Removal and Replacement of NDB Board Chassis Assembly

TM 11-5725-271-34

(41), lockwasher (40), and flat washer (39) and reinstall

NOTE

securing solder-lug (42).

Identify the location of the two solder lugs

(6) Connect two BNC connectors (37) to the rf

(26) held in place by the connector XA4

filter assembly AlA5 (38).

attaching hardware.

(7) Refer to figure 4-1 (3). From the inside of

the cabinet, insert BNC connector J3 (31) through the

(8) Remove one nut (21), lockwasher (20) and

hole in the cabinet and aline the four mounting holes.

flat washer (19) securing two solder lugs (18) to the

(8) Secure BNC connector (31) and solder lug

mounting bracket. Tag two solder lugs and replace the

(33) to the cabinet using four screws (32), nuts (36),

attaching hardware on the screw for reassembly.

lockwashers (35), and flat washers (34).

(9) Refer to figure 4-1 (3). Loosen 12 screws

(9) Install fanning strip (29) on terminal strip

(30) securing the fanning strip (29) to the terminal strip

TB3 of the transformer chassis assembly. Tighten 12

TB3 on the transformer chassis assembly; disconnect

screws (30) on the terminal strip to secure the faning

the fanning strip.

strip.

(10) Remove four screws (32), nuts (36), lock-

(10) Refer to figure 4-1 (2). Secure connector

washers (35), and flat washers (34) securing BNC

XA4 (22) to the bracket using two flathead screws (28),

connector J3 (31) to the cabinet. Tag BNC connector

hex pillars (27), nuts (23), lockwashers (24), and flat

and the one solder lug (33), identify the attaching

washers (25). Ensure that two solder lugs (26) are

hardware and retain for reassembly.

secured by attaching hardware.

(11) Refer to figure 4-1 (4). Tag and disconnect

NOTE

two BNC connectors (37) from the rf filter assembly

A1A5 (38).

When installing connector XA4, make

(12) Remove one nut (41), lockwasher (40), and

certain that pins 1 through 4 are at the front.

flat washer (39) securing the solder lug (42) to the rf filter

assembly AIA5 (38) Tag solder lug and replace the

(11) Remove one nut (21), lockwasher (20) and

attaching hardware on the screw for reassembly.

flat washer (19) and reinstall securing the two solder lugs

(13) Refer to figure 4-1 (5). Using the pcb

(18).

extractors (47), remove the monitor assembly A1A7 (48)

(12) Reinstall 50W pa assembly A1A4 (16) in

and the exciter assembly A1A2 (46). Retain both

connector XA4 (22) and secure by engaging captive

assemblies for reassembly

screw (17).

(14) Disengage two captive screws (50) on the

(13) Refer to figure 4-1 (1). Remove one nut

control panel assembly (49) and swing the control panel

(13), lockwasher (12) and flat washer (11) and reinstall

out.

securing solder lug (10).

(15) Remove eight screws (45), lockwashers

(14) Install connector XA6 (15) on the mounting

(44), and flat washers (43) securing the board chassis

bracket using two screws (14), nuts (7), lockwashers (8),

assembly to the cabinet cover; carefully remove the

and flat washers (9).

board chassis assembly. Retain the attaching hardware

NOTE

for reassembly.

When installing connector XA6, make

b. Replacement. Proceed as follows.

certain that pin 17 is positioned near the

(1) Refer to figure 4-1 (5). Position board

front of the cabinet

chassis assembly so that the eight holes in the board

(15) Insert power probe assembly A1A6 (6) into

chassis assembly aline with the eight clinch nuts on the

connector XA6 (15) and secure to the hex pillars using

inside front cover. Place the loose ends of the cableform

two screws (3), lockwashers(4), and flat washers (5).

into the cabinet.

(16) Install fanning strip (1) on the power probe

(2) Install and tighten eight screws (45), lock-

terminal strip and secure by tightening three screws (2)

washers (44) and flat washers (43) to secure the board

on the terminal strip.

chassis assembly to the inside of the cabinet cover.

(17) Install the five cable clamps to secure the

(3) Swing the control panel assembly (49) in.

cableform to the cabinet.

Engage and tighten two captive screws (50) to secure

NOTE

the control panel assembly.

The one small cable clamp must be used to

(4) Replace monitor assembly A1A7 (48) and

retain the two coaxial cables leading to the

the exciter assembly A1A2 (46) by inserting pcb into

power probe assembly A1A6.

guide rails (51) and pushing pcb connector into the

cableform connector.

(5) Refer to figure 4-1 (4). Remove one nut

4-2