Chapter 3. DIRECT SUPPORT MAINTENANCE INSTRUCTIONS

TM 11-5825-271-34

CHAPTER 3

DIRECT SUPPORT MAINTENANCE INSTRUCTIONS

Section I. GENERAL

troubleshooting/maintenance instructions in TM 11-5825-

3-1. Introduction

271-12.

a. This chapter contains the direct 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 direct support maintenance for the

waveforms are provided as a reference and are not

change-over unit.

required for direct support maintenance tasks.

b. Direct support maintenance for the NDB

transmitter and ATU comprises removal and

replacement of authorized assemblies, subassemblies

3-3. Tools and Test Equipment

and certain chassis-mounted components. Procedures

Tools and test equipment required for direct support

are included in this chapter to make sure that repair has

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

been successfully accomplished.

3-4. Troubleshooting

3-2. Voltage,

Resistance

and

Waveform

Maintenance procedures, including troubleshooting

Measurements

instructions, for direct support maintenance are identical

a. Overall voltage or resistance checks are not

to those authorized at the organizational maintenance

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

applicable to the maintenance of the NDB transmitter

and ATU.

Pertinent resistance and voltage

measurements

are

given

the

Section II. DIRECT SUPPORT MAINTENANCE OF NDB TRANSMITTER

(2) Carefully remove two nuts (14), lockwashers

3-5. General

(15), and flat washers (16) securing two solder lugs (17)

a. This section provides instructions for performing

to back of TEST meter M1 (11). Tag solder lugs and

the maintenance functions allocated to direct support

replace the attaching hardware on TEST meter M1.

maintenance on the NDB transmitter.

(3) Tag and unsolder all cableform wires

b. Support illustrations are provided to aid in the

terminated at the control panel assembly (13). Before

performance of procedures.

The numbers in

unsoldering any wire, slide the rubber sleeving away

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

from the solder joint so as not to burn it inadvertently

correspond to the item callout on the illustration.

(4) Remove one screw (10), nut (5), lockwasher

c. All wires removed/unsoldered during the

(6), and flat washer (7) securing cable clamp (8).

disassembly procedure, should be tagged for

Remove cable clamp from cableform and reinstall on

identification.

control panel assembly (13).

WARNING

(5) Remove three screws (9), nuts (1),

Make sure that external ac circuit breaker

lockwashers (2), and flat washers (3) securing the

and battery supply are switched off and

control panel assembly (13) to the board chassis. Note

tagged with a warning not to be turned on

the location of the cable clamp (18) and solder lug (4) on

while maintenance is being performed

the hinge. Leave cable clamp on cableform and retain

all attaching hardware for reassembly.

3-6. Removal and Replacement of Control Panel

b. Replacement. Proceed as follows.

Assembly

(1) Refer to figure 3-1. Prepare the control

a Removal. Proceed as follows.

panel assembly by removing the cable clamp (8). Retain

(1) Refer to figure 3-1. Disengage two captive

cable clamp and attaching hardware (5), (6), (7), and (9)

screws (12) on the control panel assembly (13) and

for later use.

swing the control panel assembly out.

3-1