Chapter 2. DEPOT TROUBLESHOOTING

TM 11-5820-549-50-1

CHAPTER 2

DEPOT TROUBLESHOOTING

2-3. Test Equipment Required for Troubleshooting

2-1. Scope of Depot Troubleshooting

The following chart lists test equipment required for

This chapter covers the troubleshooting procedures

troubleshooting the AN/PRR-9(XE-9). The associated

assigned to the depot category of maintenance for

technical manuals are also listed.

Receiving Set, Radio AN/PRR-9(XE9).

These

procedures supplement those described in the operation

Item

Technical manual

and organization maintenance manual TM 11-5820-549-

12-1.

Indicator, Channel Align-

TM 11-6625-937-12

ment ID-1189(XE-2)/

2-2. Organization of Troubleshooting

Multimeter TS-352B/U

TM 11-6625-366-15

a. General. The first step in troubleshooting is to

Power Supply PP-3514/U

TM 11-6625-617-12

determine which functions are not operating correctly.

The AN/PRR-9(XE-9) may receive signals satisfactorily,

2-4. Troubleshooting Test Setup

but the squelch may be inoperative. Complaints may

also include weak reception, or completely inoperative

a. Bench tests of the AN/PRR-9(XE-9) require

equipment.

connection to a power source. The power source must

b. Operational Tests.

Operational tests may

be connected to the AN/PRR-9(XE9) for all dc voltage

indicate the general location of trouble. In many

measurements. The power supply should be set for 3.2

instances, the tests will help determine the exact nature

vdc. TS-352B/U connections are made to pads of the

of the fault. The operational test (TM 11-5820-549-12-1)

printed circuit board in the electronic unit assembly, or

may be used to determine general performance. The

to other points designated in the voltage and resistance

use of Indicator, Channel Alignment ID-1189(XE-2)/PR

chart, paragraph 2-6.d. In making measurements on the

may also help to locate trouble. Some troubles may be

printed circuit pads, always observe the polarity of the

due to poor alinement.

test equipment as specified for the particular tests.

c. Visual Inspection.

Obvious faults such as

broken battery connector pin, and a loose or broken

CAUTION

antenna housing assembly can easily be determined

This equipment contains integrated

from visual inspection.

circuits. If any test equipment item

d. Intermittent Troubles. In all troubleshooting, the

does

not

have

isolation

possibility of intermittent troubles should not be

transformer in its power supply

overlooked. If present, this type of trouble often may be

circuit, connect one in the power

made to appear by tapping or gently jarring the

input circuit. A suitable transformer

AN/PRR-9(XE-9) while operating the receiver control.

is identified by FSN 5950-3561779.

The use of higher than normal input voltages for the

purpose of locating intermittent faults should be avoided

since damage to the integrated circuits could result.

(1) Never connect test equipment (other than

multimeters and vtvm's) outputs directly to an integrated

e. Voltage and Resistance Readings. The best

circuit; use a coupling capacitor.

technique for locating trouble is the measurement of dc

voltages and resistances.

The most significant

(2) Make test equipment connections with

measurements on the integrated circuits are the

care so that shorts will not be caused by exposed test

collector terminal voltages. Detailed instructions for

equipment connectors. Tape or sleeve (spaghetti) test

voltages and resistance measurements are provided in

prods or clips as necessary to leave as little exposed as

paragraph 2-6.

needed to make contact to the circuit under test.

(3) When a power supply is used in place of

the battery normally used with the equipment,

2-1