Honeywell BENDIX/KING KAP 140 Maintenance Manual page 79

4.3.3 KS 271C ROLL SERVO INTERFACE TO THE KC 140
PIN
P1401 -- 1
P1401 -- 5
P1401 -- 18
P1401 -- 19
The KS 271C Roll Servo consists of the following interfaces: a clutch high--side and a clutch
low--side input, and a command high and a command low input. These interfaces are similar to
the equivalent interfaces for the pitch servo. See Pitch Servo Interface for more details. When
ROLL_SERVO_VALID is invalid, the KC 140 locks out operation of the autopilot (since pitch
operation is not allowed without roll).
4.3.4 KS 272C TRIM SERVO INTERFACE TO THE KC 140
PIN
P1402 -- 1
P1402 -- 2
P1402 -- 4
P1402 -- 31
P1402 -- 36
P1402 -- 44
The KS 272C Trim Servo consists of the following interfaces: a clutch high--side and a clutch
low--side input, a command high and a command low input, and a trim servo disable input.
The TRIM_CLUTCH output from the KC 140 is used to drive the low side of the clutch solenoid
on the KS 272C. The high side of the clutch is wired to the aircraft power through the AP DISC
switch. When the clutch is disengaged by the FCC, there should be 28V on the low side clutch
(assuming AP DISC is not pressed). When the clutch is engaged, there should be >0.1V and
<2.5V on the low side of the clutch. If AP DISC is pressed, 28V is removed from the clutch solenoid
and the clutch will disengage.
If there is less than 0.1V on the low side clutch, when it is engaged
and AP DISC is not pressed, there is a possibility that the low side
clutch has inadvertently been shorted to ground and pre--flight test
will fail since the clutch current is monitor by the KC 140.
The TRIM_SERVO_CMD high and low signals form a differential input that is used to drive the
servo motor via the internal servo amplifier. The command high input is a +/-- 10V signal generated
by the KC 140 Flight computer. The command low input is a reference back to the internal KC 140
Flight computer ground. The internal servo amplifier has a gain of approximately 5; therefore, a
Revision 2, Dec/2002
CS:15574F02.IDU
BENDIX/KING
KAP 140
DESCRIPTION
ROLL_CLUTCH
ROLL_SERVO_VALID
ROLL_SERVO_CMD_+
ROLL_SERVO_CMD_REF
DESCRIPTION
TRIM_CLUTCH
TRIM_VOLT_--
TRIM_VOLT_+
TRIM_SERVO_CMD_+
TRIM_SERVO_CMD_REF
NOTE
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