This indicator signalling switchboard extends the capacity range of desk-top
cordless units to five exchange lines and 20 extensions. Seven connecting circuits are
provided. CB
5+20
Cordless PMBX
Indicator Signalling
with Auto or CB exchange lines
This indicator signalling switchboard extends the capacity range of desk-top
cordless units to five exchange lines and 20 extensions. Seven connecting circuits are
provided.
By the use of miniature keys and indicators, and lightweight structural materials, the size and weight are kept to the minimum.
An improved form of construction contributes to the switchboard's modern appearance and
provides increased access to equipment for maintenance.
Facilities
Construction and Finish
The pressed-steel frame, welded to prevent distortion, is mounted on a hardwood base. The
front panel can be swung down, as shown in the illustration overleaf, to afford
access to the internal wiring. Each vertical row of keys is removable as a unit for spring
inspection.
Replaceable plastic laminated panels enclose the equipment. The back and top are a
single sheet which clips in at the top and can be removed to obtain access to the rear
equipment after releasing three captive screws at the bottom. The switchboard is
attractively coloured : the equipment panel, covered with grained dove-grey p.v.c. above
the black bottom strip and base, tones well with the buff side and rear panels, which are
outlined by bronzed metal strips.
The appearance is enhanced by black indicators and a black handset and cord. A dial
dummy instead of the dial
is provided on C.B. switchboards.
The equipment has full tropical finish; i.e. coils are impregnated and metal parts specially finished.
Conductors are insulated with p.v.c., which is moisture-proof and not subject to fungoid growth or attack by insects.
An internal terminal field permits direct termination of incoming lines. Alternatively, a flexible connecting cord and cable distribution box can be supplied.
Apparatus
Type N9300 miniature keys, and totally enclosed miniature twin shutter indicators are
used. Extension line indicators Type N4831 are non-locking and self-restoring. Exchange
line indicators Type N4832 operate and lock to ringing current and are restored by
pressing down a projection at the top of the plastic front cover. The curved shutters open
horizontally to display a red (exchange line) or green (extension line) number against a
white background.
The handles of the associated keys are tipped with red or green inserts to match; this facilitates accurate operating and enables operated keys to be instantly discerned.
The dial has standard numbering and a 2:1 break/make pulse ratio. The hand generator is of the rotating-magnet type, but can be replaced or supplemented by a transistor ringing unit if specially ordered. Relays and battery-feed retards are Type N30000 (BPO 3000).
Also included are an alarm buzzer and cut-off key, and a plug-in light-weight handset
with capsule receiver and coiled cord. In lieu of, or in addition to, the handset, a
lightweight headset can be supplied.
Power Details
Nominal operating voltage: 24V d.c. normally provided by a mains operated 1A power unit.
Alternatively, storage batteries with charging equipment can be supplied, if preferred.
Busy hour current drain for fully equipped board: 0.84A.
Extension Telephones
Plesseyphones (catalogue sheet 7159) or Etelphones (catalogue sheet 7145) are recommended.
For automatic working, dials are normally adjusted to transmit 10 p/s with a 2:1
break/make pulse ratio, and have standard numbering (i.e. 1 to 0). Other speeds and
numbering can be provided to customer requirements.
Switchboard Dimensions
Height: 12.5 in (317mm)
Width: 23in (584mm)
Depth: 9.5 in (241 mm)
Weights (approx.)
Switchboard (fully equipped 5+20): 58lb (26.3kg) net.
Plessey Publication No. 7131 (1971)
Click for an article from the Ericsson Bulletin
| Home page | BT/GPO Telephones | Ericsson Telephones | Ericsson Home Page | Ericsson PABX | All Telephone Systems |