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3. Hybrid Adjustment
Note
Tests 1 and 2 are performed at the factory. These two gain settings
should never again need to be adjusted. Test 3 needs to be
performed during installation.
Each test runs for up to 3 minutes. During that time, if the Connect button is pressed
again, the next test will commence. The unit will return to normal operation mode in any
of these cases:
• The Connect button is pressed during test 3.
• The current test is allowed to time out.
• The Connect button is pressed and held for 3 seconds. Holding the Connect button
down to return to normal operation mode is acknowledged by a rapid blinking of
the Ring LED. The rapid blinking stops and the Ring LED goes out when the
Connect button is released.
Each test indicates that it is running by blinking its test number of
1
or 3
/
-second blinks) every 3 seconds.
3
Accessing the Test Points
To perform the tests and adjustments, the cover of the phone coupler must be removed to
gain access to the test points and some of the potentiometers.
To remove the cover
1. Disconnect the power cord from the unit.
2. Disconnect the phone line(s).
3. Disconnect all cabling.
4. Remove the three Phillips-head screws on the rear of the unit.
5. Slide the cover back, then lift it to remove it.
6. Reconnect the power cord and interface cables to P1.
7. Reconnect the phone line to the modular connector of each channel.
Test Points
Table 36: Test points
TP1
Rx audio from the console at the output of the first gain stage.
TP2
Power Up Reset circuit. +5 VDC = Reset; 0 VDC = Operate.
TP3
Dial Click Decode circuit, after sensitivity adjustment.
TP4
Tx audio from the phone just after the hybrid.
TP5
"VP" bias voltage. Should be +2 VDC.
Series 4000 Phone Coupler (Optional)
1
/
-second blinks (1, 2,
3
95
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