AT&T System 85 manual Auxiliary Power Supply, Terminating Resistor

ISDN 8520T Voice/Data Terminal

Distance Limitations

For DEFINITY G2 and G3, in which multipoint configuration is used, the maximum signaling dis- tance possible from the port board to the work location jack is: (the terminating resistor should be within 250 feet of the work location; the distances listed are applicable for up to two voice/data terminals)

If 24 AWG cable is used = 1600 feet

If 26 AWG cable is used = 1330 feet

Power Requirements

Auxiliary Power Supply

The 8520T needs auxiliary power from an auxiliary power supply. Recommended power supplies are the MSP-1 (local) Power Supply and the 1145A Bulk Power Supply.

Terminating Resistor

The terminating resistor setting must be set by either a service representative or the system administrator.

The terminating resistor setting should be set to OUT when the voice/data terminal is in a point-to-point configuration and the terminating resistor is in the closet.

The terminating resistor setting on the terminal should be set to IN when the voice/data terminal is in a point-to-point configuration and the terminating resistor is not in the closet.

When terminals are part of a multipoint configuration and the terminating resistor is in the closet, all sets should be set to OUT.

When the terminating resistor is not in the closet and the terminals are part of a mul- tipoint configuration, only one of the sets in this configuration needs to be be set to IN. All the rest of the sets in this configuration should be set to OUT.

To change the terminating resistor setting, do the following:

1. Press Menu and then Mute .

2. Dial the numbers ‘‘87’’ (TR).

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