3-109. Frequency Adjust Rheostat.
See (57, fig. 3-18) and proceed as follows:
a . Inspection.
(1) Gain access to rear of control
panel (96).
(2) Inspect FREQUENCY ADJUST
for breaks, loose mounting, evidence of
or other damage.
b . Testing.
cubicle
rheostat (57)
corrosion,
(1) Tag leads and remove screws which secure
leads to the FREQUENCY ADJUST rheostat (57).
(2) Connect an ohmmeter probe to each of the
outer terminals on the FREQUENCY ADJUST rheo-
stat (57), The ohmmeter should read 500 ohms ±3%.
(3) To check wiper arm of the FREQUENCY
ADJUST rheostat (57), connect one ohmmeter probe
to either outer terminal and the other probe to the
center terminal (wiper arm). Turn the FREQUENCY
ADJUST rheostat slowly throughout its range, which
should be 0 to 500 ohms. As the shaft is rotated, the
ohmmeter indicator should move at the same rate as
the rotating shaft. If the pointer does not move, or
moves unevenly, the FREQUENCY ADJUST rheostat
is defective and should be replaced.
(4) Reconnect leads as tagged using screws and
washers.
Remove tags.
c. Replacement. Replace defective FREQUENCY
ADJUST rheostat (57) as follows:
(1) Removal.
(a) Tag leads and remove three nuts and
lockwashers which secure the three leads to FRE-
QUENCY ADJUST rheostat (57).
(b) Remove knob and hardware which se-
cure rheostat to panel and remove rheostat,
(2) Installation. Install FREQUENCY ADJUST
rheostat (57) using removal steps in reverse order.
Remove tags.
3-110. Voltage Adjust Rheostat.
See (54, fig. 3-18) and proceed as follows:
a. Inspection.
—
(1) Gain access to rear of control cubicle
panel (96).
(2) Inspect VOLTAGE ADJUST rheostat (54)
for breaks, loose mounting, cracks, evidence of
corrosion, and other damage.
b. Testing.
—
(1) Tag and unsolder leads from VOLTAGE
ADJUST rheostat (54) and test rheostat as described
for FREQUENCY ADJUST rheostat (para 3 -109),
3-40
except that the resistance value is 250 ohms ±3%
and the range is 0 - 250 ohms.
(2) Resolder leads to terminals as tagged.
Remove tags.
c.
Replacement.
—
(1) Removal.
(a) Tag leads and unsolder leads from
VOLTAGE ADJUST rheostat (54).
(b) Remove knob and hardware which secure
VOLTAGE ADJUST rheostat (54) to panel (96) and
remove rheostat.
(2) Installation.
Install VOLT AGE ADJUST
rheostat (54) using removal steps in reverse order.
Solder leads to rheostat. Remove tags.
3-111. Frequency Transducer and Meter. (See
fig. 3-18. )
a. Inspection. Inspect transducer (6) and frequency
meter (7) for loose mounting, loose leads and other
damage.
b. Replacement. The transducer (6) and frequency
meter (7) are a matched set (5) and must be replaced
by another matched set. Replace frequency meter and
transducer as follows:
(1) Removal.
(a) Gain access to rear of control cubicle
panel (96).
(b) Tag and remove frequency meter (7) leads.
(c) Remove screws (3) and nuts (4) which
secure the frequency meter to the panel (96) and re-
move frequency meter (7).
(d) Tag and remove transducer (6) leads.
(e) Remove screws (1) and nuts (2) which
secure transducer (6) to the rear panel and remove
the transducer.
(2) Installation. Install frequency meter (7) and
transducer (6) using removal steps in reverse order.
Remove tags.
3-112. AMPS-VOLTS Selector Switch.
See (48, fig. 3-18) and proceed as follows:
a. Testing.
—
(1) Gain access to rear of control cubicle
panel (96).
(2) Tag AMPS-VOLTS selector switch (48) leads
and removes crews and lockwashers which secure leads
to AMPS-VOLTS selector switch (48) and test AMPS-
VOLTS selector switch for continuity using ohmmeter
and schematic, figure 3-21. Sequentially select each
