Gould J3b User manual

'

L.F.

SIGNAL

GENERATOR

J3B

Instruction

M a

nua

I

•}

GOULD

ADVANCE

Roebuck Road, Hainault,

Essex

..

Telephone: 01-500 1000

Telex: 263785

Telegrams: Altenuate Iiford.

FOR

SERVICE

MANUALS

CONTACT:

MAUR!TRON

TECHNICAL

SERVICEf

www

.mauritron.co.uk

TEl.

01844

·

351694

FAX: 0i

844

-

352554

Contents

SECTION

INTRODUCTION

SECTION 2

SPECIFICATION

3

SECTION 3

OPERATION

4

3.1

Switching On 4

3.2 Block Diagram 4

3.3 Selection

of

Frequency 5

3.4 Balanced

Output.

15-0-15v

rms

emf.

5

3.5

Low-Z

Output

3V

rms

emf.

Zo

""

10hm

6

3.6

Low Distortion Output 2.5V

rms

emf.

Zo~5K

Ohm

6

3.7 Square

Output

0

to

+SV Z

Zo<>1K!J

6

3.8

Output

Level

Meter

& Decibel

Scale

6

3.9 Relative Phase 6

SECTION 4

CIRCUIT

DESCRIPTION

7

4.1 Wien Bridge Oscillator 7

4.2

Power

Amplifier

7

4.3

Power Outputs 8

4.4

Square Wave

Output

8

4.5

Power

Supply 8

4.6

Meter

Circuit

9

4.7

Mains

Input

9

4.8

External D.C.

Supply

9

SECTION 5

MAINTENANCE

10

5.1 Removal

of

Covers 10

5.2 Removal

of

Oscillator Box

Cover 10

5.3 Removal

of

Printed Circuit

Board

Assemblies

10

5.4 Setting up

of

Wien Bridge FOR SERVICE MANUALS

Oscillator 10

5.5 Setting up

of

Power Supply

11

CONTACT:

5.6

Setting

up

the

Power

Amplifier

11

MAURITRON

TECHNICAL

SERVICES

5.7

Setting

up Squarer

11

5.8 Distortion 11·12

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.mauritron.co.uk

TEL:

01844-351694

SECTION 6

COMPONENTS

LISTS

and FAX:

01844-352554

ILLUSTRATIONS

13·18

SECTION 7

GUARANTEE

AND

SERVICE

FACILITIES

22

ILLUSTRATIONS

Fig.1 Power

Supply

Tappings, links,

and Fuse ratings 4

Fig.2 Block Diagram 4

Fig.3

Graph

of

Distortion

and

Frequency

12

Fig.4

Component

Location Diagram 19

Fig.5

Circuit

Diagram

21

'

2

Introduction

The

Gould

Advance

J

38

Signal Generator

is

an

LF

instrument

mcorporating

a high

output

level

from

a balanced, floating

600

n

output.

The

main

output,

which

is

metered,

gives

15V

into

SOC

n

(30V

EMF).

The frequency range

of

10Hz

to 1OOkHz

is

provided

on

four

decade

ranges, and

the

6: 1

reduction

drive

with

capacitor

tuning

gives high resolution

of

frequency

with

minimum

bounce.

Three

additional

outputs

are available, a

lW

low impedance

output,

a

square

wave

output

and

a

low

distortion

output.

The

solid

state

circuitry

results in low

heat

dissipation,

giving a

high

order

of

frequency

stability

and

reliability.

Switched

step

attenuators

give 60dB

of

attenuation

and

the

variable level

control

can

be used

to

provide a

further

20dB

of

attenuation

with

negligible

hum

and

noise on

the

output.

'

Section1

FOR

SERVICE

MANUALS

CONTACT:

MAURITRON

TECHNICAL

SERVICEf

www

.mauritron.co.uk

TEL:

01844-

351694

FAX:

01844-

352554

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FOR

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CONT/,CT:

MAURITAON

TECHNICAL

SERVICE/:

www

.mauritron.co.u\;;.

TEL: 01844 · .':\51694

FAX:

01844

·

352554

21

F1g.

5

Circuit

Otagram

Specification

FREQUENCY

Range:

10Hz

to

100kHz

in 4

decade

ranges.

Common

320°

circular

scale

for

all

ranges.Scale:

Setability:

To

1

part

in

10

4

Accuracy:

2%

of

reading

+

1HZ

Typically

1%

+1

HL

OUTPUTS

1)

MAIN

OUTPUT

30V

r.m.s.,

e.m.f.

(15-0-15V)

from

balanced floating

output

of

impedance

300-0-300

Ohms

(15V

r.m.s.

into

600

~!load).

Output

Impedance

tolerance:

5%-

Balance 3%

Balanced

Attenuator:

20dB and 40dB (60dB

total).

Accuracy:

0.3dB

and

0.5dB

respectively,

each

half.

Fine level

control,

from

0

to

full

output

(Common

to

Outputs

1,2 and 3).

2)

LOW

IMPEDANCE

OUTPUT

3)

41

3V

r.m.s.,

e.m.f.

from

approximately

1

Ohm.

With

Output

1

fully

loaded,

Output

2

will

deliver

a

typically

of

1

Watt

into

5

Ohms.

LOW

DISTORTION

OUTPUT

(at rear

of

instrument).

typically

2.5V

r.m.s.

from

approxir:1ately

5k

~!.

Overall flatness

0.3

dB.

SQUARE

WAVE,

0

to

+5V,

independently

controlled.

Source

Impedance

approximately

lk~!.

Rise

and

Fall

times

better

than

1>-<s

into

less

than

lOOp F. Mark-

space

ratio

better

than

1.1:

1.

NOTE:

Section

2 3

OUTPUT

LEVEL

METER

Scaled

0-30V

r.m.s.

Open

Circuit

for

Output

1.

Scale

also

common

to

Output

2.

Decibel

scale,

referred

to

+20dBm

into

600

il

The

meter

accuracy

is

3%

ofF

.S.D.

DISTORTION

1I

2)

Outputs

1

&2:

less

than

0.1%

above

100Hz

rising

to

less

than

0.5%

at

1OHz.

Typically

better

than

0.05%

from

200Hz

to

100kHz

Low

Distortion

Output:

Typically

better

than

0.02%

above

200Hz

rising

to

0.2%

at

10Hz.

PROTECTION

All

outputs

rated

for

full

load

simultaneously

All

outputs

Short-Circuit

proof.

Visible

indication

of

overload

on

Output

Level

Meter

(Intermittent

reading).

SUPPLY

VOLTAGE

85-130V

and

170-255V

40-400Hz,

approximately

20VA.

Also

42-52V

.

DC/300mA

Max.

OPERATING

TEMPERATURE

RANGE:

DIMENSIONS

27 x 27 x 13 ems 110.7 x 10.7 x 7.2 in.)

WEIGHT

6kg (131bs.)

All

outPut

levels

are

flat

within

ldB

over

the

full

frequency

range.

Below

30Hz

the

maximum

output

level

may

not

be

available

on

full

lead,

on

outputs

1 & 2

(typically

20V

available

at

1OHz).

FOR SERVICE MAI\IUALS

'

MAURITRON

T!?Cf!~ICAL

SERVICES

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TEL:

0184A

351694

FAX:

01844-352554

4

Operation

3.1

SWITCHING

ON

(i)

Make

sure

that

the

voltage

supply

tap

on

the

transformer

is

set

correctly,

and

that

the

correct

fuse

is

used.

The

transformer

is

accessible

upon

removal

of

the

top

cover

of

the

instrument.

(see

5.1).

Unless

labelled

otherwise,

the

J3A

is

delivered

for

234V

+ 10%

(See Fig. 1

for

transformer

taps,

links

and

fuse ratirlgsl.

In

addition,

an

over-voltage

tap

(41V)

IS

available

on

the

secondary

Winding,

which

effectively

extends

the

range

of

effectively

extends

the

range

of

supply

voltage

to

-20%.

(ii)

Set

the

support/carrying

handle

to

the

required

operating

position.

The

handle is released

by

pulling

both

fixing

bushes

outwards,

and

it

can

then

be

turned

to

lock

in

any

one

of

three

positions.

(iii)

It

is

advisable

to

turn

the

Output

Level Fine

control

to

minimum

before

switch·on,to

avoid

large surge

outputs

for

the

few

seconds

that

the

oscillator

takes

to

stabilise.

(iv)

The

Instrument

is

ready

for

use

half

a m1nute

after

switching

on

and

fully

'settled'

within

five

minutes.

No

special

precautions

with

cooling

need

to

be

taken

normally

but

natural

ventilation

should

not

be

restricted

when

operating

at

high

ambient

temperatures.

3. 2

BLOCK

DIAGRAM

The

broad

outlines

of

the

instrument

are shown in

the

block

Diagram in Fig. 2.

Power

is

supplied

by

a Regulated

supply

which

includes

the

protection

circuits.

The

low

distortion

output

from

the

Wien

bridge

oscillator

of

variable

frequency

is

taken

through

a

front

panel

Fine

Output

Level

control

to

-

-II>--

'

POWER

SUPPLY, SERIES REGULATOR

EXT!:

D.C.

So

PROTECTION CIRCUIT

.--

--

9

0/P

+31V

POWER AMPLIFIER

WIEN

BRIDGE

0/P

0/P<r

-

OSCILLATOR

0/P

..

LEVEL

2-

l

Section

3

Fig. 1

Power

Supply

Tappings,

links,

and Fuse ratings

36V Secondary Tap.

195-230V

(170-210)

n;;,

255V

Figures in

brackets

refer

to

use

of

41V

secondary tap.

the

Power

Amplifier,

which

drives

the

transformer·coup!ed

power

outputs

and

the

Meter

circuitry.

The same

oscillator

drives a

Squarer,

the

level

being

adjustable

through

a second

front

panel

control.

L

i Mains METER

N

r-

CIRCUIT

e

r

-

II

<>

f-o300n

II

~

+22V

~

SQUARER

C.T

'--

f-oi/P

0/P()-

-

~

-

~

<>

f-o

JOOn

ATifNUATOR

2:--

~

l

CCNY

OISTORTK>N

0/P

LOW·Z

0/P

=-

O(P

Fig. 2

Block

Diagram

'

I

l

I

r

;

......

l

r

\

'

•

Operation

3.3

SELECTION

OF

FREQUENCY

To

set

frequency,

the

Range

Switch

is

turned

to

the

appropriate range.

The

fine

control

of

Frequency

is

a

circular

dial

which

is

set

at

the

desired

part

of

the decade

in

use.

Although

the

accuracy claimed on the dial calibration

is

typically

1%,

the

resolution

of

the

gang

capacitor

in

the

oscillator

is

essentially infinite and frequency can be

set

to

any required value

to

within

1:

10

4. It

is

often

convenient

to

use

the

independent

square

wave

output

to

monitor

the

exact

frequency

by

a

Timer

Counter.

3.4

BALANCED

OUTPUT

15·0·15V

r.m.s

.•

e.m.s.,

(i)

Output

1

is

mainly

intended

for making balanced

600

n'

line

measurements.

In

such use

the

desired

amplitude

is

set

on

the

Meter-

remembering

that

half

the

Open

Circuit voltage will

appear

across

the

load-

and

the

balanced

attenuators

are used to give

-7-

10

or...;..

100

facilities.

(i

i)

The

balanced

output

can be used unbalanced,

terminated

in 60011 ,

in

which

case Metering and

the

use

of

the

attenuators

is

exactly

as

above. If a low

level

unbalanced

signal from a

600

source

is

required

from

the

J3A-

i.e. less

than

-40dB-

it

is

advisable

to

use

half

the

balanced

output

with

the

centre

tap

at

the

low

impedance

end,

and

use a

300

resistor

in

series

externally

to

make

up

to

600

Q . This avoids

the

pickup

of

sma!l

spurious

signals due

to

the

unbalance

of

the

output,

which

can be significant

at

high

attenuation.

(iii)

Half

the

balanced

output

can also be used. If

terminated

with

300n,

again

the

Metering and use

of

attenuators

remain

unchanged,

but

of

course

only

half

the

output

voltage

is

being used, i.e.

the

output

is

a

quarter

of

the

e.m.f. indicated.

(iv)

In

addition,

the

balanced

output

can be used

in

any

of

the

above

ways

without

matched

termination,

i.e.

operated

into

any

load

between

open

and

short

circuit

It

would

then

behave like an e.m.f. with a source

impedance

of

600

or

300

n ,

depending

on

whether

the

whole

or

half

the

output

is

used. The

attenuators

remain

operative.

(v)

Finally,

there

is

no

reason

why

different

loads

should

not

be used

on

each half

output,

remembering

that

they

will be in phase

opposition,

and

the

resultants

either

measured

or

calculated.

(vi)

The

e.m.f.

from

the

bifilar

transformer

secondaries

is

essentially

balanced.

The

output

resistances

at

the

terminals

are

balanced

to

within 3%. Each

attenuator

may

introduce

unbalance

of

3%

in

e.m.f.,

but

the

unbalance

of

output

impP.dance remains unchanged,

at

a

maximum

of

3%.

Section

3 s

Warning:

1.

The

maximum

voltage applied

between

the

balanced

output

and

ground

must

not

exceed

500V

d.c.

or

peak

a.c.

2.

The

passage

of

direct current

through

~he.

balanced

output

must

be

restricted

to

less

than

50mA,

to

prevent

damage

to

the

output

resistors. A

muci"J

smaller

current

than

this, however, can

saturate

the

output

transformers-and

severely increase

distortion.

If

some

d.c.

must

be passed, it

is

an advantage

to

use

the

attenuators

which will effectively reduce

the

current

reaching

the

transformer

by

the

same ratio.

The

permissible d.c.

is

a

function

of

frequency

and

acceptable

distortion,

and can best

be

found

by

experiment.

3.5 LOW·Z OUTPUT

3V

r.m.s., e.m.f. Z0

<>1

Ohm

(i)

This can

be

used

unloaded,

and

the

e.m.f. can be read

as

1/1 Oth

the

Meter reading.

The

response

is

flat and

the

distortion

less

than

at

the

Balanced

Output.

The

full range

of

amplitude,

i.e.

3V

r.m.s.,

e.m.f.,

is

avail-

able when

output

2

is

loaded by 5 Q

or

more,

simultaneously

with

normal loading

of

output

1.

[f

cutput

1

is

unloaded

and

unattenuated,

the

load

on

output

2 can be generallv

reduced

to

3

Qat

full

output.

Loads smaller

than

3 Q may cause

the

protection

circuit

to

operate,

unless level

is

reduced.

Under

near

short

circuit

conditions

the

maximum

current

available

from

output

2

is

approximately

0.9A

r.m.s.

Below

30Hz

and

at

full

cutput/loading,

the

protection

circuit

may be

trigg~red

at

the

peak

of

a cycle.

Note

When

the

protection

circuit

operates

because

of

excessive loading,

the

output

level

automatically

'cycles

on

and

off'

at

intervals

of

about

2 seconds

This

is

indicated by a

corresponding

swing

on

the

output

Meter.

3.6 LOW

DISTORTION

OUTPUT

2.5V

r.m.s., e.m.f.

z0

<>5k

Ohm

(i)

This

output,

directly

from

the

oscillator,

is

taken

from

the

slider

of

the

Fine Level

Potentiometer

through

a

buffer

resistor.

It

can

be

loaded

without

detriment

to

the

performance

of

the

other

outputs,

although a

change

of

loading reflects

on

the

output

levels.

(ii) An

external

signal from

another

Generator

can be

injected

into

this

output

and

be resistively mixed

with

the

low

distortion

J3A

signal.

The

mixed

signal

is

then

available at. amplified

outputs

1 and 2

to

permit

intermodulation

measurements

on

amplifiers,

etc.

However, leads

left

attached

to

this

output

can pick

up and inject

unwanted

signals and noise

into

the

J3A.

60peration

It

should

be

noted

that

maximum

injection

occurs

with

the

Fine Level

control

at

its mid seuing.

See also

4.2,

last

paragraph.

3.7 SQUARE

OUTPUT

0

to

SV Z0

<>1

K

Iii A

fraction

of

the

oscillator

signal

is

taken

to

the

Squarer

circuit,

and

the

independently

controlled

output

is

made

available

~t

the

front

panel as a

positive-going

square

wave

from

OV

(ground}.

The

mark/space

ratio

and

rise

and

fall

times

(see Specific·

ation)

are

maintained

over

the

entire

frequency

range

of

the

J3A.

If

the

mark/space

ratio

is

preset

to

unity,

the

square

edges 'lag'

all

the

sinusoidal

outputs

of

the

generator

by

approximately

1%

of

the

period+

0.1 us. In

the

1.

10kHz

range, however, because

of

transformer

phase

shift,

the

floating

output

begins

to

lag

the

square

wave progressively,

after

approximately

4kHz,

by

a small

amount.

(ii)

The

square

output,

being

independent

in

level

of

all

the

other

outputs,

can

be

conveniently

used

for

Frequency

Counting,

for

externally

locking an

oscilloscope

time

base,

etc.

'

Section

3

(iii) If

terminated

in

50~2

,

the

square

wave

is

reduced

to

150mV pk. approximately at full

output.

and

the

rise

and

fall

times

improve

to

better

than

0. 1 u s.

3.8 OUTPUT

LEVEL

METER & DECIBEL SCALE

(i)

The

Met~r

effectively measures

the

primary

voltage

of

the

output

transformers

and

is

calibrated

0 ·

30V

r.m.s.

e.m.f

..

the

total

open

circuit

voltage available

at

the

balanced

output.

Items

3.4

and

3.5

above

describe

most

of

the

likely

arrangements

of

load,

etc.,

as well

as

the

use

of

the

matched

and

balanced

Attenuators.

{ii)

The

(red) decibel scale

is

a

'relative'

scale

to

enable

amplitude/frequency

response

measurements

to

be

made

conveniently.

The

OdB

point,

however,

has been

chosen

to

equal

+20dBm,

for

convenience

in

power

measurements

in

600

12

3.9

RELATIVE

PHASE

The

signal

out

of

the

left

hand

terminal

of

Output

1 with

respect

to

the

Centre

Tap,

is

in

phase

with

Outputs

2,

3

and

4 with

respect

to

ground.

FOR SERVICE MANUALS

CONTACT:

MAURITRON

TECHNICAL

SERVICES

www.mauritron.co.uk

TEL: 018.14-351694

FAX:

01844-352554

'

I

l

J

I

r

L

Circuit

Description

4.1 WI EN

BRIDGE

OSCILLATOR

Transistors,

TR

1 -

TR6,

comprise

the

oscillator

amplifier.

Transistor

TR7,

is

a

supply

rail stabiliser.

The

input

of

the

amplifier

goes

to

a field

effect

transistor,

TR2,

which

is

in

a long-tailed

coupling

with

TR3.

TR2

is

driven

in

cascade

with

TR

1,

to

avoid Miller

capacitance

to

the

input

gate.

The

base

of

TR

1

is

d.c.

coupled

to

the

'common'

emitters

of

TR2

and

TR3.

thus

providing

TR2

with

a

constant

emitter-collector

voltage

to

reduce

distortion

with

the

large signal

swing

at

the

emitter

of

TR2

(3Vp-p).

The

signal from

the

collector

of

TAl

is

fed

to

emitter-

follower,

TR4,

with

bypassed

collector

resistance, R35,

serving

to

limit

current

at

switch-on,

before

the

oscillator

d.c. levels are

established.

Diode

04,

from

the

collector

of

TR5

to

the

emitter

of

TR4,

'catches'

the

collector

of

TR5

and prevents it

from

rising and

bottoming

by

almost

the

full Zener

potential

of

02.

TR4

drives

the

base

of

the

transistor

TR5,

which

inverts

the

signal, feeding it

to

the

output

emitter-follower,

TR6.

From

the

emitter

of

TR6

the

signal

is

taken

to

the

input

of

the

Wien Bridge consisting

of

ganged variable

capacitors,

C7

A,

C7B, and

the

switched

Range resistors, R1-RS.

The

range resistors, R1

to

R4, are

returned

to

variable bias

at

T.P. (A) which sets

the

d.c. level

at

the

output,

T.P. (E).

The

stability

of

this d.c. level

is

maintained

by

feedback

to

the

base

of

TR3.

In

the

symmetrical

Wien Bridge

configuration

used

in

the

J3A

oscillator.

the

voltage

transfer

ot

the

bridge

at

'resonance'

is

precisely

1/3.

A

similar

voltage

transfer

is

effected

in

the

feedback

network

comprising

Thermistor,

R44, its

shunt

resistors

R33

and

R34,

and

the

feedback resistor, R30,

thus

maintaining

the

high-gain amplifier in

operational

equilibrium.

If

the

output

level

is

low,

Thermistor

R44,

is

cold

and

hence

its resistance

is

high. This reduces

the

negative feedback

which,

in

turn

increases

the

gain

of

the

amplifier until

equilibrium

is

re-established.

The

opposite

happens

if

the

output

level

is

high.

The

same voltage

transfer

of

1/3

is

also a.c.

coupled

to

the

resistor, R28 (the

'long

tail'

of

TA2,

TR3),

effectively

producing

constant

current

in R28.

The

same

1/3

voltage

is

also applied

through

buffer

resistor,

R31,

to

the

'Guard'

T.P. (C),

which

is

connected

to

guard

screens placed

around

the

variable

capacitor

gang

to

reduce

variations

of

capacitance

between

the

rotor

and

ground.

R27,

C24,

and R37,

C30

are

frequency

roll-off elements

to

maintain

stability

and

diode,

03,

provides signal

continuity

and

circuit

stability

when

TR6

cuts

off

during

the

period

before

the

termistor

reaches

operating

temp-

erature

and

thus

reduces

output

signal level

to

normal.

The

full

output

of

the

oscillator

from

the

emitter

of

TR6,

is

applied

through

R9

and

C8

to

amplitude

control,

R10, and

thence

to

the

Power

Amplifier. A

tap

on

the

load resistor

of

TA6

supplies a lower level signal

to

the

input

of

the

Squaring

circuit,

A46 provides

extra

current

to

TR6

to

assist

"pull-up".

The

entire

oscillator

is

mounted

in

a screen

box

to

minimise

hum

and

noise pick-up.

Thermistor

R47

compensates

for

amplitude

changes

in

the

oscillator with

temperature.

'

Section

41

4.2

POWER

AMPLIFIER

The

power

amplifier

of

the

J3A

is

fed

from

a regulated rail

of

+37V and consists

of

transistors,

TR101

-TR 106.

TR101

and

TR102

are

connected

in

a

'long

tail'

configuration

the

input

signal from

the

amplitude

control,

R10, being

applied to

TR101

and

the

negative feedback

to

TR102.

The

base

of

TR101

is

biased at

1/4

rail voltage via

R104

and

R102, and

the

input

signal

is

a.c.

coupled

through

002.

The signal path through

the

Amplifier

is

from

the

collector

of

TR101

through

emitter

follower,

TR103,

and

the

common·emitter

stage,

TR

104,

to

the

complementary

output

pair,

TR105

and

TR106.

There are

two

negative feedback paths

to

the

base

of

TR

102, via equal resistors, R

108

and R120. R

120

is

connected

directly

to

the

output,

and R

108

is

returned

to

a feedback winding

on

the

output

transfo'rmer.

As

this

is

effectively

'grounded'

for d.c., stability

is

reached when

the

mean

output

voltage

is

twice

the

base voltage

of

TR102,

that

i9

half

the

rail voltage, enabling

the

Class B

output

transistors,

TR105

and

TR106,

to

swing equally

in

both

directions.

For

signal currents,

R108

and

R120

are

in

parallel, since

the

feedback winding has

turns

equal

to

the

primary

of

the

output

transformer.

The

negative feedback signal

through

these resistors develops a voltage across R

11

O+R

111, which

defines

the

voltage gain

of

the

Power Amplifier. Bypass

capacitor.

C106,

is

large

enough

not

to

affect

the

feedback

at

the

lowest

frequency.

Quiescent

current

for

the

output

transistors, TR

105

and

TR106,

is

controlled

by

transistor

TR108

which,

together

with diodes

0103

and

0104,

is

in

intimate

contact

with

the

heat

sink

on

which

the

output

pair are

mounted.

When

the

heat

sink

temperature

begins

to

rise,

TR108

also heats

up'

and

as

its base-

emitter

voltage

is

fixed, it draws increasing

emitter-collec~or

current,

thus

diverting bias

current

away

from

the

oUtput

transistors

and restoring equilibrium.

To

increase

the

gain

of

inverting stage, TR 104, and

to

assist

'pull-down',

the

load

of

TR

104

is

bootstrapped

to

the

output

of

the

amplifier. A

tap

on

the

bootstrap

through

resistors, R

116

and

R

117,

provides a voltage

approximately

equal

to

the

negative feedback

at

TR102

base, and

to

this

is

returned

the

common

emitter

resistance

of

the

i~put

pair,

TR101

and

TR102.

As

in

the

oscillator, this

technique

reduces

distortion

by

maintaining

constant

signal

current

in

the

long tailed pair.

R109 and C104, R107 and C105,

R118

and C112, and C113

are

frequency

roll-off

components

to

maintain

stability.

Bypassed resistance, A112, limits

switch·dn

surge

currents

in

the

amplifier, and

0102

prevents

hard

bottoming

of

TR104,

which

could

occur

while

the

oscillator

amplitude

is

settling.

The

input

to

the

amplifier

is

taken

via R101

to

a

socket

at

the

back

of

the

instrument,

thus

providing

the

low

distortion

amplitude

controlled

signal

directly

from

the

oscillator. An

external

signal

can

be

infected

at

this

point

also,

to

mix resistively

with

the

oscillator

waveform,

be

amplified and

become

available

at

the

power

output

of

the

J

3A.

The

injected

signal

must

be

within

the

frequency

range

of

t::he

output

transformer

in

circuit

at

any

one

time.

a

Circuit

Description

4.3 POWER

OUTPUTS

The

output

of

the

Power

Amplifier

is

coupled

through

C

116

and a

section

of

the

Frequency

Swrtch

of

the

J3A,

to

the,

primary

of

Tl

or

T2. These are

the

Low

Frequency

and .

High

Frequency

output

Transformers

and

operate

respectively

from

10Hz

--10kHzand

10kHz-

100kHz.

Their

feedback

and

secondary

winding

are

also

switched

by

the

Frequency

Switch

as

range

is

changed.

(i)

LOW -Z

OUTPUT

A

tapping

on

the

primary

of

each

output

transformer

provides

3V

r.m.s.,

e.m.f.,

between

ground

and

the

Low

-Z

terminal.

The

source

impedance

is

approximately

1 n

permittrng

about

1

Watt

to

be

delivered

into

a

load

of

5

Ohms.

The

maximum

available

current

IS

approximately

0.9A

r.m.s.

Iii)

300·0·300

Ohm

OUTPUT

Bifilar

wound

seconrlaries

on

each

transform~r

supply

2 x

15V

r.m.s.,

e.m.f.

to

the

balanced

output

termtnal!l

through

balanced

attenuators

of

20

and

40dB.

Separate

resistors

are

brought

in

by

the

Frequency

Switch

to

pad

the

secondaries

of

both

transformers

to

300

Ohms

each.

The

respective

centre-taps

are

alsu

switched

and

the

outputs

are

thoroughly

screened

(iii) A

protection

circuit

will

cause

the

J3A

to 'Cycle"

on·uff

this

condition

being

visible

on

the

output

meter

if

an

attempt

is

made

to

draw

excess

power

from

the

instru·

ment.

In

view

of

its

low

output

resistance

excess

power

is

almost

invanably

drawn

from

the

Low-Z

output

by

a

short

circuit.

The

protection

circuit

will be

explained

in

the

section

dealing

with

the

Power

Supply.

(See

reference

to

peak

current

limiting

l.

4.4

SQUARE

WAVE

OUTPUT

As has

already

been

mentioned,

a

tap

on

the

load

res1stot

of

thtt

output

at

the

Wien

Bridge

Oscillator

supplies

the 1nput

signal

to

the

Squarer.

Emitter

follower.

TR

131,

further

isolates

the

Oscillator

from

the

Squarer

to

min1m1se

inter

action.

The

output

from

TR

131

·,s

coupled

through

C132 to the

base

of

TR132,

which, With

TR133

forms a

Schmitt

trigger

circuit

in wh1ch

the

long-tail

current

through

A

134

is

switched

on-off

at

the

collector

of

TR

133.

The

output

level

is

controlled

by

potentiometer.

A

142.

and

taken

to

the

output

terminal

\lia

R139.

C133

is

a

speed·up

capacitor

to

the

base

of

TR133

and

preset

trimpot,

A136,

sets

the

mark-space

ratio.

R143

is

selected

on

testm

parallel

with

R

142

to

adjust

the

output

level

to

be

between

+SV

and

+5.5V.

The

Squarer

is

supplied

through

buffer

emitter-follower,

TR134,

and Zener

base

reference,

0131,

to

isolete the fast

transients

from

other

peru

of

the

J3A.

The

same

Zener

0131

after

filtering

serves

as

the

reference

for

the

Power

Supply.

'

Section

4

4.5

POWER SUPPLY

Long-tailed

pair,

TR

161

and

TR162,

compare

the

Zener

reference

to

a

fraction

of

the

d.c.

output

voltage

at

the

slider

of

trimpot,

R

162.

The

collector

of

TR161

conventionally

drives

compounded

series

output

emitter

followers,

TR

164

and

TR

165,

the

latter

being

the

main

series

regulator

connected

to

a

heat

sink.

Zener

diode

0162

applies

bootstrap

feedback

from

the

emitter

of

TR165

to

R168,

the

collector

load

of

TR161/TR163.

thus

presenting

a

high

impedance

load

and

Increasing

the

loop

gain.

R169

and

C164

are

frequency

roll-off

stability

components.

The

input

to

the

P.S.

is

provided

by

the

secondary

of

mains

transformer.

T3,

and

Bridge

Rectifier,

BR

161,

feeding

Reservotr

capacitor.

C

166.

whose

negative

terminal

is

taken

to

the

0-volt

(ground)

line

through

1

Ohm,

A170.

The

protectton

ctrcuit

referred

to

under

Section

4.3

(iii)

is

composed

of

R

164,

a

2.2

Ohm

resistor

b'etweer.

TR

165

and

the

P.S.

output.

tranststor,

TR163;

R170;

trimpot,

A165,

and

C163.

TR163

is

connected

so

that

its

base-emitter

monitors

rhe d c.

voltage

drop

1n

R164,

its

collector

being

1n

comrr10n w1th

that

of

control

transistor,

TA161.

Hence,

d a

current

ot

more

th;:tn

approximately

250mA

is

taken

through

R

164,

TR

163

will

conduct

and

reduce

the

base

current

av<1dahle

to

the

senes

control

transistor.

This

convent1unal

current

senstng

and

limtting

alone,

would

also

l1m1t

the

poslttve

current

peaks

of

the

output

waveform,

especially

at

the

lower

lrequencies.

While

the

current

overlo<Jd

stmsor,

TR163,

is

arranged

so

that

its

base

1s

d.c.

htased

hy

potential

across

R164,

the

a.c.

component

is

llnlanced

out

in

trimpot,

R166,

with

a

fraction

of

the

opposing

~1gnol

voltage

generated

across

R

170

and

a.c.

coupled

VIJ

C163.1ncreasing

mean

current

in

R164

causes

TR163

to

conduct.

l1m1t1ng

the

drive

to

TR164

and

TR166,

ttlus

dropptng

tt1e

output

voltage.

C163

then,

however,

dtscharges

through

R

178

into

the

base

of

I R

163,

thus

collaps1ng

thP.

supply.

In

addition,

the

t1me

constants

arc

suctl

that

wll"'!n

the

supply

collapses

on

overload,

the

Wien

bridge

oscillator

is

stopped

and

waits

until

its

control

thermistor

cools

before

it

can

restart.

The

ebsance

of

signal

effectively

removes

the

overload

from

the

P.S.

which

then

restores

output

The

cycle

of

events

continues

until

thi

overload

is

removed

or

the

signal level

is

turned

down.

Overload

1s

shown

by

the

Output

Level

meter

cycling

on·off

at

approxtmatelv

2

second

tntervals.

A

faster

'cycling'

VISible

on

the

Output

Level

meter

generally

indicates

an

1nternal

fault.

rather

than

excessive

external

loading.

Nutt!

Under

certatn

condittons

of

overload,

the

peak

current

lim1t1ng

c~rcuitry

of

the

output

stage

can

tnl!tate

the

'cycling'

of

the

protection

circuit.

This

Situation

is

most

l1kely

to

arise

when

excessive

magnet1s1ng

current

IS

required

by

the

output

transformer.

etther

because

of

external

d.c.

magnet·

. 1sat1on

or

through

a

fault.

This

initiation

of

cycling

wilt

cause

no

damage

to

the

instrument.

I

1

l

I

J

I

l

I

Circuit

Description

4.6

METER

CIRCUIT

Equal signals

from

the

output

of

the

P.A.

and

ihe

feedback

winc!ing,

supply

the

germanium

diode

full wave bridge

rectifier

through

equal

resistors, R151

and

R

152.

The

resultant

d.c.

is

then

set

and

filtered by R

153,

R

154

and

C151.

The

rectifier

is

essentially average

current,

as

most

of

the

applied voltage

is

dropped

across

the

two

equal

resistors.

By

monitoring

the

two

points

1:hat

supply

the

feedbacK

to

the

Power Amplifier,

the

rrieter

circuit

is

effectively

connected

to

the

'ideal'

transformer

driving

the

balanced

Outputs,

and

thus

compensates

for

transformer

losses.

4.7

MAINS INPUT

Transformer,

T3,

is

conventionally

arranged

with

a series-

parallel

primary

and

has a single well-screened secondary.

The

primary

is

sWitched and fused, and a Neon

indicator

is

fed

from

one

half

primary.

(See 3.1 (i)

and

Fig.

21

4.8

EXTERNAL

D.C. SUPPLY

Two

coded

sockets

at

the

back

of

the

instrument

permit

operation

from

a

FLOATING

D.C. supply

of

40·48V.

Current

at

maximum

output

and

l"oading

is

approx.

250mA.

A

diode,

internally,

protects

against

incorrect

polarity

of

the

external

supply.

Section

4 9

FOR SERVICE MANUALS

CONTACT:

MAURITRON

TECHNICAL

SERVICES

www.mauritron.co.uk

TEL:

0Hl44

· 351694

FAX:

01844-352554

10

Maintenance

5.1

REMOVAL

OF

COVERS

Warning:

Take

care

not

to

touch

the

supply

transformer or

fuse

with

the

supply

ON.

To

remove

the

covers

from

the

instrument,

firstly remove

the

bottom

by

unscrewing

the

4

retaining

screws.

Then

by

gently

pulling

the

side

panels

outwards

the

cover

should

lift

off.

It

will

generally

be

found

more

convenient

to

carry

out

adjustments

or

repairs

with

the

bottom

of

the

instrument

upwards

and

to

use

an

external

supply

(See

48)

for

testing

and

calibration.

5.2

REMOVAL

OF

OSCILLATOR

BOX

COVER

This

is

held

on

by seven screws, 4

at

the

bottom

and 3

at

the

top,

all 7 screws

working

in

slots.

After

undoing

each

screw

by

about

3

turns,

the

cover

can

be

slid

out.

Refitting

is

a reversal

of

the

above

procedure,

being careful

to

butt

the

cover

well

against

the

steel

oscillator

box

when

tightening

the

screws.

5.3

REMOVAL

OF

PRINTED

CIRCUIT

BOARD

ASSEMBLIES

(i) Removal

of

Oscillator

P.C.B. (Fig. 4)

This

is

released

by

undoing

4 screws,

as

shown

in

the

figure.

Then

the

yellow

lead

on

the

underside

of

the

board

to

'C'

(Guard)

is

unsoldered.

The

board

is

now

free

and

can

be

eased

out

and

swivelled

about

the

cables

and

leads

going

to

the

Range

Switch.

(ii) Release

of

Master

P.C.B.

(a)

Remove

4

screws

securing

rear panel. Disconnect

the

2

leads

from

the

Low

Distortion

terminals.

(b)

Undo

the

two

screws

that

hold

the

board

to

the

bracket

near

the

Mains

transformer.

(c)

Disconnect

the

two

brackets

that

support

the

board

to

the

case

(top

and

bottom)

towards

the

middle

of

the

P.C.B.

ld)

Remove

the

top

screw

securing

the

output

transistors'

heat

sink

to

the

side

member,

near

the

two

large

electrolytics

mounted

on

the

board.

Slacken

the

corresponding

bottom

screw

securing

the

heat

sink.

The

board

can

now

be

swivelled

against

the

cables

and

harness

to

remove

damaged

components,

although

many

of

these are accessible

simply

by

removing the

rear panel.

Note:

Complete

removal

of

the

P.C.B.'s requires

disconnection

of

all

leads,

which

should

be clearly labelled

for

correct

reconnection.

5.4

SETTING

UP

OF

WIEN

BRIDGE

OSCILLATOR

(i) Work

which

is

possible

with

cover

removed.

The

cover

should

not

be

removed

unless a fault exists

in

the

oscillator

board.

1.

Turn

Fine

Output

Control

to

minimum.

2.

Disconnect

coax.

lead

from

Point

0

(to

squarer)

3.

Check

incoming

+37V

rail

at

check

position

on

switch,

or

on

master

P.C.B. (red leads). If faulty,

disconnect

the

oscillator

from

+37V

rail and

use

an

external

+37V

supply

rated

at

SOmA

to

supply

the

oscillator.

4.

Connect

an

a.c.

coupled

oscilloscope

(1V/div.,

0.1

mS/div.)

to

'Oscil.

Test

Point'

as

shown

in

Fig. 4

(On

the

middle

switch

wafer

outside

the

oscillator

box).

5.

6.

7.

8.

Section

Set

frequency

to

approximately

3kHz,

and

switch

on.

5

If

there

is

no

fault,

oscillations

should

build

up

die

out,

restart

and

stabilise.

Connect

D.V.M.

or

20k

11

V

Voltmeter,

across C25.

Trim

R22

for a

reading

of

12.5-13V

Examine

the

waveform

on

the

oscill·

oscope

for possible clipping,

etc.

It

should

be

clean.

Trim

R34

for 8v p-p

on

the

oscilloscope.

Restore

wiring

to

normal.

(ii) Work

with

cover in posi'tion:

(In

the

absence

of

a fault, begin

setting

up

here)

Step

7

above

may

be

carried

out

by

connecting

a d.c.

Voltmeter

to

'Oscil.

Test

Point').

'

1.

Connect

the

a.c. high

impedance

Voltmeter

~o

'Oscil.

Test

Point'

replacing

the

oscilloscope.

The

Voltmeter

should

be

calibrated

to

1%

at

2.8V

r.m.s., and have a flat

frequency

response

from

10Hz

to

100kHz,

inclusive

of

the

screened

cable

connector.

2.

Connect

the

Frequency

counter

to

the

Squarer

output.

Set

this

to

a

convenient

level.

3.

Select

the

1-10kHz

Range,

and

set

the

dial

to

1kHz.

Note

the

frequency

on

the

counter.

4.

Trim

R34

for

2.8V

r.m.s.

on

the

Voltmeter

and

tune

towards

the

high

frequency

end

of

scale,

carefully

observing

the

voltmeter

reading.

If

the

Wien bridge

is

trimmed

correctly,

the

reading

should

stay

constant

at

2.8V.

5.

Set

the

dial

to

10kHz

and

trim

C2

and

C3

to

obtain

ten times

the

frequency

noted

in

step

3

above.

Note

that

increasingC2

and/or

C3,

decreases

the

frequency,

and

that

increasing C2

and

decreasing C3,

can

keep

the

frequency

constant

while decreasing

the

output

of

the

oscillator.

The

two

trimmers

should

be

set

for

the

right

frequency

and

least

amplitude

variation

over

the

range.

Note

the

amplitude

at

10kHz.

6.

Reset

1kHz

on

the

counter.

Slacken

the

two

grub

screws

that

hold

the

tuning

gang

spindle

in

the

epicyclic

drive

and

reposition

the

scale

to

agree

with

the

counter.

7.

Set

the

dial

to

1OkHz

and

trim

frequency

to

agree,

with

amplitude

retained

at

that

giving least

variation

over

the

band.

(Step

5.)

8.

Check

frequency/dial

agreement

on

100-lOOOHz

and

10-lOOkHz ranges

at

various

points,

and

if

necessary,

reset

the

dial

(repeating

Steps

6

and

7)

for

minimum

frequency

error

overall. If

the

error

approaches

2%

a

fault

in

the

appropriate

range

resistors

should

be

suspected,

or

else in

the

gang.

9.

Check

10-lOOHz range,

allowing

for

the

+1Hz

tolerance

in

the

specification.

The

oscillator

should

now

be

set

and

be

flat

within

0.3d8.

10.

Finally,

return

to

the

1-10kHz

Range

at

9kHz

setting,

note

frequency

reading

and

'rock'

the

tuning

knob

whilst

adjusting

C2

and

C3

for

minimum

amplitude

bounce.

Check

that

the

noted

frequency

reading

has

been

held

unaltered.

It

should

be

noted

that

clockwise

dial

rotation

producing

amplitude

increase

requires

increase

(frequency

lowering)

of

the

Trimmer

C3

nearest

the

edge

of

the

oscillator

box

(grounded

trimmer).

Conversely,

C2

has

the

opposite

effect.

I

J

1

I

1

l

r

\

...

f

!

Maintenance

Note:A piece

of

insulated wire

is

wrapped around the

highest range resistor

R8

shunting

it

by

approx.

1/4pF

This

raises

the

frequency

at

the

top

end

of

the

highest

range

by

1%

approx.,

to

produce

closer

agreement

with

the

scale.

5.5

SETTING

UP

OF

POWER

SUPPLy

Note:

All

trim

potentiometers

on

Master P.C.B. can

be

adjusted

from

the

back

of

the

board

through

suitable holes.

1.

Turn

the

level

control

to

zero.

2.

Adjust

R

162

for

+37V

:t

0.5V

at

+"37V'

carrying

red lead.

3. Provisionally set R165

at

its mid setting.

After

adjusting

the

Power

Amplifier,

the

frequency

is

~

set

to_~z

and

a.c.

coupled

and

float;ng

millivoltmeters

is

connected

between

+37V

pomt

and

the

slider

of

R

165,

to

test

point

marked

"SET

NULL".

The

P.Ashould

be

loaded

with

approximately

5

Ohms

at

the

Low

·Z

tap, the

40dB

attenuator

engaged

to

load

the

balanced

output,

and

the

Level

control

should

then

be

advanced

and

R

165

adjusted,

for

minimum

stgnal

on

the

voltmeter

while

increasing level

to

maximum.

The

adjustment

is

eased

if

the

oscilloscope

Timebase

is

set

to

1

~

s/div.

and

'free

run',

in

which

case

the

3kHz

signal

appear

as a

multiple

trace

whose

width

should

be

reduced

to

a

minimum.

If

the

protection

circuit

operates,

switch

off

and

check

R164

and

R170.

The

minimum

unbalance

signal

is

generally

less

tnan

1 millivolt.

4.

Check

that,

at

the

nominal

mains voltage

for

the

transformer

tap

in use,

the

reading

between

the

collector

of

TR

165

(heat

sink)

and

ground,

is

not

less

than

+44V

under

load

as

in

Step

3

above.

5.6

SETTING

UP

THE

POWER

AMPLIFIER

(i) Quiescent

Current

of

Output

Stage.

1.

Set

the

Level

control

to

zero

and

remove

the

loading

from

the

instrument.

Switch

out

the

attenuator.

2.

Switch

off

and

disconnect

the

link

between

the

collector

of

TR106

and

ground

(Fig. 4) The

link

is

at

the

bottom

rear right

corner

of

the

instrument,

near

a large

electrolytic.

Replace

the

link

by

a

d.c.milli-ammeter(-ve

to

ground)

and

solder

a

capacitor

of

value

0.5

to

1

fJ

F across

the

link

pins.

R129

is

adjusted

to

give a

quiescent

current

in

the

output

pair

of

18-30mA.

It

should

be

noted

that

current

through

R130

modifies

the

behaviour

of

TR108

(see

4.2, oar

a.

4)

so

that

quiescent

current

IS slightly

reduced

with

increased

heat

sink

.temperature,

caused

by

running

at

full

load

over

long

periods.

3.

Switch

off

and

restore

circuit

link.

(ii) Check

the

output

d.c.

devel between

ground

and the

+ve end

of

C114

(See

Fig.

4).

It

should

be

within

1

volt

of

half

the

supply

rail.

If

not,

check

R102

R104, R108,

R120

and

C106

for

leakage.

'

5.7

(i)

Iii)

,iii)

(iv)

(v)

(vi)

5.8

(i)

Section

5n

SETTING

UP

SQUARER

Connect

the

oscilloscope

to

Square

Output,

1V/div..

0.1ms/div.

Select

Range

1-10kHz

and

a

frequency

of

1kHz

so

that

1 cycle

(square)

occupies

exactly

10

oscilla'scope

divisions.

Trim

R

136

for

mark/space

ratio

Of

unity.

Change

the

polarity

of

trigger on

the

oscilloscope

and

retrim,

if

necessary,

so

that

the

transition

of

the

square

wave

occurs

at

the

same

point

on

the

oscilloscope,

near

the

0.5ms

centre

..

This·

should

eleminate

possihle

oscilloscope

nonlinearity.

Verify

that

amplitude

is

within

specification.

If

excessive,

suitably

shunt

front

panel

control

R142

(1

k

ll

)

by

A.O.

T. resistor, R

143

across the pins at

the

output

of

the

squarer

projecting

from

the

track

side

of

the

PCB.

Should

the

outpUt

be

less

than specified, check D131

(24V

Zener),

R142,

R132,

R

133

and R

134,

in this order.

Confirm

that

rise

and

fall

times

are

within

specification.

If

not,

check

R135

and

C133.

DISTORTION

(See

Fig. 3)

lf

the

preceding

adjustments

nave

been

carried

out

correctly,

distortion

should

be well

within

specification

Apart

from

obviously

faulty

circuitrY.

the

following

is

a

short

check

list of

the

more

likely causes of

excessive

distbrtion,

if

the

instrument

is

functioning

in

other

respects. If available, a DistortiOn

Factor

Meter

is

invaluable

in

tracking

down

disto.rtion,

particularly

if possessing an

output

giving residual

component

frequencies

after

cancellation

of

the

fundamental.

1. Change

of

component

parameters

could

cause

short

burst

of

high

frequency

oscillation

at

some

specific

point

of

the

signal

cycle,

as

seen

on

an

oscilloscope,

particularly

immediately

after

switching

on

when

oscil.lator

amplitude·

is

'still

unstablised.

When

the

J3.B

with

this

forni

of

distortion

is

used as a signal

source,

it

will .

generally

result

in

'noisy'

or

flickering

measurements.

2.

3.

4.

5.

Cross-over

distortion

in

the

power

output

stage,

generally

due

to

failure

or

error

in

the

bias

components

(see

section

5.

7 i)

or

damaged

output

transistors.

Supply

hum

or

signal ripple across

th~

37V

rail, caused

by

power

supply

failure

or

damaged

electrolytic,

C115.

At

full

loading, the

total

supply+

signal ripple across

C115,

should

not

exceed

40·50

mV

p-p.

Square

Wave

break-through,

caused

by

failure

of

TR131

or

TR134.

If

the

distor_tion

~gives

predominantly

3rd

harmomc

at

~OkHz~

higher

than

the

value

s~ecifi~d.

with

co·~esP9nding

increases

of

dtstortton

at

lower

t'ri(quencies,

suspect

a

faulty

stabilising

Thermistor

in

the

oscillator.

12

Maintenance

Section

5

(ii)

Any

failure

or

error

in

the

feedback paths (including

Switching)

in

the

P.A.,

or

wrongly

set

protection

and limiting

circuits

in

the

P.S., can cause large

distortion,

increasing

with

output

level.

(iii)

If

the

distortion

increases

with

output

level

beyond

the

specified limits

then

the

fault

is

with

the

P.A.

If

the

fault

is

in

the

oscillator,

then

distortion

is

sensibly

independent

of

level

at

all

outputs.

Fig. 3 Graph

of

Distortion

and Frequency

1

0·

5~

0·

·-"'~

.~~

,.,:.o,C'

'·~

'

"'

.

0

--~&v.

~

2~r~~

'

...

! 0

,,

·1

'

VJ-.

SPECIFICATION

OUTPUTS

1

&.

2

z

0

i=

a:

0

....

</)

2i

..1

0·0

;! 2

0

....

0·01

0·001

10

..•

""'-.

'-..fv,..

'

20QH,

I

·..

--,<>

' SPECIFIED

·..

'·

-·

""'T_"!P.!,C,!L_

O~!P~~!.,

~2-

_ -------------

·..

......

...

....

...

_

··

....

~"

....

...

__

SPECIFIED ::l\t\

TYPICAL

LO

DISTORTION

OUTPUT

, ,

··~

·-r

-

...

-

...

_

...

_

~,

,,

---

.

••

.;<~~

tg

.ft£"

••• •t

,,

II£

•••

••

Dt8

'~&,

··

..

•ulltt

Measuremers

made

at

oujput

level

setttg

of

25V.RMj

'

103

FREQUENCY

Hz

.,...._0/Pl--;...._

,,

-~~;,~-

---·

·~,

...

'••

r

•••••

...

.

..

0:1

P.------

0·05

,

,,

,

0·03

/

'

-

.

.........

10'

r,

!

1

I

r

'

,.

..

1

i

'

i

l

Components

List

and

Illustrations

Section

613

ABBREVIATIONS USED

FOR

COMPONENT DESCRIPTIONS

RESISTORS

cc

CF

MO

MF

ww

CP

PCP

CAPACITORS

CE(1)

CE(2)

SM

PF

PS

PE

PC

E

T

Carbon

Composition

Carbon

Film

Metal

Oxide

Metal

Film

Wire

Wound

Control

Potentiometer

Preset

Potentiometer

MPD

PC

Ceramic

Silver Mica

PlastiC Film

Polystyrene

Polyester

Polycarbonate

Electrolytic

(aluminium)

Tantalum

NOTE:

Components

coded

on

the

master

PCB

in

YELLOW

are

not

used.

'

'hW

1/8W

"hW

"4W

6W

500V

10%

5%

2%

1%

5%

20%

+

80%

-

25%

:!:_

10%

:!:_

10%

:!:_

10%

+ 50%

10%

+ 50%

10%

unless otherwise stated

unless otherwise

stated

unless

otherwise

stated

unless

otherwise

stated

unless otherwise stated

unless

otherwise

stated

unless otherwise stated

unless

otherwise

stated

unless otherwise stated

FOR SERVICE MANUALS

CONTACT:

MAURITRON

TECHNICAL

SERVICES

www.mauritron.co.uk

TEL: 01844

··

351694

FAX:

01844-352554

I

14

Components List and Illustrations Section 6

'1'

I

Circuit Ref. Value Description

Tolerance%

Part

No.

l

RESISTORS

R1

30M

MF

+1

32772

R2

3M

MF

:!:_0.5

32773 •

R3

300K

MF

:!:_0.5

32774

R4

30K

MF

:!:_0.5

32775 I

R5

30M

MF

:!:.1

32772

R6

3M

MF

:!:_0.5

32773

R7

300K

MF

:!:_0.5

32774

R8

30K

MF

:!:_0.5

32775 r

R9

270

CF

:!:_5

1/8W

28720

R10

5K

Cp

A4/32606

R11

47K

CF

:!:_5

1/8W

21815

R21

lOOK

CF

:!:_5

1/8W

21819

...

R22

25K

PCP

29602

R23

47K

CF

:!:_5

1/8W

21815 I

R24

1K

CF

:!:_5

1/8W

21799

R25

15K

CF

:!:_5

1/8W

28727

R26

5K6

CF

:!:_5

1/8W

21806

R27

560

CF

+5

1/8W

21798 I

R28

1K8

CF

:t5

1/8W

28725

R29

750

MO

+2 28790

R30

390

MO

:!:_2

26740 I

R31

2K2

CF

+5

1/8W

21802

R32

1K5

MO

:!:.2

26733

R33

820

MO

:!:.2

27346

R34

2K5

CP

28969 I

R35

12K

CF

:!:_5

1/8W

21810

R36 330

CF

+5

1/8W

28721

R37

180

CF

:!:.5

1/8W

21795

R38

1K8

CF

:!:_5

1/8W

28725 I

R39

680

CF

+5

1/8W

28723

R40

lK

CF

:!:_5

1/8W

2f799

R41

33K

CF

:!:_5

1/8W

21814 t

R42

100

CF

:!:_5

1/8W

21794

R43

2K7

CF

:!:_5

1/8W

28726

,.;

R44

1.9V

/1

ma

Wkg.

Thermistor R

15

3mW

SELECTED

32421

R45

330

CF

+5

1/8W

28721

R46

3K9

CF

:!:_5

1/8W

21804

R47

1

K8/25"C

Thermister

RP152CY

1/4W

'-

10% 35712

R101

4K7

CF

:!:_5

1/8W

21805

R

102

33K

CF

+5

1/8W

21814

R103

l

R104

lOOK

CF

:!:_5

1/8W

21819

R

105

6K8

CF

-<:5

1/8W

21807 r

R106

3K3

CF

:!:_5

1/8W

21803

R

107

82

XX

+5

1/BW

28717

R108

16K

MO

:!:.2

1/8W

28!!05

R109

820

CF

:!:_5

28724

R110 330

CF

28721

R

111

2K7

MO

:!:.2

1/8W

26728

R112

8K2

CF

:!:_5

1/8W

21808

R113 68

CF

:!:_5

1/8W

28716 \

R114 330

CF

:!:_5

1/8W

28721

'

l

R115

1'K

CF

+5

1/8W

21799

R116

270

CF

:!:.5

1/8W

28720

'

Components

List and Illustrations Section

615

Circuit Ref. Value Description Tolerance% Part No.

RESISTORS (Con't)

R

117

120

CF

+5

1/BW

28718

R118 56

CF

±_5

28715

R119

1K5

CF1

+5

1/8W

A.O.T.

21801

R120

16K

MO

:;:-2

28805

R

121

1

ww

34200

R122

1

ww

1/8W

34200

R123

330

CF

±_5

28721

R124

2R2

ww

1/8W

31894

R125

R126

R127

470

CF

+5

1/8W

21797

R128 220

CF

±_5

1/2W

18524

R129

1K

PCP

32523

R130

15K

CF

±_5

1/8W

28727

R131

12K

CF

±_5

1/8W

21810

R132

15K

CF

±.5

1/8W

28727

R133

8K2

CF

+5

1/8W

21808

R134

2K7

MO

+5

1/8W

A.O.T.

26728

R135 150

CF

+5

1/8W

28719

R136

2K5

PCP

28969

R137

15K

CF

±.5

1/8W

28727

R138

8K2

CF

±.5

1/8W

21808

R139

470

CF

+5

1/8W

21797

R140

2K2

CF

±.5

1/8W

21802

R141

12K

CF

:':.5

1/8W

21810

R142

1K

CP

A4/32607

R143

CF

±.5

1/8W

A.O.T.

R144

I

FITTED

IN

561

CF

:':.5

1/8W

28715

R145

I

PLACE

OF

2R2

ww

±_5

2%W

31894

R151

I 'SET

10

LINK'.

!OK

CF

±_5

1/8W

21809

R152

!OK

CF

±.5

1/8W

21809

R153

2K5

CP

28969

R154

1K5

CF

±.5

1/8W

21801

R

161

12K

CF

±.5

1/8W

21810

R162

5K

PCP

28970

R163

22K

CF

:':.5

1/8W

21812

R164

2R2

CF

34201

R165

5K

PCP

28970

R166

22K

CF

±.5

1/8W

21812

R

167

2R2

CF

±.5

1/8W

34201

R168

6K8

CF

±.5

1/8W

21807

R169

68

CF

±.5

1/8W

28716

R170

1

ww

34200

R

171

470

CF

±.

1/8W

21797

R174

1-10M

A.O.T.

R178

1K2

CF

±.5

1/8W

21800

R201

1480

MF

+1

32776

R202

15K

MF

+1

32777

R203

1480

MF

+1

32776

R204

15K

MF

±.1

32777

R205

367

MF

±_1

32778

R206

306

MF

±_1

32779

R207

367

MF

±_1

32778

R208 306

MF

±_1

32779

R209

367

MF

±_1

32778

R210

306

Mr-

±.1

32779

R211

367

MF

±.1

32778

R212

306

MF

±_1

32779

'

I

16

Components

List and Illustrations

Section

6 '

'

J

C~rcuit

Ref..

Value Description Tolerance% Part No. l

RESISTORS (Can't)

R221

OR68

CF

:!5

31888

R222 280 MF

_:!:1

32826

R223 280 MF :!1 32826

R224 187 MF

_:!:1

29471 ]

R225 187 MF

_:!:1

29471

CAPACITORS

C1

l

C2

6/25pF

Trimmer 23593 •

C3

6/25pF

Trimmer 23593

C7

518pF C7A +

C7B

33999

+518pF

C8

681'F E

16V

32174 I

r.g 1.5pF

S/M

813

C21

150 F E

16V

32175

C22

0.22~F

PE

250V 35607

C23

681'F E 6.3V 32162 I

C24

68pF

CE(21

:!10

500V

22374·

C25

1000J.~F

E

16V

32178

C26

5.6pF

CElli

500V

22361

C27

1501'F E

16V

32175 I

C28 4701'F E

6.3V

32164

C29

.011'

F

CE(ll

250V 22395

C30 33pF

CE(2~

_:!:10

500V

22370 I

C31

470,F

E

40V

32191

C32 47,.F E

40V

32188

C101

0.22~F

PE

31379

I

C102

221'f

E

25V

32161

C103 5.6pF CE(2) 500V 22361

C104 56pF

CE(21

500V 22373

C105

6BOpF

CE(2)

.:!

10 500V 22385 I

C106 1501'f E 16V 32175

C107 82pF CE(2)

500\'

22375

C108 4701'F E

6.3V

32164

C109 .Ol,.F

CElli

250V

22395

C110 56pF

CEI21

500V

22373

C111

4701'f

E

6.3V

32164

C112 56pF CE(2) 500V 22373 t

C113 5.6pF CE(2)

.500V

22361 i

C114 3301'F E 16V

33998

C115 220011' E

40V

31844

C116 2200f'F E :?5V 32520 r

C117 1001'F E

4V

34994

C131

.1

l'f

CElli

30V

36709

C132 25f'F E 25V 32181

C133

3J,F

E 500V 22370

C134

471'f

E

25V

32182

·-

C135 560 pF

CE

22384

C151

471'F E

10V

32167 i

I

C161

331'f

E L

16V

32173

C162 47uF E

25V

32182

C163 47uF !:

63V

32199 f.'

!

'

Gould J3B User manual

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