Section VII. ELECTRICAL SYSTEM

TM 55-4920-231-14

(2) Remove pipe nipple (15, figure 25)

78. SELECTOR VALVE.

from oil reservoir (36) and selector valve (37).

The selector valve (9, figure 24) is removed

b. Installation.

and replaced as follows:

(1) Install pipe nipple (15, figure 25) on

a. Removal.

selector valve (37) and-oil reservior (36).

(1) Remove oil reservoir (7, figure 24)

(2) Install oil reservoir (7, figure 24) on

from chassis (20) as instructed in paragraph 77a.

chassis (20) as instructed in paragraph 77e.

Section VII. ELECTRICAL SYSTEM

a. Removal.

79. GENERAL.

(1) Remove chassis assembly (figure 24)

The electrical system is designed to operate on

from tester case (paragraph 73a) and disconnect

28 vdc current at 2.2 amps, 115 vac single phase

plug connector (21).

current at 50 to 500 cps, and 115 vac three phase

50 to 500 cps current at 0.75 amps for a power

(2) Remove vacuum check valve (17, figure

25), as instructed in paragraph 75a.

source. The major components of the system are

a stepdowm transformer (6, figure 24), selenium

(3) Remove tube assemblies (33 and 34).

(4) Remove screws (47) and lockwashers

rectifier (4), electrolytic capacitor (2), and an

(48) securing motor and pump assembly (49)

electric motor and pump assembly (3). The elec-

trical system is energized through a multipin

to chassis (51). Remove motor and pump assem-

bly.

connector (1) and power switch (15). The inter-

b. Disassembly. Disassemble the motor and

al connections of the power cables and tester

pump assembly in the sequence of the index num-

automatically provide for operation with the

bers shown in figure 28 only to the extent re-

power sources specified. This prevents connec-

tion of the tester to the wrong power source.

quired to perform the following procedures.

c. Cleaning and Inspection.

See figure 10 for the electrical schematic dia-

gram,

(1) Remove dry accumulations of dirt with

low-pressure compressed air (not over 15 pounds

per square inch), a vacuum cleaner, or by wiping

80. RECTIFIER.

with a clean, dry sloth.

The selenium rectifier (4, figure 24) is re-

(2) Remove excess oil or grease with a

placed as follows:

cloth moistened with an approved solvent. If in-

sulation or insulated parts are coated with oil or

a. Removal

grease, solvent may be sprayed on the parts or

(1) Remove chassis assembly (figure 24)

they may be dipped directly into the solvent and

from tester case (paragraph 73a).

(2) Unsolder wiring harness leads (4, fig-

then wiped dry.

ure 25) from terminals on rectifier (45).

(3) After cleaning, check brushes for con-

dition, length, and spring tension. Replace

(3) Remove nuts (21), lockwashers (22),

brushes if they are less than 7/16 of an inch

and screws (35 ) securing rectifier (45) to chas-

long (see f below). Minimum usable brush

sis (51). Remove rectifier.

length is 5/16 of an inch.

b. Installation.

(4) Check all wiring, connections, and ter-

(1) Place rectifier (45, figure 25) in posi-

minals for general condition and good contact.

tion on chassis (51) and secure with screws (35),

(5) Inspect commutator for pitting, scoring,

lockwashers (22), and nuts (21).

roughness, corrosion, or burning. Check for high

(2) Solder wiring harness (4) leads to ter-

mica. Replace the motor if the commutator is

minals on rectifier (45) as identified, or refer

burned, badly pitted, or grooved. Report condi-

to figure 10 for identity.

tion of high mica or other defects to higher

(3) Install chassis assembly (figure 24) in

authority.

tester case (paragraph 73c).

(6) Inspect all wiring for evidence of over-

heating, Replace motor if insulation on leads or

81. MOTOR AND PUMP ASSEMBLY.

windings is burned, cracked, or brittle.

(7) Inspect bearings (16 and 28, figure 28)

Remove motor and pump assembly (3, figure

for wear and smoothness of operation. Report de-

24) from chassis (20) for inspection or replace-

fective bearings to higher authority.

ment as follows: