3M 478DA (D-15) - Manual (Page 7)

Model 481BA (D-20) Technician Troubleshooting Guide
3
Troubleshooting Table
Problem Possible Cause Correction
No inbound audio. Power
Indicator Light (green) is
OFF. No AC power to the unit. Check power supply
transformer or wall outlet.
No inbound audio:
•
Power Indicator Light
(green) is ON.
•
LISTEN Indicator Light
(green) is OFF.
Defective logic board or
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.
Defective speaker/mic or
analog board. Check and replace speaker or
analog board.
Inbound audio distorted. Defective speaker/mic or
analog board. Check and replace
speaker/mic or analog board.
No outbound audio:
•
Power Indicator Light
(green) is ON.
•
TALK Indicator Light
(red) is OFF when TALK
SWITCH is pressed.
Defective logic board or
touch pad. Check and replace logic
board or touch pad.
No outbound audio:
•
Power Indicator Light
(green) is ON.
•
TALK Indicator Light
(red) is ON when TALK
SWITCH is pressed.
Defective speaker/mic or
analog board. Check and replace
speaker/mic or analog board.
The VEHICLE Indicator
Light (yellow) blinks, but
vehicle detection tone does
not sound. Alert volume too low. Check and adjust alert
volume control on analog
board.
Defective analog or logic
board. Check and replace analog or
logic board.
(Continued)