Jvc KD-A77 Service Manual

JVC

MODEL

KD-A77

STEREO

CASSETTE

A/B/C/E/J/U

DECK

No.

September

4186

1979

KD-A77A/8/C/E/J/U

Contents

r-

Erasure Heads

No.4186

Specifications Features Controls and Connections

Main Parts Location Maintenance New

Technique Removal Main

Adjustments Block Diagram Integrant Circuit Standard Schematic Diagram

Amplifier Mecha. control

Wiring

Connection

.........................................................

..................................................................

..........................................

...................................................

............................................................

of

......................................................

the Main Parts

...................................................

......................................................

circuit

(1

..........................................

of

................................................

..........................................

)

of

KD-A 7 7

KD-A

..............................

Specifications

Type Track

system Tape speed Frequency response

OVU

Metal

tape

SA/Cr02

-20VU

Metal SA/Cr02 SF/Normal tape

SIN ratio

Effect

Improvement Improvement

Improvement

Wow Crosstalk

Hormonic Bias

tape

of

Super ANRS : (normal tape)

of

and

flutter

distortion

SIN : the same

frequency response

distortion

Stereo cassette 4-track,

1-7/8

25-12500Hz 25

15-20000Hz

*

1

25 15-20000Hz

*2

2515-19000Hz

*

3

25-17000Hz Surpases DIN 60dB (from peak level, weighted, Metal tape)

The SIN is improved by 5dB

1 kHz and by with (DIN

:

OVU

+

5VU recording; 12dB at 10kHz

OVU

+

5VU recoridng;

0.04%

0.14% 65dB K3;

(metal tape, 1 kHz OVU) AC bias AC erasure 3 heads SEN SEN

playback and ALLOY head

2-channel

inch/sec

-

8000Hz

-1

8000Hz

1

8000Hz

ANRS on. 45

500

as

recording; 6dB

recording;

(WRMS), (DIN

(1

kHz)

0.4%, (85kHz)

ALLOY head ALLOY X

77

deck

(4.8

cm/sec)

±3dB(Typical)

± 3dB(Typical)

± 3dB(Typical) ± 3dB(Typical) ±3dB(Typical)

45

500

10kHz

at

for

SEN

at

10kHz

10dB

above 5kHz

weighted)

with

ANRS

at

3 % or less 3 % or less at 10kHz

45

500)

THD:

1.0%

(85kHz)

for

recording,

cut

type

two-gap

for

erasure

2

Wiring Connection (2)

3

Enclosure

3 4 4 5 6

1 0 16 18

1 9 20 21

- 2 -

Mechanical Components Parts

Printed Wiring Board Parts Main Power Supply P.W. Board Parts

Main Power

Other

Other Packing Accessories

Motors

Fast Rewind Semiconductors

Input terminals

Output

Power requirement

Power consumption Dimensions

Weight

Note:

Design and specifications are subject notice.

Ass'y

Enclosure Mechanical

Amp.

P.W.B Parts

P.

......................................................

forward

time

terminals

*

1 ... SCOTCH MET AFINE or Equivalent

*

2 ... TDK SA or Equivalent

*

3 ... MAXELL

and Electrical Parts

Ass'y

Components

P.W. Board Parts

P.

W.B

Supply P.W.B Parts List

W.B

...................................................

Parts List

................................................

time

of

KD-A77

and Electrical Parts List

Parts List

FG Capstan) DC 85 85

1 8 ICs, diodes, Mic jack x

Max. sensitivity; Matching impedance;

Input jack x

Min. input level; Input impedance;

Output

Output Output Matching impedance:

Phones jack x 1,

Output

Matching AC AC

AC 36W

17-3/4"

4-3/4"

12-7/16"

18.3

UD

or Equivalent

..............................

...........................

.................................

Parts List

....................................

.......................................

type

motor sec. sec.

120V,

240/220/120V, 240/220/120/1

50/60Hz

Ibs

........................

.................................

..............................

DC

servo

(for

Reel)

with

C-60

with

C-60

49

transistors,

14

LEDs

2,

0.2mV 6000-10kO

2,

80mV

jack x

2,

level;

0-300mV

impedance; 6kO

50kO or more

level;

0-0.5mW/SO

impedance:

60Hz

(KD-AnCW

(450

mm) W

(120

mm) H

(316mm)D

(8.3

kg)

to

change

..................

Back cover Back cover

motor

(for

cassette cassette

59

(-72dBs)

(-20dBs)

100kO

80-1

50/60Z

(KD-A

n

A/B/E)

OOV,

(KD-A77U)

without

22 25 23 26

28

33 34 30 35 37

39

kO

Features

1. 3

SA

(SEN-ALLOY) heads Combined heads make possible record monitoring. The erase head is a 2-gap head also made

2.

Two-motor This mechanism incorporates a Tension

with

3.

Self-illuminated

operation (excluding STOP or REC-MUTE modes.)

4.

Three position Metal-Tape-Compatible tape select

switch. METAL - FeCr _

(Automatic

5. The mechanical operation

SA

(SEN-ALLOY) record/play (X-cut type)

ID (independent Drive) mechanism

the

REC

system head.

switching

MUTE

which

gives improved tape

buttons

SA/Cr02

button

for

NORM

between

is at

buttons.

from

SA

(SEN-ALLOY).

newly

developed Back

full logic mechanical

SA/Cr02

the

right side

contact

and NORM)

of

the

6.

7.

8. Recording equalizer

9.

10.

11.

12.

13.

Controls and Connections

KD-An

ANRS

which

reduces tape hiss

which

and Super ANRS quencies are incorporated. MEMORY/AUTO

Timer

standby playback using an Geared and oil-damped cassette holder. New

Metal-Tape-Compatible dicators together coverage tion

easier.

OUTPUT volume (for LINE and HEADPHONES use)

Remote control terminal (for trol

unit

capability

(+

9dB,

with

back-lit VU meters

from + 7VU

- R-30E).

improves linearity

REW

switch

AC

timer.

+ 6dB, +

to -20VU,

to

for

automatic

multi-peak

3dB,

the

optional remote

an

inaudible level

-2dB, -7dB).

with

the

make level observa-

A/B/C/E/J/U

at

high fre-

recording or

level in-

expanded

con-

1.

VU

meters and

2.

INPUT LEVEL control

3.

TAPE

indicators

4.

ANRS/Super ANRS indicators

5.

Cassette holder

6.

MEMORY/AUTO REW

7.

Tape counter/counter reset

8.

EJECT

9.

10.

11.

12.

13.

14.

15. 1

6.

button

TIMER STANDBY

PHONES MIC jacks INPUT SELECT

ANRS

switch

TAPE

SELECT

REC

EQ

OUTPUT LEVEL

switch

Multi-point

switch

jack

switch

control

10

11

12

20

==

r-

==

'-

peak level indicators

switch

button

14

21

. .

2 3

15

n

LJ

4

16

17

22

[f]

23

~1

-[

•

1 7. MONITOR 1 8. Cassette Operation

~~

REW

~~

FF

(fast

~

PLA Y

• STOP o

REC

11

PAUSE REC

19.

POWER

20.

Power

cord

21.

Voltage select

22.

REMOTE CONTROL

23.

LINE

IN

24.

LINE OUT (PLAY) terminals

5

18

24

~

switch

(rewind)

forward)

button

switch

terminals

r

I

r~:f

(record)

MUTE

switch

(REC)

buttons

button

socket

6

19

(KD-A

77

A/B/E/U)

- 3 -

No.4186

KD-A77

A/B/C/E/J/U

Main Parts Location

2 3 4 5 6

7

9

1.

2.

3.

4.

5. Variable resistor (INPUT LEVEL control) 5. Take-up reel

6.

7.

8.

9.

10.

11.

12.

13.

Other Please refer

Maintenance

To Do

Cleaning

After etc. -will Dirty drop-off. A dirty unstable Always

1.

Heads

1)

Push the EJECT

2)

Push

3)

Use

the

(it

2.

Pinch roller and capstan

Close ed. Press partment cleaning of

oop"an.

No.

4186

Front

panel assembly DC solenoid Reel

motor

Geared and oil-damped brake Meter

LED P.W. Board Hall

element Power Power

Remote Pin

jacks

Mecha.

mechanical parts are

get

long, trouble-free service,

not

forget

long,

heads cause

tape speed, leading

keep

up

the

tape

is

effective

the

cassette

the

and

stick

the

cassette

for

playback

cover

ass'y

P.W. Board switch transformer

control control

to

the

become

them

the

head cleaning

comes

socket

ass'y

P.W. Board

the

service manual 0

cleaning and

heads and tape

dirty

imperfect

capstan and pinch roller

clean

button

transparent

into

to

moisten

holder

tape

detection

set

the

deck

into

the

hole on

holder and clean

ass'y

(DIN

the

demagnetizing.

part

with

dust

to

by

following

to

open

cover

stick

contact

the

with

its

pin inside

in

the

~~:,"'h

~.~

Cleaning stick

ass'y

socket)

ass'y

same

as

location

KD-A6

maintenance

- capstan, or

magnetize

erasing

increased

to

or

the

cassette

to

remove

wipe

the

with

the

cotton

with

transparent

the

playback

right

side

the

high

wow

procedure

surface

head.

cassette

mode.

at

pinch roller and

"",,

of

model

A/B/C/E/J/U

is

important.

pinch

roller,

particles.

frequency

will

cause

and

flutter. below.

holder.

it.

where

alcohol.)

cover

remov-

com-

Insert

the

bottom

(Mechanical parts)

1.

Switch

2.

Supply

3.

Idler

4.

Reel

6.

Switch

7.

Connecting

8.

Capstan

9.

Slide base

10.

Stad

11.

Erase head

12.

Combined

13.

Pinch roller

KD-A6:

(No.

4179

- page

3.

Cleaning the cabinet and panel

Wipe

the a neutral cleaner. Do other

strong

surface

Demagnetizing

The heads are made tion,

but

magnet causing excess noise. demagnetize the

following

1.

Turn

2.

Wrap cloth the

demagnetizer

3.

Move and Gradually at a distance

4.

The shaft same

* Do

not

for

example) near

Oiling

Feed one or once

or

Avoid

oiling

regular because

- 4 -

1 1

holder (U

reel

ass'y

motor

ass'y

holder

ass'y

with

pad (for

SA

4).

cabinet

solvents,

finish

of

after

long use

brought

the

procedure.

the

POWER

the

tip

of

so as

not

the

tip

right,

then

move

erase head need

and

tape

way

as

bring a magnetized metallic

two

twice

a year

them

1 2 1 3

ass'y

(R)

wire

(for play solenoid)

back

tension)

(SEN-ALLOY) record/play heads

ass'y

and panel clean

not

use thinner, benzine,

as these

the

cabient

from

into

their

heads

switch the to

damage

and bring

of

the

up and

it

away

of

more

guide should be demagnetized in

the

record/playback

the

drops

under

excessively, or

of

oil splashes.

and panel.

a material resistant

they

may

vicinity

If

noise seems

with

a head

OFF.

demagnetizer

the

demagnetizer

down

from

than

not

be demagnetized.

head as

of

machine oil

normal

with a soft

will

cause

become

can magnetize

to

demagnetizer

with

head surface.

it

close

to

slowly

in

front

the

head and

30

cm

(1

2").

head. object

this

will

to

conditions

rotation

"--------

cloth

dipped in

alcohol

damage

to

magnetiza-

magnetized.

the

have inceased,

vinyl

the

first

of

the

(a

increase noise.

pinch

may

heads,

through

tape

of

Switch

head.

to

the

head.

switch The

capstan

screwdriver

roller

of

use.

become

to

soft

it

shaft

8

or

the

A

on

left

off

the

ir-

KD-A77

A/B/C/E/J/U

New

Combination Due

to recording and having ventional record/playback both

employ The

SA head has various fields curacy, its

biggest

ty.

Because

the

superior

true

for cies;

something

usual

cassette

The

playback head

ture

to range. is

subject shown effect

tape-to-head

ding

frequency. diagonally ly,

but

The

result is, as

contour

Configuration

SA

its

high

a greater

ferrite

SA

better

feature

of performance

its

extended

improve

With

ordinary core

to

peaks and dips in

in Fig.

is caused

contact

to

enable

with

a gradually lessening

effect.

Technique

heads

for

recording and

recording

playback

maximum heads,

(Sen-Alloy)

advantages

such

as

wear

is its high

this,

the

that

has never been possible

tapes.

incorporates

the

B.

This is called

by

interference

With

the

shown

(Fig.

C)

of

record/playback

density,

heads

magnetic

or

permalloy.

newly

to

fewer

and corrosion resistance.

maximum

SA

head can bring

of

Metal

frequency

characteristics

configurations,

area and

the

X-cut

tape

to

in

the

Metal

that

are made

flux

The

developed

ensure high

over

conventional

core loss, greater gap ac-

magnetic

Tape. This is especially

response

a unique

of

the

low

frequency

the

"contour

between

the

wavelength

design

leave

the

contact

diagram, reduction

combination

playback

Tape requires

of

density

for

X-cut

the

head,

materials

than

combined

the

KD-A

performance.

heads in

However,

flux

the

most

at

high frequen-

to

realize

core

low

frequency

playback

range as

effect".

length

of

the

core is

not

area.

SA heads

(Fig.

con-

77,

densi-

out

with

struc-

output

:this

of

the

recor-

cut

abrupt-

of

the

Al

of

Comparison core and

in

~

QJ

>

~

...

:J

B-

:J

0

in

:9

a;

>

~

...

:J

Cl.

...

:J

0

X-cut

-.

-11

16

10

11

between

onventlona

c

core

standard

characteristics

I h d . h

Wit

ea

core

constructi

of

conventional

on

I

:J

@~

~

/

/,1./

Usign

/

X

10

-cut

I

,

standard

I I I I

.0

70

100

Frequence (Hz)

Fig. B

core

construction

100

curre

.00

nt

recorded

cut

tape

CD

SA recording head

® 4/lm gaps

® 1/lm gaps ®

X-cut

SA

playback

® SA chips

® Shield plate

rJ)

Zinc die-casting head base

head

Fig.

A

Note:

16

10

t--off----+

SA

(Sen-Alloy) is a

Using

10

.0

Frequence (Hz)

Fig. C

standard

I I I

70

100

trademark

current

.00

of

JVC.

recorded

tape

- 5 -

No.4186

KD-An

A/B/C/E/J/U

Removal of the Main Parts

This cassette deck ranged. Take special care

which

when

features a

servicing it.

Lever

knobs

compact

design and high performance uses miniature sized parts

Enclosure assembly

1 . Cassette door

Push

the

it

upwards

remove

2.

Lever knobs (INPUT SELECT, ANRS, TAPE SELECT, MONITOR) and level control knobs (INPUT LEVEL - L

R,

and

3.

~--~.

.11

Q

~

~~~;;;;;:;;.;...f='.

OUTPUT LEVEL and

Pull

them

Top cover

Remove 6

.....

EJECT

button

(approx. 5 mm)

it

to

frontward.

to

frontward

.....

screws

to

open

to

REC

fastening the

which

are closely ar-

the

cassette door. Slide

unlock

its

pawls,

EQ)

top

cover.

and

Screws

(Top

(Bottom

view)

Screw

Screws

Screw

l'

Front

4.

Bottom Remove

cover

7

screws

fastening the

bottom

cover.

5. Front plate assembly

1) Remove 5 screws assembly

2)

Remove TAPE & ANRS indicators wires

When adjusting or replacing REC/PB heads or Erase

head .....

1)

Remove wire clamp and 2 the top

2) Remove 2 ches (on section panel assembly.

Caution When

assembling

front

panel,

not

to

damage

1 ) Wrap

tape, etc.

2)

Insert

3)

Remove

4) Fasten 2

screws

on

bottom

the

cover.

screws

the

forwards

do

in the

the

sharp edges

the

control

the

vinyl

screws

wires

wire

positioned

bottom

- no need

the

front

switch

tape.

for

(3

screws

on upper side and 2

side) fastening the

of

the

control

sockets

switches

after

below

of

the deck) and pull

of

removing

control

order

switch

of

the numbers as

panel.

of

the

front

assembly in the

the

control

switch

front

socket.

from

having removed

the

control

the

assembly

below

panel

with

front

assembly.

plate

the

swit-

control

front

to

the

as

vinyl

panel.

No.

4186

- 6 -

KD-A77

A/B/C/E/J/U

Gear frame

ass'y

,CD

P.W.B holder

Door brake and its related parts

1.

Gear frame

2. Brake arm and tire

spring ®.

3.

Spur gear and brake spring

4.

Rack plate

5. Brake lever

@.

ass'y

.....

ass'y

.....

Remove 2

.....

Remove

drum

Remove

the

.....

Remove the E-ring

.....

screw

screws the

Remove

and

Electrical parts

1. Power supply P.W.B. parts assembly.

CD.

E-ring and

the

E-ring, and

the

collar

@.

torsion

@.

Screws

(Bottom

® Push

view)

Screws

1)

Remove a

numbers in

2) Remove 3

3)

Open

the

pawls

the

screws

P.W.B

illustration

2. Main amp P.W.B parts assembly

- 7 -

1) Remove 4 Board (on

2) Remove 4 front

3)

Remove 5 washers and 5 PHONES, MIC-L, MIC-R jacks and LEVEL control shafts.

screws the screws

bracket.

bottom

of

P.W.B. holder in

fastening

to

fastening

arrow

upper side.

fastening

side).

the

mark.

the

P.W. Board.

the

main amp. P.W.

lever

switches

nuts

fastening

REC

order

EO,

of

the

on

the the

OUTPUT

No.4186

K D-A

77

A/B/C/EI J/U

Power

switch

~ckPlate

3.

Power

1) Remove

2) Remove a bracket.

3) Remote 2

4.

Power Remove power

switch

the

lock

screw

screws

transformer

the 2 screws

transformer.

plate

®

(j)

CID

holding

fastening

and 2

the

washers

remote

power

fastening

bar.

switch

switch.

the

(Top

Screws

view)

-----,rl-I~rv

I

Screws

(for

door

related parts)

brake

Removal of the mechanical assembly

1 . Remove a

(Left side

fastening

related parts.

2.

Remove 5 the

screw

fastening

of

the

cassette

the

gear

frame

screws

amp. chassis (Right - 2 p.c.S,

fastening

the

arm

holder), and Remove 2

ass'y

to

the

mechanical

of

gear-oil

Remove

Left

- 3

damper

screws

door

bracket p.c.s).

brake

to

No_4186

tIP_--_Screw

(Right side)

- 8 -

3.

Remove a

front

screw

bracket.

fastening

the

counter

bracket

to

the

(Top

(Front

view)

Screws

..

4.

Remove 2

panel (upper side) .

Removal

1 . REC/PB head

Remove Remove

2.

Erase head Remove Remove

3.

Pinch roller arm

4.

Supply

5. Take-up

Note:

1) Remove metal inserted

2)

Be

6. Reel reel

screws

of

the the

reel

disc

careful

motor

motor.

fastening

the

joint

the mechanical parts

.....

screw

CD

for

head

adjustment.

screw

CV.

.....

screw

®.

screw

®

ass'y

disc

.....

the

not

.....

: .... Remove

.....

Pull

out

Remove

reel disc

between to

stain

Remove

out

the

stoppers

the

the 3 screws ® fastening

the

reel

stopper

counter

with

reel

disc

counter

the

KO-An

bracket

E-ring

stopper

(j) .

belt.

a piece and

belt.

to

the

A!B!C!E!J!U

the

front

@. @.

of

sheet

stopper.

the

(Rear

view)

- 9 -

7.

Capstan

1) Remove

2) Remove

3)

Turn removal.

Note:

When

1 )

Is

the

(Don't

2) Does pulley?

3) Does

motor

the

replacing

motor

deflect

the

capstan

the

capstan

.....

the

screw ® fastening

its

motor

belt.

motor

counter

the

motor,

placed in

the

check

the

motor

at

belt

run in

belt run in

clockwise

the

correct

mounting

the

center

the

rubber

and pull

following

position?

it.)

center

of

the

items.

of

the

flywheel?

stopper.

it

for

motor

No.4186

K

D-A

77

AIBICIEI

J/u

Main Adjustments

[I] Equipment and measuring instruments used for adjustment

1.

Electrical adjustment

1) Electronic

2)

Audio (range; 600fl)

3)

Attenuator

4)

Standard tapes

Maxell UD TDK SCOTCH MET AFINE -

5) Reference tapes VTT-658 VTT-656 VTT-664

TMT-6002N

6) Resistors 1

oon

600n

2.

Mechanical adjustment

1) Gauge

2)

Torque

3) Blank tape

voltmeter

frequency

50 -20kHz

SA -SA

(for (for

for

gauge.

oscillator

and

for

RECIPB

SF

tape

(for

head

(for

motor

(for Reference level 1 kHz)

(for

measurement attenuator

checking

(C-120)

(for normal) }

(for

Cr02)

Metal

for

playback

azimuth

speed,

playback

matching)

the

head position.

for

tape

output

OdB

tape

(JVC

Test

adj.)

wow

flutter

frequency

of

the

bias current)

running checker.

with

impedance

or

equivalent

Tape)

adj.)

response)

KO-A77

[11]

Mechanical adjustment

Head adjustment

1.

After

installing positions: A.

Snug turns.

B.

Snug This tape For filed screwdriver

screw @ gently, will path.

tightening

down

the

screw This makes

roughly

CD

position

screw

to

the

specifications

can be used

Back-tension

specified parts in gently,

the

heads nearly horizontal.

@"

use a to

then

then the

tighten

pad

back

tape in

home

shown

Clearance (A)

off

make

screw

the

appropriate

off

about

the

center

screwdriver,

below.

(1).

about

two

one

turn.

of

The same

Pad

the

(attached

Combination

2.

Make assembly and also the

Next,

3. cassette ing

the

indication

to

the

cassette)

head

sure

that

the

moves

@.

of

adjust

proper

smoothly

that

the

Watching

both

the

confirm

play mode.

make an operational

and

screw

guides

Tape

Pinch roller

moving

around

there

is

adjustment.

height

of

that

the

combination

adjustment.

part

of

the

erase head

the

pivot

of

screw

by

@

20

turn-

curl

enough clearance (A) in

Load a C-1

the

erase head

tape does

and erase heads is

not

at

No.4186

Screwdriver

-10

__

f

Incorrect

Tap€

Tape l

'

guide

--,

Tape guide

_~--

Tape

Correct

-1

Tape guide

t -Tape

-

KD-A77

A/B/C/E/J/U

Item

Adjusting motor

speed

Checking play-

back

torque

Checking forward

Checking rewind

Checking and

fast

torque

wow

flutter

Adjustment

Connect OUT VTT-656 Adjust motor the

Employ tape cassette gauge.

Measure ward

the

Measure mode above.

Connect a wow the Play Check meter

terminals.

the

P.W.

speed

a

for

the

mode

above.

in

the

LINE

back

to

is

within

a speed

test

semi-fixed

board until

torque

checking, or remove

cover

the

torque

in

the

same manner

OUT

the see

meter

to

Play

back

tape.

meter

the

torque

terminals. VTT-656

if

resistor

the

reading

is

3000Hz.

testing

and

use

in

the

same manner as in

in

the

and

flutter

test

the

reading

0.04%

(WRMS).

Adjusting

point

the

LINE Semi-

the

fixed

resistor

on

the

on

the

of

motor

P.w. board

cassette

the

torque

a

fast

for-

rewind

as

in

the

meter

to

tape. re-claim

of

the

Standard

value

3000Hz

40-70

gr-cm

More than

70

gr-cm

More than 70

gr-cm

If

the and deck meter.

If

the replace

If

the perform 1 . Clean

cumference, take-up the

2. Replace If

the clean pulley, ding idler

circumference, If

the

even

necessary.

Remarks

speed

meter

flutter

to

the

standard

the

standard

the

flywheel

standard

the

capstan

flywheel

circumference,

reading becomes

if

conforming

may

functions

meter,

INPUT

torque

take-up

torque

following.

capstan

the

reel

disc

circumference,

the

belt and idler. torque

circumference,

etc.

be raised. Repairs are

also,

terminals

disc

motor

belt, idler,

to

as a

connect

is

not

obtained,

assembly.

is

not

obtained,

belt,

the

idler

pulley,

circumference,

is

not

obtained,

left

reel

moving

the

standard,

wow

the

of

the

cirthe

etc.

motor

rewin-

disc

value

a

[Ill] Repair of

If

wow

If generated revolutions.

and

there

is

Section

Capstan and

Pinch roller

Belt

Back tension

Motor

Damping gear

Oil

employed - Torque grease specified

Applying method -

flutter

defect

will

wow

flutter

increase,

in

revolving

increase in

flywheel

oil

Apply

check

the

parts,

proportion

Capstan Flywheel

(shaft

Rough ches, or dust) The

angular

not

is

The pinch roller pressure is

Belt has undue run-out. Clean

Belt is Back tension

sion Motor

Motor

in both concaved sections

following

the

wow

to

the

shaft

turns seisure,

rotation

position

correct.

dirty

or slippery. Replace

is

too

strong.

shaft

has undue run-out. Replace motor.

pulley

is

by

points.

and

flutter

number

Trouble

has excessive

heavily. Clean

thrust

(Deformation

irregular, or back ten- Replace back tension spring (under supply disc).

oily and

JVC

of

play,

of

the

pinch

not

dusty.

(KANTO KASEI GP-608)

as

Play a detected

run-out

etc.)

scrat-

roller shaft.

correct.

shown

in

the

3000Hz

from

Replace flywheel.

Apply Replace

Replace pinch roller, or pinch roller spring. Clean

Adjust

the

Replace

Clean

figure.

test

the

oil

the

capstan shaft.

the

motor

tape, and

sound.

flywheel.

capstan

to

the

metal

the

capstan assembly.

pinch roller

the

pinch roller so

the

pinch roller spring.

belt.

the

belt.

pulley.

Repair

shaft

position.

or

defective

and

the

apply oil

that

it

part

groove

to

is

parallel

the

can

in

the

rotary

with

be

-11-

K

D-A

77

A/B/C/E/

[IV]

J/U

Adjustment

Power

Location

Supply P.W. Board

of

Electrical

Circuit

Front

t

VR803

11

,,~

VR703Rtl

L For

Q-

_

__#

l]-R

'~'

U L

VR302

_____

'-----------.J

_ 1

.,,'

'"

(Turning

VR801

(3-R

VR701

\G-L

L _

ANRS

(Turning

In

m

...

om"'''''"

in

the

For

playback

(Turning

adjustment

the

direction

For

(Turning

frequency

In

the

at

playback

of

playback

direction

the

',,""'m,m

of

the

arrow

level

In

the

direction

response

of

the

mode

arrow

Increases

adjustment.

of

adjustment

arrow

Increases

the

ANRS

deflection

arrow

the

gains.)

_

angles.)

increases

signal

the

current)

playback

levels.)

Main

P.

W Board

Front

1

VRAOl

VRBOl

(eR

L ] For

(Turning

VR501

T.;-L

VR601 G L

·0

ANAS

VR504

T.P-R

adjustment

in

the

direction

VR502

~

at

recording

of

the

VR503

((~((~G-

Q Q

VR604

G-

VR602

I

LL'::=~==rNORM~

I R I I J

L I

R---~

For

recoridng

level

Rl

(Turning

creases

mode.

arrow

increases

the

L J ero, t -For bias CUrrent

:

v

603

r

METAL

in

the

ANRS

direction

recording

gains.)

(Turning

creases

adjustment.

in

the

of

levels.)

the

bias

the

arrow

adjustment.

direction

current

in-

of

the

value.1

arrOw

in-

No.4186

In

nl

~12~

n