Avaya MCC1 Maintenance Procedures page 228

Packet and serial bus maintenance
Isolating and repairing packet-bus faults
TN771D in stand-alone mode
In TN771D stand-alone mode, a terminal is connected to the Maintenance/Test circuit pack with an
Amphenol connector behind the cabinet. This setup allows direct inspection of the packet bus and
identifies shorted or open leads. This mode does not use the usual MT Maintenance User Interface and is
therefore available even if switch is not in service. When in stand-alone mode, the TN771D does not
reconfigure the packet bus.
Required hardware
• TN771D: Standard or high-reliability systems may not have a TN771D in each PN. (Use list
configuration to determine whether this is so.) When this is the case, take one to the site. See the
following section,
• Terminal or PC with terminal-emulation software: The EIA-232 (RS-232) port should be
configured at 1200 bps with no parity, 8 data bits, and 1 stop bit. This is a different configuration
than the G3-MT. If a terminal configured as a G3-MT is used, change the SPEED field from 9600
bps to 1200 bps on the terminal's options setup menu. (This menu is accessed on most terminals
by pressing the CTRL and F1 keys together. On the 513 BCT, press SHIFT/F5 followed by
TERMINAL SET UP.) Remember to restore the original settings before returning the G3-MT to
service.
• 355A EIA-232 adapter
• 258B 6-port male Amphenol adapter (a 258A adapter and an extension cable can also be used).
• D8W 8-wire modular cable with an appropriate length to connect the 258A behind the cabinet to
the 355A adapter. The relevant comcode is determined by the cable's length, as follows:
7 feet (2.1 m) — 103 786 786
14 feet (4.3 m) — 103 786 802
25 feet (7.6 m) — 103 786 828
50 feet (15.2 m) — 103 866 109
Selecting a slot for stand-alone mode
When selecting a slot to use for a TN771D in stand-alone mode in a PN that does not already contain one,
keep the following points in mind:
• A port circuit slot (indicated by a purple label) should be used. The service slot (slot 0) cannot be
used for stand-alone mode, even though a TN771D might normally be installed there.
• -5 Volt power supply must be available in the carrier. (For a description of carrier's power supply
units, refer to
• A slot in a PN's A carrier is preferable if the previous conditions are met.
228
Special precaution concerning the TN771D
CARR-POW (Carrier Power
on page 234.
Supply).)
Maintenance Procedures
December 2003