Noise Reduction Module
Model A125
Installation Instructions
Description
The 3M A125 Noise Reduction board (3M part number 78-9236-6453-2) improves the inbound intelligibility of an
intercom system by reducing environmental background noise from vehicles, airplanes, noisy intersections, wind,
etc.
System Requirements
The 3M A125 Noise Reduction Module requires a 3M model C921BA or C922AA Base Station.
Installing the Noise Reduction board into the 3M Base Station
1. Remove the right-hand and left-hand top covers from the 3M base station. Be careful that the main circuit
board does not fall out of the plastic base.
2. See
***Important installation notice***
on next page before performing this step.
Plug the A125 ribbon cable onto connector J8, located at the top of the left side of the circuit board. Be careful
to support the rear side of the base station circuit board when plugging in the A125 ribbon cable.
3. Position the holes near the edge of the A125 circuit board over the plastic standoffs on the base station.
4. Attach the left-hand base station cover after configuring the A125 board, and performing the Final Checkout
Procedure.
Install the A125 board here
Figure 1. Mounting the A125 to the C921BA Base Station
