Section III. TROUBLESHOOTING - TM-11-6625-2609-340010

TM 11-6625-2609-34

Section Ill. TROUBLESHOOTING

attempt made to localize the fault to a particular

3-3. General Instructions

circuit.

Troubleshooting at direct support includes all the

(2) Operational tests. Operational tests fre-

techniques outlined for organizational mainten-

quency indicate the general location of trouble.

ance and any special or additional techniques

In many cases, the tests will help in determining

required to isolate a defective part. The syste-

the exact nature of the fault.

matic troubleshooting procedure, which begins at

(3) Troubleshooting, The trouble symptoms

organizational, must be completed by means of

l i s t e d in table 3-2 will aid in localizing the

localizing and isolating techniques. The para-

trouble to a part or circuit. For physical location

graphs which follow provide intraunit (within the

of parts (figs. 3-1, 3-2, and 3-3).

unit) troubleshooting procedures and describe the

(4) Resistance and continuity measurements.

localizing and isolating techniques that must be

Make the resistance and continuity measurements

performed at direct support,

listed in table 3-3. Where results other than those

indicated are obtained, isolate the faulty part by

3-4. Organization of Troubleshooting

further resistance measurements.

Procedure

(a) Remove cover from maintenance kit.

(b) Remove test panel from equipment

a. General. The first step in servicing a defec-

case.

tive test set is to localize the fault. Localization

means tracing the fault to a defective circuit

CEIVER connector on front of test panel.

responsible for the abnormal condition. Some

(d) Set the switches or controls to the

faults, such as burned or loose wires, can often

position indicated in the Point of measurement

be located by sight. The majority of faults, how-

column in table 33.

ever, must be localized by resistance measure-

(e) Refer to the schematic diagram (fig.

ments.

34) and connect the TS-352B/U as indicated

b. Localization. The tests listed in table 3-2 will

in the Point of measurement column (table 3-3).

aid in isolating the trouble. First, localize the

Refer to TM 115821277-35 for the schematic of

trouble to a single circuit and then isolate the

the radio control.

trouble within that circuit by resistance and con-

(5) Intermittent troubles. In all tests, the

tinuity measurements.

possibility of intermittent troubles should not be

overlooked. If present, this type of trouble often

(1) VisuaI inspection. The purpose of visual

may be made to appear by tapping or jarring

inspection is to locate faults without testing or

the instrument, Check the cables, wiring, and

measuring circuits. All panel lamp indications or

connections of the equipment.

other visual signs should be observed and an

Table 3-2. Troubleshooting

Corrective action

Malfunction

Probable cause

a. Set POWER CB circuit breaker to

1. 28.7 VDC lamp on test panel and

POWER CB circuit breaker CB1

panel lamps on radio control and

ON.

is at OFF.

intercom control do not light.

b. Replace CB1.

POWER CB circuit breaker CB1

defective.

Replace lamps.

Defective lamps . . . . . . . . . . . . . . . .

2. Panel lamps on radio control and

Replace CR2.

Diode CR2 defective . . . . . . . . . . . .

intercom control do not light,

Replace Ml.

Meter Ml defective . . . . . . . . . . . .

3. VHF COMM frequency indicator not

S e t VHF COMM OFF-PWR

VHF COMM OFF-PWR switch is

illuminated.

switch to PWR.

at OFF.

b. Replace lamps.

Radio control lamps DS1 and DS2

defective.

c. Replace switch S4.

Radio control switch S4 is defec-

tive.

4. No output at RECEIVER OUTPUT

a. Check and correct wiring.

Open or shorted wiring from

jacks with proper 132.500-MHz

W1P2B-35 and W1P2B-36 to

signal to AN/ARC-134.

test panel jackS J8 and J9.

Set VHF COMM frequency selec-

VHF COMM frequency not set to

tor switch to 132.500 MHz.

132.500 MHz.

3-2