Ndtu - Toshiba Perfecptione Installation And Maintenance Manual

INSTALLATION INSTRUCTIONS
SECTlON200-255-204
FEBRUARY1992
2) Determine the proper impedance for each
trunk and then strap its NCOU circuit for either
600- or 900-ohm operation. Install the short-
ing bar across the center pin and the outer pin
labeled either 600 or 900 at each strapping
location (Figure 4-19). Each circuits strap-
ping location is shown as follows:
CIRCUIT STRAPS -
OPERATION
600 ohm 900 ohm
1 TB101
2 TB201
3 TB301
A-B B-C
4
TB401
3) In some installations, particularly those near
the serving Central Office, noise may be intro-
duced over the CO trunk that will appear as
sidetone at the telephone. In such situations,
a 2dB pad can be inserted into the line to
reduce thesidetone. The following table shows
the strapping position for each circuit to either
insert or remove the 2dB pad.
3.74 Three separate strappings must be made for
each of the four circuits on the NLSU PCB (Figure
4-20).
1) Determine the proper impedance for the trunk
line to be used, and then set the 600-ohm/900-
ohm loop termination for each circuit as follows:
CIRCUIT STRAPS
OPERATION
6000hm 1 900ohm
1 1 TBlOl 1
I I
2
TB201
3
TB301
A-B
B-C
4
TB401
2) When the CO distance exceeds 2,000-ohm
loop resistance, Battery-to-Ground Dial Puls-
ing should be used. Foradistance of less than
2,000-ohm loop resistance, use Loop Dial
Pulsing. Strap each circuit as follows:
CIRCUIT STRAPS
OPERATION
r
BAT-GND DP( LOOP DP
3) Each NLSU circuit must be adjusted for CO
trunk loop resistance to ensure proper detec-
tion of incoming digits. Each circuit adjust-
ment is made by strapping as follows:
CIRCUIT STRAPS -
OPERATION
LEAST MID MOST
1 TB102
2
3
TB202 c-d bwc awb
TB
302 _
4 TB402
NOTE:
This strapping should be made only after the
appropriate CO distance strapping (step 2)
has been made. The CO trunk loop resistance
values are arbitrary and are used as an initial
strapping guide. If the incoming digits are not
being detectedproperly, move the strap to the
next most sensitive position and test again for
proper operation.
3.80 NDTU
3.81
A maximum of two NDTU PCBs (Figure 4-21)
may be installed. The system must be equipped
with an NTWU-3 to ensure proper operation of the
NDTU. The NDTU is connected to the telco through
a customer-supplied Channel Service Unit (CSU).
A separate CSU is required for each NDTU. Each
NDTU has 11 DIP switches and 8 strapping op-
tions, which must be verified before installation.
NOTE:
The factory-default switch settings and strap-
ping options are indicated by an asterisk (*).
1) Select thedesired operating mode using mode
selection switch
Sl
(4-element DIP switch)
4-15