Clear-Com TW-12C - Manual (Page 12)

S y s t e m I n s t a l l a t i o n M a n u a l 1 - 2
The following chart describes the functions of the pins on the rear panel
connectors:
Figure 2-4: Pin Connections
4. When the TW-12C is properly connected to a powered intercom system, the
LED power indicator for that side should be illuminated.
Warning: Pin 1 and the connector shield of cables connected to the TW-12C
SHOULD NOT be connected together.
SYSTEM ADJUSTMENT: HYBRID NULL
You can connect the output side of the hybrid network to the headset jack on the
TW-12C front panel by pressing the Null Test button. This enables an internal
oscillator on the input of the network. Use a standard intercom headset to obtain
a near-perfect match to an intercom line at all frequencies. The test signal is a
400 Hz square wave that provides low- and high-frequency content for nulling
the entire bandwidth.
To make the adjustment:
1. Connect a standard intercom headset into the front panel headset socket.
2. Press the Null Test button on the SYSTEM 1 side. You should hear a tone in
the headset, unless the circuitry is already nulled properly. If you do not hear
a tone, continue with the procedure to verify proper setup.
3. While pressing the Null Test button, adjust the “R” control on the SYSTEM
1 side, for a minimum audible tone in the headset.
4. While pressing the Null Test button, adjust the “L” control on the SYSTEM
1 side for a minimum audible tone in the headset.
5. While pressing the Null Test button, adjust the “C” control on the SYSTEM
1 side for a minimum audible tone in the headset.