Technics Rs-ch770 User manual

ORDER

NO.

AD9603056C8

Service

Manual

Stereo

Cassette

Deck

Cassette

Deck

System:

SC-CH770

OU

[DOLBY

B

NR

|*’

R

S

=

C

+

vA

O

*2.*3

§B-CH770

*2,*3

SB-PC10

*2.*9

SB-CH770

ST-CH770

SL-CH770

Colour

(K)

:

Black

ySBPSIO

poe

Suffix

for

Area

Colour

Model

No.

Europe,

Asia,

Latin

America,

Middle

East,

Africa

and

Oceania

*2,*3

SB-PS10

RS-CH770

SE-CH770

Remote

Control

Transmitter

System:

SC-CH570

*2.*3

§B-CH570

*2.*3

SB-PC570

*2.*3

SB-CH570

*2

$B-PS570

#

*2$B-PS570

*1:

Dolby

noise

reduction

manufactured

under

or

i

or

license

from

Dolby

Laboratories

Licensing

*3SB-PS10

|

So

ee

as

|

gai?

SB-PS10

Corporation.

:

as,

re

“Dolby”

and

the

double-D

symbol

are

trade

marks

of

Doiby

Laboratories

Licensing

Corporation.

Remote

Control

Transmitter

RS-CH770

SE-CH570

AR-2

MECHANISM

SERIES

Specifications

(IH

F

78)

Frequency

response

(Dolby

NR

off)

.

TYPE

I

(NORMAL)

20

Hz-1

6

kHz

(DIN)

@

Cassette

Deck

Section

TYPE

II

(HIGH)

20

Hz-1

6

kHz

(DIN)

Deck

system

Stereo

cassette

deck

TYPE

IV

(METAL)

20

Hz-1

6

kHz

(DIN)

Track

system

4-track,

2-channel

S/N

(signal

level

=

max

recording

level,

TYPE

II

type

tape)

Recording

system

AC

bias

NR

off

56

dB

(A

weighted)

Bias

frequency

100

kHz

Dolby

NR

B

on

66

dB

(A

weighted)

Erasing

system

AC

erase

Input

sensitivity

and

impedance

Heads

REC

(IN)

400

mV/23

kQ

DECK

1

Playback

head

(Permalloy)

x

1

Output

voltage

and

impedance

DECK

2

Recording/Playback

head

(Permalloy)

x 1

PLAY

(OUT)

280

mV/360

O

Erasing

head

(Double-gap

ferrite)

x

1

Hi

General

Motors

: ;

DECK

1,

2

Capstan

drive

(DC

servo

motor)

=

1

Dimensions

(W

x

Hx

D)

270

x

118.5

«

269.5

mm

Tape

speed

4.8

cm/sec.

weelant

1.9

kg

Wow

and

flutter

0.16%

(WRMS)

Notes:

Fast

forward

and

rewind

times

Specifications

are

subject

to

change

without

notice.

Approx.

110

seconds

with

C-60

cassette

tape

Weight

and

dimensions

are

approximate.

Tuner/sound

Compact

disc

el

System

processor

player

Amplifier

Cassette

deck

|

Front

speakers

|

Center

speaker

|

Surrournd

speakers

SC-CH770

ST-CH770

SL-CH770

SE-CH770

¥2.*3SB-CH770

|

*2°°SB-PC10

|

*°°3

SB-PS10

*2

SB-PT570

SC-CH570

ST-CH570

SL-CH570

sE-cH5s70

|

FS

CH770

|

s2s358.cH570

|

“SB-PCS70

*2SE3-PS570

*3SB-PT570A

*3

SB-PC570

“8S

B-PS10

*2

For

Europe

area:

oo...

Made

in

PAES

*3

Except

for

Europe

area:

.....

Made

in

NABEL

©

1996

Matsushita

Electric

Indusiriaal

Co.,

Ltd.

e

®

:

All

rights

reserved.

Unauthorized

c

©pying

i

ec

]

and

distribution

is

a

violation

of

law.

re

RS-CH770

A\WARNING

This

service

information

is

designed

for

experienced

repair

technicians

only

and

is

not

designed

for

use

by

the

general

public.

It

does

not

contain

warnings

or

cautions

to

advise

non-technical

individuals

of

potential

dangers

in

attempting

to

service

a

product.

Products

powered

by

electricity

should

be

serviced

or

repaired

only

by

experienced

professional

technicians.

Any

attempt

to

service

or

repair

the

product

or

products

dealt

with

in

this

service

information

by

anyone

else

could

result

in

serious

injury

or

death.

Location

of-

Controls

iscetei

es

hick

aie

eee

eisai

etanariann

Cotas

aks

2

Wiring

Connection

Diagram

Operation

Check

and

Function

oflG

Terminals:

23,

ccecsse.cscesecesdauseavivesctds

ay

tice

vals

aan

Main

Component

Replacement

Procedures

0...

eee

3~12

Block

Diagram

.......ccceeccseetseetereee

Service

Mode

Function

of

Cassette

Mechanism...

13,14

Replacement

Parts

List

oe

Measurements

and

Adjustments

........

cece

ecceceeeerserecteeetiieens

15~17

Cabinet

Parts’

Location

iin.

ii.

itie

ities

aude

eens

neinarieaGane

Schematic

Diagram

occ

erect

eeseeeereees

Mechanism

Parts

Location

Printed

Circuit

Board

Diagram

uo...

cece

ce

cererrseeeeeetsereeeens

NOTE:

Refer

to

the

service

manual

for

Model

No.

SE-CH770

(ORDER

No.

AD9603055C8)

or

SE-CH570

(ORDER

No.

AD9603054C8)

for

information

on

“Accessories”,

“Stacking

the

Components”,

“Connections”

and

“Packaging”.

@

Location

of

Controls

G@)

Deck

1

cassette

holder

@

Deck

1

indicator

(DECK

1)

3)

Deck

1/deck

2

select

button

(DECK

1/2)

(4)

Reverse

mode

select

button

(REV

MODE)

()

Deck

2

cassette

holder

©

Dolby

noise

reduction

button

(DOLBY

NR)

@

Record

pause

button

(@

REC

PAUSE)

Record

pause

indicator

(REC

PAUSE)

@)

Deck

2

indicator

(DECK

2)

Deck

1

cassette

holder

open

button

(4

OPEN)

@)

Counter

reset

button

(RESET)

42)

Counter

display

button

(DISPLAY)

(3

Fast

forward/rewind/tape

program

sensor

buttons

(<<,

>>)

Playback

buttons

and

indicators

(<1,

>>)

@®

Stop

button

(0)

Tape

edit

buttons

(TAPE

EDIT,

NOR,

HIGH)

@)

Deck

2

cassette

holder

open

button

(4

OPEN)

RS-CH770

i

OPERATION

CHECKS

AND

MAIN

COMPONENT

REPLACEMENT

PROCEDURES

1.

This

section

describes

procedures

for

checking

the

operation

of

the

major

printed

circuit

boards

and

replacing

the

main

components.

2.

For

reassembly

after

operation

checks

or

replacement,

reverse

the

respective

procedures.

Special

reassembly

procedures

are

described

only

when

required.

3.

Select

items

from

the

following

index

when

checks

or

replacement

are

required.

4.

illustrated

screws

are

equivalent

to

actual

size.

5.

Refer

the

parts

No.

on

the

page

of

“Main

Component

Replacement

Procedures”,

if

necessary.

e

Contents

*Checking

Procedure

for

each

P.C.B.

Page.

1.

Checking

for

the

main

P.C.B.

and

power

supply

P.C.B..sseeeceeecceecccsccccccccccescsecescvses

ee

34.

2.

Checking

for

the

operation

P.C.B..

Coo

omer

eererererereseesereoesreesereenecseneseseeeeeoer

oe

56,

«Main

Component

Replacement

Procedures

1.

Replacement

for the

cassette

lid

ass'y,

se

eereecereccccsccsescesescccssesceseseeseesesvvcsvoce

7.

2.

Replacement

for the

cassette

holder,

s*eeecercsccsccrvecvereeccccveesesesesesesesesesecesenes

7:

3.

Replacement

for

the

motor

ass’y,

capstan

belt

and

winding

belt.

sesercerreseeccceercesccscscveeeeeee

8.44,

4.

Replacement

for the

plunger

ass’y

and

the

parts

mounted

on

mechanism

P.C.B..

seeececerceeesesccevess

14.42,

5.

Replacement

for

the

head

block

and

pinch

roller

ass’y.sseesecceccesccsvccsscsscessscescsecsceve

se

t2

Mi

Checking

Procedure

for

each

P.C.B.

1.

Checking

for

the

main

P.C.B.

and

power

supply

P.C.B.

Remove

the

top

cabinet.

Cup

@x4

()\

mp

©

(Black)

[RHD30007

-

K1]

(ID

©

Black)

[XTBS3+8JF-Z1]

RS-CH770

Remove

the

flat

cable

from

connector.

cD

Release

the

4

claws,

and

then

remove

the

front

panel

ass’y.

Connector

(CN901-—1/CNS01—2)

Main

P.C.B.

Connect

the

flat

cable

to

the

connector.

Connector

(CN6O1A)

Release

the

2

claws,

and

then

remove

the

power

supply

P.C.B..

Socket

(CN601B)

Power

supply

P.C.B.

t

step

9

Connect

the

socket

(CN601B)

to

the

connector

(CN601A).

*

Check

the

main

P.C.B.

and

power

supply

P.C.B.

as

shown

below.

Main

P.C.B.

istep

10)

Connect

the

lead

wire.

Cabinet

Place

the

power

supply

P.C.B.

on

the

insulation

material

not

to

short-circuit

the

solder

side

of

power

supply

P.C.B..

(i)

+

(Black)

[XTBS3HJFZ1]

RS-CH770

2.

Checking

for

the

operation

P.C.B.

Press

the

eject

rod

in

the

direction

of

arrow,

and

then

open

the

cassette

holder.

+

Follow

the

@eamp

~

of

the

item

1

in

checking

procedure

for

each

P.C.B.

on

pages

3

and

4.

Cassette

holder

(DECK1)

Cassette

holder

(DECK2)

Remove

the

shield

plate

(L)

/

(R).

Shield

plate

(L)

Shield

plate

(R)

Release

the

claw,

and

then

remove

the

mechanism

unit.

Remove

the

cassette

lid

ass’y

in

the

direction

of

arrow.

Cassette

lid

ass'y

(DECK1)

Cassette

lid

ass’y

(DECK2)

Release

the

2

claws.

(SID

©

(Black)

[XTB3+1

OJFZ]

(3)

‘bY

[XTBS26+10J]

RS-CH770

|

Remove

the

deck

mecha

frame

in

the

direction

of

arrow.

Remove

the

operation

P.C.B..

Operation

P.C.B.

Connect

the

flat

cable

to

the

connector.

\

Connector

(CN601A)

Socket

(CN601B)

Power

supply

P.C.B.

aD

Connect

the

socket

(CN

601B)

to

the

connector

(CN6(4A).

¢

Check

the

operation

P.C.B.

as

shown

below.

Operation

P.C.B.

Connect

the

lead

wire

NOTE

Place

the

power

supply

P.C.B.

on

the

insulation

material!

not

aes

to

short-circuit

the

solder

side

GND

plate

of

power

supply

P.C.B..

Cabinet

eae

|

_

RS-CH770

i

Main

Component

Replacement

procedures

1.

Replacement

for

the

cassette

lid

ass’y

+

Follow

the

G2aD

~

GED

of

the

item

1

in

checking

procedure

for

each

P.C.B.

on

page

3.

Cassette

holder

(DECK2)

Cassette

holder

(DECK1)

c=

Press

the

eject

rod

in

the

direction

of

arrow,

and

then

open

the

cassette

holder.

Eject

rod

Remove

the

cassette

lid

ass’y

in

the

direction

of

arrow.

Cassette

lid

ass'y

(DECK1)

(RYF0412-K]

Cassette

lid

ass'y

(DECK2)

[RYF0413-K]

2.

Replacement

for

the

cassette

holder

*

Follow

the

G&D

~

GEEED

of

the

item

1

in

checking

procedure

for

each

P.C.B.

on

pages

3

and

4.

M@

Open

spring

installation

*

Follow

the

ZUR

~

of

the

item

2

in

checking

Cassette

holder

ass'y

procedure

for

each

P.C.B.

on

pages

5

and

6.

(DECK1)

[RFKLACH430GA]

Cassette

holder

ass

y

(DECK2)

——,

[RFKLACH430GB]

»

Release

the

lug

of

Cassette

holder

Sy

in

the

direction

of

arrow.

RS-CH770

3.

Replacement

for

the

motor

ass’y,

capstan

belt

and

winding

belt

+

Follow

the

@25ED

~

GREED

of

the

item

1

in

checking

procedure

for

each

P.C.B.

on

pages

3

and

4.

*

Follow

the

G&D

~

G&D

of

the

item

2

in

checking

procedure

for

each

P.C.B.

on

page

5.

Mechanism

P.C.B.

SG

5

|

aun

qs,

NOTE

Kr

ie

Ea

wi

ue

Handle

the

connector

)

aN

:

;

with

care

so

that

me

When

removeing

the

Oe

4

3

LTS:

a

shape

of

terminals

mechanism

control

P.C.B.,

;

be

toe

Rae

nae

i.

:

different

from

others.

remove

it

with

holding

the

¥

=

mechanism

P.C.B.

by

finger.

Unsolder

the

terminals.

Release

the

claw,

and

then

remove

the

main

P.C.B..

The

illustration

below

shows

DECK2

mechanism.

For

DECK1

mechanism,

perform

the

same

procedure

as

DECK2.

Remove

the

sub

chassis.

Head

connector

Re

€

its

Remove

the

P.C.B.

support.

ex)

hs

;

(se)

ump

ra)

Release

the

2

claws,

:

and

then

remove

the

.

head

connector.

a

:

XTBS26+8]

f)ump

©

XTW26+10S]

RS-CH770

@)p

©

[RHD26022]

Motor

ass'y

[REM0055]

Capstan

belt

[RDV0034]

Remove

the

flywheel

R.

Winding

belt

[RDV0033-1]

|

Release

the

2

calws,

and

then

step

11

remove

the

winding

belt

and

Remove

the

flywheel

F,

SPN9-

Put

the

winding

belt

on

the

flywhe

el

F.

Veh

The

boss

and

marking

should

be

positioned

horizontally.

F

lywheel

F

Winding

belt

Tweezers

Install

the

flywheel

F.

NOTE

Take

care

not

stick

the

grease

onthe

belt.

Put

the

winding

belt

on

the

pulley

temporarily.

RS-CH770

The

winding

lever

should

be

positioned

as

shown

below.

Winding

lever

Capstan

belt

A

(Side

view)

Winding

arm

Install

the

winding

lever

and

spring

while

pressing

the

winding

arm

in

the

direction

of

arrow.

(The

winding

lever

must

be

inserted

completly

and

latched

with

claws.)

Put

the

capstan

belt

A

temporarily

as

shown

below.

dss

505:

Boss

Capstan

belt

A

Install

the

sub

chassis

to

the

mechanism,

and

then

tighten

screws.

Mechanism

~10-

@)mm

0

[XTW226+10S]

RS-CH770

Put

the

capstan

belt

on

the

motor

ass’y

pulley.

Capstan

belt

4.

Replacement

for

the

plunger

ass’y

and

the

parts

mounted

on

mechanism

P.C.B.

*

Follow

the

@2EED

~

@25ED

of

the

item

1

in

checking

procedure

for

each

P.C.B.

on

pages

3

and

4.

*

Follow

the

GEER

~

G2EZD

of

the

item

2

in

checking

procedure

for

each

P.C.B.

on

page

5.

*

Follow

the

@23aD

~

ERED

of

the

item

3

in

main

NOTE

t t

n

page

8.

[NOTE

|

poMPenent

replaceinsnk

procauies-

OmnPage

6

Le

aged

pal

snes

DECKS

mechanism.

or

K1

mechanism,

perform

the

same

cum

O

procedure

as

DECk2.

af

Claws

Release

the

3

claws,

and

then

remove

the

mechanism

P.C.B..

®)}mm>

Oo

Unsolder

the

terminals.

[XYC2+JF17]

Plunger

ass'y

bg

EZ)

Release

the

4

claws.

[RSJ0003]

ee

RS-CH770

Plunger

ass'y

Shaft

[RMS0398-1]

NOTE

Notice

for

installing

the

plunger

ass’y

*

The

shaft

of

plunger

ass'y

should

be

aligned

with

the

slot

of

lever.

Plunger

ass'y

5.

Replacement

for

the

head

block

and

pinch

roller

ass’y

+

Follow

the

GSD

~

G2IED

of

the

item

1

in

checking

procedure

for

each

P.C.B.

on

pages

3

and

4.

*

Follow

the

GSD

~

RZD

of

the

item

2

in

checking

NOTE

procedure

for

each

P.C.B.

on

page

5.

The

illustration

below

shows

DECK2

mechanism.

*

Follow

the

GED

~

G@SED

of

the

item

3

in

main

For

DECK1

mechanism,

perform

the

same

procedure

as

DECK2.

component

replacement

procedures

on

page

8.

i

step

1)

Release

the

2

claws,

and

then

remove

the

pinch

roller

ass’y

(R),(F).

Pinch

roller

ass'y

(R)

[RXLO125}

Pinch

roller

ass'y

(F)

[RXL0124]

Claw

Head

block

DECK1

:

RED0038

DECK2

:

RED0037

Release

the

2

claws,

and

then

remove

the

|claw

head

connector.

Head

connector

IXTW2+5L]

ep

RS-CH770

m@

Service

Mode

Function

of

Cassette

Mechanism

This

unit

is

equipped

with

a

service

mode

function

of

cassette

mechanism

using

the

LED

indicators

[R.

PLAY

(««),

F.

PLAY

(p)]

and

cassette

holder

illuminations

[DECK

1,

DECK

2].

Use

this

function

during

maintenance

to

check

faults

of

the

items

below.

©

Cassette

tapes

to

be

prepared

Metal

tape:

|

Recorded

music

tape

with

only

one

erase-prevention

tab

intact

(use

middle

portion

of

tape).

Normal

tape:

}

Recorded

music

tape

with

both

erase-prevention

tabs

intact

(use

middle

portion

of

CrO2

tape:

}

tape).

®@

Selecting

Service

Mode

1.

Turn

on

the

power

to

the

unit.

(If

RS-CH770

unit

is

removed

from

system,

turn

it

on

according

to

the

procedure

on

page

15.)

2.

Check

that

no

tape

is

inserted

in

the

cassette

deck.

STOP

DOLBY

NR

Press

the

DOLBY

NR

button

for

about

2

seconds,

and

keep

pressing

it,

also

press

the

STOP

Lal

Qo

button

for

about

2

seconds.

(Service

mode

cannot

be

selected

with

a

tape

inserted

in

the

cassette

deck.)

3.

The

LED

indicator

for

REC

PAUSE

flashes,

the

service

mode

has

been

activated.

@

Deck

1

Mechanism

Check

st

Bw

—

Use

the

Deck

1/2

select

Open

the

Deck

1

Insert

a

CrO2

tape

into

Press

the

TPS

>>

button

to

change

the

cassette

holder.

the

Deck

1

and

close

button.

(Tape

fast

flashing

Deck

2

(OPEN

button)

the

cassette

holder.

forwards

for

about

2

indicator

to

Deck

1.

(No

change

required

if

[——>

Deck

1

indicator

already

flashing.)

DECK

1/2

seconds

then

stops.)

BIS

G)

as,

ae

ee

4

OPEN

Press

the

<<

TPS

Press

the

PLAY

button.

(Tape

rewinds

(After

TPS

operation

for

about

2

seconds

and

check,

the

tape

then

stops.)

>|

stops.)

Open

the

Deck

1

cassette

holder

and

replace

the

tape

with

a

Close

the

Deck

1

normal

tape.

cassette

holder.

(OPEN

button)

4

OPEN

Press

the

REC/PAUSE

Press

the

STOP

button.

Fault

items

1

to

7

can

be

checked

as

button.

(No

record

the

four

LED

indicators

turn

on

or

off.

(Refer

to

Table

1.)

operation.)

p|

Each

time

the

STOP

button

is

pressed,

the

fault

items

are

displayed

in

sequence.

@REC

PAUSE

*

If

no

fault,

all

indicators

go

out.

243

RS-CH770

|

Table

1:

Service

Mode

Diagnostic

Items

LED

indicator

and

illumination

status

(on/off)

Notes:

DECK

1

DECK

2

Fault

location

;

©

:

eee

MODE

detect

switch

*

If

no

fault,

all

indicators

go

out.

REC

prevention

switch

Half

detect

switch

CrO2

tape

detect

switch

Metal

tape

detect

switch

Reel

pulse

detect

system

(Hall

IC,

etc.)

TPS

operation

®

Deck

2

Mechanism

Check

Use

the

Deck

1/2

alact

|

Open

the

Deck

2

|

Insert

a

metal

tape

into

button

to

change

the

cassette

holder.

the

Deck

2

with

an

intact

flashing

Deck

1

|—

ey

(OPEN

button)

erase-prevention

tab

on

Close

the

Deck

2

indicator

to

Deck

2.

the

right side.

cassette

holder.

DECK

1/2

&

OPEN

(slums)

{roy

oy

aw

Press

the

TPS

>>

|

Open

the

Deck

2

cassette

holder

Press

the

«qq

TPS

button.

(Tape

fast

and

turn

over

the

metal

tape

(intact

button.

(Tape

rewinds

forwards

for

about

2

erase-prevention

tab

on

the

left

for

about

2

seconds

then

stops.)

|_|

side).

(OPEN

button)

Close

the

Deck

2

|_,|

then

stops.)

cassette

holder.

Press

the

PLAY

button.

Open

the

Deck

2

cassette

(After

TPS

operation

holder

and

replace

the

CrO2

and

check,

the

tape

with

a

normal

tape.

stop.)

hag

(OPEN

button)

Pa

oon,

|

|S

Open

the

Deck

2

cassette

holder

and

replace

the

metal

tape

with

a

CrO2

tape.

Close

the

Deck

2

(OPEN

button)

cassette

holder.

4

[=|

4

cM

Press

the

REC/PAUSE

Press

the

STOP

button.

Fault

items

1

to

7

can

be

checked

as

button.

(No

record

the

four

LED

indicators

turn

on

or

off.

(Refer

to

Table

1.)

Close

the

Deck

2

operation.)

Each

time

the

STOP

button

is

pressed,

the

fault

items

are

cassette

holder.

displayed

in

sequence.

@REC

PAUSE

@Cis

NS

*

If

no

fault,

all

indicators

go

out.

©

Exiting

Self-Check

Mode

1.

Press

the

STOP

button

for

more

than

6

seconds.

(Diagnostic

contents

stored

in

memory

for

both

Deck

1

and

2

are

erased.)

(<=)

2.

Remove

the

cassette

tape

from

the

cassette

holder.

3.

Turn

off

the

unit.

444

stamens

shia

ha

pu

IN

iPM

ALBA

i

Ne

icp

ccc

phasic

taine

eubchind

ning

eid

eg

RS-CH770

M@

Measurements

and

Adjustments

This

unit

RS-CH770

is

designed

to

operate

on

power

supplied

from

the

Amplifier

(SE-CH570

or

SE-CH770)

through

Tuner/Sound

Processor

(ST-CH570

or

ST-CH770).

When

connecting

the

unit

to

other

system

components,

do

not

connect

to

the

Amplifier

(SE-CH570

or

SE-CH770)

directly.

Be

sure

to

connect

this

unit

through

the

Tuner/Sound

Processor

(ST-CH570

or

ST-CH770).

When

operating

the

unit

RS-CH770

alone

for

testing

and

servicing,

without

having

power

supplied

from

the

Amplifier

(SE-CH570

or

SE-CH770)

and

the

Tuner/Sound

Processor

(ST-CH570

or

ST-CH770),

use

the

following

method.

®@

To

Supply

Power

Source

Apply

11

V

AC

power

to

test

points

between

BUEMS¢g

and

Bilase74

(GND),

and

Bulsek#

and

Buldsievd

(GND).

Notes:

When

operated

alone,

this

unit

automatically

enter

the

TEST

mode,

causing

either

the

DECK1

or

DECK2

indicators

to

blink.

In

TEST

mode,

please

make

sure

whether

the

Dolby

B

indication

is

on

or

off

by

the

illumination

of

DECK

1

cassette

holder

is

lighted

on

or

off.

(DECK

1

illumination

is

lighted

on:

Dolby

ON,

illumination

is

lighted

off:

Dolby

OFF)

®

To

Check

Signals

Connect

an

TaN

or

a

built-in

amplifier

soeaker

between

line

output

for

L-ch

(

Eiiteryd

)

and|A.GND},

and

line

out

for

R-ch

(Meds

)

and|

A.GND

|

and

check

if

the

signals

are

outputting

from

this

unit.

(Power

P.C.B.)

(Main

P.C.B.)

LINE

IN

(R-ch)

TAPE

SPEED

TAPESPEED

PLAYBACK

GAIN

PLAYBACK

GAIN

TP606

DECK

1

(DECK

2:

High)

(DECK

1:

R-ch)

(DECK

2:

R-ch)

A.GND

VR801

VR802

VR103

LINE

IN

(L-ch)

7

PLAYBACK

GAIN

DECK

2

VR104

(DECK

2:

L-ch)

LvR803

|

VR102

LINE_OUT

(R-ch)

TP608

TP601

cen

ae

fied

GND)

—+-+e—

LINE

QUT

(L-ch)

Fig.

2

~~

Unsoldered

side

Soldered

side

Note:

The

above

symbol

indicates

a

jumper

soldered

on

one

side.

When

this

jumper

is

levered

up

using

a

©

screwdriver,

its

unsoldered

side

is

raised

so

that

it

can

be

seized

with

an

alligator

Clip.

Fig.

1

Measurement

Condition

Test

tape

®

Dolby

NR

switch;

OFF

®

Head

azimuth

adjustment

(8

kH,

-20

dB);

QZZCFM

@

Make

sure

heads

are

clean.

©

Tape

speed

adjustment

(3

kHz,

-10

dB);

QZZCWAT

®

Make

sure

capstan

and

pressure

roller

are

clean.

®

Playback

gain

adjustment

(315

Hz,

0

dB);

QZZCFM

©

Judgeable

room

temperature

205°C

(68+9°F)

®

Recording/playback

frequency

response

adjustment;

QZZCFM

(315

Hz/0

dB,

315

Hz/-20

dB,

12.5

kHz~

63

Hz/-20

dB)

Measuring

instrument

QZZCRA

(Norma!

blank

Tape)

EVM

(Electronic

Voltmeter)

QZZCRX

(CrO2

blank

Tape)

@

AF

oscillator

QZZCRZ

(Metal

blank

Tape)

®

Digital

frequency

counter

S15

E

§

5;

3

F

i

El

Ne

RS-CH770

HEAD

AZIMUTH

ADJUSTMENT

(DECK

1/2)

(L-ch)

Bubdsieyé

1.

Connect

the

measuring

instrument

as

shown

in

Fig.

3.

or

EVM

2.

Replace

azimuth

screws

for

both

forward

and

reverse

direction

after

removing

(R-ch)

Siete}

the

screw-locking

bond

left

on

the

head

base.

Fine

adjust

t

of

azimuth

can

not

be

performed

with

remaining

the

bond

on

°

justment

of

a

f°)

p g

AGND

.

the

head

base.

(Supply

part

No.

of

azimuth

adjusting

screw:

RHD17015)

3,

Playback

the

azimuth

adjustment

portion

(8

kHz,

-20

dB)

of

test

tape

(QZZCFM).

Adjust

the

azimuth

adjusting

screw

until

the

outputs

of

the

L/R-ch

R/P.

HEAD

(Deck

2)

are

maximized.

(Refer

to

Fig.

4.)

Make

sure

that

the

difference

in

the

peak

level

between

the

left

and

right

E.

HEAD

(Deck

2)

P,

HEAD

(Deck

1)

channels

does

not

exceed

0.5

dB.

4.

Perform

the

same

adjustment

in

reverse

playback

mode.

Check

of

the

level

difference

forward

and

reverse

directions

5,

Playback

the

playback

gain

adjustment

portion

(315

Hz,

0

dB)

of

test

tape

(QZZCFM).

Check

if

level

difference

between

forward

and

reverse

direction

is

within

1.5

dB.

;

Azimuth

Screw

Azimuth

Screw

6.

After

the

adjustment,

apply

screwlock

to

the

azimuth

adjusting

screw.

(Forward)

(Reverse)

Fig.

4

Fig.

3

TAPE

SPEED

ADJUSTMENT

(DECK

1/2)

Note:

When

connecting

the

unit

to

other

system

components

for

testing,

short

the

section

between

the

test

points

and

Eieand

turn

on

the

entire

system.

(The

unit

is

set

to

the

TEST

mode,

and

either

the

DECK1

or

DECK2

indicators

will

blink.)

Normal

speed

(Standard

value:

3000

+

45

Hz)

1.

Playback

the

middle

portion

of

the

test

tape

(QZZCWAT).

(L-ch)

Bubdsieyé

2.

Adjust

Deck

1

=

VR801

and

Deck

2

=

VR803

for

the

output

value

shown

or

E

‘

below.

(Refer

to

Fig.

2)

(R-ch)

[Gee

requency

counter

O+

Adjustment

target:

3000

+

15

Hz

(NORMAL

speed

i

9

(

peed)

GND

a

Deel

Standard

value:

3000

+

45

Hz

(NORMAL

speed)

High

speed

[Set

the

unit

to

forward

(FWD)

mode.]

Fig.

5

3.

Playback

the

middie

portion

on

the

test

tape

(QZZCWAT).

4.

Press

the

one

touch

tape

edit

(High)

button.

This

will

set

the

high

speed

mode.

5.

At

that

time,

check

if

the

output

from

DECK

1

is

within

the

standard

value.

Standard

value:

5000

=

600

Hz

(HIGH

speed)

—_—|

6.

Adjust

VR802

so

that

the

output

frequency

of

DECK

2

is

within

+

30

Hz

for

the

value

of

the

output

frequency

of

DECK

1.

(Refer

to

Fig.

2.)

Note:

When

connecting

the

unit

to

other

system

components,

disconnect

the

short

between

the

test

points

ULd0]

and

—ubgtud.

PLAYBACK

GAIN

ADJUSTMENT

(DECK1/2)

1.

Find

the

start

of

the

315

Hz/0

dB

section

of

the

test

tape

(QZZCFM),

insert

the

(L-ch)

Mibscterd

tape

into

Deck1

and

2,

and

play

it

back

(FWD)

or

EVM

3.

Adjust

Deck

2

:

VR102

(L-ch)

[VR103

(R-ch)]

and

Deck

1:

VR104

(L-ch)

(R-ch)

@ibedstes3}

K_]

[VR101

(R-ch)]

so

that

the

output

is

within

the

standard

value.

(Refer

to

Fig.

2.)

©

Fig.

6

[Standard

value

:

280

mV+

15

mV

|

ERASE

CURRENT

CONFIRMATION

(DECK2)

1.

Insert

the

blank

tape

into

Deck2,

and

press

the

REC

PAUSE

button.

3.

Check

if

the

output

at

this

time

between

the

erase

current

confirmation

point

TP301

kab

and

PuGsteg

(the

output

on

both

edged

of

R313)

is

withinthe

standard

—

Erase

Head

value.

(Refer

to

Fig.

7.)

Standard

value

EVM

reading

Normaltape

:85+25mA

(85

+

25

mV)

CrO2tape

:150+25mA

(150+

25

mV)

TP302

Metaltape

:185+25mA

(185+

25

mV)

sedate

dikes

a

he

a

Note:

The

test

tape

is

not

required

when

confirming

the

erase

current.

Fig.

7

istitiei

tins

46=

RS-CH770

Playback

frequency

response

check

(DECK

1/2)

Playback

the

315

Hz/-20

dB

and

12.5

kHz

to

63

Hz/-20

dB

sections

of

the

test

tape

(QZZCFM)

and

then,

using

the

315

Hz/-20

dB

playback

output

as

a

reference

(0

dB),

confirm

that

the

playback

frequency

response

is

within

the

range

shown

in

Fig.

9.

(L-ch)

Miler

or

(R-ch)

Bien

A.GND

Fig.

8

Fig.

9

Recording/playback

frequency

response

and

gain

check

(DECK

2)

Normal

tape

check

1.

Insert

a

Normal-type

blank

tape

(QZZCRA)

into

Deck

2.

Record

signals

at

50

Hz,

100

Hz,

200

Hz,

500

Hz,

1

kHz,

2

KHz,

10

kHz

and

12.5

kHz

(28

mV).

3.

Set

the

playback

frequency

of

the

recorded

signals

at

1

KHz

as

the

reference

response

(0

dB).

4.

Playback

the

recorded

signals

to

confirm

that

the

output

is

within

the

range

of

the

overall

frequency

response

shown

in

Fig.

11.

|

CrO2/Metal

tape

check

5.

Repeat

steps

2

to

4

for

each

tape

and

confirm

that

the

output

for

each

is

within

the

range

of

the

overall

frequency

response

shown

in

Fig.

12.

Main

P.C.B.

aul

Fig.

10

Normal

Overall

frequency

response

chart

(NR

OFF)

5OH2

100Hz

200Hz

500Hz

1kHz

2kHz

10kHz

Fig.

11

CrO2

Metal

Overall

frequency

response

chart

(NR

OFF)

SOHz

100Hz

200Hz

S500Hz

1kHz

2kHz

12.5kHz

Fig.

12

S47=

Ee

RIE

aS

a

ae

RS-CH770

|

m

Schematic

Diagram

Page

A

MAIN

CIRCUIT

2:seeccsccch

cen

cece

teesi

sisi

aeteaveritanebe

certs:

19~22

[E]

MECHANISM

CIRCUIT

(DECK

1)

.0......::ceceieeeeieeeseeesessenenernne

21

[eo]

MECHANISM

CIRCUIT

(DECK

2)

.........scsessseseeseeeeeessteettesesssssseeess

21

[PE]

POWER

SUPPLY

CIRCUIT

|...

ceeeeeseeeneeeeseittetesnaneneren

22

[2]

OPERATION

CIRCUIT

........ssssccecsssteccesteeeeessnneeeeeneetessneeesssineneen

23

@

This

schematic

diagram

may

be

modified

at

any

time

with

the

development

of

new

technology.

Notes:

@$900-

-

Stop

switch

(MH)

@S901

:

DECK

2

cassette

holder

open

switch

(&

OPEN)

©S902

:

One-touch

tape

edit

switch

(TAPE

EDIT/HIGH)

®S903

;

One-touch

tape

edit

switch

(TAPE

EDIT/NOR)

@S904_

-

Record

pause

switch

(®

REC

PAUSE)

@$905_

-

Dolby

noise

reduction

switch

(DOLBY

NR)

eS906_

.:

Fast

forward/tape

program

sensor

switch

(

3)

©S907_

:

Forward

side

playback

switch

(B>)

@S909_

-

Reverse

side

playback

switch

(~d)

@S910

;

Rewind/tape

program

sensor

switch

(<<

)

@S911

;

Reverse

mode

select

switch

(REV

MODE)

@S912

;

DECK

1/DECK

2

select

switch

(DECK

1/2)

®S913

:

Counter

display

switch

(COUNTER/DISPLAY)

S914

—

;

Counter

reset

switch

(COUNTER/RESET)

©S915

:

DECK

1

cassette

holder

open

switch

(&

OPEN)

@S951

:

DECK

1

mode

detect

switch

®S952

-

DECK

1

half

detect

switch

®S953

.

DECK

1

CrO2

tape

detect

switch

@S971

:

DECK

2

mode

detect

switch

@®S972

:

DECK

2

half

detect

switch

@®S973

:

DECK

2

CrOz

tape

detect

switch

©S974

:

DECK

2

reverse

side

record

prevention

tab

detect

switch

e@S975

:

DECK

2

forward

side

record

prevention

tab

detect

switch

@®S976

.DECK2

METAL

tape

detect

switch

@®VR101

:

DECK

1

Playback

gain

adjustment

(R-ch)

@®VR102

;

DECK

2

Playback

gain

adjustment

(L-ch)

@®VR103

:

DECK

2

Playback

gain

adjustment

(R-ch)

@VR104

:

DECK

1

Playback

gain

adjustment

(L-ch)

®VR801

:

DECK

1

tape

speed

adjustment

(normal)

®VR802

;

DECK

2

tape

speed

adjustment

(high)

®VR8O03

:

DECK

2

tape

speed

adjustment

(normal)

@

Indicated

voltage

values

are

the

standard

values

for

the

unit

measured

by

the

DC

electronic

circuit

tester

(high-impedance)

with

the

chassis

taken

as

standard.

Therefore,

there

may

exist

some

errors

in

the

voltage

values,

depending

on

the

internal

impedance

of

the

DC

circuit

tester.

No

mark:

Playback

( )

:

Recording

®

Important

safety

notice:

Componenis

identified

by

AY

mark

have

special

characteristics

important

for

safety.

Furthermore,

special

parts

which

have

purposes

of

fire-retardant

(resistors),

high-quality

sound

(capacitors),

low-noise

(resistors),

etc.

are

used.

When

replacing

any

of

components,

be

sure

to

use

only

manufacturer's

specified

parts

shown

in

the

parts

list.

®

Caution!

IC

and

LS|

are

sensitive

to

static

electricity.

Secondary

trouble

can

be

prevented

by

taking

care

during

repair.

Cover

the

parts

boxes

made

of

plastics

with

aluminum

foil.

Ground

the

soldering

iron.

Put

a

conductive

mat

on

the

work

table.

Do

not

touch

the

legs

of

IC

or

LSI

with

the

fingers

directly.

©

Voltage

and

signal

line

oweepeneees

©

Positive

voltage

line

mum

©

Playback

signal

Line

{

>

:

Recording

signal

Line

-~i8-

a

oe

RS-CH770

Al

MAIN

CIRCUIT

(P.C.Board:on

page

24)

a

10101

zs

C143

C115

CXA1998QT6

2

470P 470P

R/P

EQ

AMP

=A

Q101

aa

2SJ164RATA

HEAD

SELECT

(REC:ON)

Q105,106

2SD1819RATX

Se

DECK

1

Li

by

MUTING

-8

Leh

§_]

PLAYBACK

&

-$

ye

6)

es

r

3}

SIGNAL(Lch)

5

5a

PLAYBACK

a

mn

Ne.

e

HEAD

ie

mt

R

ch»

§)

|

R107

ory)

10K

ov

60)

PBEQ

4

DECK

2

ee

re)

Beco

Eee

LATCHES

(9

Loh

ae

0

(18)

R/P

HEAD

(0.2¥)

a7

c

G5)

5

(0.1V}

Sz:

tev

68

4

Q103,104

«

ay

28J164QTA

za

63°:

HEAD

SELECT

i=

aioe

(PLAY:ON)

t

3

330K

8>e

+

ow

1§

rs)

R158

|

22K

Q303,304

2SD2436STXRA

2SD1450RSTA

SWITCHING

BIAS

OSC

(REC:ON)

ERASE

CURRENT

CHECK

POINT

301

2SD1819ATX

BIAS

OSC

CONT.

Q306

DTC144EUT107

BIAS

OSC

CONT.

DTC144EUT107

BIAS

OSC

CONT.

21955

RS-CH770

Al

MAIN.

CIRCUIT

(P.C.Board:on

page

24)

R213

221

3.3K

50V0.47

+

R730

2.2K

C133

(C134

1C201

CXA1102M-T4

a

DOLBY

NR

DTA143EUT107

R/P

SELECT

PLAYBACK

GAIN

ADJ.

Q201

(Lch.DECKT)

DTA1443EUT107

DOLBY

ON/OFF

VR104

20K

(B)

<

a

as

og

R148

VR102

5.6K

20K(B)

R150

5.6K

PLAYBACK

GAIN

ADJ.

(L

ch,DECK2)

1102

MC14066BFEL

DECK

1/2

SELECT

PLAYBACK

GAIN

ADJ.

GAIN

ADJ.

(R

ch,DECK2)|

(R

ch,DECK1)

1

ge

R147

VR101

5.6K

20K(B)

1C202

DTC143EUT107

MC14066BFEL

SWITCHING

SIGNAL

CONT.

DTA143EUT107

@Q

be

ENC/DEC

SELECT

at

C216,,50V1

1

+H

R233

C215,,50V1

100

+H

Technics RS-CH770 User manual

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