Polarity Check - Northern Telecom DMS-100 Series General Description, Installation And Maintenance

3. VERIFICATION PROCEDURES
LOOP CHECK

POLARITY CHECK

STATION RINGER
TEST
ACD Sets
Test Set-up
3.01 Loop and linecard tests must be performed at the Central Office (ref.
297-2011-180). It is assumed that loops and linecards have been checked out
prior to the installation of any business sets.
3.02 Verify that the loop resistance is less than or equal to 1230 Ohm, and
that the dB loss is less than or equal to 24 dB at 8 kHz. To guarantee operation
of a particular configuration, the 8 kHz attenuation should be measured when
all terminals and add-ons are installed. If this is not feasible, an allowance of
0.5 dB at 8 kHz should be made for each additional terminal or add-on placed
on the loop.
3.03 The DMS-100 Family business sets are polarity sensitive. Only if
problems arise when the set is to be put into service, perform the following
steps:
(a) If the set does not respond (no dial tone), reverse tip and ring leads.
(b) If tip and ring lead reversal does not solve the problem, change the set.
(c) If the set still fails, call the Local Repair Service Bureau to have the
appropriate diagnostics tests (loop, linecard, station ringer test software
check, etc.) performed.
(d) After the equipment has passed all tests, verify that the loop resistance
remains at less than or equal to 1230 Ohm, and that the dB loss remains
less than or equal to 24 dB at 8 kHz.
3.04 The Station Ringer Test (SRT) tests the hardware of the DMS-100
Family business sets and can be performed by the installer or repairman at the
site with no involvement of the Central Office personnel.
3.05 The Station Ringer Test can be activated on an ACD set only if that set
has a Prime Directory Number (PDN) key because the test requires dialing of
the access number from the set to be tested. If the ACD set is software
programmed for "call originations denied," the test cannot be performed for
that set.
3.06 With the handset on hook and all LCD indicators off, press the prime
directory number (prime DN) key and dial the 3 to 14 digit access code. The
access code consists of a one to seven digit number which is assigned by the
telephone company according to local preferences, followed by the last two to
seven digits of the prime DN assigned to the telephone to be tested. In North
America, the access code usually consists of the number 57, followed by the
last five digits of the prime DN. If the required digits are dialed incorrectly, a
REORDER tone will sound which makes it necessary to press the RELEASE
key and start again. If all digits are correct, all LCD indicators at the set light up
and the dialed digits are cleared from the display. The test can now proceed in
PRACTICE 297-2011-200
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