3
C921BA Base Station
Installation Instructions
This is an addendum to the C960AA Headset Intercom System Installation Instructions. The only change in the
System is the C921BA Base Station.
Description
The 3M C921BA Base Station is improved over the C921AA Base Station in several ways:
•
Improved Duplex Operation
•
Improved Monitor Speaker Operation
•
A reduced click when the Talk button is pressed
•
Ability to add an optional Internal Loop Detector
•
Ability to add an optional internal Noise Reduction Module
•
C5000 compatibility
Installation
Installation of the C921BA Base Station (78-9236-6491-2), is the same as the C921AA Base Station
(78-9236-6330-2), with the following additions:
Additional Jumper Settings:
J6 - MENU PWR SEL - STD or DPLX
STD - applies power to outbound speaker amplifiers only when the TALK switch is pressed.
Note: For Standard (half-duplex) systems jumper J6 must be placed in the STD position.
DPLX - applies power to outbound speaker amplifiers constantly. This will reduce the click that is
sometimes heard in duplex mode when the TALK button is pressed.
J9 – TALK MON LVL
REDUCE – reduces the volume to the Monitor Speaker by 16dB while the TALK button is
pressed. This decreases the chance of feedback when a headset is operating near the Monitor Speaker in
duplex mode.
NONE – mutes the volume to the Monitor Speaker while the TALK button is pressed.
Additional Connectors:
C5000 Terminal Strip – 4 terminals at the bottom of the right-hand terminal block.
J7 – Loop Detector Connector
J8 - Noise Reduction Connector (under left cover)
3M Food Services Trade Department
3M Center, Building 551-1E-02
Printed in U.S.A.
St. Paul, MN 55144-1000
© 3M 1999
Summary of Contents for C860
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