Bruel & kjaer 1621 User manual

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3640

Brliel &

Kjcer

Tunable Band

Pass

Filter

Type

1621

Valid

from

serial

no.

694126

037-0225

BRUEL &

KJkR

Service Instruction

1621

Ncerum -

Denmark

037-

0125

Table

of

contents:

Service Instruction

Technieal

Description

Adjustment

Procedure

ZE

0161

Filter

C;rcuit

ZG

0109

Filter

and

Power

Supply

Circuit

ZH

0159

SynchronlZatlon

Circu;t

Parts List

with

Circuit

Diagram.

Tunable Band Pass Filter

Type

1621

Valid

from

serial

no,

694126

Trouble Shooting

page date

9.77

If any

faults

should

occur

please

check

the

instrument

according

to

the

9.77

AdJustment

Procedure.

1-1

977

When

a

fault

has

been

traced

and corrected,

the

valtages and

adjust·

1-2

9.77

ments

influenced

by

the

eorreetion

must

be rechecked, The

complete

in·

1--3

977

strument

should

then

be

tested

10

make

sure

thaI

all basic

functions

are

operative.

2-1

2-2

9,77

977

The

tolerances

given

in

these

notes

are

intended

for

use as

guide

for

ad-

2-3

9.77

justments,

1

2

9,77

Before

correcting

any

apparent

deviation

make

sure

that

the

measuring

instrument

has

tolerances

small

enough

not

to

affeet

the

measuremenl.

9,77

Modifications

9,77

Duc

to

the

constant

teehnical

progress

the

instrument

will

be

modified

3--1

9.77

from

time

to

time

in

order

to

provide

continously

improvad

performanee,

For

this

reason

there

may

be

small

differencies

between

the

instrument

and

the

Service

Instruction,

However,

the

loeal Representative Service IS in possession of

all

informa-

tion

regarding

the

modifications

that

have been

made.

Spara Parts

Please state type

and

serial

number

of

the

instrument

when

ordering

spare parts,

9,77

0-1

.

. n

1621

Servlc

. e InstructlO

BROEl

Nrerurr

Block

Di

Principl!!

fvO\

-~

~

@

~

\ \ \

@

CD

()

lOOk8 a

\

~~~

@3004

10~i2

®/~

l

;12

0-2

9.77

Region

for

Amplifier

BROEL

&

KJ.LER

Nffirum

Denmark

Technical Description 1621.1

Block

Diagram

St.p

Tunln!j

Pul~es

Vol

log.

from

2

)06

~UIO

...

O Menuol

M--~.

l I

In

put

O---.

Bonowidth

SeLt"c

tor

inveri:er

O....

rtoad

Lomp

Int·orotor

Int.grator

Ovtr!ood

~

I

II

t I

-

Principle

of

the

Filter

circuit

Feedback

I

lo

overload

Inlegrotor

I

Integralor

II

>--<1>--------.-.0"

V

out

..

Feedback

il

Region

for

Amplifier

Vin

Inverter

The Type

1621

consists

of

a

tunable

single

pole

bullerworth

filter

with

switchable

bandwidths.

The

princlple

of

the

filter

is as

follows:

The

Integrators

I and

II

tagether

with

the

first

Inverter

and

feedback

I.

works

as a

tunable

oscillator

The

circuit

starts

osclllating

when

the

input

Irequency

is

the

same

as

the

tuned-in

Irequency

Feedback

II

con-

trals

that

the

amplitude

01

the

output

is

the

same

as

the

input

amplitude.

When

the

input

Irequency

and

the

filter

is

tuned

to

resonanee

the

ampli-

fication

of

the

integratars

will

be

exactly

x 1.

For

an

input

frequency

lower

than

resonance,

the

amplilicatlon

af

Inte-

grator

II

will

be

very

high

due

to

C2

which

through

feedback

Ideerease

the

input

to

the

first

Inverter

and

thus

stops

the

oscillating.

Now

the

eir.

cuits

works

as

a

normal

amplifier

where

the

amplification

is

controlled

by

Cl

and

C2.

For

an

input

frequeney

higher

than

resonance

the

output

of

Integralor

I

decreases

due

to C1

which

then

stops

the

oscillating

and

the

eireuit

turns

over

to

a

normal

amplifier

condition,

The

FREOUENCY RANGE

switch

seleet

a

subrange

of

the

overall

fre-

quency

range

between

0,2

Hz

and

20kHz.

The

frequeney

is

swept

through

the

subrange

by

the

FREOUENCY TUNING

potentiometer

Valid

from

serial

no.

6941

26

9.77

1-1

I

1

Technical Description

1621.1

~3

~"Frequency

Tuning"

OmV

to

-60

mV

P120

>

....

-----------------1.to

Integrator

circuit

+

6V

1

L

____________

J

(HV)

Q3

-300

mV

beLow

300

mV

p

(above

,,300

mVp)

Input

from

V

12

"

3G

ot

Y!?_-_

Ref. tor

Overloan

-mV

-300

mV

tamp

On

La

mp

On

Feedback

l

Input

t-L.}---:-----<~--{)

I

Vl

V4

I

1----------

3%~

1V~

23'100

O)VO

01

Nl

FiLter

Max

voltage

1-2

(V

9,

10 "A")

"A"

I

45

mV

to

450

mV

>

.....

;-----J~to

Integrator circuit

(V9,

10

"8")

Vl0 I

Q4

I

1

bandwith

seleetor

(V4)

cLosed

during overLoad

( 3'10

position)

Frequency

Tuning

Circuit,

Manual

The

filter

centre

frequency

is

controlled

by FREOUENCY TUNING

potentio-

meter

P120

on

the

front

panel.

The

voltage

to

the

potentiometer

is

taken

from

the

voltage

divider

R20,

R21 and P3.

The

output

of

V17

can

be

variated

between

O

mV

and

-60

mV

DC.

This

voltage

is

fed

to

the

transistor

"A"

in

the

tuning

circuit

(and

to

"A"

in

the

two

integrator

circuits).

Transistor

"A"

is

basicly

used

to

controi

the

current

to

transistor

"B"

which

acts

as a

variable

resistor

tuning

the

integrators

within

one

decade,

but

"A"

is

also

used

for

temperature

and

distortion compensation.

The

output

of

V

15

will

be

approximately

+

45

mV

to +

450

mV

DC

de-

pending

of

the

P120

position.

Sync.

from

o---

Overload

Circuit

The

input

to

the

overload

circuit

is

taken

from

the

Feedback

I.

The

over-

load is

activated

when

the

feedback is

more

negative

than

-300

mV

peak.

For

an

input

voltage

to

the

overload

circuit

more

positive

than

-300

mV

peak

the

voltages

will

be as

follows:

V14

6

(output)

will

be

-9,5

V DC.

and

the

"Overioad"

lamp

is

inac-

tive.

At

3

there

will

be

approximately

-300

mV

DC

due

to

the

resistors

R58,

R59

and

R63.

The

two

diodes

03,

04

will

not

be

conducting

When

the

input

voltage

at

2 goes

more

negative

than

-300

mV

peak,

the

output

voltage

(pin

6)

changes

to

approximately

-r

8,5

V.

The

"Overioad"

lamp

is

now

activated,

and

the

voltage

at

3

changes

value

from

-300

mV

DC to + 4

DC

due

to

the

diode

04.

C22

starts

charging

against

+

8,5

Vand

the

input

at

2

increase

as

weil

due

to

the

diode

03.

When

the

voltage

at

2

reaches

+ 4 V DC

the

circuit

switches

back

to

the

-9,5

V

DC

at

pin 6

which

switches

off

the

lamp,

and

-300

mV

DC

to

3.

Now

C22

discharges

against

-9,5

V DC.

When

the

voltage

across

C22

is

decreased

to

-300

mV

DC

the

"Overioad"

is

switched

on

again

and

a

new

cycle

takes

place.

This

function

will

be

continued

as

long

as

the

voltage

from

Feedback I is

more

negative

than

-300

mV

peak.

The

drawing

shows

the

voltage

across

C22

during

overioad.

The

signal

from

the

output

of

V14

6 to

the

bandwidth

seleetor

is

used

to

switch

automatically

the

3%

bandwidth

to

23%

during

overioad.

This

is

done

in

order

to

get

a

quicker

reaction

of

the

filter

circuit

espe-

cially

at

very

low

frequencies.

9.77

470 k

n..

R

62

-9,5V

(+8,

SV)

to

Technical

Description

1621

1

FREQ<

TUNING

Filt.r

~~nU_Q_l

____

~~

______

~

-'

Tuning

Vol

toge

rx

Auto

Ramp<

Synt

< putsos COllOlor

Gen

<

Stor!

I

Ck

Re.et

Stop

FF

from

Le

...

eL

Rtcordtr

Decoder

for

one

Decode

Frequency Tuning

Circuit,

Auto

This

circuit

will

start

paper

movement

of

alevei

Recorder,

when

SWEEP

CONTROl

is

pressed

down

to

"Start"

During

movement

of

the

paper,

sync<

pulses

will

be

applied

to

1621

These

pulses

clock

up

a

Counter,

when

the

number

of

pulses

are

equal

10

one

decades

movement

of

the

paper a

Decoder

will

reset a

Start/Stop

Flip-Flop

and

thus

the

paper

movement

will

stop<

The

output

of

the

Counter

is

also

applied

to a

Ramp

Circuit

which

will

generate

a

voltage

for

tuning

the

Filter

in

synchronization

with

the

paper

movement

9<77

Valid

from

seriaI

no<

6941

26

r

BRUEL & KJA:R

Ncerum

Denmark

Power

Supply

FilTER:

"linear"

INTERNAl BATIERY

Frequency

Tuning

Volta

ge

FILTER:

"Linear"

FREQUENCY TUNING

"r

SWEEP

CONTROl

"Manual"

DC-Off-set

Adjustment

FILTER

"23%"

FREQUENCY TUNING

"20"

SWEEP

CONTROl

"Manual"

Adjustment Procedure

1621.2

Check the

following

voltages and adjust if necessary. +

12V

±0,3V

DC.

(P113)

+

lOV

±O,l

V DC.

(Pl11)

~10V

,,0,1

V DC.

(P112)

Remove

the

connection

between

P3 and

R26

on

lE

0161.

(Marked

'F'

on

the

P.

C board)

Adjust

the voltage on

the

slider

of

P3:

-1.20V

=

0,05

V

Reconnect P3 to

R26.

Check the voltage across

P120

FREQUENCY TUNING:

66

mV ± 2 mV

If necessary

adjust

P1O

Check if the voltages are

OV

0,2

mV

DC

between

ground

on

lE

0161

and

the

following

components (pin

2)

Component

V16 V15

V6

V12

If necessary ad]ust P4 P6 P9

P8

Amplitude

Controi

FilTER to

"Linear"

FREQUENCY RANGE

"2002K"

FREQUENCY TUNING:

"10"

MAX.

VOLTAGE:

"1

V"

SWEEP

CONTROl'

"Manual"

FILTER

to

..

3%"

FREQUENCY RANGE to

"2k-20k"

FilTER to

"Z3%"

Frequency

Control,

Manual

FilTER

"3%"

FREOUENCY RANGE

"ZO-200"

FREQUENCY TUNING

"2"

MAX.

VOLTAGE:

"1

V"

SWEEP CONTROL'

"Manual"

FREQUENCY TUNING to

"20"

FREQUENCY TUNING to

"2"

9.77

Check the voltage

between

pin 2 and 3 on

V17:

OV ±

0,2

mV.

If

necessary

ad]

ust P1.

Input

signal to

"Filter

Input";

1000

Hz

adjusted

for

1 V

deflection

on an electronic voltmeter

connected to

"Filter

Output"

Fine adJust FREQUENCY TUNING

for

maximum

output

voltage.

Deflection:

1 V ±

O,6dB.

If necessary adjust P

114.

(lG

0109)

C~ange

signal frequency to

10kHz

and check the

output

voltage

Deflection:l

V

0,6

dB.

If necessary

adjust

Pl15.

(ZG

0109)

For

the

positions

of

FREQUENCY RANGE

"0.2·Z",

"Z-20",

"ZO-200"

the tolerances are

±

O,6dB,

but

no adJustments.

Check as above.

Tolerance'

0,3

dB

0,6

dB

in"2

k

20

k"range

Input

signal:

20

Hz

0,01

Hz

• 1 V

Fine

adjust

FREQUENCY TUNING

for

maximum

output,

voltage

loosen

the

knob and

turn

the

pointer

to position 2.

Change signal frequency to

200

Hz

0,1

Hz

Adjust

P5

{ZE

0161)

for max.

output

voltage

Repeat

the

above adJustments

as

they

influence

e8ch

olhers

Check the frequency

for

the

other

positions

of

FREOUENCY

RAt'<GE.

Tolerance: ± 1%

In

the

rango"Zk-20k'

the frequency can be

adjusled

by

C

118.

(ZG

0109).

Valid from serial no.

6941Z6

-

2-1

Adjustment

Procedure

1621.2

Bandwidth

Controi

FILTER:

"Linear"

FREOUENCY RANGE

"20·200

MAX.

VOLTAGE: "1

V"

SWEEP

CONTROl

"Manual"

FILTER

to

"23%"

FILTER

to "3%"

Overload

Adjustment

FILTER:

"3%"

FREOUENCY RANG

E:

"200-2k"

FREOUENCY TUNING:

"2"

MAX. VOLTAGE: "1

V"

SWEEP CONTROL:

"Manual"

Input

signal:

63.2

Hz

adjusted for 1 V on

"Filter

Output""

Frequ

Check

that

the

output

signal

is

damped mora than

15

dB

with

FREOUENCY TUNING at the po-

sitions

35.5

Hz

and

112

Hz

Check

that

the

output

signal

is

damped mora than

30

dB

WIth FREOUENCY TUNING at the

above mentioned Irequencies

Adjust

P7 for

OV

±

100mV

DC

at

the output

of

V6

Input

signal:

200

Hz, 6 V peak

Adjust

P2

to the position

where

the

"Overioad"

lamp

just

starts flashing.

Check

that

"Overioad"

start flashing at

the

voltages mentioned in

the

scheme.

Input

Frequency

200Hz

20kHz

20Hz

I I

MAX.

VOLTAGE: -

3% Output voltage:

5,5

V -

6,5

V peak

"1

V"

23%

MAX.

3°'

10

VOLTAGE:~

Output voltage: 1.1 V -

1,3

V peak

"0,2V"

23%

Noise Short circuit

"Filter

Input"

to ground.

Check the noise on

"Filter

Output"

according to the seheme

below.

Notiee! The noise should only

be

measured in the range from

DC

up to

20

kHz.

FREOUENCY TUNING

FREOUENCY RANGE I

"0,2

2"

I

"2

-

2

20"

I

"200

2k"

"2k-

20k"

MAX.

VOLTAGE

"1

V"

MAX.

VOLTAGE

"0,2V"

i3%

r---

23%

3%

r---

23%

Noise below

10

mV

Noise

below

2 mV

Noise

17mV

I Noise

3,4

mV

Distortion

FILTER:

"Linear"

FREOUENCY RANGE:

"2k-20k"

Input signal

10

kHz. 3 V RMS.

FREOUENCY TUNING:

"20"

MAX. VOLTAGE:

"1

V"

SWEEP CONTROL:

"Manual"

FILTER

to

"3%"

Check

the

distortion at

20

kHz

to be below

40

dB

at

the

1621

output.

2-2

9,77

9.77

Adjustment

Procedure

1621.2

Frequency

Controi

Auto

FILTER

"3%"

FREOUENCY RANGE

"2002k"

SWEEP CONTROL

"Manual"

MAX

VOLTAGE:

"1

V"

SWEEP CONTROL:

"Aula"

SWEEP CONTROL:

"Manual"

SWEEP CONTROL:

"Auto"

Input

signal:

200

Hz, 1 V

AdjusI

FREOUENCY TUNING

for

max. vollage on

"Filler

Oulput"

AdjuSI P201

(ZH

0159)

for max. vallage on

"Filler

Oulput".

Change

Input

FreQuency

lO

2 kHz and adjusI FREOUENCY TUNING

for

max voltage on

"Filter

Output",

Short

circuit

11 on

V202

(ZH

0159)

to ground.

Remove

the

jumper

between

R204

and R21 1

Connect a cable

for

filter

synchronization

between

Level Recorder Type

2306

and

"Sync"

on

1621.

Press SWEEP CONTROL

for

"Start"

of

sweep.

After

one decade the

"Auto"

lamp

will

extinQuish and

1621

will

remain

tuned

in

102kHz.

Adjust

P202

for max. voltage on

"Filter

Output"

Alter

adjustment

remove the

short

circuit

and

mount

jumper

belween

R204

and

R211

9.77

Valid from serial no.

6941

26

2-3

BROEL

& KJtER Layout Diagram with Parts List

ZE

0161

Nrerum -Denmark

Filter

Circuit

to P

120

-c::J-

R

--H-

c

-rL-

a

Ov

1 Electrolytic

47/JF/40V

CE

8965

R 1

Metal

1/4

W 1

,}~

249

kO

RF

5249

2 Polycarbonate

330nF/l00V

CS

0340

R 2 1

MO

RF

6100

C 3 Electrolytic

47/JFi

40

V

CE

8965

R 3

374

kO

RF

5374

C 4

10/JFi

40V

CE

0458

R 4

174

kO

RF

5174

C

5-7

Polystyrene 2

nF/

63

V

CT

1123

R 5 1

MO

RF

6100

C 8 Ceramic

2,2

pF/400

V

CK

0220

R 6 Carbon

5%

100

kO

RB

5100

C 9

15pF/400V

CK

1150

R 7 Metal

1%

1

MO

RF

6100

C

10

30

pF/400

V

CK

1330

R 8 Carbon 5%

100

kO

RB

5100

C

11

Electrolytic

100/JF/

40V

CE

0443

R 9 Metal

1%

14,3

kO

RF

4143

C

12

Ceramic

10

pF/400

V

CK

1100

R

10

Carbon

5%

820

O

RB

2820

C

13

Polystyrene 2

nF/

63

V

CT

1123

R

11

Metal

1%

14,3

kO

RF

4143

C

14

Ceramic

3,3

pF/400

V

CK

0330

R 12

487

kO

RF

5487

C 15

30

pF/400

V

CK

1330

R

13

71,5

kO

RF

4715

C

16,17

100

pF/400

V

CK

0077

R

14

Carbon

5%

100

kO

RB

5100

C

18-20

30

pF/400

V

CK

1330

R

15

820

O

RB

2820

C

21

47

nFI

30

V

CK

4470

R

16

1 MO

RB

6100

C

22

Polycarbonate

680nF/l00V

CS

0388

R

17

Metal

1%

71,5

kO

RF

4715

C

23

Trimmer

2,55

pF/400V

CV

0033

R

18,19

1

kO

RF3100

R

20

6.04

kO

RF

3604

P 1 Cermet

0.5W

lin.

22

kO

PG

3221

R

21

1,4

kO

RF

3140

P 2 1

MO

PG

5108

R

22

Carbon

5%

560

kO

RB

5560

P 3

220

O

PG

1221

R

23

Metal

1%

60,4

kO

RF

4604

P 4

100

kO

PG

4108

R

24

249

O

RF

2249

P 5

220

O

PG

1221

R

25,26

4,99

kO

RF

3499

P 6

100

kO

PG

4108

R

27

Carbon 5%

560

kO

RB

5560

P 7 1

MO

PG

5108

R

28

4,7

MO

RB

6470

P

8.9

100

kO

PG

4108

R

29.30

Metal

1%

4,99

kO

RF

3499

P

10

2.7

kO

PG

2207

R

31

332

O

RF

2332

R

32

Carbon 5%

820

O

RB

2820

Q

1,2

Silicon

BAX13

50

V/ISO

mA

av

0223

R

33

Metal

1%

27,4

O

RF

1274

Q

3,4

lN4004

400

V/

1 A av

0237

R

34

90,9

kO

RF

4909

Q 5

BAX13

50

V/150

mA

av

0223

R

35

9,09

kO

RF

3909

Q

6,7

Zener

lN825

5,9-6,5

VI

0,4

W av

1346

R

36

27,4

O

RF

1274

R

37

90,9

kO

RF

4909

R

38

9,09

kO

RF

3909

R

39

27,4

O

RF

1274

R

40

90,9

kO

RF

4909

Continued

1621

from serial no

694126

9.77

BRUEL & KJAER 1621 User manual

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