Chapter 4. GENERAL SUPPORT MAINTENANCE INSTRUCTIONS

TM 11-5825-271-34

CHAPTER 4

GENERAL SUPPORT MAINTENANCE INSTRUCTIONS

Section I. GENERAL

ments are given in the troubleshooting/maintenance

4-1. Introduction

instructions in TM 11-5825-271-12.

a. This chapter contains the general support

b. Appropriate waveforms are shown on the

maintenance instructions for the NDB transmitter and the

schematic diagrams, figures FO-2 to FO-12. These

ATU. There is no general support maintenance for the

waveforms are provided as a reference and are not

change-over unit.

required for general support maintenance tasks.

b. General support maintenance for the NDB

transmitter and ATU comprises removal and

4-3. Tools and Test Equipment

replacement of authorized assemblies, subassemblies

Tools and test equipment required for general support

and certain chassis-mounted components. Procedures

maintenance tasks are listed in TM 11-5825-271-12.

are included in this chapter to make sure that repair has

been successfully accomplished.

4-4. Troubleshooting

Maintenance procedures, including troubleshooting

4-2. Voltage,

Resistance

and

Waveform

instructions, for general support maintenance are

Measurements

identical to those authorized at the organizational

a. Overall voltage or resistance checks are not

maintenance level; refer to TM 11-5825-271-12.

applicable to the maintenance of the NDB transmitter

and ATU. Pertinent resistance and voltage measure-

Section II. GENERAL SUPPORT MAINTENANCE OF NDB TRANSMITTER

(2) Remove two screws (3), lockwashers (4),

4-5. General

and flat washers (5) securing the power probe assembly

a. This section provides instructions for performing

A1A6 (6). Remove the power probe assembly A1A6 by

the maintenance functions allocated to general support

pulling it up out of connector XA6 (15). Retain power

maintenance on the NDB transmitter.

probe assembly A1A6 and the attaching hardware for

b. Support illustrations are provided to aid in the

reassembly.

performance of procedures.

The numbers in

(3) Remove two screws (14), nuts (7), lock-

parentheses referenced in the text, e.g., (1), (2), etc,

washers (8), and flat washers (9) securing connector

correspond to the item callout on the illustration.

XA6 (15) to the mounting bracket. Identify the attaching

c. All wires removed/unsoldered during the

hardware and retain for reassembly.

disassembly procedure, should be tagged for

(4) Remove on nut (10), flat washer (12), and

identification.

lockwasher (11) securing the solder lug (13) to the

WARNING

mounting bracket. Tag solder lug and replace nut,

Make sure that external ac circuit breaker

lockwasher and flat washer on the screw for reassembly.

and battery supply are switched off and

(5) Remove five cable clamps securing the

tagged with a warning not to be turned on

cableform to the interior of the cabinet. Retain the cable

while maintenance is being performed.

clamps and attaching hardware for reassembly.

(6) Refer to figure 4-1 (2). Disengage one

4-6. Removal and Replacement of NDB Board

captive screw (17) securing the 50W pa assembly A1A4

Chassis Assembly

(16). Remove the 50W pa assembly A1A4.

a. Removal. Proceed as follows.

(7) Remove two flathead screws (28), nuts (23),

(1) Refer to figure 4-1 (1). Loosen three screws

lockwashers (24), flat washers (25), and hex pillars (27)

(2) securing the fanning strip (1) to the power probe

securing connector XA4 (22). Identify the attaching

assembly A1A6 (6) terminal strip and disconnect the

hardware and retain for assembly.

fanning strip.

4-1