JVC KD-A11 User manual

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MODEL

KD-A11

A/B/C/E/J/U

STEREO

CASSETTE

DECK

No.

4192

June

1980

KD-A11A/B/C/E/J/U

Contents

Page

SPECIE

CATIONS

55

5-5

cok

Bars

4a

fae

Ses

ress

Seca

Sh

eR

Fae

BO

RR

Gd,

wee

det

Rae

oe

a

Starla

ah

dors

eats

2

F@AtUres

i.

gag

5

ote

het

rsel

e

e

Se

het

iw

Sg

Weptncas!

eyecare

ose

ead

ev

hes,

te

ea

edde

sd

was

wPensiya

alone:

Bones

eae

ye

3

Controls'and

Comnections:s

s/s:

0:30

%s.

si6!

9%

ores

aie:

wh

8

av

eee:

whe

eed

ae

Be

Ne

ae

Avenel

eee

ele

we

Oba,

8

Sie

anar

wes,

Aes

3

Mairi

Parts

Locations

i.-c.

5

Soe

dondeet

etd aie

ered.

ee

ol

eee

ws

Boh

al

stele

rela

Pieter

tee

sak

a

ee

ee

oe Ge

4

Wa

iri

teria

Ce

i

osteo

Sic

Se

ain

cae

ah

aw

aes

wie

Sica

ontee

0

AS

caw

stn

Sadan

es

BAM

Soe

wr

cues

MUR

abe

>

hdd

Dore

Mebane

5

Removal:

of

the

Main.

Parts:

36065.

6

65

8

aie

ae

ee

oo

8

aw

Se

eb

ere

Blas,

wk

RE

ieca

&

@

pele

eee

ene

5

Mair

Adjustment

sic.

g.5:

3:55,

c5.d55

ce

coe

p

Syagasee

oar

ee

bb

wale

ole

See

enh

ersten

dg

cedteisbte

ued

aa

ow

we

ewe,

mie

Sees

9

[niteatant:

Circuits

io

c:o

ss.

g

cece

eis

ead

ie

aes

ee

A

Are

eee

EASE

tae

white

et

SG

13

Block

'Diagranny

ses

sresin

yo

Giaee

ceases

fone

hore

aceves

tne

vel

Tegel

gaa

Ricudse

ay

lees

Glatace

eed

duasae

a,

Pelle

oeeaa

4

14

Wiring

CONMOCHORN

G6

scic

eek

eee

cee

Se

Ee

aerate

Be

NSE.

wy

cece

elle

te

hd!

SPaeeaw

oe

Sesh

ele

ig

iceeteg

aboa

te

6

15

Standard

Schematic

Diagram...

2...

0.0.6.

ee

eee

eee

te

ee

ee

ete

16

Mechanical

Component

Parts...

.......

0.0

eee

ee

ee

ee

ee

eee

ee

tee

e

ee

nee

eae

17

Mechanical

Component

Parts

List...

........

2c

eee

ee

ee

ee

ee ee ee

ee

eee

eee

ee

18

Enclosure

Assembly

and

Electrical

Parts

List

..........

000

eee

eee

ee

tet

eee

eee

eee

nes

21

Enclosure

Assembly

and

Electrical

Parts

........

0.

cc

ee

ee

ee

ee

ee

eee

ee

23

Main

Amp

P.W.

Board

Parts.

........

0c

cee

enc

tc te et

tet

et ee

ene

we ee

ene

ease

rest

eesene

24

Main

Amp

P.W.

Board

Parts

List...

2...

2.

2

ee

eee

ee

ee

ees

25

Other:

P.W..

Board

Parts:

ists:

e's

cox.

4

assed

Sete

ear

ogo

eae

ee

eee

a

eho

Satay

hs

le

Ace

ad

BG

Sg

ab

eae

28

Packing,

Packing

Material

List.

0...

ce

cc

cc

we

eee

abet

ee

eee

sete

deena

ecceceas

28

AINGCESSOM

GSS»

57552

ono

69

ela

latte

Gy

oo

eee

epee

le

ee

hse

a

ayeie

abe

eaten

acaba

colin

liner

evade:

Ai.che

a

bay

Sine

aban

oars

29

Specifications

Type

Track

system

Tape

speed

Frequency

response:

(O

VU

recording)

Metal

tape

SA/Chrome

tape

SF/Normal

tape

(-20

VU

recording)

Metal

tape

SA/Chrome

tape

SF/Normal

tape

:

Stereo

cassette

deck

:

4-track,

2-channel

:

1-7/8

inch/sec

(4.8

cm/sec)

*1

;40-11,000

Hz

(+3

dB)

*2;40-8,000

Hz

(+3dB)

*3

;40—8,000Hz

(+3

dB)

*1

;30—16,000

Hz

40—15,000

Hz

(+3

dB)

*2

;30—16,000

Hz

40—15,000

Hz

(+3

dB)

*3

;30—15,000

Hz

40-—14,000

Hz

(+3

dB)

Surpasses

DIN

45

500

Note:

*1...

SCOTCH

METAFINE

or

Equivalent

*2....

TDK

SA

or

Equivalent

*3

...

MAXELL

UD

or

Equivalent

S/N

ratio

Wow

and

flutter

Crosstalk

Harmonic

distortion

Bias

Erasure

Heads

No.

4192

:

60

dB

(from

peak

level,

weighted,

Metal

tape)

The

S/N

is

improved

by

5

dB

at

1

kHz

and

by

10

dB

above

5

kHz

with

DOLBY

N.R.

on

(DIN

45

500

weighted)

:

0.05%

(WRMS),

0.15%

(DIN

45

500)

:

65

dB

(1

kHz)

:

K3;

0.5%,

THD;

1.0%

(metal

tape,

1

kHz

0

VU)

:

AC

bias

:

AC

erasure

:

2

heads

METAPERM

head

for

recording/

playback

and

2-gap

ferrite

head

for.

erasure

Motor

:

Fast

forward

time

:

Rewind

time

Semiconductors

Input

terminals

Mic

jack

x

2

:

Input

jackx2

;

Output

terminals

Output

jack

x

2;

Phones

jack

x

1

;

DIN

socket

Power

requirement

:

Power

consumption:

Dimensions

Weight

Electronic

governed

DC

motor

95

sec.

with

C-60

cassette

95

sec.

with

C-60

cassette

3

1Cs,

21

transistors,

17

diodes

1

LED

Max.

sensitivity;

0.2mV

(-72

dBs)

Matching

impednace;

6002

—

10k2

Min.

input

level;

80mV

(-20

dBs)

Input

impedance;

100kQ2

Output

level;

300mV

Output

impedance;

5kQ

Output

level;

0.3mW

(822)

Matching

impedance;

BQ

—

1kQ

Min.

input

level;

0.1mV/kQ

Input

impedance;

10kQ

Output

level;

380mV

Output

impedance;

5kQ

AC

240V,

50Hz

(KD-A11A)

AC

240/220/120V,

50/60Hz

(KD-A11

B/C/E/J)

AC

240/220/120/100V,

50/60

Hz

(KD-A11U)

10W

16-1/2"

(420

mm)W

5-1/4"

(134

mm)H

10-3/8"'(264mm)D

9.9

Ibs

(4.5

kg)

Design

and

specifications

are

subject

to

change

without

notice.

me

ee

an,

KD-A11A/B/C/E/J/U

Features

@

Single

lever

4-stage

tape

select

switch

makes

the

KD-A11

are

assured

through

employment

of

IC-built

circuitry.

compatible

with

all

types

of

tape

including

the

new

(Dolby

”*

is

trademark

of

Dolby

Laboratories

Inc.)

metal

Tape

format.

(else

Reduction

System

manufactured

under

Rees)

®

{C-built

Dolby*

Noise

Reduction

System

from

Dolby

Laboratories

Inc.

Dolby

System

greatly

improves

performance

by

cutting

@

METAPERM

head

for

recording/play

back

out

tape

hiss,

without

changing

the

original

music,

thus

2

Gap

ferrite

head

for

erasure

making

it

every

bit

as

good

as

professional

standard

type

©

Automatic

input

select

open

reel

tapes.

High

reliability

and

optimum

quality

Controls

and

Connections

°0

@e8

®@

tweninecy

—

FEC/PLAY

we

outipcay)

R

L

@@O

WU

meters

®

Cassette

operation

buttons.

@

Recording

indicator

(REC)

@4

STOP/EJECT

button

@

Cassette

holder

<<)

REWIND

button

@

Tape

COUNTER/counter

reset

button

oO

Record

button

(REC)

@

POWER

switch

>»

PLAY

button

@

PHONES

jack

>>

FF

button

@

MIC

jacks

1

PAUSE

button

@

REC

LEVEL

controls

@®

Voltage

select

switch

(KD-A11

B/C/E/J/U)

@

TAPE

SELECT

switch

@®

LINE

IN

(REC)

terminals

@

Dolby

noise

reduction

switch

(DOLBY

NR)

@®

DIN

(REC/PLAY)

socket

@®

LINE

OUT

(PLAY)

terminals

@

Power

cord

SAR

us

No.

4192

~

KD-A11A/B/C/E/J/U

Main

Parts

Location

)@

@)

4)

No.

4192

Flywheel/capstan

belt

Auto

stop

solenoid

Motor

Recording

indicator

P.W.B.

Meter

cover

Remote

bar

Power

switch

P.W.B.

Main

Amp

P.W.B.

Recording

spring

Power

Transformer

.

Oiled-gear

damper

assembly

.

Reed

switch

P.W.B.

OANOAIPWNH>

-_—

—

—

N=

(Mechanical

parts)

1.

Pinch

roller

arm

assembly

2.

Pinch

roller

spring

3.

REC/PB

Head

4.

Erase

Head

5.

Pause

switch

6.

Flywheel

7.

Motor

switch

8.

Take

up

reel

disc

ass’y

9.

Supply

reel

disc

assy

10.

Recording

safety

lever

11.

Take

up

idler

assembly

12.

Stop/eject

bar

assembly

13.

Rewind

bar

assembly

14,

Recording

bar

assembly

15.

Play

bar

assembly

16.

Fast

forward

bar

assembly

17.

Pause

bar

assembly

18.

Motor

19.

Flywheel/Motor

bracket

oon

Maintenance

To

get

long,

trouble-free

service,

maintenance

is

important.

Do

not

forget

cleaning

and

demagnetizing.

Cleaning

After

long

use,

the

heads

and

tape

part

—

capstan,

pinch

roller,

etc.

—

will

become

dirty

with

dust

or

magnetic

particles.

Dirty

heads

cause

imperfect

erasing

or

high

frequency

drop-off.

A

dirty

capstan

and

pinch

roller

will

cause

unstable

tape

speed,

leading

to

increased

wow

and

flutter.

Always

keep

them

clean

by

following

the

procedure

below.

1.

Heads

1)

Push

Eject

button

to

open

the

cassette

holder.

2)

Use

the

head

cleaning

stick

provided

to

wipe

the

surface

where

the

tape

comes

into

contact

with

the

head.

(It

is

effective

to

moisten

the

cotton

with

alcohol.)

2.

Pinch

rollar

and

capstan

Do

the

same

method

as

heads.

3.

Cabinet

When

the

cabinet

becomes

dirty,

wipe

it

with

a

soft

cloth

soaked

with

a

neutral

cleaning

solution

of

a

polishing

cloth.

*

Do

not

use

thinner

or

benzine.

1

KD-A11A/B/C/E/J/U

Demagnetizing

The

heads

are

made

from

a

material

resistant

to

magneti-

zation,

but

after

long

use

they

become

magnetized.

A

magnet

brought

into

their

vicinity

can

magnretize

the

heads,

causing

excess

noise.

if

noise

seems

to

have

increased,

demagnetize

the

heads

with

a

head

demagnetizer

through

the

following

procedure.

1.

Turn

the

POWER

switch

OFF.

2.

Wrap

the

tip

of

the

demagnetizer

with

viny!

tape

or

soft

cloth

so

as

not

to

damage

the

head

surface.

Switch

on

the

demagnetizer

and

bring

it

close

to

the

head.

3.

Move

the

tip

of

the

demagnetizer

slowly

first

to

the

left

and

right,

then

up

and

down

in

front

of

the

head.

Gradually

move

it

away

from

the

head

and

switch

it

off

at

a

distance

of

more

than

30

cm.

(12”)

4.

The

erase

head

need

not

be

demagnetized.

The

capstan

shaft

and

tape

guide

should

be

demagnetized

in

the

same

way

as

the

record/playback

head.

Do

not

bring

a

magnetized

metallic

object

(a

screw-

driver,

for

example)

near

the

head

as

this

will

increase

noise.

Removal

of

the

Main

Parts

Observe

care

in

handing

the

parts

since

the

parts

are

small

in

size

and

the

distance

between

them

are

short

due

to

a

deck

design

aimed

mainly

at

compactness

and

high

performance.

Screw

(1)

Lever

Knobs

Control

Knobs

ENCLOSURE

ASSEMBLY

PARTS

Cassette

lid

..........

1)

To

open

the

cassette

lid,

push

on

the

eject

lever.

Remove

a

screw

(1)

fastening

the

cassette

lid.

(its

right

low

side)

Be

careful

of

holding

a

nut.

2)

Pull

off

the

cassette

lid

to

upper

side.

TOP

Cover

.......0-

Remove

6

screws

(left

and

right

.....

3

screws

(2)

on

each)

Control

knobs

(REC

LEVEL)

..........

Pull

off

them

to

forward.

Lever

knobs

(TAPE

SELECT,

DOLBY

NR)

.........-

Pull

off

them

to

forward.

Bottom

cover

..........

Remove

3

screws

fastening

the

bottom

cover.

(center

screw

is

long

size.)

Remove

the

bottom

cover

from

3

pawls

of

mold

chassis.

=

No,

4192

KD-A11A/B/C/E/J/U

|

Front

plate

assembly

..........

Remove

5

screws

(3

screws

(3)

on

upper

side

and

2

screws

(4)

on

bottom

side.)

fastening

the

front

plate

assembly.

(Top

View)

(Bottom

View)

Screws

®

This

screw

is

fastened

with

same

as

earth

wire.

Front

panel

assembly

1.

Remove

a

screw(S)

fastening

the

button

escutcheon

ass’y

(left

side)

2.

Open

the

cassette

holder,

and

remove

a

screw

fastening

the

arm

ass‘y

for

oiled-gear

damper.

3.

Remove

4

screws

(6)

fastening

the

front

panel.

(left

and

right

.....

2

screws

on

each)

4.

Remove

a

washer

and

a

nut

@)

fastening

the

REC

LEVEL

control

VR

shaft.

5.

Remove

a

screw

(8)

fastening

the

lever

switch

on

main

amp

P.W.

Board

ass’y.

(Mechanical

assembly

is

removed

with

the

same

as

front

panel.)

Screws

@)

Washer

and

nut

Screw

Screw

()

MECHANICAL

ASSEMBLY

1.

Remove

the

counter

belt

from

counter.

2)

Remove

4

screws

(Q)

fastening

the

front

plate.

2.

Remove

4

screws

(Q)

fastening

the

front

panel.

(When

assembling

the

mechanical

control

plate,

it

need

a

new

parts

=

the

mechanical

control

plate

cannot

use

If

you

remove

the

mechanical

assembly

with

not

removed

the

front

panel,

do

the

following

method.

1)

Remove

the

mecha

control

plate.

again.)

Screws

@)

Screws

(9)

No.

4192

a

Aten,

ELECTRICAL

PARTS

(Main

amp

P.W.

Board

ass’y)

1)

Remove

a

nut

and

a

washer

fastening

the

REC

LEVEL

control

VR

shaft.

2)

Remove

a

screw

fastening

the

lever

switch.

3)

Remove

3

screws

fastening

the

main

amp

P.W.

Board.

Koa

1A/B/C/E/S/U

4)

Remove

2

plastic

rivets

fastening

the

PIN

jack

assembly.

5)

Remove

the

record

spring.

6)

Remove

4

pawls

for

holding

the

main

amp

P.W.

Board.

Plastic

rivet

paw!

=>

Recording

spring

(Top

View)

@

Supply

disc

assembly

Stop

cover

Take

up

disc

assembly

Lock

bush

Take

up

sping

Gear

base

E

Head

REC/PB

Head}

Pinch

roller

arm

ass‘y

(Front

View)

Take

up

idler

arm

ass’y

:

Ee

Screw

.

=

MECHANICAL

PARTS

1.

REC/PB

head

..........

Remove

a

screw

(1)

Remove

a

screw

(2)

for

adjustment.

2.

Erase

head

..........

Remove

a

ea

Remove

a

screw

()

for

adjustment.

3.

Pinch

roller

arm

ass’y

..........

Remove

an

E-ring

®

holding

its

assembly.

Pull

it

off

from

the

shaft.

4.

Supply

reel

disc

..........

Pull

out

the

reel

disc

stopper

©

and

pull

out

its

disc

from

shaft.

5.

Take-up

reel

disc

..........

Pull

out

the

ree!

disc

stopper

@)

and

remove

the

counter

belt,

pull

out

its

disc

from

shaft.

Note:

(1)

Remove

the

reel

disc

stoppers

with

a

piece

of

sheet

metal

inserted

between

the

reel

disc

and

the

stopper.

(When

assembling

the

reel

disk,

the

stopper

need

a

new

parts.

(the

stopper

can

not

use

again.)

(2)

Be

careful

not

to

stain

the

counter

belt.

No.

4192

KD-A11A/B/C/E/J/U

(8)

Screws

Rubber

stopper

\

aT

Set

screw

dQ

Screws

(Rear

View)

9?

3

screw

es

3

cushions

1.0mm

+£0.2mm

Gear

frame

ass‘y

aa

Brake

drum

a

Rack

plate

~

E

(4)

@—

Of

a

No.

4192

,

o

D

assy

Flywheel

assembly

1.

Remove

3

screws

(8)

and

a

set

screw

(Q)

fastening

the

flywheel

and

motor

bracket.

2.

Remove

a

capstan

belt.

3.

Remove

3

screws

fastening

the

capstan

metal.

4.

Remove

the

pressure

lock

bushing

and

the

take

up

spring

on

front

side,

and

then

remove

the

take

up

idler

arm

assembly.

5.

Remove

the

pressure

position

of

stopper

cover,

and

move

the

gear

base

to

supply

disc

direction,

and

then

remove

the

gear

base

tip

from

the

groove

of

capstan

metal.

6.

Pull

off

the

flywheel

assembly.

Note:

When

assembling

the

flywheel,

fasten

the

screws

after

assembled

the

chassis

to

the

groove

of

capstan

metal.

Motor

1)

Remove

a

screw

fastening

the

rubber

stopper.

2)

Remove

the

capstan

belt

from

the

motor

pulley.

3)

To

remove

the

motor,

turn

it

in

counter-

clockwise

direction

and

pull

it

out

backward

(with

3

cushions

and

3

screws

for

fastening

the

motor).

Note:

When

replacing

the

motor,

check

the

following

points.

(1)

Is

the

motor

placed

in

correct

position?

(Don’t

make

the

motor’s

position

deflective.)

(2)

Does

the

capstan

belt

run

in

the

center

of

the

motor

pulley?

DOOR

BRAKE

AND

ITS

RELATED

PARTS

1.

Gear

frame

ass’y

.......

2.

Brake

arm

and

tire

spring

@.

3.

Spur

gear

and

brake

drum

spring

@).

4.

Rack

plate

.......

Remove

the

screw

and

the

collar

@).

5.

Brake

lever

ass’y

.......

Remove

the

E-ring

©.

Remove

a

screw

@.

wasters

Remove

the

E-ring

and

torsion

Remove

the

E-ring,

and

PB,

etn

Main

Adjustments

[1]

1.

[11]

Equipment

and

measuring

instruments

used

for

adjustment.

Electrical

adjustment

1)

Electronic

voltmeter

2)

Audio

frequency

oscillator

(range;

50-20

kHz

and

output

0

dB

with

impedance

600

&2)

3)

Attenuator

4)

Standard

tapes

for

REC/PB

SONY

CS-30

—

FeCr

tape

BASF

T308S

—

NORMAL

tape

BASF

C401R

—

CrO2

tape

SCOTCH

METAFINE

—

METAL

tape

5)

Reference

tapes

for

playback

(JVC

Test

Tape)

VTT-658

(for

head

azimuth

adj.)

VTT-656

(for

motor

speed,

wow

flutter

adj.)

VTT-664

(for

Reference

level

1

kHz)

VTT-675N

(for

playback

frequency

response)

6)

Resistors

100

22

(for

measurement

of

the

bias

current)

600

{2

(for

attenuator

matching)

or

equivalent

.

Mechanical

adjustment

1)

Gauge

for

checking

the

head

position.

2)

Torque

gauge

3)

Blank

tape

(C-120)

for

tape

running

checker.

Adjustment

and

repair

of

the

mechanism

Audio

Freq.

Osc.

La

KD-A11A/B/C/E/J/U

Electronic

Voltmeter

_,

Attenuator

oe

S304

“13

6000

OUT/PUT

(Adjust

the

mechanism

or

confirm

that

it is

in

normal

Operating

condition

prior

to

the

adjustment

of

the

electrical

circuit.)

Adjusting

record/

playback

head

position

Adjusting

erase

head

height

.

Connect

an

electronic

voltmeter

to

the

LINE

OUT

terminals.

2.

Play

back

the

VTT-658

test

tape.

3.

Adjust

the

head

angle

with

the

screw

(@)

until

the

reading

of

the

electronic

voltmeter

becomes

max-

imum

for

both

channels.

4.

After

adjusting,

set

the

screw

with

screw

bond.

Tape-to-head

contact

adjustment

1.

Turn

the

adjusting

screw

for

aligning

the

erase

head

until

it

stops.

Then,

turn

the

screw

in

the

re-

verse

direction

by

180°

(a

%

revolu-

tion).

2.

Employ

a

special

cassette

(C-120)

©

from

which

parts

to

the

casing,

where

the

erase

head,

record/play

back

head

and

capstan

engage,

has

been

cut

away.

Perform

tape

trans-

port

with

the

cassette

tape.

Adjust

the

screw

until

the

tape

runs

in

the

center

of

the

egase

head

tape

guide.

3.

Check

it

again

with

a

BASF

C401R-

CrOQ2

tape.

Checking

method:

Record

a

400

Hz

or

1

kHz

signal

with

OVU+20dB.

Erase

the

record-

ing.

Check

if

the

erasing

is

satisfac-

torily

performed.

4.

After

adjustment,

apply

screw

bond

on

the

adjusting

screw

to

prevent

its

loosening.

Proper

Tape

guide

EF

Improper

ct

Screw

®

Maximum

|

1.

If

the

head

is

worn,

disconnected

or

exceedingly

magnetized

so

as

not

to

provide

the

necessary

characteris-

tics,

replace

it

with

a

new

one.

After

replacement,

the

head

posi-

tion

adjustment

as

well

as

the

play-

back

level

adjustment,

the

bias

cur-

rent

adjustment

and

the

recording

level

adjustment

are

all

necessary.

2.

If

the

output

difference

between

the

left

and

right

channels

exceeds

3—4

dB,

the

head

is

defective.

Replace

it

with

a

new

one.

Be

sure

to

perform

this

adjustment

after

replacing

the

erase

head.

KD-A11A/B/C/E/J/U

|

Adjusting

|

Standard

point

value

Adjusting

motor

Connect

a

speed

meter

to

the

LINE

Semi-fixed|

3000

Hz_

|

If

the

speed

meter

functions

as

a

wow

speed

OUT

terminals.

Play

back

the

VTT-

resistor

in

and

flutter

meter,

also,

connect

the

656

test

tape

Adjust

the

semi-fixed

the

motor

deck

to

the

INPUT

terminals

of

the

resistor

in

the

motor

until

the

read-

meter.

ing

of

the

speed

meter

is

3000

Hz.

Checking

play-

Employ

a

torque

testing

cassette

tape

If

the

standard

torque

is

not

obtained,

back

torque

for

the

checking,

or

remove

the

cas-

replace

the

take-up

reel

disc

assembly.

sette

cover

and

use

a

torque

gauge.

Checking

fast

Measure

the

torque

in

the

fast

forward

More

than

|

If

the

standard

torque

is

not

obtained,

forward

torque

mode

in

the

same

manner

as

in

the

80

gr-cm

|

perform

the

following.

above.

1.

Clean

the

capstan

belt,

the

idler

cir-

cumference,

the

motor

pulley,

the

take-up

reel

disc

circumference,

the

flywheel

circumference,

etc.

.

Replace

the

capstan

belt

or

idler

ass’y.

Checking

rewind

Measure

the

torque

in

the

rewind

More

than

|

If

the

standard

torque

is

not

obtained,

.

torque

mode

in

the

same

manner

as

in

the

80

gr-cm_

|

clean

the

capstan

belt,

idler,

motor

above.

pulley,

flywheel

circumference,

supply

reel

disc

circumference,

etc.

[111]

Repair

of

wow

flutter

If

wow

and

flutter

increase,

check

the

following

points.

If

tions.

there

is

defect

in

revolving

parts,

the

wow

and

flutter

gener-

Play

a

3000

Hz

test

tape,

and

defective

part

can

be

detected

ated

will

increase

in

proportion

to

the

number

of

revolu-

from

the

sound.

Replace

flywheel.

Clean

the

capstan

shaft

in

the

flywheel.

Replace

the

capstan

assembly.

Capstan

shaft

has

excessive

run-out.

Flywheel!

turns

heavily.

(shaft

seisure,

thrust

play,

etc.)

Pinch

roller

Rough

rotation

(Deformation

scratches,

|

Replace

pinch

roller,

or

pinch

roller

spring.

or

dust)

Clean

the

pinch

roller.

The

angular

position

of

the

pinch

roller

|

Adjust

the

pinch

roller

so

that

it

is

parallel

with

the

capstan

shaft.

is

not

correct.

The

pinch

roller

pressure

is

not

correct.

Belt

Belt

has

undue

run-out.

Check

the

belt.

Belt

is

dirty

or

slippery.

Replace

the

belt.

Back

tension

|

Back

tension

is

irregular,

or

back

ten-

Replace

back

compression

spring

(under

supply

disc).

sion

is

too

strong.

Motor

Motor

shaft

has

undue

run-out.

Replace

motor.

Motor

pulley

is

oily

and

dustry.

Clean

motor

pulley.

Capstan

and

flywheel

No.

4192

—10—