G900X/G950 Installation and Maintenance Manual – Pinouts Page A-75190-00719-00 Revision DA.8 GCU 476 (optional)A.8.1 P4751 ConnectorView of J4751 connector from back of unitPin Pin Name I/O1 RS-232 OUT 1 Out2 RS-232 IN 1 In3 RS-232 OUT 2 Out4 RS-232 IN 2 In5 POWER GROUND --6 SIGNAL GROUND --7 AIRCRAFT POWER 1 In8 SIGNAL GROUND --9 AIRCRAFT POWER 2 In10 CONTROL UNIT REMOTE POWER OFF In11 LIGHTING BUS HI In12 LIGHTING BUS LO In13 RESERVED --14 RESERVED --15 POWER GROUND --A.8.2 PowerPin Name Connector Pin I/OAIRCRAFT POWER 1 P4751 7 InAIRCRAFT POWER 2 P4751 9 InPOWER GROUND P4751 5 --POWER GROUND P4751 15 --SIGNAL GROUND P4751 6 --SIGNAL GROUND P4751 8 --AIRCRAFT POWER 1 and AIRCRAFT POWER 2 are “diode ORed” to provide power redundancy.A.8.2.1 Remote Power OffPin Name Connector Pin I/OCONTROL UNIT REMOTE POWER OFF P4751 10 InThis input is used to power down the GCU 476, by a remote source. An input voltage between 6.5 VDCand 33 VDC will power-off the GCU 476. An input voltage of 3.5 VDC or less will allow the GCU 476to power on.
