Symptom		Corrective Action		Remarks
1.	Only one station handset is dead. Blank display on handset.	1.	For portable handsets, check connector for bent or damaged pins.
		2.	For all handsets, including portables, swap suspected handset and cable with a known good handset, or other handset connected to system. If symptom follows the suspected handset, replace handset. If not, swap CDBR or handset cabling.
2.	All handsets are dead. Blank display on handset.	1.	Check C-2000 circuit breaker is engaged.	* Allow five minutes for Built in Test to complete. * Red light on ARTU front panel will remain lit and blink on/off every two to three minutes if DC voltage to ARTU is less than 22 VDC (system is in current limit). If this condition occurs, ensure that a -802 mounting tray is installed. An -801 tray will let voltage spikes thru and reset the ARTU.
		2.	Cycle power to the system, using a 30 second interval between breaker off to breaker on.
		3.	Observe indicator lamps on front panel of ARTU. Green light should be on when power is applied. Red light will be on while system is performing Built In Test. (Approximately five minutes) If red light stays on for more than eight minutes, remove and replace ARTU.
		4.	If ARTU red "fault" indicator is not illuminated (built in test passed), then check LAN Bus for wiring problems or defective LAN Device.
3.	Handset displays " Temporary Service Disruption" or  "Check CDBR Cabling."	1.	Check ARTU to CDBR and inter-CDBR cables for opens, shorts to ground, or shorts between pins. Disassemble EMI backshells on cable ends to ensure there are no wires being pinched between the two backshell halves.	* An AC short can occur at the cable ends by pinching a signal wire between the two backshell halves. You will not be able to verify an AC short with an ohm meter. * Hot insertion of inter-CDBR cabling may cause "Check CDBR Cabling" on handset is displayed.
		2.	Check tightness of hardware, securing all connectors to CDBRs.
4.	Aircraft not receiving CA115.	1.	Verify uplink numbers are programmed into handsets. Station uplink number should be displayed at bottom of screen on handset when handset is on-hook ("Services" menu).
		2.	Verify "Air-Ground" appears on  "Services" screen (handset on-hook) when aircraft is at an altitude of 18,000 feet or above.
5.	A ringing phone is answered and dial tone is heard.	1.	Enable direct call pick-up	Start maintenance section press "4" For phone number, select "2" for aircall. Select "+" for more. Select "1" for yes.
		2.	Verify C.A.S. is programmed correctly.