Section III. REPAIRS AND REPLACEMENT

TM 11-6625-601-34

CAUTION

(3) Connect the ohmmeter negative lead to

chassis ground of the unit under test unless

Before using any ohmmeter to make

otherwise indicated.

r e s i s t a n c e measurements, check the

(4) Make all resistance measurements with-

open-circuit voltage across the ohmme-

out power applied to the test set.

ter test leads. Do not use the ohmmeter

if the open-circuit voltage exceeds 1.5

3-5. Voltage and Resistance Table

volts. Make resistance measurements

CAUTION

in the test set only as directed in the

chart below. Sensitive transistors can

Before making any voltage or resis-

be ruined if unauthorized resistance

tance measurements, refer to parag-

measurements are made.

raph 2-4 a and b. Use only authorized

test equipment or its equivalent. Dam-

b. Resistance Measurements. The resistance

a g e to transistors may result from

readings in the table (para 3-5) were obtained

improper measurement techniques or

under the conditions outlined in (1) through (4)

t h e use of unauthorized test equip-

below. Always make resistance measurements

ment.

under these conditions, or the readings may be

All voltage readings in the table are positive dc.

inaccurate.

The test points listed in the table correspond

(1) Make all resistance measurements with

to transistor connections in the equipment.

Multimeter TS-352/U, or equivalent. The open

Transistor connections are on terminal boards

circuit voltage across the ohmmeter test leads

and are identified by the following designations:

must not exceed 1.5 volts.

(2) For each resistance measurement, set

B--terminal board connection to base of transistor.

the ohmmeter range switch to the resistance

C-terminal board connection to collector of transistor.

scale specified in the chart.

E--terminal board connection to emitter of transistor.

Table 3-2. Voltage and Resistance Measurements for Blower Inverter (Part of TS-1967/ARC-54)

Section Ill. REPAIRS AND REPLACEMENT

(1) Disconnect plug P1 (3) and plug P2 (4)

3-6. General Instructions

from their respective jacks on the directional

The general support maintenance procedures

coupler (5).

given in this section supplement the procedures

(2) Disconnect the two lower plugs (1 and

d e s c r i b e d in Chapter 2, Section III and the

2) from their respective jacks. (A IN21 crystal

procedures d e s c r i b e d in the operator and

diode is in each of the two jacks; be careful when

organizational maintenance m a n u a l ( T M

removing the two plugs.)

11-6625-601-12).

( 3 ) Remove the four screws and lock-

3-7. General Parts Replacement Techniques

washers (6) that secure the directional coupler

(5) to the test set chassis.

Refer to paragraph 2-7 above.

(4) Remove the directional coupler (5).

3-8. Removal and Replacement of Directional

b. Replace directional coupler DC1 as follows:

Coupler DC1 (located in TS-1967/

(1) Place the directional coupler (5) in its

ARC-54)

proper position and secure with four screws and

a. Remove directional coupler DC1 (fig. 3-1)

lockwashers (6).

as follows:

(2) Carefully connect the two lower plugs (1

3-2