Instruction Manual

Page 5-86 G1000 / GFC 700 System Maintenance Manual - 200/B200 Series King Air
Revision 8 190-00915-01
• If the 28 VDC is missing, check the C/B.
• If 28 VDC power to the computer is present, check the transducer
excitation voltage on TP 24 (Hi) and TP 25 (Lo). The voltage should be 10
± 0.75 VAC at 720 ± 72 Hz.
• If the excitation voltage is not within the ranges specified, replace the
computer.
• If the excitation voltage is within the ranges specified, check the LAA
output on TP 18 (Lo) and TP 19 (Hi). The output is a varying DC voltage
based on the transducer vane position. The output from the computer with
the vane in neutral position depends on the flap position. See table below.
Flaps Output
Full Up +0.3 to 1.3 VDC
Approach +0.75 to 1.75 VDC
Full Down +1.1 to 2.1 VDC
• If the output on TP 18 (Lo) and TP 19 (Hi) is not within the ranges
specified, replace the Lift Computer.
• If the output on TP 18 (Lo) and TP 19 (Hi) is within the ranges specified,
check the aircraft wiring in accordance with the appropriate Garmin wiring
schematic.
5.25.1 Lift Computer Functional Pinout
Pin I/O Function Information
1 I 28 VDC Input
2 28 VDC ground
4 O Flap Transmitter Excitation 28 VDC
5 I Flap Transmitter Input (Half Flap) 28 VDC input from the flap transmitter
6 I Flap Transmitter Input (Full Flap) 28 VDC input from the flap transmitter
7 I Squat Switch Input Logic: Open/Ground Ground = In-Air
8 I Self Test Input Ground = Test
9 O Valid 28 VDC = Valid, Open = Fail
10 I 28 VDC Essential Bus Input Jumpered from pin 1 of the mating connector
12 O Pre-Stall Warning #1 28 VDC = Stall Warning
15 O Pre-Stall Warning #2 Ground = Stall Warning
16 O Transducer Self-Test Output +15 VDC for On-Ground self test to Lift
Transducer (Pin 8 of the transducer).
17 O System Fail 28 VDC output = Fail
18 O Low Airspeed Awareness (LAA) (Lo) This output is (0 VDC) at stall warning. Potentiometers
3, 4 and 5 on top of the computer are used to adjust the
(LAA) outputs to 2.2 VDC.
Pot 3 = (0 flaps) LAA adjustment.
Pot 4 = (½ flaps) LAA adjustment.
Pot 5 = (full flaps) LAA adjustment.
19 O LAA Output (Hi)
22 O Lift Transducer Test Point Varying voltage from Lift Transducer
23 Signal Ground
24 O Lift Transducer Excitation Voltage (Hi)
10 VAC 700 Hz nominal
25 O Lift Transducer Excitation Voltage (Lo)