rotor of the indicator has come up to speed, a reading of
4-5. TEST PROCEDURES.
the voltmeter shall be taken. It shall be 28 v plus or minus
CAUTION
2.
The following should be kept in mind during
(b) Switch no. 5 shall be rotated to three
the operation of this tester in order not to
phases of the 115 volt, 400 cycle current, AB, BC and AC,
force the switches which would damage the
respectively, and a reading of the voltmeter taken at each
tester and probably cause damage to the
point. During this test, the pointer of the voltmeter in the
instrument under test. When switch no. 4 is
tester shall fall at 115 v plus or minus 5. The frequency of
set in the "OFF"' position, switches no. 1
the 115 volt current shall be 400 cycles plus or minus 16
and 3 will operate freely. When switch no. 4
cycles as indicated by the frequency meter of the tester.
is rotated from the "OFF" position, switches
The phase rotation shall be ABC as indicated by the green
no.
1 and 3 will be interlocked and
panel light. If the red light comes on, the phase rotation is
impossible to turn. When switch no. 1 is
wrong. Also, in conjunction with phase rotation, the "A" leg
set in the "GND CHECK," "SLAVE CHECK"
of the 3-phase current should always be grounded on a J-1
or "POWER CHECK" positions, switch no. 3
installation. To check this, turn switch no. 1 to "GROUND
will move freely, and switch no. 4 will be
CHECK" position, connect Test Lead no. 50A7513 to the
interlocked in the "OFF" position. Switch
ground test jack and connect the other end of this lead to
no.
4 must be returned to the "OFF"
aircraft structure. The green light shall not light. Should
position before changing switch no.
3
the green light come on, then "A" leg is not grounded.
during continuity check. Switch no. 4
Disregard the red light as it has no bearing on this test.
should always be on "OFF" position except
b. SLAVE CHECK. The following procedure shall be
during continuity check of the flux valve.
followed in checking t he slaving of the J-1 Compass.
Switch no. 3 should be in "CALIBRATE"
(1) LEAD CONNECTIONS. The lead connection
position except when otherwise directed.
is shall be t he same as those specified in paragraph 4-6a1.
Never force these switches.
(2) TEST PROCEDURE.
(a) Switch no. 1 of the tester shall be turned
4-6.
FIELD CHECKING THE SLAVED GYRO
to the "SLAVE CHECK" position and switch no. 2 to the
MAGNETIC COMPASS TYPE J-1.
"ZERO" position. The letters 'L" and "R" of switch no. 2
a. POWER CHECK. The following procedure
have reference to slaving of the indicator to the clockwise
shall be followed in checking the power supplied to the
or counterclockwise direction only when the ship is in a
instrument under test:
North heading. "L" signifies the planes' turn to the left;
(1) LEAD CONNECTIONS.
therefore, the slaving shall be in the clockwise rotation of
(a) Connect lead 47B7488 to the 10-pin
the Master Indicator Compass dial. "R" position causes the
receptacle in the tester and the receptacle end of this
dial to be slaved in the counterclockwise direction. When
lead shall be connected to the 10-pin plug of cable
the ship is in any other heading, the letters "L" and "R" shall
47B7491.
be used as reference accordingly.
(b) Remove the 5-pin plug from the back
(b) The indicator and the flux valve shall be
of the indicator case and connect this to the receptacle
aligned. This is indicated by the annunciator in the upper
of cable 47B7491. The 5-pin plug of this cable shall be
right face of the indicator. If the annunciator is blank, they
connected to the 5-pin receptacle In the back of the
are aligned.
indicator.
(c) Turn switch no. 2 to the "L" position.
NOTE
The gyro shall precess clockwise at a rate of not less than 2
If a 6-pin connector is used substitute
degrees nor more than 6 degrees per minute. Switch no. 2
50B7827 6-pin connector in lieu of the
shall then be returned to "0" position. The gyro shall
47B7491 5-pin connector.
precess back to null. Turn switch no. 2 to "R" position.
(c) Connect lead 47B7489, which is the
The gyro shall precess counterclockwise at a rate of not
power lead, t o the 4-pin receptacle of the tester. The
less than 2 degrees nor more than 6 degrees per minute.
receptacle end of this lead shall be connected to the 4-
Switch no. 2 shall then be returned to "O" position. The
pin plug of lead 47B7490.
gyro shall precess back to null.
(d) Disconnect the 6-pin plug from the
c. FLUX VALVE CHECK. The following procedure
back of the indicator and connect to the receptacle of
shall be followed in testing continuity of the Flux Valve.
lead 47B7490. Connect the 6-pin plug of this lead to the
(1) LEAD CONNECTION. Lead connections are
back of the indicator.
the same as those specified in paragraph 4-6a1 except for
(2) TEST PROCEDURES.
connections to the Master Indicator. Disconnect both 5 and
(a) Turn switch no. 1 of the tester to a
6-pin plugs from the rear of the Master Indicator.
POWER CHECK" position; switch no. 5 to the "28 v
DC" position, and turn on the ship's power. After the
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