3
Final Checkout Procedure
1.
Turn the ON/OFF switch of the A121 ON. The red LED should blink slowly. Listen for a reduction in the
background noise.
2.
If the A121 is in a half-duplex system, set SW2 number 2 OFF and proceed to step 3.
If the A121 is in a full-duplex system set SW2 number 2 OFF. Speak into the headset mic or intercom mic.
The echo should increase. Turn SW2 number 2 back ON. The echo should decrease.
3.
Set SW2 number 3 for appropriate level of noise reduction. Set SW2 number 3 OFF for restaurant mode.
Set SW2 number 3 ON for truck stop mode.
4.
Set SW2 number 4 (Hi Frequency Equalization) to customer’s preference.
Troubleshooting
Problem
Possible Cause
Correction
1. Status fault indicated.
Inbound audio exceeded maximum
level.
Switch A121 off for one second.
2. No inbound audio.
Mode setting is incorrect.
Wiring is incorrect.
Check mode configuration.
Check wiring.
3. No outbound audio.
Wiring is incorrect.
Check wiring.
4. Loud audio in 3M
headset when headset user
talks.
Inbound audio on 3M base station too
low.
Increase MENU MIC SENS
potentiometer. Headset user should
then reduce the headset audio volume.
5. Excessive echo
Excessive feedback from menu
speaker to menu mic.
Add extra acoustic insulation to menu
mic chamber.
Table 4. A121 Noise Reduction Module Troubleshooting
Wiring Diagrams
Menu Post
A121 Noise Reduction Module
MENU SPKR
ALT ALERT
ALERT OUT
MENU SPKR
SHIELD
MIC
MIC
AUDIO OUT
3M Base Station
MENU
MIC
MENU
SPKR
MENU
SPKR
MENU
SPKR
MENU
SPKR
MENU
SPKR
SHLD
SHLD
MIC IN
MIC OUT
1
2
3
4
5
5
4
3
2
1
MIC OUT
MIC IN
MENU
INTERCOM
MIC OUT
MIC OUT
12V UNREG
VEH DET
MENU SPKR
MENU SPKR
Figure 1. Wiring for 3M C760/C960 Base Station
Summary of Contents for C960
Page 3: ...Model C960 Headset Intercom System Revision History b E 3M 2000 May Blank Page ...
Page 7: ...Model C960 Headset Intercom System Table of Contents iv E 3M 2000 May Blank Page ...
Page 17: ...Model C960 Headset Intercom System Operation and Diagrams 1 10 E 3M 2000 May Blank Page ...
Page 19: ...Model C960 Headset Intercom System Operation and Diagrams 1 12 E 3M 2000 May Blank Page ...
Page 21: ...Model C960 Headset Intercom System Operation and Diagrams 1 14 E 3M 2000 May Blank Page ...
Page 22: ...Headset Intercom Systems Model C960 C860 Installation Instructions ...
Page 23: ......
Page 32: ...7 Brown Yellow Figure 7 Connecting Components to the Interconnect Module ...
Page 70: ...Headset Intercom System Model C960 Operating Instructions ...
Page 71: ......
Page 75: ...Important Information Model C960 3M 1999 May iv Blank Page ...
Page 109: ...4 Figure 2 Wiring for 3M C760 C960 Base Station with Interconnect Module ...
Page 140: ...2 5 Connect the cables from the module to the base stations as shown in Figure 1 Figure 1 ...
Page 153: ...3 Figure 2 Attenuator Connections ...
Page 156: ...2 Figure 1 Typical Installation on a Speaker Post ...