Bell System Practices 851 Identification, Installation, Connections, And Maintenance page 6

SECTION 503-601-1 0 1
Fig. 7 -Inside Wiring Cable, Exposed Wiring (Early
Version)
rotary and TOUCH-TONE sets, a loudspeaker and
transmitter must be installed external to the set
and wired to the 55-type control unit. The control
unit can be located near the telephone set (Fig. 21)
or at the KTS equipment.
3.13
4A Speakerphone: If 4A speakerphone
is provided, the 223D adapter is recommended,
however, the 82-type adapter also may be used to
interconnect the 4A speakerphone components
[680-type transmitter, 108-type loudspeaker set,
and the 85B1 power unit, (Fig. 22 and 23)].
3.14
For connections to the 3-type (MD) or 4A
speakerphone system, refer to the appropriate
section in Division 512.
3.15
When an 851- or 2851-type set is multipled
with sets furnishing speakerphone features,
certain leads must be disconnected, insulated, and
stored to avoid interference with working circuits.
The designation of leads to be removed are as
Page 6
Fig. 8-lnside Wiring Cable, from Outlet Box (Early
Version)
follows: T1 (V-G), R1 (G-V), P3 or IT (V-BR),
P4 or IR (BR-V), AG (V-S), and LK (S-V).
3.16
Buzzer: The KS-20419L1 buzzer is mounted
on an insulated bracket below the dial (Fig.
13). If required, an additional KS-20419L1 may
be added or the existing KS-20419L1 may be
replaced by the KS-8109L2 buzzer (14-30 volt ac
or de) which would be mounted using both screws.
3.17
Station Busy Lamp: A 533K diode is
used to provide a station busy lamp feature
for multibutton wall telephone sets used in 1A1
and 1A2 key telephone systems.
For connection information, refer to Table B.
3.18
Key Features.
• All pickup positions of the 635A5 key are
convertable to signaling by the removal of
the 812857738 (P-28E773) locking pins from