Northern Telecom DMS-100 Series Installation And Maintenance Manual page 101
Digital switching systems
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Also See for DMS-100 Series:
- Maintenance manual (238 pages) ,
- Manual (168 pages) ,
- User manual (88 pages)
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0
0
2.
To perform a tip-and-ring loopback test, unplug the
0
the
backplane in order to gain access to SW2.
0
(T-and-R Loop position) as shown in Figure 4.7 on page 4-15.
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3.
Plug the DU into the backplane.
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formed on the DU.
0
remains on.
0
4.
Go to the DTE and type a string of characters on the DTE key-
0
board.
If the typed characters are echoed back to the termi-
0
nal, the path from the DTE to tip and ring is good.
0
5.
Unplug
the DU from the backplane and return SW2-4 to the OFF
0
(normal) position.
0
6.
Plug the DU into the backplane.
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formed on the DU.
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7.
Press the Busy key to turn the Busy LED
0
Family switch returns the DU to service.
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The
far-end
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The data is looped back at the RS-232C interface of
0
DU toward the near DU.
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There
are
two
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Choose the one that is appropriate for the installation:
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*
Method one is for testing a rackmount DU connected to
0
capable
0
to the NT4X25AD /CH /DF data units.
0
*
Method two is for testing a rackmount DU connected to a dial-
0
up DTE, such as a mainframe computer.
0
applies
0
known good desktop DU connected to a DTE
0
characters.
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Far-end Loopback Test - Method One:
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1.
To
perform
0
backplane in order to gain access to SW2.
0
ON
position
0
4-15.
See Figure 4.6 on page 4-14 for the location of SW2.
0
2.
Plug the DU into the backplane.
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formed on the DU.
0
remains on.
0
3.
Establish
0
feature at the DTE.
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The Under Test LED
The under test LED turns off.
loopback
test
methods
of
of
keyboard dialing.
to
the
NT4X25AV data unit.
a
far-end loopback test, unplug the DU from the
(Far-end
Loop)
The Under Test LED
a call to another DU by using the keyboard dialing
A power-up self-test is per-
on
A power-up self-test is per-
off.
checks the end-to-end data channel.
performing a far-end loopback test.
This method typically applies
This method
Method two requires a
that
as shown in Figure 4.7 on page
A power-up self-test is per-
on
297-2121-226
VINTAGE 05.01
DU
from
Set SW2-4 ON.
the
DU
faceplate
The
DMS-100
the
far-end
a
DTE
typically
can
transmit
Set SW2-3
to
the
the
DU
faceplate
5-11
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