(2) Inspect for damage and for loose ter-
netted from the shop set and stop the truck
engine.
minals. Replace a defective frequency meter.
c. Installation. Install the frequency meter as
b. Testing. Disconnect both ends of the wire
under test. Touch the probes of a multimeter to
3-27. Frequency Switch
indicates an open circuit, replace the wire. Always
a. On-Equipment Testing.
use wire of at least equal size.
(1) Tag and disconnect electrical leads from
3-23. A. C. Voltmeter
the frequency switch.
(2) Place switch in the 50-cycle position.
(3) Use a low-voltage test lamp circuit or
b. Cleaning and Inspection.
minal and its corresponding center terminal.
(1) Clean the A. C. voltmeter with a clean,
lint-free cloth.
Continuity should be indicated. Test between
(2) Inspect for broken glass, loose terminals,
be indicated. Repeat this test on the upper left
and other damage.
terminal.
(3) Replace a defective A. C. voltmeter.
(4) Place switch in the 60-cycle position and
c. Installation. Install the A. C.
voltmeter as
repeat the test in (3) above, testing between the
bottom and center terminals for continuity.
3-24. Dynamotor Switch
b. Removal. Remove the frequency switch as
a. On-Equipment Testing.
(1) Tag and disconnect the leads from the
c. Cleaning and Inspection,
switch.
(1) Clean the switch with a clean, lint-free
(2) With the start button depressed, use a
cloth.
low-voltage test lamp circuit to test between the
(2) Inspect for defects and loose terminals and
switch terminals. Continuity should be indicated
replace a defective frequency switch.
between the top two terminals only.
d. Installation. Install the frequency switch as
not be indicated between the bottom terminals
3-28. Circuit Breakers (120 and 240-volt)
only.
a. Removal. Remove the circuit breakers as
(4) Replace a defective switch.
b. Removal. Remove the dynamotor switch as
b. Cleaning and Inspection.
(1) Clean circuit breakers with a clean, lint-
c. Cleaning and Inspection.
free cloth.
(1) Clean with a clean, dry, lint-free cloth.
(2) Inspect circuit breakers for cracks, loose
(2) Inspect for cracks, and defects, and
terminals, and test for continuity across the ter-
replace a defective switch.
d. Installation. Install the dynamotor switch as
breaker ON, and not indicated with the breaker
OFF.
3-25. D. C. Ampere Adjusting Rheostat
c. Installation. Install the circuit breakers as
a. Removal. Remove the D. C. ampere ad-
b. Cleaning and Inspection.
a. Removal. Remove the 120 and 240-volt
(1) Clean with a clean, dry, lint-free cloth.
(2) Inspect for broken insulation, burnt
b. Cleaning and Inspection.
wiring, and defects and loose terminals. Replace a
defective rheostat. Test with a multimeter;
cloth.
graduated continuity should be indicated.
(2) Inspect for loose terminals and damage
c. Installation. Install the D. C. ampere ad-
and replace a defective receptacle.
c. Installation. Install the receptacles as
3-26. Frequency Meter
a. Removal Remove the frequency meter as
3-30. D. C. Voltmeter
b. Cleaning and Inspection.
lint-free cloth.
3-26