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For Magneto, C.B. and Auto/C.B. Working
CS6100 Series and MS6130 series

Small C.B. and Auto/C.B. switch-boards in the Catalogue No. CS.5120 series, described in catalogue leaflet CSL.8, which have a maximum of twelve lines, have been superseded by a new range of switch-boards described in this leaflet.  A similar new range of magneto switchboards replaces those in the Catalogue No. MS.5120 series and MS.5130 series, described in leaflet MSL.5, which have a maximum of twelve lines.

The new switchboards have a pleasing appearance that blends well with modern-style furnishings.  Each switchboard has a two-tone colour finish of light and dark grey.  An alternative finish of green and biscuit can be supplied when specified. The switchboard will operate under tropical and temperate climatic conditions.

The keys and indicators used in all the switchboards are of a new miniaturised type.  Magneto and C.B. models are mounted on the same size base and have the same outer cover, but different keyboards and indicator panels. The Auto/C.B. model has the same base and keyboard as the C.B., but the front panel of the cover is moulded to accommodate a dial.  Wiring for the dial is included in both models, a five-way plug and socket being used to connect the dial to the main wiring.  Conversion from C.B. to auto working is thus simply by changing the cover, plugging in the dial and removing a strapped connexion.

The cover can be simply removed by loosening four captive screws.  The key shelf and apparatus mounting are hinged to open outwards so giving easy access to all components and wiring for maintenance.  A terminal strip is fitted on the base of the switchboard and connexion of exchange and extension lines can be made direct without the need for an external junction box.  However, a flexible multiway cable can be used to connect the switchboard to a nearby junction box to allow wiring changes to be tarried out without interfering with the operation of the equipment.

All switchboards are fitted with a heavy-duty rotating-magnet hand generator.  This is particularly smooth and quiet in operation, and requires less effort to turn than the former rotating armature type.  In general, the operating features of the new switchboards are similar to former models, but the smaller keys and sloping keyboards permit speedier and smoother operation.

The C.B. and Auto/C.B. switchboards are equipped for either two exchange lines and four extensions or three exchange lines and nine extensions. An extension user calls the switchboard by simply lifting the handset. A springset in the telephone closes to complete a loop and operate an indicator on the switchboard.  The operator answers by throwing the associated speak key and her own telephone key, then completes the connexion either to another extension or to the main exchange.  She is then free to deal with other calls.  On the completion of the call a clear down signal is given at the switchboard automatically when the extension handsets are restored.  Provision is made for exchange lines to be switched to selected extensions for night service or at other times when the switchboard is unattended.

Three connecting circuits are provided for the 2+4 line model and five connecting circuits for the 3+9 line model.  Telephones recommended for use with these switchboards are described in G.E.C. Catalogue Leaflet STL.13. Satisfactory operation can be obtained if the line loop resistance between exchange and extension does not exceed 1000 ohms.

Power for the exchange may be obtained either over a separate power line from the exchange, or from a local power unit or battery. The nominal operating voltage is 24 volts, and the busy hour drain is approximately 0.4 amp for a 2+4 line and 0.6 amp for a 3+9 line switchboard.  A battery fuse is fitted at the side of the base.  This can be replaced without removing the switchboard cover.  Power for the exchange calls is obtained from the public exchange battery.

3+9 Desk Style Cordless Switchboard - CS6128 Internal View - CS6128

The magneto switchboards are equipped for either six or twelve lines.  An extension user calls the switchboard by turning the generator handle and lifting his handset. At the switchboard the indicator operates and the operator answers by throwing the associated speak key and her own telephone key.  She then completes connexion by ringing the required line and connecting the two parties for speech.  The operator is then free to deal with the next call.  At the conclusion of a conversation the extensions replace their handsets and "ring off" by turning their generators to signal to the operator that the connexion is no longer required.  Three connecting circuits are provided for the 6 line model, and five connecting circuits for the 12 line model.

A 3 volt battery (two 1.5 volt cells) is required in the switchboard operators telephone (speech) circuit, and a similar battery is required to operate the audible calling alarm.  These batteries are only supplied when specified on orders

Telephones for use with these switchboards are described in G E C Catalogue Leaflet STL.11.

12 line Magneto Desk Style Cordless Switchboard - MS6132 Internal View - CS6132


Catalogue No. Type No. of lines Connecting Circuits Weight Dimensions
Exchange Extension kgs cms
CS.6123 C.B. 2 4 3 10.5 33 x 21.6 x 33
CS.6124 Auto 2 4 3 10.5 33 x 21.6 x 33
CS.6127 C.B. 3 9 5 12.5 33 x 21.6 x 33
CS.6128 Auto 3 9 5 12.5 33 x 21.6 x 33


Catalogue No. Extension Lines Connecting Ccts Weight Dimensions
kgs cms
MS.6131 6 3 7.26 33 x 21.6 x 33
MS.6132 12 5 8.85 33 x 21.6 x 33

Supplement to GEC Catalogue Leaflets Nos. CSL.8 and MSL.5

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Last revised: November 25, 2021