TELEPHONE No. 746 & 8746 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Switches for Telephones Telephone No. 8746 - Telephone No. 746 modified for PST working General Information on 700 Type TelephonesHow to wire your Telephone No. 746 to make it work on Plug and Socket Click here to hear a Telephone No. 746 bell ringing Click here for Additional Buttons N849 - Web users - CD users. Click here for the Auxiliary Switches N848 - Web users - CD users. Click here for the circuit diagram N846 - Web users - CD users. Click here for the colour range
In 1967 the 746 Type telephone was introduced (See also Telephone No. 736). This was an improved version of the 706 range and offered similar facilities. The case styling is slightly different from the 706 although it retains the same overall look. The case now has an integral handle which obviates the need for a separate handle (the Telephone 706 plastic handles used to break). Originally the case had a slope from above the dial, sloping backwards, under the handset, finishing at the raised handset stops to the rear of the case. This design was found to allow the handset to sometimes not slide backwards enough to operate the switchooks correctly - leaving the phone on hook. The case was later modified and the handset now rests in a recess, with raised sides to stop the handset sliding forward. The pictures above show both the early and later style cases. Inside the circuitry is different in that the regulator components are soldered directly onto the printed circuit board, the switch-hooks and other components were miniaturised. No conventional wiring version was produced. The same colour options as for the 706 were offered to the customer. Available to all customers in 1970. Still supplied into the late 1980's as maintenance stock. Later phones and refurbished phones had the Transmitter No. 16 replaced by the Transmitter No. 21 (blue or red variants) due to transmitter noise issues. ENGINEERING INSTRUCTIONS TELEPHONES 740 AND 746 General
Many parts of the Telephones 740 and 746 are identical with those of the Telephones 710 and 706 which are described in A 1063 and A 1060 respectively. This Instruction describes only those parts particular to the Telephones 740 and 746. The telephones, which as issued are for use in automatic areas only, are suitable for use on lines of up to 1000 ohms T.E.R. The telephones can be modified for a variety of uses by the fitting of add-on units,' adapters etc. and these will be described in later instructions. The Telephone 746 is available in black, blue, two-tone green, two-tone grey, ivory, red and yellow. The Telephone 740 is available in black, two-tone grey and ivory only. Cover The telephones, as issued, have the aperture for the press-button(s) closed with a dummy button held in place by a clip. When a press-button unit is fitted the dummy button and clip should be secured within the telephone for subsequent refitting. A phone with the single switch is shown to the right. The outer dial ring fits round the hole in the sloping face of the cover through which the dial protrudes. The dial ring is secured by dropping the lugs on the ring into the recesses provided on the edge of the hole in the case and turning clockwise until the two recesses provided for the finger-stop line up. To remove or refit the ring the cover must be taken off the telephone assembly. An 'off-rest' position is provided with the handset resting across the instrument just above the dial. A carrying-handle, in the form of a recessed finger ledge, is provided between the horns directly below the normal handset position. Base The plunger-supporting brackets are riveted to the base. Printed wiring board
The printed wiring board is located by mating slots in the front edge of the board and in the sides of the plunger-mounting bracket. The regulator is an integral part of the telephone circuit and provision is not made to render it inoperative. The gravity spring-set consists of a microswitch positioned alongside the left-hand support of the plunger-mounting bracket. The switch is operated by a lever pivoted on a bracket at the rear edge of the switch cover, the upper end of the lever being formed into a channel in which a projection on the plunger assembly rides. A coiled spring holds the lever in position. The switch is operated when the handset is on the rest. Dial and dial cord Terminal block and line cord Bell Telephone circuit Press-buttons and switches Press-buttons for the Telephone 740 are provided by removing the dummy button and fitting a Part 1/ ... 10/DBU/372 using the pin, Part 1/DPI/203, provided in the telephone. A single press-button for the Telephone 746 is fitted by removing the dummy button and clip and inserting a Part 1/ or 2/DBU/362 which is retained by two pins, Parts 1/DPI/203. When two press-buttons are required, two Parts 1/ ... 6/DBU/363 are fitted, each with one Part 1/DPI/203. Where a single change-over contact (non-locking) is required in association with a press-button in either telephone a Switch No. 5A-4 together with an operating plunger, Part 1/DPL/1022, is fitted. Other non-locking contact assemblies can be provided on either telephone by fitting the spring-sets described in Dgm. N 848 together with a Part 1/DPL/1022. There a locking single change-over contact is required in association with a, press-button on either telephone a Switch No. 5A-9 is fitted (this switch includes an operating plunger and is now superseded by Switch No. 23A). Other locking contact assemblies can be provided on the Telephone 740 by means of the latch-plate as described in A 1063 and Dgm. N 848. Additional gravity switches can be fitted to either telephone when required as follows:-
Replacement parts TABLE 1 Part To be requisitioned as:-
References:- A 1060 & A 1063 How to remove a Telephone No. 746 or 740 case
Re-fitting is the process in reverse, except you may have to slide the casing dial ring to locate it over the dial. If the casing screw does fall out - fit back as follows:-
Additional information
The Telephone No. 9746 can be found in C, D, F, G, GR and R variants. The GR and R variants were fitted with Earth recall switches. All these models date from 1981 onwards. Telephone No SA 4284 Tele SA 4284 is a Tele No. 746 used for Teleprax working. The Tele No. 746F is modified for buzzer calling and 6v working.
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Last revised: April 06, 2010FM |
On both types of telephone the cover is secured to the telephone assembly by a lug on the front skirt which engages in a recess in the leading edge of the base and by a single fixing screw located above the cord entry at the rear of the case. The screw, which is held captive by a bush and a spring, engages in a tapped hole in the cord clamp, a T-shaped metal bracket riveted to the rear of the base.
