TELEPHONE No. 1/SA 4271
|Introduced in 1977 as a special phone for the Jubilee year.
The Bell Unit SA4271 in some cases may have a suitable termination for dropwire in addition to terminations for internal cable, thus avoiding the need for a separate terminal block; dimensions are less than existing bellsets permitting the unit to be mounted within the majority of window alcoves, etc. It is a clip-on fit to a wall plate which can be screw fixed to a flat surface, conduit box, or with the addition of angle brackets, to skirting boards or wooden window sills. When used on Plan 4 installations can be fitted with a jack into which can be plugged a portable telephone. It can be mounted within a wall bracket which also provides a secure shelf for the telephone. When mounted within the wall bracket the bell unit can also be provided with a jack.
The Telephone 2/SA4271 is of smaller dimension than existing 700 type instruments and will fit in narrower window ledges and recesses than existing telephone apparatus. It has a carrying handle and an extensible cord that will extend to approximately 3 metres length. There is provision for add-on switches to control the bell and also provide call exchange and operator recall conditions when required. An auxiliary gravity micro-switch may also be fitted.
BELL UNIT SA4271
The bell unit base (Part 1/DBA/209) provides a mounting for a Bell No. 79A, a printed wiring board (Part 1/DWI/311), which includes a 1.8 micro-farad capacitor, and an instrument cord anchor block (Part 1/DBL/122), or alternatively a Jack No. 136A. There are two groups of terminals. One has seven terminals, located around the instrument cord anchor block, suitable for terminating cord conductors and internal wiring, the other has three terminals, permanently connected to their equivalents in the seven terminal group, suitable for terminating dropwire. NOT ALL bell units issued will have the three terminals for dropwire connection.
A Dial Automatic No. 21 is secured to the base of the telephone by a two part retaining strap which is tensioned by a clamping screw. The tips of the two parts of the retaining strap are stepped and engage in two slots formed in the base moulding. To remove the dial from the base loosen the clamp screw and move the dial clear of the retaining straps, it is not necessary to disengage the retaining straps from the base moulding. To refit the dial locate it in position on the base. rotate the dial until the finger stop is positioned between the two vertical ribs formed on the base to the right of centre and tighten the clamping screw.
A Printed Circuit Board (Telephone Unit D93240) mounting the telephone circuit components, is mounted below the cradle lever and behind the dial; it is secured to the base moulding by a single fixing screw passing through the printed board. The regulator is an integral part of the telephone circuit and no provision is made for it to be rendered inoperative. A microswitch is mounted on the board and provides the changeover and make gravity switch contact units. Provision is also made for the handset, dial and Instrument cords to be screw terminated on the printed board.
The Cradle Lever is pivoted by knife edges bearing in V shaped sockets, formed in the base moulding, positioned either side of the dial. Coil restoring and retaining springs are attached to the cradle lever adjacent to the knife edges and anchored in the base moulding. A flat surface is formed on the under-side of the cradle lever and presses directly upon the gravity micro-switch operating button. When the hand set is in the 'on-hook' position the button of the gravity micro-switch is pressed fully into the switch housing so that the cradle lever rests upon the top surface of the micro-switch case.
A 'Linesman's Latch' in the form of a small segment with an extended lever is pivoted on a pin formed on the right-hand side of the cradle lever (when the telephone is viewed from the front). To engage the latch the lever should be pulled gently upwards until its movement is arrested by its forward stop. Check that the cradle lever rests on the top of the micro-switch case, the gravity switch will now be in the 'on-hook' position. To release the latch depress the lever fully. If the telephone cover is replaced when the latch is in the ton-hook' position, the cover will depress the lever thus releasing the latch.
The mounting plate has a variety of slots allowing various fixings; it may be by two Round Read screws secured to a conduit box (screws aligned horizontally or vertically), a wood backboard or fixture or a hard wall surface by plugged screw fixing.
It can be secured to a plaster or other soft wall surface by three No. 8 roundhead wood screws. By using the 4BA screws supplied, it can be fitted to an angled adapter (Part 1/DBR/686) which permits edge mounting to a window frame or similar structure. It can also be fitted, using the 4BA screws supplied, to an extension bracket (Part 1/DBR/687) which permits fitting to a skirting board, but positioned above the board, thus avoiding damage from vacuum cleaners or sweeping brushes.
The mounting plate has two slots stamped out of one of its long sides. The bell unit is a slide fit to the mounting plate and is locked in position by the cover overlapping the edge of the mounting plate in which these slots are stamped. For the purpose of explanation this edge is considered to be the bottom edge of the mounting plate and the fixing procedure is as follows:-
Remove the bell unit cover and release the mounting plate.
The mounting plate must be positioned, before fixing, so that there is a minimum gap of approximately 25 mm (1 inch) between the top and side edges of the mounting plate and any angle wall, window frame, or other obstruction. This gap is necessary to permit the bell unit to be engaged with the mounting plate before it is slid into its final position..
Secure the mounting plate to the wall or flat surface with the previously described edge at the bottom. Any of the slots stamped in the mounting plate may be used for the screw fixing.
There are two methods of gaining entry to the bell unit for cables, one for internally run cables the other providing direct access for drop wire cable.
Internal cable is fed into the bell unit through the hole below the instrument cord anchor block fixing screw, viewed with the bell unit gongs uppermost, which will align with the correct slot in the bottom edge of the mounting plate when the bell unit is slid into its final position. The cable is then terminated on the group of seven screw terminals. When the mounting plate is secured to a conduit box the internal cable may be passed through any of the empty slots in the mounting plate, except the two slots with flanges if a Bracket Telephone 1/D93235 is to be fitted.
The bell units that have been specially manufactured for the Jubilee Year Version of the Compact Telephone DO NOT have the three terminals for direct connection of drop-wire. BUT there are existing stocks of earlier manufactured bell units containing these three terminals, and if they are issued and the position for the bell unit in the Customer's premises is suitable for direct connection of drop-wire, the procedure can then be as follows:-
Slide the bell unit on to the mounting plate. Run the drop-wire to the bottom right hand corner of the bell unit and then feed upwards to terminate on the special drop-wire terminals. The drop-wire must NOT be wrapped around the screw terminals but after removal of the insulation be fed direct into the clamp device and secured by screwing down. Check that a firm connection has been made. Ensure that the cable is secured so that it does not obstruct the bell unit cover when it is replaced.
Having run and terminated either internal or external type cable make sure that the bell unit is correctly aligned on the mounting plate, and then replace the bell unit cover.
WALL ADAPTER BRACKETS
Part 1/DBR/686 is an angle bracket allowing the mounting plate to be secured at a right angle to a window sill, etc. Two holes for suitable wood screws are provided in its narrowest side for securing it to the window sill. After securing, the Part 1/DPL/2253 (mounting plate) should be screwed to the widest side of the angle bracket with the two 4BA screws. Any two of the three tapped holes may be used depending upon the position required for the bell unit.
Part 1/DBR/687 is an extension bracket which is secured to a skirting board but has a fixing for the mounting plate that positions the bell unit above the skirting board. The extension bracket is a flat plate with a double right angle formed across the middle. One half of the bracket has three clearance holes for wood screws whilst the other part has three tapped holes for securing the Part 1/DPL/2253 (mounting plate). Secure the extension bracket to the skirting board with suitable wood screws so that the double right angle across the middle of the bracket positions the upper half of the bracket close to the wall. The mounting plate can now be secured to the extension bracket, with the two 4BA screws using either of the three tapped holes, depending upon the position required for the bell unit.
Call Exchange or Recall Switch
Bell On/Off Switch
The switch and dummy should be provided in a similar manner to that described for the Switch 30A-2.
Auxiliary Gravity Switch Micro-switch
When the Switch 19A-1 has been secured and the leads connected to the telephone circuit, check that the leads do not foul the cradle lever and that the gravity micro-switches function correctly.
Bracket Telephone 1/D93235
The Bracket Telephone 1/D93235 consists of three parts, the body moulding (Part 1/DBR/684), a lid (Part 1/DPL/2254) to cover the bell unit and provide a resting surface for the telephone, and a plug (Part 1/DPL/2255) which is used to fill a hole in the body moulding which provides access to a Jack 136A. This jack is only required for Plan 4 arrangements and is described later.
To install the Bracket Telephone 1/D93235 It is not necessary to disconnect the cord from either the telephone or the bell unit during installation in the wall mode. No attempt should be made to teed the telephone cord through the hole in the body moulding; this hole is for the insertion of a plug into the jack on a Plan 4 installation. Secure the mounting plate (Part 1/DPL/2253), which is packed with the Telephone SA4271-1, to the wall or other fixture. The mounting plate may be secured to a conduit box but it should be confirmed that the box is secured firmly enough to support the weight of the telephone, bell unit and telephone bracket. A clearance of at least 130 mm (5 inches) must be allowed above the mounting plate which must always be secured with the surface run cable entry slots at the bottom. The body moulding, with the flat back surface uppermost, should be raised above the mounting plate and slid downwards so that the web formed on the side of the moulding engage with the flanges on the side of the mounting plate and the bottom edges of the body moulding and mounting plate align. The moulding will now be held firmly, except for upwards movement, by the mounting plate.
Inside the body moulding, at the front, two hook projections are formed. adjacent to the edge of the large centre hole, and adjacent to the rear edge of the centre hole a clip is formed. The two hooks and the clip are used to secure the bell unit, minus cover, within the body moulding in a position with the components facing upwards, bell gongs at the front.
Remove the cover from the bell unit, this item is no longer required and should be returned to stock. Remove the screw securing the instrument cord anchor block to the bell unit base. Disengage the anchor block from the bell unit base, slight tilting of the anchor block will ease disengagement. Slide the cord grommet out of engagement with the anchor block and turn it so that the cord conductors emerging from the grommet are pointing upwards. Slide the grommet into re-engagement with the anchor block. Replace the anchor block within the bell unit base and secure with the fixing screw. The instrument cord now feeds downwards from the bell unit.
The plug (Part 1/DPL/2255) which is packed with the body moulding and the lid, should now be fitted into the hole in the right hand side of the body moulding. The plug should be fitted from the inside, with the flange inwards, and should be a close fit into the body.
The bell unit should now be fitted into the body moulding by the following manner. Hold the bell unit, minus cover, in the hand with the components facing upwards, bell gongs at the front. Turn the bell unit so that the edge containing the cord anchor block is at the bottom. Rotate the bell unit by approximately 45 degrees, clockwise or anti-clockwise, and feed it upwards right through the hole in the centre of the body moulding until it is above and clear of the moulding. Turn the bell unit until the components are facing upwards, bell gongs at the front, and gently place the bell unit inside the body moulding. Raise the rear edge of the bell unit and locate the front edge of the bell unit, adjacent to the bell gongs, under the two hooked projections formed in the body moulding. Check that the instrument cord falls clear of obstructions and then press the rear edge of the bell unit downwards until it is held by the body moulding clip.
Surface run internal cables can be fed into the bell unit, via the mounting plate, through the slot adjacent to the anchor block. Where special drop-wire terminals are provided surface run drop-wire or leading-in cable can be fed into the bell unit via a gap between the corner of the bell unit adjacent to the leading-in terminals and the body moulding. Cable running to the bell unit via a conduit box, to which the mounting plate is secured, can be fed into the bell unit via the slot adjacent to the anchor block.
On top of the lid (Part 1/DPL/2254) is a box formation; adjacent to it, on the rear edge, are two projections and on the front curved edge is formed a clip. To fit the lid, first ensure that the bell unit and body moulding are correctly located. Present the lid tilted downwards at an angle of approximately 45 degrees with the clip highest, to the moulding so that the two projections pass through the two slots in the back of the moulding. Press the front of the lid downwards until the clip engages. This secures the lid. The box formed on the top of the lid fits into a recess formed in the base of the telephone. If the telephone is now placed on the Bracket Telephone 1/D93235 it will be secure against accidental displacement.
One portable compact telephone - wired to MS22016 or 22017
Two portable instruments or more - wired to MS22016 or 22017 but all portable instruments must be changed to the Compact type.
If only one Compact telephone is charged on the Advice Note then Sales Division must be contacted to negotiate the additional charge for the extra Compact telephones.
Jack No. 136A
When the Bell unit is to be mounted within the Bracket Telephone 1/D93235 fit the Jack No. 136A to the bell unit before the bell unit is fitted into the bracket.
To allow insertion of the telephone plug, through the body moulding into the jack, the Part 1/DPL/2255 (plug) should be omitted. The recovered anchor block and Part 1/DPL/2255 should be returned to stock.
Plug 420 Grey-5A
The recovered cord should be returned to stock.
Bell unit covers made spare when Bracket Telephone 1/D93235s are used should be returned to Section Stocks for maintenance spares.
Instrument cords recovered when Plug 420 Grey-5A axe used should also be returned to Section Stocks.
Shift and Change
MS 22013 - Connections for Exclusive Service, Shared Service, PBX Extension and details of add-on units.
MS 22015 - Shared Service
MS 22016 - Plan 4 Exclusive Service
MS 22017 - Shared Service
The compact telephone was first introduced in 1977 as a limited edition in the colour
'Balmoral Blue' to mark the occasion of the Queens Silver Jubilee. This version was known
as the Telephone No SA 2/SA 4271-1.
If the case will not clear the dial finger plate, then remove the finger plate and refit later.
Last revised: November 20, 2011