TM 55-4920-429-13
(4) U11-1,2 contacts close. This inserts the ac to dc converter into the signal path.
(5) U12-8, 9 contacts close. This connects the output of the ac to dc converter stage to the
programmable-gain amplifier.
(6) U14-8, 9 contacts close. This bypasses the offset/inverter amplifier.
c. Program No. 3. Selected for monitoring the HDG ENGAGE ON, BARO ALT ENGAGED,
RADAR ALT ENGAGED, L LDG GEAR ON GND, and R LDG GEAR ON GND for 12 volt dc or
open circuit. Program 3 uses the ac/dc amplifier, the programmable-gain amplifier (gain -2.1047),
and the threshold-detector.
(1) An active-low signal on this input line is applied to matrix inputs U7-12 and U10-12, 13. This
causes electronic-switch sections U11-6, 8, 9 and U12-12, 10, 11 to turn on. It also allows electronic-
switch sections U11-5, 4, 3 and U14-6, 8, 9 to be activated.
(2) U11-8,9 contacts connect resistor R62 to logic ground. This provides a 0 volt dc input to the
ac/dc amplifier when the +12 volt dc input signal is inactive (open circuit).
(3) U11-4,3 contacts close. This bypasses the ac to dc converter.
(4) U12-10, 11 contacts close. This connects the ac/dc amplifier to the programmable-gain am-
plifier.
(5) U14-8, 9 contacts close. This bypasses the offset/inverter amplifier.
NOTE
Programs No. 4, 6, and 8 are not used and are non-interfering.
d. Program No. 5. Selected for monitoring the BIT ENABLE STOP, HYDR PRESSURE FULL,
and VERT GYRO VALID for a ground or open circuit. Program 5 uses the ac/dc amplifier, the
programmable-gain amplifier (gain -6.6566), the offset/inverter, and the threshold-detector circuits.
(1) An active-low signal on the input line is applied to matrix inputs U8-8, 9, U10-5, and U7-3.
This causes electronic switch sections U11- 12, 11, 10, U12-5, 4, 3 and U14-5, 4, 3 to turn on. It also
causes section U14-6, 8, 9 to turn off. Electronic-switch section U11-5, 4, 3 will be activated.
(2) U11-11,10 contacts connect resistor R62 to voltage divider R55 and R56. This provides a
+7.5 volt dc input level to the ac/dc amplifier when the input signal is inactive (open-circuit).
(3) U11-4, 3 contacts close. This bypasses the ac to dc converter.
(4) U12-4, 3 contacts close. This connects the ac/dc amplifier to the programmable-gain am-
plifier.
(5) U14-8, 9 contacts open. This disconnects the offset/inverter amplifier bypass.
(6) U14-4, 3 contacts close. This connects the offset/inverter amplifier into the signal path.
e. Program No. 7. Selected for monitoring RADAR ALT SELF TEST GO and RADAR ALT
VALID for 4.5-volt or 0-volt dc. Program 7 uses the ac/dc amplifier, programmable-gain amplifier
(gain -6.6566), and threshold-detector.
(1) An active-low signal is applied to matrix input U10-6. This causes electronic-switch section
U12-5, 4, 3 to turn on, and allows electronic-switch sections U11-5,4, 3 and U14-6, 8,9 to be activated.
(2) U11-4, 3 contacts close. This bypasses the ac to dc converter.
(3) U12-4, 3 contacts close. This connects the ac/dc amplifier to the programmable-gain am-
plifier.
1-20. Extensible-Link Servo-Control Circuit.
(See FO-4, 1-2, 1-3 and FO-6.) The extensible-link servo-control circuits contain three independent
closed-loops that provide position control over the pitch, roll, and yaw extensible links (actuators).
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