Note:
The signals will not be heard on the
conference set loudspeaker.
(b) The customer may be provided with a 2500S
telephone set modified in accordance with
Table A and shown in Fig. 4.
Tone signaling
may be accomplished by inserting the 309 plug
into the AUX DIAL jack on the rear of the
control unit and depressing the AUX DIAL key
button. The dial of the modified telephone set
may be used without lifting the handset. Signals
will be transmitted to both the telephone line
and the conference set loudspeaker. The VOLUME
control on front of the control unit adjusts the
listening level of the TOUCH-TONE signals.
(c) If TOUCH-TONE service is not available,
the modified 2500S telephone set must be
used as described in (b) to provide signaling to
a computer terminal.
OFF Button
4.11
When in the hands-free mode, depressing
the nonlocking OFF-button deactivates the
conference set, extinguishes the associated indicator
lamp, and disconnects the call.
D.
2- or 4-Wire Operation
4.12
An internally mounted switch (Fig. 6) allows
easy selection between 2- or 4-wire mode
of operation.
In the 4-wire mode, transmit and
receive channels are each connected through separate
pairs of the telephone line.
E.
Ringer
4.13
This control unit is equipped with a PlB
ringer. The ringer volume control is located
on the bottom of the unit.
ISS 2, SECTION 512-630-111
5.
MAINTENANCE
Caution: Disconnect ac power cord and
the D4BU line cord before attempting any
maintenance to the interior of the control
unit.
5.01
Set repair at customers' premises should be
limited to replacement of those parts listed
in the Ordering Guide. Repair of other components
affects set performance and requires detailed testing.
5.02
To remove the front and rear housing
assemblies from the 73B control unit, disconnect
the hand telephone set first, using a KS-16750 type
releaser or equivalent. Release the three captive
screws located in access holes at sides and rear
of the unit base pan (Fig. 3) and remove the rear
housing assembly first. Then remove two screws
located on the sides of the base pan and captive
screw at the front to release microphone and front
housing assembly.
The proper dress of wires in
the vicinity of the ringer gong, line switch, and
internal microphone terminal connections should be
maintained to prevent interference with the front
housing assembly when it is replaced after performing
maintenance.
5.03
Replace 220A hand telephone set by connecting
plug of H4DB cord to hand telephone set
jack, and to jack located on left side of control
unit.
Note:
Replace the 53B dial lamp furnished
with the hand telephone set with a 53A lamp.
Refer to appropriate section in Division 502
for replacement procedures.
5.04
If a light appears under the MIKES OFF
button, it indicates dial light power is
supplied on Tl and Rl leads.
Do not remove
this lamp from the conference set.
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