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Test 2: Repeat Audio Gain
Note
1. Advance to Test 2 by pressing the Connect button. Verify that Test 2 is running:
you should see two
2. From the console, take the phone coupler off hook and transmit a steady 1 kHz
tone. Observe the 1 kHz tone on the Rx connector and on the Tx connector. This is
a verification test only.
3. The test will time out after 3 minutes, unless the Connect button is pressed again.
If the test is allowed to time out, the system will return to normal service. If the
Connect button is pressed before the test times out, Test 3 will start.
Test 3: Hybrid Adjustment
Note
1. This adjustment needs to be done on any system that will be supporting full duplex
operation. It will reduce the amount of audio reflected back to the console from the
hybrid.
2. Connect an oscilloscope to TP4.
3. Place a phone call to the coupler from another phone. While the phone line is
ringing, press the Connect button to advance to Test 3. Verify that Test 3 is
running: you should see three
The coupler will now answer the ringing phone line and emit a dual-tone signal
comprised of a 400 Hz tone and a 2500 Hz tone. Adjust the two hybrid
potentiometers, R95 and R96, to obtain the lowest deviation on the coupler or the
lowest signal at pin 5 of P1. It is necessary to repeatedly adjust the potentiometers
to obtain the lowest signal level.
4. The test tone is available on the Rx input to the dual-channel card and can be heard
on the console speaker. It can be used to adjust the hybrid by adjusting to minimum
speaker output.
Coupler Signals
The following table identifies the punch-down block connections required for the Phone
Coupler.
Note
This test is performed at the factory and should never need to be
done again.
1
/
-second blinks of the Ring LED every 3 seconds.
3
This test needs to be performed during installation.
1
/
-second blinks of the Ring LED every 3 seconds.
3
On any single channel, the black connections are jumpered
together and the red connections are jumpered together.
Series 4000 Phone Coupler (Optional)
97
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