon washer (in that order) on the mounting

a. Cut the tie-wraps holding the wires going

stud of the replacement CR1 and insert it back into the

into A3 together and slide the plastic insulating sleeves

hole in the power supply chassis.

back along the wires to expose the solder connections

e. On the CR1 mounting and protruding

on the pin contacts of A3.

through the bottom of the power supply chassis,

b. Tag and unsolder the wires from the bottom

assemble the insulating disk, two washers and nut, and

of A3.

secure CR1 to the power supply chassis.

Prepare the two leads for soldering and

NOTE

using good soldering practices, solder them back to

Do not remove A3 in the next step.

CR1.

4-11. Removal and Replacement of -48 Vdc Power

c. Hold the defective A3 in place and remove

Supply Multipin Connectors

the four nuts and washers which hold A3 to the power

supply

chassis.

a. The procedure outlined in paragraph 3-6b

above should be followed, except in this case the

4-22