Bell System 26340 Service Manual

BELL SYSTEM PRACTICES
AT&TCo Standard
SECTION 502-612-403
Issue 2, July 1972
SERVICE
26340 AND 26350 TELEPHONE SETS
1.
GENERAL
1.01
'This section contains connection and maintenance
information for 18- and 30-button telephone
sets equipped with 12-button TOUCH-TONE® dials
and used with station line concentrators.
1.02
This section is reissued to:
e Change title from 2634- and 2635-type
e
Show the 2634D and 2635D telephone sets
rated MD
e
Add priority hold using 657L key
• Add new insulating deta il for 656- and
657-type keys
• Remove common maintenance information
which is now covered in Section 502-600-100
2.
CONNECTIONS
2.01
See SD-69498-01 (key telephone systems,
6A, 1A1, and 1A2, station line concentrator)
and appropriate sections in Division 518 for
connections to station line concentrator using 235B
or 236B key telephone units.
2.02
A 235B KTU is associated with each 2634D
telephone set and a 236B KTU with each
2635D telephone set. Because of the single common
talking and control lead pattern in these sets, a
line concentrator KTU must be associated with
each telephone set installed and cannot be shared,
even on a bridged station basis.
2.03
A 599B or 657B key may be used in the
first key position to provide ringer or line
cutoff (Notes 5 and 6, Fig. 2 or 3). When other
uses are required, they must be provided for by
means of an auxiliary relay separately mounted
and controlled by the turn key contacts since there
are insufficient mounting cord conductors to permit
full switching at the key.
2.04
•Priority hold can be supplied in these sets
by installing a 657L key in the first module
and modifying set as shown in Fig. 5. Refer to
Section 518-310-405 for connections to the 235- or
236-type KTU and to Section 518-215-125 and
SD-69530-01 for connections to the 429A and 430A
KTUs .•
2.05
To convert a key position from pickup
(locking) to signaling (nonlocking) remove
the screw detail P-10E837 entirely from the plunger
at t he key position to be converted. •Make the
necessary wiring changes as shown in Table B and
use 840157473 insulating detail to isolate the ring
and tip contacts . Refer to Division 512, section
e nti tled Modular Keys, Lamp Sockets, and
Transmitters (KS-Type connector Equipped) for
more information on keys and insulators .•
3. MAINTENANCE
3.01
Maintenance of handsets, dials, and ringers
is covered in Division 501 and modular keys
in Division 512.
3.02
Refer to the appropriate Reference section
in Division 502 for replaceable components.
3.03
•For maintenance information covering these
sets refer to Section 502-600-100 .•
@
American Telephone and Telegraph Company, 1972
Printed in U.S. A. Page 1