C.B. Intercommunication Telephones
AUTO-RESET, PUSH BUTTON SELECTOR TYPE
|N 1636C Type||N 1637C Type|
One of the most effective means of inter-office communication where a relatively small number of lines is required, is the intercommunication telephone system, as immediate connection is established on the pressure of a button ; no operator or automatic dial being necessary. It may also be installed in large establishments as a supplementary system for the use of executives.
For many years our intercom telephones have been markedly popular by reason of their efficiency and reliability. In conformity with our progressive policy, we have redesigned these telephones on lines more in keeping with current requirements, and we are confident that they will have instant appeal, as they embody the simplicity of outline favoured for the modern office, while still retaining the proved advantages of their predecessors.
The instruments have moulded cases in fadeless black or ivory, and ivory moulded push buttons; thus, as there are no external metal parts to become tarnished, a lasting "new" appearance is ensured.
The casing is loose-hinged, and fastened by one screw, to a strong plastic baseplate
carrying the internal components which are therefore accessible for maintenance when the.
case is lifted off.
These components include the push button mechanisms mounted in pre-wired units of five, each unit bearing a paper strip printed with the appropriate numbers. The mechanisms are protected by a moulded panel having apertures for the buttons and designation strips, the latter being covered by convex transparent plastic windows which are bonded in and give prominence to the printed numbers.
Highly satisfactory reproduction of speech is given by the inset transmitter and electromagnetic receiver incorporated in the moulded micro-telephone, the cord from which enters the case through a rubber protector arranged to accommodate also the desk cord of the table instrument.
A moulded desk terminal block is supplied for the connection of the line wires to the
table set, whilst the wires to the wall set enter through a hole in the baseplate and are
connected to screw terminals. A combined instruction/directory card is supplied with each
To make a call, lift the micro-telephone and press the appropriate button to its full extent. If the called number is free, a buzzing tone will be heard in the receiver, indicating that the required person is being called.
A button, having been pressed, is retained in an intermediate position during the call, and is automatically released when the micro-telephone is replaced or another button is pressed; successive calls can therefore be made without replacing the micro-telephone.
Incoming calls operate a buzzer in the instrument. To reply, it is necessary only to lift the micro-telephone and speak.
The system is operated from a central battery, or via an eliminator when an a.c. supply is available. In either case, the best results are obtained when the source of supply is as near as possible to the centre of the system.
For a maximum line length of 2,000 feet (the approximate economic limit) a battery of nine dry or inert cells is usually adequate. Where the distance is less, the battery is proportionately smaller.
If a station is remote from the main installation, an N1112A type call and reply telephone is usually supplied as a subsidiary to the nearest intercom station. The call and reply telephone can be rung from any station but can only call the one to which it is subsidiary. This arrangement effects a considerable saving in cable costs.
For a complete installation, junction boxes, cells with boxes (or an eliminator) and cable are supplied.
The type of cable recommended for a particular installation is specified in the quotation and comprises suitably insulated 9, 14 or 19, No. 23 s.w.g. copper conductors, respectively, for the 5, 10 or 15-line systems.
|Code No.||Type||No. of Lines|
Dimensions (excluding h.m.t.): 6.5" x 8.75" x 4.1" (168 x 222 x 105 mm)
Total weight : 4.6 lb. (2.1 kg.) max.
Note - Orders for telephones should specify the Type No. and colour ; black or ivory.
Taken from the Ericsson catalogue, edition No. 49
Introduced around 1953 - superseded N1620 - N1627
INTERCOM. TELEPHONES TYPES N.1636, N.1637, N.1732, N.1733
These instructions cover:-
1.1 General Maintenance.
2.1 Adjustment of push-button keys.
2.2 Adjustment of cradle switch.
Part Nos. referred to are shown on the relevant equipment drawings.
1.1 GENERAL MAINTENANCE
The simplicity of construction and operation of these telephones, coupled with the fact that the materials used are not liable to corrosion or excessive wear, ensure long, reliable service with minimum attention. The instruments are subjected to stringent tests in the factory and, provided that they are treated with reasonable care, should require no routine maintenance apart from a periodic check of the associated batteries to ensure that the output is satisfactory.
Experience has shown that while these telephones are working efficiently they are best left undisturbed.
The majority of faults which occur have been found attributable either to the deterioration of batteries or to low insulation of the cable brought about during structural alterations or through some building fault, therefore these possibilities should first be investigated, unless the source of the trouble is obvious, e.g. a sticking push-button or cradle switch plunger.
However, these are unlikely contingencies in the reasonably dust-free atmosphere of the average office. In order to cover every eventuality, the following information for the adjustment of push-button keys and cradle switch springs has been extracted from our factory specification.
2.1 ADJUSTMENT OF PUSH-BUTTON KEYS
For Telephones N. 1636 or N.1637, Drawing N.78795.
For Telephones N. 1732 or N.1733, Drawings N. 78793 (or N.78794) and N. 78795.
Note:- The part must not move when gauge is set at the specified low limit, but should begin moving at any tension above this, up to the high limit.
2.2 ADJUSTMENT OF CRADLE SWITCH
Relevant Drawing, N.82934.
Note:- The parts mentioned in (a), (b) and (c) must be free, to ensure true reading of tensions.
Springset Tensions (see Fig. 3)
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