TM 55-4920-429-13
(4) Remove the jumper wire.
NOTE
When a test includes a requirement that an ac voltage be in-phase or
out-of-phase, oscilloscope channel A must be connected across the
digital multimeter. Oscilloscope channel B must be connected to the ac
source and the oscilloscope externally triggered from the ac source.
(5) Connect a variable ac power supply to receptacle pins J1-FF and J1-GG. Voltage shall be 180°
out of phase with respect to the 115 volt ac source at J l-B.
(a) Set the YAW switch to MAX EXT.
(b) Adjust the ac power supply for .0000 on the dmm.
(c) With an external digital multimeter, set to measure ac volts, measure the output, voltage of
the ac power supply. The voltage shall be 1.720 to 2.190 vat.
(6) Connect a variable ac power supply to receptacle pins J1-FF and J1-GG. Voltage must be in
phase with respect to the 115 volt ac source at J1-B.
(a) Set the YAW switch to MAX RETR.
(b) Adjust external voltage source to reach .0000 on the dmm.
(c) Connect an external digital multimeter, set to measure ac volts, to the output of the ac power
supply. The voltage shall be 1.720 to 2.190 volts ac.
(7) Disconnect the external power supply and decade resistor.
4-33. Gyro test. (See fig. 4-3.) This test ensures that the test set circuits which evaluate the output of
the pitch, roll, heading, and heading error signals function as required. (See FO-8 for connector pin
patterns.)
a. Fabricate the test aid. (See fig. 4-3, sheet 2.)
b. Set the METER SOURCE switch to GYRO TEST.
c. Perform the following tests with ac power supply connected to the pins listed below and GYRO
TEST SIGNAL MONITOR switches set to the position listed. The dmm shall read within the range
listed. For (open) readings, connect a 10K-ohm resistor across HI and LO binding posts.
4-20
