INSTALLATION MANUAL
CMA-5024 GLSSU
This document includes Proprietary Information and shall not be reproduced or communicated to third party
without prior written permission by CMC Electronics Inc.
Page 117
November 21, 2008
7. PRELIMINARY WIRE HARNESS CHECKS
Perform the following verifications before installing the GLSSU and prior to connecting the aircraft wiring
harness to the GLSSU connectors J1, J3:
(1) GLSSU: Verify that the GLSSU wire harness input power line, mating to pin J1-35 of the 41-pins GLSSU
connector J1, and (if the auxiliary HIS power input is used) to pin J3-1 of the 100-pins connector J3, are
correctly wired to a circuit breaker fed from the aircraft 28 VDC power distribution system.
(2) GLSSU: Verify that the GLSSU wire harness input power return line, mating to pin J1-34 of the 41-pins
GLSSU connector J1, and (if the auxiliary HIS power return is used) to pin J3-2 of the 100-pins
connector J3, are correctly wired to the negative side of the aircraft 28 VDC power distribution system
(3) GLSSU: Verify that the GLSSU wire harness chassis ground line, mating to pin J1-33 of the 41-pins
GLSSU connector J1, and (if the approach connector J3 is used) to pin J3-3 of the 100-pins connector
J3, are correctly wired to the aircraft frame.
(4) GLSSU: If the APD Parity Discrete Check APD parameter is enabled in the selected APD Configuration,
verify the continuity to ground at the APD Select Parity pin J3-16.
Note: The APD Select Parity pin (J3-16) must be set so that the number of the APD Select Parity pin,
APD Select Parity pins (J3-14, 15, 45, 66), and SDI pins (J1-5, 36) being connected to ground is
odd. A pin connected to ground indicates a logical "1"; a pin left opened indicates a logical "0".
For example, for APD = 0 (pins J3-14, 15, 45 and 66 opened) and SDI = Center Unit (pins J1-5
and 36 grounded), J3-16 must be grounded. Conversely for APD= 2 (pin J3-15 grounded and
pins J3-14, 45 and 66 left opened) and SDI = Center Unit (pins J1-5 and 36 grounded), J3-16
must be left opened.
Note: If the "APD Parity Discrete Check" parameter is enabled and If the APD Select Parity
discrete input line (J3-16) is not set correctly, the GLSSU will enter Fault mode and will be
inoperative (no ARINC 429 outputs).
(5) Verify the Input and Output Discretes for continuity as per aircraft installation drawing.
(6) Verify the ARINC 419/429 and Time Mark connections for continuity between the GLSSU and other
systems as per the aircraft installation drawing.
(7) Verify the continuity to ground at the SDI signal pins: J1-5 and 36 on the GLSSU.
(8) Verify the other lines of the connectors on the GLSSU for continuity as per aircraft installation drawing.
8. PRE-INSTALLATION INSPECTION
A. GLSSU Inspection
(1) Check the GLSSU for dents, scratches or other external damage and ensure that they are free of
foreign material.
(2) Check aircraft interwiring cables and the GLSSU connectors J1 J3 and J2 for foreign contaminants,
corrosion and physical damage such as bent or loose pins, broken wires, insulation damage and
loose cable clamps.
(3) Check that the shields of the shielded cables are grounded at both ends.
The document reference is online, please check the correspondence between the online documentation and the printed version.
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