Replacement of Preregulator Electronic Component Assenbly and Preregulator Gasket

TM 9-1240-369-34

b. Replacement

Preregulator

Electronic

(3) Remove eight screws (28), PFN A77Z1

Component Assembly and Preregulator Gasket (see fig.

(29) and PFN gasket (30).

(4) Loosen two captive screws on screw

3-2).

locking assembly (34), and disconnect cable harness

(1) Remove eight screws (5) eight washer (6)

connector P1 (35) from J1 on electronic filter component

and partially remove preregulator cover (7) from the

assembly (33).

power supply unit.

(5) Remove four screws (31) four washers

(2) Loosen two captive screws on the

(32), and electronic filter component assembly A77A8

connector screw locking assembly (8), and disconnect

(33).

cable harness connector P2 (9) from connector J1 on the

(6) To lubricate PFN gasket (30) by applying a

preregulator electronic component assembly (10).

thin, uniform, film of grease, MIL-G-4343. Apply by hand

(3) Remove preregulator gasket (11).

to both sides of the rubber portion of the gasket.

(4) Remove four screws (12), four washers

(7) Install new electronic filter component

(13), and preregulator electronic component assembly

assembly by performing steps (1) thru (5) in reverse

(10).

order.

(5) Lubricate preregulator gasket (11) by

f. Replacement of Switch S1 on Reply Gating

applying a thin. Uniform, film of grease, MIL-G-4343, to

Circuit Card Assembly A77A4 (see fig. 3-2).

the high point on the bead of the gasket. Do not apply so

(1) Remove access cover assembly as

much grease that it fills the grooves on either side of the

instructed in paragraph 3-5 a.

bead. Apply by hand to both sides of the gasket.

(2) Remove reply gating circuit card assembly

(6) Install

new

preregulator

electronic

A77A4 (19) as instructed in paragraph 3-5 c.

component assembly and/or preregulator gasket by

(3) Tag the leads to the terminals on switch

performing steps (1) thru (4) in reverse order. Note

S1 for identification. Unsolder the leads.

orientation of preregulator gasket and preregulator

(4) Remove two nuts, two lockwashers, two

electronic component assembly to ensure dowel pin hole

washers, actuator switch adapter, and switch S1 from

in both parts engage dowel pin in housing (36).

c. Replacement of Printed Circuit Cards A77A1

component side of the card assembly.

thru A77A5 and A77A7 (see fig. 3-2).

(5) Remove two screws and two nonmetallic

washers from the opposite side of the card assembly.

(1) Remove access cover assembly as

Inspect the washers for damage and replace as

instructed in paragraph 3-5 a.

necessary.

(2) Remove the desired printed circuit card

assemblies (14) thru (20) from the power supply unit.

Remove desired printed circuit card assembly with circuit

CAUTION

card puller (7), table 2-1).

When installing switch S1, ensure

(3) Install new printed cards by performing

that its actuator switch adapter is not

steps (1) and (2) in reverse order. Do not use the circuit

installed too high reply gating circuit

card puller when installing the printed circuit cards.

card assembly A77A4 or it may be

d. Replacement of PFN Charge Power Supply

damaged when the access over

A77A9 (see fig. .3-2).

assembly is installed.

(1) Remove access cover assembly as

instructed in paragraph 3-5 a.

(6) Install new switch S1 by performing steps

(2) Remove two screws (21) and PFN charge

(1) thru (5) in reverse order. During installation switch

power supply A77A9 (22). Inspect screws for damage

S1, ensure that when the reply gating circuit card

and replace as necessary. No special instructions are

assembly A77A4 is seated in the housing, switch S1 is

required for removal or replacement or the PFN charge

adjusted to a height where the access cover will adjust

power supply.

barely activate switch S1 (an audible click can be heard).

(3) Install new PFN charge power supply by

g. Replacement of PFN A77Z1 (see fig. 3-2).

performing steps (1) and (2) in reverse order.

(1) Remove PFN charge power supply A77A9

e. Replacement of Electronic Filter Component

(22) as described in Paragraph 3-5d.

Assembly A77A8 (see fig. 3-2).

(2) Remove two nuts (23), two lockwashers

(1) Remove PFN charge power supply A77A9

(24), two terminal lugs (25) and two washers (26) from

(22) as instructed in paragraph 3-5d.

terminals (27) on PFN A77Z1 (29).

(2) Remove two nuts (23), two lockwashers (24), two

(3) Remove eight screws (28), PFN A77Z1

terminal lugs (25) and two washers (26) from terminals

(29)and PFN gasket 130).

(27) on the PFN (209).

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