Isolating Faults Using Test Equipment:

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Test equipment can be used to generate and monitor alarms and errors. Test equipment is connected to the T1 facility in a variety of ways. Bantam jacks are often available on the equipment. When the plug is inserted into the jack the circuit is interrupted. Sometimes a monitor jack is available. When a plug is inserted into the monitor jack the circuit is not interrupted and a -20 dB signal is available at the jack. When none of these is available, the signal may be monitored at a connection block, sometimes referred to as a "punch-down block". The "T1 Facility Access Methods" table below describes the three typical access methods.
T1 Facility Access Methods

Access method	Test set configuration	Notes
Test Jacks	Terminated	Circuit is broken when plug is inserted into jack. The test equipment is normally set to "Terminate" and provides 100 Ohm termination.
Monitor Jacks	Monitor	The circuit is not interrupted when the plug is inserted into the jack. The actual signal is available at a level 20 dB lower than the original. The test set normally set to "Monitor" provides a 100 Ohm termination and expects the signal to be 20 dB down from what is usually expected.
Direct Connection to "Punch Down Block".	Bridged	The circuit is not interrupted in this mode. The test set impedance is greater than 1000 Ohms so that the circuit is minimally affected. Test set is set to "Bridged"

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WARNING:

The following table describes the typical levels encountered in a T1 circuit. It is important to remember that 90 volts DC may exist between the transmit and receive pair. This voltage can be lethal!

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Typical Levels Encountered in a T1 Circuit

0 dBdsx	6 Volts peak to peak
-7.5 dBdsx	2.53 Volts peak to peak
-15 dBdsx	1.07 Volts peak to peak