Bell 4a User manual

(

\

•

()

BELL

SYSTEM PRACTICES

AT&TCo

Standard

SECTION 512-700-lOD

Issue

2,

September 1974

4A

SPEAKERPHONE SYSTEM

1. IDENTIFICA

TiON

1.01 The

4A

speakerphone system

is

a hands-free

voice switched system for use as a telephone

adjunct

and

is

a

replacement

for

the

3-type

speakerphone system.

1.02 This section is reissued to add information

on:

• lOSAR loudspeaker

set

• 680AR and 680AR14

transmitters

• 82B connecting block

• Station

busy

lamp circuit

1.03 The

4A

speakerphone

system

consists

of

a

transmitter,

loudspeaker

set,

power

unit,

and either a connecting block

or

adapter

that

when

connected to a suitable telephone set, provides:

o Hands-free telephone operation

• On-hook dialing (when dial

is

not

obstructed)

• Automatic switching from speakerphone to

handset

operation

•Transmitter

muting for private conversation

• Visual indication when system is in use

•

Cutoff

common

ringer

or

other

signaling

devices when desired.

1.04 Components

of

the

4A

speakerphone system

!ire shown in Fig.

2.

1.05 This system may be used with

the

lA,

lAl,

and 1A2 key telephone s '.ems

and

all PBXs.

1.06 For additional schematic ant! circuit information

refer

to

SD-

and CD-69909-01, respectively.

Ordering Guide

1.07 Components which make

up

the

4A

speakerphone

systems

are ordered separately

as

follows:

•Set,

Loudspeaker,

108A-* (includes 7-foot ·

D20N mounting

cord)"

••Set,

Loudspeaker, 108AR-* (includes 7-foot

D20N

mounting

cord)

for

use

when radio

frequency interference is a problem•

•Transmitter,

680A-* (includes 7-foot, DSS

mounting cord)

••Transmitter,

680Al4-* (includes 14-foot,

DSS mounting cord)

•Transmitter,

680AR-* (includes 7-foot, D8S

mounting cord) for use when radio frequency

interference is a problem

• Transmitter, 680AR14-* (includes 14-foot

DSS

mounting cord) for use when radio frequency

interference

is

a problem•

• Unit, Power, 85Bl-49

• Only one required-either Block, Connecting,

82B-49

or

Adapter, 223A-49 (includes 7-foot,

M16C and

25

foot M2FG cords).

Note:

•The

82B (when

it

becomes available)

may

be

substituted

for

the

82A connecting

block.•

•Add color suffix.

1.08 Mounting cords

are

available only in

satin

silver (-

87).

The M2FG cord or

the

223A

adapter

only comes

in

25

foot length.

A 14-foot cord may be ordered for field replacement

for

the loudspeaker

set

or

223A adapter. Example:

Cord, D20N-87,

14

feet

Cord, M16C-87,

14

feet

1974

Printed

in

U.S.A.

Page

l

SECTION 512-700-100

CONN

CABLE

CONNECTOR

CABLE

~~~~

.......

OPTION

PLUG

8581

POWER

UNIT

82-TYPE

CONNECTING

BLOCK

108-TYPE

LOUDSPEAKER SET

680-TYPE

TRANSMITTER

TELEPHONE

SET

(ROTARY OR"TOUCH-TONe:"

DIAL)

A.

CONNECTIONS

USING

82-TYPE

CONNECTING BLOCK

MOUNTING

CORD

D20N

MTG

CORO

108-TYPE

LOUDSPEAKER SET

NOTE:

680-TYPE

TRANSMITTER

8.

CONNECTIONS USING

2Z3A

ADAPTER

WHEN

Ml6C

CORD

IS

TERMINATED

IN

SET,

DISCONNECT, INSULATE, AND STORE

ALL

SPEAKERPHONE LEADS IN MOUNTING

CORD

AT SET.

Fig.

1-Typical

Arrangements

of

4A

Speakerphone

System

Page

2

0

()

)

(_

0

()

108-TYPE

LOUDSPEAKER SET

\

8581

82-TYPE

CONNECTING BLOCK

,.-,/'

p

ISS

2,

SECTION 512-700-

H.1:1

(3)

When

speech

is

transmitted,

the

gain

of

the

transmitter

circuit increases to normal.

Simultaneously, the gain of the loudspeaker circuit

lowers

to

avoid

singing

as

a

result

of

the

increased

transmitter

gain. The

amount

of

the

k:'.

gain

change

depends

upon

the

setting

of

the

volume control.

POWER

Ut<IT

71~

Fig.

2-Components

of

4A

Speakerphone System

1.09 The

transmitter

and loudspeaker

set

will be

shipped

in

four promoted colors: Black

(-03),

Green

(-51),

White

(-58),

and

Light

Beige

(-60).

The following kits may be ordered if a color change

is desired.

Each

kit

contains all

necessary

color

,ignificant

parts

to

convert

both

the

loudspeaker

and transmitter.

Kit

of

Ports Color

D-180507 Black

D-180508 Ivory

D-180509 Moss Green

D-180510 Red

D-180511 Yellow

D-180512 White

D-180513 Lt. Beige

D-180514 Lt. Gray

D-180515 Aqua Blue

1.10 4A speakerphone circuitry:

(1)

The

4A

speakerphone

incorporates

a

voice-switching circuit, eliminates singing,

and essentially eliminates far-end

talker

echo.

_q

(2)

When

there

is no

transmission

of

speech,

gain

is

automatically

removed

from

the

transmitter

circuit and added to

the

loudspeaker

circuit. This avoids a

singing

condition while

receiving.

(4)

A circuit, referred to as a switchguard utilizes

the

voltage

in

the

loudspeaker

circuit

to

reduce

the

possibility

that

surrounding

room

noise will cause false operation of

the

switching

circuit while receiving speech.

(5)

A predetermined voice level is necessary to

switch from

the

receiving to

the

transmitting

condition.

In

the presence

of

steady

room noise,

a special circuit automatically raises the required

threshold

level

to

prevent

operation

of

the

switching control circuit by

the

noise. Talkers

will still switch satisfactorily because they increaEe

their levels

under

noisy conditions.

Radio Frequency Interference (RFI)

1.11

•In

areas

where

RFI

is a problem, install a

680AR or 680AR14

transmitter

and a 108AR

loudspeaker set. These components are the same

as

the

680A

and

680A14

transmitter

and

108A

loudspeaker

set

respectively

with

the

exception

that

circuit components

necessary

to reduce

RFI

have been added

.•

680A

•680A

14, 680AR, or 680AR1

~

Transmitter

1.12 The

transmitter

is a small

unit

incorporating

the

microphone,

preamplifier,

an

indicator

lamp, and the operating controls for the speakerphone.

The controls include

the

ON OR QUIET

button,

the

OFF

button,

and

the

volume

control.

The

control

button

and

a

stationary

button

comprise

the

color significant portions

of

the

transmitter.

The ON OR QUIET

button

activates

the

system

and,

if

held depressed,_ilisables

the

microphone

.l?_O

that

the

spea~erohone

user

may conduct a private__

cOnVersation

without

the

party

at

the

far

end

hearing:., The

OFF

button

simply

turns

off

the

system.

The volume

control

varies

the

received

sound level. The indicator lamp lights when

the

system

is

on.

Page

3

SECTION

512-700-100

108A

•or

108AR.

Loudspeaker

Set

1.13 The loudspeaker

set

contains

the

electronic

circuitry,

the

loudspeaker,

and

the

relay

and

transformer

necessary to couple to the telephone

system.

The electronics,

loudspeaker,

and

cord

comprise

the

non-color-significant subassembly, and

a color

significant

plastic

housing

completes

the

set.

Fig.

3-108A

loudspeaker

Set

with

Cover

Removed

82-Type

Connecting

Block

1.14

The

82-type

connecting

block

is

used

to

interconnect

the

4A

speakerphone

system

(680-type

transmitter,

108-type

loudspeaker

set,

and

the

85Bl

power unit}

for

use with plug-ended

6-button key telephone sets. A reversible option

plug provides

the

key

system

options,

ringer

cutoff

or

operation

of

an auxiliary relay.

~

ft:;:"

block includes

tbru

~ip

.;oDHw::to~.

one

for

the

telephone

set,

one

for

the

key

system

connector

cable,

and

one

that

accepts

the

transmitter

and

loudspeaker

set

connectors

with

the

reversible

option plug. The arrow on

the

plug

of

the

D20N

mounting cord should point to the option required

on the option plug. There are seven screw terminals

(82A)

or

eleven

screw

terminals

(82B)

for

AC

power connections and

lAl,

1A2,

or

IA

key system

operation (Fig.

6).

TELEPHONE

SET

MOUNTiNG

CORD

·

..

·.;

..

r..:.::,~.

·.

.

.·.

f,

"'"""'""

.,·::::-~

.......

""

.

';''·

'

,.,......._.

.,

D8S-87

~

MOUNTING

"'<.~

CORD

'\~

Fig.

4--82-Type

Connecting Block

with

Cover

Removed

223A

Adapter

1.16

The

223A

adapter

interconnects

the

4A

speakerphone

system

(680-type transmitter,

the 108-type loudspeaker set, and

the

85Bl

power

unit) when the 82-type connecting block cannot be

used. The

adapter

consists

of

a

M16C

cord (having

a 50-pin

connector

on one

end

and

spade-tipped

leads on

the

other

end),

the

M2FG cord, (for 85Bl

power unit) and the plastic cover and base (Fig.

5).

The M16C spade-tipped leads

are

to be connected

to a connecting block

or

within

the

telephone

set

(Fig.

5).

DBS

MTG

CORD

<--------·----

..........

1.15

tThe

82B is

the

same as

the

82A

connecting'·"-,,,,

block

with

the

exception

that

access

to

• Fig.

5-223A

Adapter

terminals

10

and

35 from

the

speakerphone

plug

\

and

terminals

21

and

46

from

the

telephone

set

)1

and line receptacle

are

made available

by

means

..

of

screw-type terminals (Fig. 6)..

,,/

___.../

......

~---~

Page

4

(~)

()

\

_./

c:

(

__

I

0

()

8581 Power Unit

1.17

The

power

unit

transforms

the

local

customer-provided 115 volt,

60

Hz power to

the

voltage

level

required

to

operate

the

4A

speakerphone

system.

An

85Bl

power

unit

(UL?/'

approved) can be used tQ._£owe@Iy

o~~

speakerphone-

system.

The

85Bl

power

unit

should be located

less

than

125

feet

from

the

108-type loudspeaker

set

when using

24

gauge

wire.

1.18 A retaining clamp (841050818) will be shipped

with

the

85Bl

power

unit

and

should

be

mounted to the

AC

receptacle to hold power unit

securely and to

prevent

accidental loss

of

power.

2. INSTALLATION

2.01 The

telephone

set

intended

for

use

in 4A

speakerphone system

must

meet the following

requirements:

(1) Provide a

set

of

line switch

transfer

contacts

to

disconnect

the

speakerphone

when

the

handset

is lifted.

(2)

Rotary

dial

sets

dialed

in

an

on-hook condition

must

provide two

sets

of off-normal (make)

contacts

in

the dial for loudspeaker and receiver

muting during dialing.

(3)

TOUCH-TONE®

sets

dialed in

the

on-hook

ISS

2,

SECT'ION

512-700-

l 00

• Shorting

the

receiver input to loudspeaker

set, disabling

the

loudspeaker

through

the

P3 and P4 leads.

2.02 Planning an installation:

(1)

Avoid placing

apparatus

with plastic covers

or parts

in

location where ambient temperatures

may exceed

140

degrees F.

(2)

Plug

the

85Bl

power unit into an

AC

power

outlet

(not

under

control

of

a switch) and

lock

in

place with retaining clamp furnished.

(3)

The 85Bl power unit should be located less

than

125

feet

from 108-type loudspeaker

set

when using

24

gauge

wire.

(4)

Place loudspeaker

set

and

transmitter

within

convenient reach

of

user

and a minimum

of

one foot apart.

(5)

Transmitter

must

be

at

least

two

feet

from

transformer

or any AC powered device.

(6)

There

should

be

no

obstructions

between

the

user, loudspeaker set, and transmitter.

(7)

Make connections

as

shown in appropriate

figures

of

this section

or

other

sections in

Division

512

for specific telephone

set

connections.

/8)

•If

82-type connecting block

is

used, install

condition

must

provide a

set

of

make contacts

(s and t) in

the

dial common switch to connect

line power (IR) from

the

loudspeaker

set

to

the

dial oscillator.

If

a polarity

guard

is provided

these

contacts

(s

and

t)

must

be isolated from

the

oscillator by the polarity guard.

/

audible

signal

cutoff

using

the

"RING

/ CUTOFF"

or

"AUX RELAY" option as needed.

(4)

Certain wiring precautions

must

be observed

when multipling

sets

wired for speakerphone.

The

Tl,

Rl,

IR

or

P4,

IT

or

P3,

LK

and

AG

leads should be disconnected

at

or

as

close

as

possible to

the

set

in those stations

not

having

speakerphone. Even

though

none

of

the

multipled

sets

have speakerphone

the

leads involved should

be disconnected.

Failure

to

do

so will

result

m:

• Tip and

ring

cross

through

the

Tl

and

Rl

leads

•

False

operation

of

an

A relay

through

the

AG lead

/

Use

the

leads

to

common

signal

control

and

' common

or

buzzer circuit for this

cutoff

feature

(Fig.

7).

-

{9)

•For

station

busy

lamp

circuit

with

4A

speakerphone system,

refer

to

the appropriate

Service section in Division 502 for telephone

set

involved

.•

3. OPERATION

Note:

4A

speakerphone

system

permits

normal use of

the

telephone

set

for originating,

receiving,

or

transferring

calls.

3.01 To originate a call using speakerphone:

(1)

Depress

transmitter

ON OR QUIET button

and release.

ON

lamp will light indicating

Page 5

..

r~·.,

/

'

I

SECTION S12-700-100

speakerphone

is

in the talking condition. Listen

for

dial

tone

transmitted

through

loudspeaker

set.

Telephone

handset

is

not

lifted

during

dialing (except where handset covers dial)

[3.01

(3)].

(2)

Operate

dial

of

telephone

set

in

normal

manner.

(3)

When originating calls from telephone

sets

which

require

off-hook dialing, dial in

the

normal manner,

then

depress and hold

the

ON

OR QUIET button until

the

handset

is

restored.

(4)

When

complete

number

is dialed,

ringing

tones,

busy

signals

or

called

party

answer

will be

heard

from

the

loudspeaker set.

(5)

When called

party

answers,

transmitter

and

loudspeaker

set

are

used

to

carry

on

a

hands-free

conversation.

Adjust

volume level

as

desired.

Note:

Best

operational

results

are

obtained

at

the

lowest acceptable volume setting.

3.02

To

answer an incoming call using speakerphone:

(1)

Telephone

set

ringer

signals

an

incoming

call.

(2)

Depress

ON

OR QUIET button on transmitter.

Ringing

is

tripped and system

is

automatically

connected to the line by

the

loudspeaker

::;et.

p;

To

disable

tr~nsmitter

':he~

it

ia

desired

' ' /

not

to

transmit

conversation m

the

room to

1

a

distant

party:

I

.

(1)

Depress

ON

OR QUIET button to full

extent

!

of

its

travel

and

hold down

during

entire

ime

transmitter

is to be disabled.

Note:

With

transmitter

disabled conversation

will

not

be

transmitted

to the

distant

party,

however,

distant

party

can still be

heard

over

the

loudspeaker.

~·=

""'

-~

(2)

After

private conversation

is

completed and

it

is

desired

to

transmit

to

distant

party

again, release ON OR QUIET button. System

is now restored to full hands-free capability.

3.04 To terminate a call on speakerphone, depress

OFF

button

on

transmitter.

ON

lamp will

Page

6

extinguish and speakerphone system will be restored

to

the

OFF

condition.

3.05

Transferring

from

handset

to speakerphone

operation:

(1)

After dialing

or

during a conversation depress

and hold

ON

OR QUIET button

of

transmitter.

(2)

Return

handset

to

mounting,

and

release

ON

OR QUIET button.

(3)

Adjust volume

as

required.

3.06

Transferring

from speakerphone to

handset

operation. Lift

handset

during speakerphone

operation

to

automatically

transfer

to

handset

operation. When

it

is necessary to

transfer

back

to speakerphone,

refer

to 3.05 to

prevent

disconnect.

4. MAINTENANCE

Remove

power

from 1()8.type

loudspeaker

set

before

attempting

any

maintenance

of

speakerphone

components.

Tests

and

Adjustments

4.01 When

system

is

installed or maintenance is

performed

on

any

component,

make

the

following

tests

of

speakerphone operation:

(1)

Place a speakerphone call to

the

testdesk.

(2)

Adjust

loudspeaker

volume

to

moderately

loud listening level.

(3)

Have

test

center

repeat

the

question

"In

what

suburb

does

Joe

live?" several times.

(4)

If

choppiness is

detected

in

the

sentence,

particularly

in

the

first

b in

suburb

and

the

t in

what,

increase

the

distance

between

the

transmitter

and

loudspeaker set.

(5)

Repeat this

test

at

a high listening level by

turning

the

volume

control

to

maximum

volume.

()

0

r~

_,J

'•

....

_..,,.-1'

)

(

4.02

If

voice-switching caused by external telepho e

audible signaling devices is encountered:

(1)

Place

audible

signaling

devices

away

from

transmitter

unit,

if

possible.

(2)

Lower

volume

of

audible

signaling

devices

to

level

that

will

not

cause voice-switching

feature

to

operate.

(3)

Install audible signal

cutoff

using

the

"RING

CUTOFF"

or

"AUX

RELAY"

option

as

needed. Use

the

leads to common signal control

and

common

ringer

or

buzzer

circuit

for

this

cutoff

feature

(Fig.

7).

4.03

If

speakerphone

fails

to

operate

properly,

refer

to Table A

for

trouble analysis.

Cleaning

4.04 Clean plastic covers and housings with

water

dampened KS-2423 cloth

or

equivalent. Do

not

use

scouring powders

or

cleaners.

Removal

of

Plastic

Parts

()

Do

not

attempt

any

changes

or

repairs

0

()

to

either

the

680-type

transmitter

or

108-type

loudspeaker

set

other

than

to

replace

the

loudspeaker

set

mounting

cord

or

the

respective

plastic

parts

for

either

the

transmitter

or

loudspeaker

set.

4.05 The plastic housing on the 108-type loudspeaker

set

is held in place by two

screws

located

ISS

2, SECTION 512-700-100

on

the

bottom

of

the

set.

To remove

the

plastic

housing, remove the two

screws

from

the

bottom

of

the

set

and

slide

the

cover

off

the

chassis

(Fig.

3).

Note:

Do

not

remove

the

circuit

board

from

the

chassis.

4.06 The plastic covers on the 680-type

transmitter

snap into place.

First,

remove the

stationary

cover by squeezing with

fingers

on the

front

and

back

surface

and

lifting

gently.

Second,

pry

up

the

rocker

cover

with

fingers,

lifting

along

the

edge

adjacent

to

the

thumb

wheel.

The

loudspeaker

and

transmitter

are

designed

so

that

color

significant

components

can

be

easily

changed.

In

order

to

reduce

shelf

faventory

it

is

suggested

that

the

kits

listed

in

1.09

be

stocked

instead

of

extra

loudspeakers

and

transmitters.

Change

of

Loudspeaker

Set

Cord

4.07

First

remove

housing

as

in 4.05.

Next,

loosen

the

screws

that

hold

the

spade tips,

and

remove

the

spade

tips.

the

screw

that

fastens

the

stay

band

of

the

cord. Slide

the

spade

tips

and

wafers

out

the

hole

in

the

bottom

of

the

plastic chassis. To install

the

new

cord,

reverse

the procedures.

Note:

Be

careful

not

to

damage

the circuit

board,

particularly

the

flexible

areas

of

the

bends.

Page

7

SECTION 512-700-100

TABLE

A

4A

SPEAKERPHONE SYSTEM TROUBLE

ANALYSIS

TROUBLE

INDICATION

PROBABLE

CAUSE

CHECK

Speakerphone

inoperative;

indicator

No

power,

or

open

wiring

Power

supply

outlet

with

a

lainp

does

not

light

neon

lamp

voltage

tester

or

()

equivalent,

or

check

LK

lead

for

open

Lamp

does

not

light

but

K-relay

Loose

connection

in

local

Switchhook

contacts

or

Al

I

(108-type

loudspeaker

set)

wiring

and

LK

leads

for

open

operates

and

releases

when

ON

OR

QUIET

button

is released

Rotary

dial pulses

heard

over

loud-

Dial wiring

For

proper

dial P3

and

P4

speaker

leads

No dial

tone

heard

when

speaker-

Open

wiring

Rl

and

Tl

leads

from

tele-

phone

is

ON,

but

can

be

heard

phone

set

in

handset

l

No

dial

tone

heard

on

speaker-

Open

wiring

Tip

or

ring

from

line

phone

or

handset

Dial

tone

cannot

be

broken

with

Incorrect

wiring

Connection

of

tip

and

ring

dial

when

on

speakerphone

from

telephone

line

to

tele-

phone

set

TOUCH-TONE

dial

inoperative

Dial wiring

For

proper

IT

and

IR

leads

when

speakerphone

is

ON

I Noise

on

speech

transmission

Electro-magnetic

Position

transmitter

on

I

associated

with

fluorescent

pickup

different

area

of

desk,

lamp

operation

table

etc.

to

reduce

noise.

Noise

on

speech

transmission

High level

radio

Install

AR

coded

loudspeaker

associated

with

radio

frequency

AM, FM,

and

transmitter

interference

etc.

in

immediate

area

)

Page

8

(

"'.-'

{

"

l

..

)

()

0

2 ,

' * *

2.4

10

35

49

0 0

/)

0

19

,

44 ,

'

20 '

21

'

CONN

45

,

CABLE

46

TO

,

'

KEY

22 ,

'

EQPT

47

23

~

48

~

24

49

,

'

25 /

'

50 ,

' /

34

r

36 (

33 '

10

~

32 <

37

~

TO

38

~

OPT!

ON

7 /

PLUG

'

9 (

8 ,

....

II

(

13

(

DBS

12

<

680-TYPE

MTG

CORD

35

f--•

TR

MTR

3

LK

(0-W) , I (

VOL

5

(W-BR)

, 2 (

'

-6.2

8

+6.2

7

(BL-W)

,

' 3 '

(W-BL)

,

' 4 '

+V

9

(BR-W)

,

'

26

'

TVL

6

(G-W)

,

27

~

GND

4

(W-G)

<28

~

ON

20--

(W-0) '

29

~

7

>--------<

32

8 33

9)--

--{34

10)--

--{35

:~~

J

dH

OPTION

PLUG

ISS

2,

SECTION

512-700-100

21

* *

(SEE

NOTE

2)

STRAP

21

19

46

"-'

Al

~

? 0

-

D2.0N

MTG

CORD

~47

(w-o)

(W-G)

L-----7 46

:::

, 48 '

(G-W)

(W-BL)

; 45 ;

(BL-W)

~

49

'

(W-BR)

:::

50 ; (R-BL)

' 22

,,

,

(W-S)

' 23

,,

/

(BR-W)

'

21

;,

(Bl-R)

'

19

'

' (S-W)

, 20 , (R·G)

AC

0 )

24

; (G-R)

AC

0 ) 25 '

(o-w)

'

18,,

(BR-R)

'

17;

, (R·BR)

'

,,

16

(R-0)

' 44 '

,

' (R-S)

,

43

; (S-R)

' 42 ;

, (0-R)

'

41

;,

NOTES:

I.

ONLY

LEADS

INVOLVED

IN

SPEAKERPHONE

ARE

SHOWN.

2.

METAL

5TRAP

FACTORY

WIRED

FOR

IAl/IA2,

(Al-2).

MOVE

TO

TERMINAL

19

FOR

IA

KTS,

(AJ-19),

ONLY

WHEN

PROVIDING

BUSY

LAMP

OPTION.

*

THESE

FOUR

TERMINALS

APPEAR

ON

THE

82B

CONNECTING

BLOCK.

2

'

19

,

'

44

'

20

'

21

' 45

MTG

,

' 46

CORD

TO

' 22

TELS

ET

' 47

' 23

' 48

24

' 49

'

25

' 50

108 -

TYPE

LSPK

SET

AG

P3-IT

P4-IR

Tl

RI

Al

B-Bl-KSB

B-81-KSC

BL-K5M

20

R-Rl-K48

R-Rl-K4C

~

AC

VOL

-6.2

+6.2

+v

TVL

GND

ON

' '

2.7

20

I

~K4M

.(/\ 2

3

.(/)

4

21

Fig.

6--Speakerphone

Connections using 82-Type Connecting Block

Page

9

Bell 4A User manual

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