Model 479 (D-30) Technician Troubleshooting Guide
3
TroubleshootingTable
Problem Possible Cause Correction
No inbound audio. Power
Indicator Light(green) is
OFF.
No AC power to the unit. Check power supply
transformer or walloutlet.
Defective analog board. Check and replace analog
board.
No inbound audio:
•Power Indicator Light
(green) is ON.
•LISTEN Indicator Light
(green) is OFF.
Defective logic boardor
touch pad. Check and replace logic
board or touch pad.
No inbound audio:
•Power Indicator Light
(green) is ON.
•LISTEN Indicator Light
(green) is ON.
Defectivemenu speaker,
menu mic,or wiring. Check and replace menu
speaker, menumic, or wiring.
Defective analog board. Check and replace analog
board.
Inbound audio distorted. Defective menuspeaker,
menu mic,or wiring. Check and replace menu
speaker, menumic, or wiring.
Defective analog board. Check and replace analog
board.
No outbound audio. Power
Indicator Light(green) is
OFF.
No AC power to the unit. Check power supply
transformer or walloutlet.
Defective analog board. Check and replace analog
board.
No outbound audio:
•Power Indicator Light
(green) is ON.
•TALK Indicator Light
(red) is OFF when TALK
SWITCHis pressed.
Defective logic boardor
touch pad. Check and replace logic
board or touch pad.
(continued)