The fitting work required in connection with this telephone centres
mainly upon the siting and fixing of the Bell Unit. The following guide
notes concerning its installation should be read thoroughly before any
cabling work is undertaken; including the entry of dropwiring to the
Two methods of installation are shown in Figs 1 & 2.
FITTING BELL UNIT SA 4271
The bell unit is made up of three parts, Cover, Base Unit and Mounting
PREPARATION FOR FIXING
Remove the cover by inserting the blade of a small screwdriver through the
sound hole (see Fig. 3 above), gently press against the sprung lug, then
lift off the cover.
With the cover removed the mounting plate can be slid out of the base
unit, ready for fixing into position.
POSITIONING THE MOUNTING PLATE
The mounting plate can be fixed to a flat surface in any one of 3 positions.
The correct position will depend upon:-
1. The entry point of the internal cable or drop wire
2. Whether the bell unit is to be mounted Horizontally or Vertically. (See
Fig. 4 below).
THE BASE UNIT AND COVER MUST NEVER BE FIXED DIRECTLY ONTO A SURFACE
WITHOUT THE MOUNTING PLATE.
FIXING THE MOUNTING PLATE
The mounting plate should be fixed into position using the slots in its bad
plate. The use of slots instead of holes enables the mounting plate to be
accurately levelled before the fixing screws are finally tightened, 2BA or
48A bolts should be used for fixing to conduit outlets, and number 8
roundhead woodscrews for other types of surfaces.
An extension bracket, also an angled adaptor are available for fitting
the bell unit above skirting boards and to wooden window frames without the
need to resort to wall plugging. See Figures 5-8.
Before fixing into position ensure that there is a clearance of about
25mm (1") surrounding the mounting plate so that the base unit and cover can
be fixed to it.
CABLING AND FITTING THE BELL UNIT BASE TO THE MOUNTING PLATE
Fig. 9 shows the cable entry points to the Mounting Plate and Bell Unit
base. To serve as an example these guide notes on cabling refer to a Bell
Unit being fitted horizontally.
- Run the cable to the appropriate entry point in the Mounting Plate.
- Feed the cable through the appropriate entry point in the base unit.
- Being careful not to trap the cable, engage the lugs on the back of
the base unit into the slots on the sides of the mounting plate. To
engage the lugs, the base unit should be positioned approx. 15mm (/8"
in.) above the bottom of the mounting plate.
- Pressing the base unit backwards and downwards, slide it into
position on the mounting plate.
Dropwire should be terminated on the right hand compression type terminal
block, and internal cables on the left hand one.
After termination, the cover can be replaced by pushing it over the base
unit, until it snaps firmly into place. The Bell Unit is now anchored firmly
to the mounting plate.
Wall Mounting The Telephone and Bell Unit Using a Brackets Telephone
The Brackets Telephone is in 3 parts (Fig.10) and when fitted to the
Mounting Plate issued with the Bell Unit, it will house the bell unit base
and form a shelf upon which the telephone will stand. Figs 11-15 illustrate
the steps and the order in which they should be undertaken, when fitting the
First, remove the cover from the Bell Unit and discard. then
slide the mounting plate out of the base unit.
Fix the Mounting Plate firmly to a flat surface or conduit
outlet, in a HORIZONTAL position and at the desired height (ask customer). A
clearance of 125mm (5") will be required above the top edge of the plate so
that the telephone can stand on the shelf. If fitting to a conduit outlet,
feed the cable through the slot indicated.
Remove the shelf from the Brackets Telephone by pressing it upwards at
the front edge.
Feeding internal cable through the right hand entry, or dropwire through
the left, slide the bracket down onto the lugs of the Mounting Plate, being
careful not to trap the cable. The bracket is 'fully home' when the bottom
edge of both mounting plate and bracket are 'flush'.
Remove the cord anchor block fixing screw and slide the
block out of Bell Unit base by pulling on the cord grommet. Re-position the
cord grommet as illustrated, then replace the anchor block and fixing screw.
Be careful not to trap the cord conductors when tightening the screw.
The cord should now be entering the underside of the Bell Unit's base.
Feed the Bell Unit upwards through the Brackets Telephone. With the bell
gongs uppermost and towards you, engage the base of the Bell Unit under the
lugs on the front edge of the bracket, then push it downwards at the back
and it will snap into position.
Terminate the cable to the Bell Unit. Internal cables on the right hand
terminal block, dropwire on the left.
Refit the shelf, by engaging the lugs into the slots in the bracket, push
it down at the front and snap into position.
The bracket is now locked securely to the mounting plate.
To remove the bracket from the mounting plate, remove the shelf and slide
the bracket upwards.
Exclusive Service Working
The telephone 2/SA 427 1-1 is supplied strapped and with cords terminated
for Exclusive Service working. Installation consists of fitting the Bell
Unit and terminating the line to it. Because a commemorative motif is to be
fitted in the dial centre, the telephone number label will be fitted to the
carrying handle under the handset, using a transparent plastic clip (Fig.
Shared Service Working
The Telephone 2/SA 4271-1 is modified for shared service working by adding a
Thermistor lA/1 to the Bell Unit and a Switch 30A-2 to the telephone. The
switch should be fitted to the right hand front edge of the telephone (Fig.
17). Packed with the switch, is Dummy Switch (Part 1/DLE/85) which should be
fitted to the left hand front edge, so as to give the telephone a balanced
To fit the switches, remove the telephone cover by slackening the screw in
the telephone base (Fig. 18). The cover is then lifted clear of the base in
two operations, (1) using both hands, place the thumbs in the dial centre,
with fingers holding sides of cover. (2) keeping thumbs in position pull
cover towards you, and off. To replace, pass the slots in the cover over the
receiver rests, and then hinge it forward over the dial. Finally, snap the
front edge lugs into position, and tighten the retaining screw in the base.
'CALL EXCHANGE' switches (Switch No. 30A-2)should be fitted to the right
hand front edge of the telephones and 'Bell ON/OFF' (Switch No. 30B-2)
switches should be fitted on the left, at extensions.
If only one additional switch is installed then a dummy switch (Part 1/DLE/85)is
fitted on the opposite side.
A switch 19A-1 can be bolted to the side of the existing gravity switch as
shown in Fig. 20.
For old style Plan 4 arrangements a Jack 136A can be fitted in the Bell
Handset - Handset No. 15A
Handset Cord - Cord Inst 4/123AX Grey 200mm
Instrument Cord - Cord Inst 6/63AX Grey 700mm
Dial - Dial Auto 21 FA Clear
Transmitter - Transmitter Inset 16
Receiver - Receiver Inset 4T
Feet - Part 2/DBU/259
Call Exch/Recall Switch and Dummy - Switch 30A-2
Bell On/Off Switch and Dummy - Switch 30B-2
Telephone and Bell Unit - Telephone 2/SA 4271-1
Telephone - Telephone SA 4271
Bell Unit - Bell Unit SA4271
Dismantling and Re-assembling the Telephone 2/SA4271-1
To remove the telephone cover by slackening the screw in the telephone base
(Fig. 18). The cover is then lifted clear of the base in two operations, (1)
using both hands, place the thumbs in the dial centre, with fingers holding
sides of cover. (2) keeping thumbs in position pull cover towards you, and
off. To replace, pass the slots in the cover over the receiver rests, and
then hinge it forward over the dial. Finally, snap the front edge lugs into
position, and tighten the retaining screw in the base.
The hand set is constructed from two separate mouldings held together by a
screw at the receiver end.
Remove this screw and pull the handset apart, some force may be needed but
do not prise apart with a screwdriver.
To remove the transmitter and receiver, push down on the black plastic
spring clips and slide outwards, they are now free to take out, (see Fig.
The dial is removed by slackening the clamping screw (Fig. 25) and then
gently pulling the dial forward. It is not necessary to completely remove
the clamping screw.
When replacing the dial ensure that the finger stop is positioned between
the locating ribs before tightening the clamping screw (Fig. 25).
Make sure that the special motif is replaced correctly.
Add On Units
SWITCHES (Cover removed)
To remove the switches and dummies, position a number 2 screwdriver between
the projection on the rear of the switch and the sprung lug on the telephone
base. Twist the screwdriver, and at the same time apply pressure to the
switch lever in an operating direction (Fig 26). The switch then comes away
from the body of the telephone.
NOTE: CARE MUST BE TAKEN WHILST CARRYING OUT THE ABOVE INSTRUCTIONS,
OTHERWISE A HAND INJURY CAN OCCUR.
This is pivoted on a pin on the right hand side of the cradle lever (when
telephone viewed from the front). To engage, it should be pulled gently
upwards until its movement is stopped. The cradle lever should now rest on
the top of the micro-switch case, this will cause the gravity switch to be
in the 'on hook' position, (see Fig 27).
The latch is self releasing when the telephone cover is
replaced, or can be restored manually.
GPO Jubilee Year Telephone Guide Notes April 1977