TM 55-4920-428-13
j. Provide an out-of-phase input signal to the SAS 1 cross demodulators as follows:
(1) Set the power switch to OFF.
(2) Disconnect the test aid in-phase wire from receptacle J1-14.
(3) Connect the test aid out-of-phase wire to receptacle pin J1-14.
(4) Connect No. 1 multimeter to the test aid out-of-phase wire and the moving contact of the
variable resistor.
(5) Set the power switch to ON.
k. Repeat steps d through i. The meter indications shall be as stated except the dc voltage indica-
tions shall be opposite in polarity.
l. Set the power switch to OFF. Disconnect the test aid and jumper wire.
4-49. SAS 1 Command Circuit Test. This test ensures the command circuits, including the square
wave generator, function as required.
(See FO-1 for J1 pin pattern.)
When performing this test, make sure the 2,000 ohm 1 W 0.1% load re-
sistor is connected to receptacle pins J1-8 and J1-10.
a. Connect the oscilloscope to the SAS 1 EXTERNAL METER + and - jacks.
b. Set the SAS 1 EXTERNAL METER SELECT switch to VALVE.
c. Set the SAS 1 FUNCTION SELECT switch to SQ WAVE.
d. Connect jumper wires between receptacle pins J1-3 and J1-4 and between J1-13 and J1-14.
e. Set the power switch to ON.
f. Rotate the SAS 1 SQ WAVE control to MAX. The oscilloscope shall display a symmetrical square-
wave. Square-wave amplitude shall increase with rotation of the control. At MAX, peak-to-peak am-
plitude of the square wave shall be 2.5 to 3.5 volts.
g. Disconnect the oscilloscope and connect the frequency counter.
h. The frequency counter shall indicate 1.538 to 2.857 sec. Set SAS 1 SQ WAVE control to MIN.
i. Disconnect the frequency counter.
j. Set No. 2 multimeter to measure dc volts. Connect it to SAS 1 EXTERNAL METER + and - jacks.
k. Set the SAS 1 FUNCTION SELECT switch to CLSD LOOP.
l. Rotate the SAS 1 VALVE CONTROL to RETRACT. No. 2 multimeter shall indicate -1.2 to -2.0
volts dc.
m. Rotate the SAS 1 VALVE CONTROL to EXTEND. No. 2 multimeter shall indicate 1.2 to 2.0
volts dc.
n. Set the SAS 1 FUNCTION SELECT switch to HARDOVER RETRACT. No. 2 multimeter shall
indicate -1.2 to -2.0 volts dc.
o. Set SAS 1 FUNCTION SELECT switch to HARDOVER EXTEND. No. 2 multimeter shall indi-
cate 1.2 to 2.0 volts dc.
p. Set the power switch to OFF. Disconnect No. 2 multimeter.
4-22
