Nortel DMS-100 Series Maintenance Manual page 53

Digitone receiver card (DTR) (NT2X48AB). The DTR contains four
Digitone receivers to collect digits during RLCM ESA.
Line test unit (NT2X10AA, AB, AC, NT2X11AA, AB, AC, AD). The
line test unit (LTU) is a testing facility that can connect to a selected line
circuit through the remote MTA. The LTU contains two cards: an
analog test and measurement card (NT2X10) and a control card
(NT2X11). The two cards must be side by side, the NT2X10AB in an
odd-numbered slot, the NT2X11AA in the next even numbered slot. The
LTU analog test card performs tests and measurements on a subscriber
loop or line card circuit. The NT2X11 control card serves as an interface
between the LTU analog card and the RMM. The LTU contains one
internal test unit.
Multiline test unit (NT2X10BA, NT2X11BA). The multiline test unit
(MTU) is an enhanced LTU that can replace the present LTU. The MTU
contains two cards, an analog test and measurement card (NT2X10BA),
and a control card (NT2X11BA). The two cards must be side by side,
and the NT2X10BA must be in an odd numbered slot. The MTU
performs the functions of the LTU with greater speed and accuracy. The
MTU also can be used to test Meridian Business Set lines and OPM
battery maintenance. The NT2X11BA control card serves as an
interface between the MTU analog card and the RMM. The MTU
contains two internal test units.
Incoming/outgoing test trunk (NT2X90). The test trunk card provides an
interface between external test equipment, like the number 14 line test
desk, and the RMM. The test trunk card provides monitoring and speech
circuits to subscriber lines. The test trunk allows operator verification
calls through a VER90 trunk.
The RMM shelf design appears in figure "Remote maintenance module shelf
layout".
DMS-100 Family RLCM Maintenance Manual XPM12 and up
Maintenance overview 1-37