Pioneer RT-707 User manual

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2

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3-MOTOR

4-HEAD

TAPE

DECK

RT-707

SERVICE

MANUAL

WMPIONEER

MODEL

RT-707

COMES

IN

TWO

VERSIONS

DISTINGUISHED

AS

FOLLOWS:

RT-707

r

T

>

Type

|

Voltage

Remarks

KU

|

120V

only

U.S.A.

model

Kc

120V

only

Canada

mode!

CONTENTS

1.

SPECIFICATIONS

........

0c

ccc

cccceccccc

ee

cescneceecnesseesssescnsens

3

2.

CONNECTION

DIAGRAM

.........

0.

cece

cece cece cece

eee

e

eee

e

ee

eeneeeeee

4

3.

FRONT

PANEL

FACILITIES

.......

0... cece

cece

cc

cect

teen

eee

eeeee

5

4.

BLOCK

DIAGRAM

.....

22...

ccc

cece

cece

cee

tenet

e

eee

een

7

5.

LEVEL

DIAGRAM

....

0...

ccc

ete

eee

e

eee

eeeeeneeeeees

9

6.

CIRCUIT

DESCRIPTIONS

6:1!

“Power

Supply

ses

ccs

ean

ie

eames

Shei

2S

ends

Ae

dae

oh

aaeee

oeteasten

10

6.2

Control

Circuit

10

6.3

Direction

Switch

Circuit

....

2.2...

ccc

cee

eee

e

eens

13

6.4

Switching

Circuit,

Muting

Circuit...

2.2...

6.

cece

eee

tee

eee

14

6.5

Playback

Amplifier...

2.2.0.6...

cece

cece

cece

eee

ee

eee

eee

e

eee

enee

15

6.6

Bias

Oscillator

.

.

16

6.7.

Recording

Amplifier

16

6.8

Frequency

Generator

........

6.

ccc cee

eect

eee

eee

eee

c

eect

teen

eeees

17

7.

DISASSEMBLY

TA

(BONNE

6.5.5

sci

ke

Sees

ee

dace

Seis

Rea

wis

We

deals

Gade

aeie

sue

tek

B

21

7.2

Rear

Panel

..

21

7.3

Bottom

Plate

22

7.4

Front

Panel

22

8.

PARTS

LOCATIONS

8.1

Front

Panel

View

...........

cc

cece

cece cece eect

teen

e

cece

eeeeeeeaees

23

8.2

Front

View

With

Front

Panel

Removed

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

00.

cece

ee

cece

cece

eee

25

8.3.

Top

View

With

Bonnet

Removed

........

27

8.4

Bottom

View

With

Bottom

Panel

Removed

29

8.5)

Rear

Panel

View

oieiecc

sci6ib

aid

oboe

sia

de

Relea

ele

niece

0 a

icia

eb/6is,

aoe

valde

a

wees

es

31

9.

MECHANICAL

ADJUSTMENTS

9.1

Reel

Base

Height

Adjustment

...........

2.0...

c

cece

cece

cece

cece

eeenees

33

9.2:

‘Brake

Adjustment:

ooo

e0.3.3

ic

cided

cspees

cee

ees

hid eek

Sis

dee

eew

eae

é

33

10.

11.

12.

13.

14.

9.3.

Takeup

Torque,

Back

Tension

Adjustment

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

00:

c

eee

eee

34

9.4

Pinch

Roller

Pressure

Adjustment

35

O15,

Pause

Adjustments.

24.4

2c.00

25

toed

etapa

dae

ARES

eae

ayeid

weeterd

serene

ge

36

9.6

Tape

Speed

Adjustment

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

0

cece

eee

e

cece

teen

ee

eeeee

36

HEAD

ADJUSTMENTS

10.1

Head

Rough

Adjustment

...............-08-

:

vee

37

10.2

Playback

Head

Adjustment

38

10.3

Record

Head

Adjustment

..........0

0

ccc

cee

eee

cece

ence

tees

eeeeeneues

38

ELECTRICAL

ADJUSTMENTS

11.1.

Playback

Level

Adjustment

2.0.0...

0...

cece

cece

cee

cnet

e

ee

eneeaes

39

11.2

Playback

Equalizer

Adjustment

39

11.3

Level

Meter

OVU

Adjustment

39

11.4

Dummy

Coil

Adjustment

..........0.

00

c

ccc

e

eee

eee

eeaee

40

115

Bias

Trap

Adjustment

......

0...

cc

cee

ccc

cect

cece

en

eet

cesses

ceeseevens

40

11.6

Recording

Bias

Adjustment

.......

40

11.7.

Record/Play

Frequency

Response

41

11.8

Recording

Level

Adjustment

...........0

0

cece

cece

cent

eee

e

eee

e

eee

n

eee

41

EXPEODED

VIEW...

cs

icciad

éccccsaid,

CaS

alades

oTSaP

Valdes

vargas

oe

eles

eae

e

Mam

42

SCHEMATIC

DIAGRAMS,

P.C.

BOARD

PATTERNS

AND

PARTS

LIST

13.1.

Miscellaneous

Parts

List

....

2.2.0...

e

eee

e

eee

ee

eee

teens

2+.

59

13.2

External

Appearance

of

Transistors,

ICs

and

Circuit

Diagrams

of

IC

60

13.3

Connection

Diagram

....

2.0...

.

cece

ce

cee

eee

eee

cence

nee

eeeneenes

61

13.4

Schematic

Diagram

.......

6...

cece

eee

eee

eee

eee

e

eee

e

nena

63

13.5

Playback

Amplifier

Assembly

(RWF-069)

..........

0.

ccc

cece

eee

enes

65

13.6

Meter

Amplifier

Assembly

(RWX-155).......

71

13.7.

Power

and

Oscillation

Assembly

(RWR-053)

73

13.8

Indicator

Assembly

(RWX-142)

......

00.

ccc

cc

cee

cee

cee

tenet eeaee

13.9

Fuse

Assembly

(RWX-141)

....

13.10

Equalizer

Amplifier

Assembly

(RWX-154)

13.11

Head

Amplifier

Assembly

(RWF-070)

...........

0.0

cece

cece

eee

eee

13.12

Connector

Assembly

L

(RWX-151)

22...

6.

cece

cece

eee

n

eee

e

eee

13.13

Connector

Assembly

R

(RWX-152)

.........

00.

cece

eee

e

eee

cece

eee

eeee

13.14

Function

Switch

Assembly

(RWS-052)

..........

0...

c

cece

eee

ce

eee

eeeeee

13.15

MIC

Amplifier

Assembly

(RWF-065)

..........

0...

c

cece

cece

ee

eee

eeees

13.16

Control

Assembly

(RWG-070)

.......

0.

cece

cece cece

eee

eect

eee

eeeees

13.17

Servo

Amplifier

Assembly

(RWG-076)

.......

13.18

Switch

Assembly

(RWS-058....

.

KC

type)

(RWS-059.....

KU

type)

PACKING)

ivccs

ce

cee Sot

oes

5,30

34

cio

eel

8

Sk

nS

se

easle

wow

Sarde

waniea

est

106

1.

SPECIFICATIONS

Type

acchanes

op

Bass

4-track,

2-channel

stereo

tape

deck

(Recording,

playback

with

reverse

playback)

.

Solenoid

drive,

Pushbutton

direct

change

system,

Timer

can

be

set

for

recording

and

playback.

HeadSis

asters

toate

e

Recording

Head

;

1

Erase

Heads

;

1

Forward

playback

Head

;

1

Reverse

playback

Heai

Motors...

02.22.0005

Capstan

drive

moto

(FG-system,

AC

servo,

direct

drive)

Reel base

drive

motors

;

2

(6-pole

inner

rotor

induction

type)

Acceptable

Reel

Size

.

Tin

(17m)

Tape

Speed

19cm/s

(7-1/2ips),

9.Scm/s

(3-3/4ips)

40.5%

Less

than

100

sec.

with

7-inch

reel

and

370m

tape

Wow

and

Flutter...

..

. .

Less

than

0.05%

WRMS

(19cm/s)

Less

than

0.08%

WRMS

(9.5cm/s)

More

than

58dB

Fast

Forward/Rewind

Times

...

.

Signal-to-Noise

Ratio.

Total

Harmonic

Distortion...

..

.

Less

than

1%

(19cm/s)

Frequency

Response

i

eee

eerie

weir

20Hz

to

28,000Hz

(30Hz

to

24,000Hz

+3dB)

SSM:

5

kis

toast

20Hz

to

20,000Hz

(30Hz

to

16,000Hz

+34B)

ome

More

than

S0dB

Channel

Separation.

.

More

than

S0dB

Erasure

Rate

.

More

than

704B

Recording

Bias

Frequency

.

.

125kHz

Equalization.

.........

NAB

Standards

Inputs

(Sensitivity/Maximum

allowable

level/Input

impedance)

MIC;

0.25mV/125mV/27k2,

6mm

diam.

jacks

(suitable

microphone,

2502

to

30k22)

LINE;

50mV/25V/100k2,

DIN;

16mV/8V/1.3k22,

DIN

standards

Outputs

(Reference

level/Maximum

level/Load

impedance)

LINE;

450mV/700mV/SOk2,

DIN;

450mV,

700mV/50k2,

DIN

standards

HEADPHONES;

70mV/822,

6mm

diam.

jack

Semiconductors.

. .

+

67

transistors

(4

FET’s),

5

IC’s,

47

diodes

(1

thyristor,

2

LED's,

4

Zener

diodes,

2

varistors,

)

Crosstalk

Accessory

Functions

©

Pitch

control

(more

than

+6%

of

rated

tape

speed)

@

Auto

reverse

playback

(with

sensing

tape:

manual

reverse

is

possible)

©

Auto

repeat

(counter-interlocked)

©

Recording

mode

switches

(L,

R

independent)

©

Tape

selectors:

BIAS

(STD/LH);

EQ

(STD/LH)

©

MIC/LINE

mixing

©

Output

volume

controls

‘©

Pause

indicator

lamp

Power

Requirements...

. .

AC

120V 60Hz

Power

Consumption

.

120

watts,

Max.

AC

Outlets,

Dimensions

.

. .

.

.

»

Unswitched

(300W

max.)

x

1

+

480(W)

x

230(H)

x

356(D)mm

18-29/32

x

9-1/16

x

14in

Weight...

22.2.0

000-

Without

package;

20.0kg

441b

loz

With

package;

23.5kg

511b

1302

RT-707

Accessories

..........

©

Tin

metal

reel

(Pioneer

PR-85)

x

1

Connecting

cord

with

pin

plugsx2

Head

cleaning

kit

x

1

Sensing

tape

x

1

Splicing

tape

x

1

Operating

instructions

x

1

NOTE:

Specifications

and

the

design

subject

to

possible

modification

without

notice

due

to

improvements.

2.

CONNECTION

DIAGRAM

LINE

output

level

controls

I

|

SS

DQUOQUNAON000

00)

QQQA0UI0N00U0U1

Ac

OUTLET

MAX

MIN

OUTPUT

LEVEL

AC

OUTLET

This

is

the

power

socket

(maxi-

mum

power

capacity:

300W).

You

can

connect

the

power

plug

on

another

tape

deck

or

amplifier

to

this

socket,

These

controls

can

be

used

to

adjust

the

LINE

output

levels.

Turn

them

clockwise

to

increase

the

levels,

They

have

a

center

click

position

where

the

standard

output

level

(450mV

with

0dB

displayed

on

the

level

meter)

of

a

standard

tape

can

be

obtained.

terminal

To

the

power

outlet

or

AC

outlet

on

the

stereo

amplifier

Ground

wire

Tape

connectors

of

RT-707's

playback

/

the

stereo

amplifier

recording

connectors

TAPE

OUTPUT

INPUT

Connections

for

recording

a

mol

|

IN/OUT

Left

channel

DIN

connector

Connections

for

playback

Right

channel

Left

channel

REC/PLAY

connector

(DIN

standard)

of

sec-

‘ond

stereo

amplifier

REC/PLAY

001006

¢@670090

Recording/

playback

cord

(DIN

standard)

3.

FRONT

PANEL

FACILITIES

POWER

SWITCH

Push

this

switch

and

power

is

supplied

to

the

tape

deck.

Push

for

a

second

time

to

turn

the

power

off.

SPEED

SWITCH

-

This

switch

selects

the

tape

speed.

Push

for

a

9.5cm/s

speed;

push

again

for

a

19cm/s

speed

(released

position).

19cm/s:

Used

for

recording

music

programs,

etc.

9,5cm/s:

Used

for

recording

lengthy

conversations,

etc.

PAUSE

LAMP:

This

green

lamp

lights

up

when

the

PAUSE

button

is

pressed

to

indicate

the

tape

has

stopped

temporarily.

PHONES

JACK

This

is

the

output

jack

for

stereo

headphones.

Signals

selected

by

the

MONITOR

switch

are

available

here.

Use

it

when

you

want

to

monitor

the

recording

or

listen

to

a

performance

directly

taped

from

the

RT-707.

The

output

level

is

not

variable.

MIC

JACKS

€)

These

are

the

input

jacks

for

microphone

recording.

The

L

(left)

and

R

(right)

channels

can

be

used

independently.

Only

the

micro-

phones’

input

signals

are

recorded

if

the

REC/PLAY

connector

(DIN

specifications)

on

the

rear

panel

and

the

MIC

jacks

are

connected

at

the

same

time,

As

long

as

the

microphones

have

a

standard

6mm

diameter

plug,

you

can

use

either

a

low

impedance

(600-ohms)

or

high

impedance

(10

—

SOkohms)

type.

MIC

RECORDING

LEVEL

CONTROLS

Use

these

controls

to

adjust

the

recording

level

when

you

are

recording

with

a

microphone

(or

microphones)

or

when

you

are

using

the

rear

panel

REC/PLAY

comnector

(DIN

standard).

Use

the

outer

control

for

the

right

and

the

inner

control

for

the

left

channel.

Input

signals

from

both

the

MIC

jacks

and

the

REC/PLAY

connector

cannot

be

recorded

simultaneously.

LINE

RECORDING

LEVEL

CONTROLS

Adjust

the

recording

input

level

from

the

LINE

INPUT

terminals

‘on

the

rear

panel.

The

level

increases

as

the

controls

are

turned

to

the

right.

The

outer

control

is

for the

right

channel

and

the

inner,

for

the

left.

RECORDING

LAMP

(REC)

This

red

lamp

lights

up

during

recording.

Check

that

it

has

lit

up

before

recording.

MONITOR

SWITCH

Use

this

switch

to

monitor

your

recording.

TAPE:

Allows

you

to

listen

to

the

recorded

signals.

SOURCE:

You

can

listen

to

the

signals

before

recording

if

this

position

is

selected

(press

switch

once).

If

this

switch

is

switched

alternately

to

SOURCE

and

TAPE

during

recording,

you

can

compare

the

sound

signals

beforé

and

after

recording.

BIAS

SWITCH

This

selects

the

recording

bias

current

according

to

the

type

of

tape

used

for

recording.

Push

for

LH

tapes;

push

again

for

STD

tapes

(released

position).

STD:

For

standard

tapes.

LH:

For

low

noise

and

high

output

tapes.

EQ

SWITCH

This

selects

the

recording

equalization

characteristics

according

to

the

type

of

tape

used.

Select

same

position

for

playback

as

for

recording

according

to

the

characteristics

of

the

recording

tape.

Push

for

LH;

push

again

for

STD

(released).

STD:

For

standard

tapes.

1H:

—

For

low

noise

and

high

output

tapes.

TAPE

COUNTER

This

indicates

how

much

tape

has

been

recorded

or

played

back

and

how

much

there

is

left

over.

REPEAT

BUTTON

This

button

allows

you

to

reverse

the

tape

forward

for

reverse

playback

automatically.

If

you

remember

to

worrk

the

tape

counter

and

REPEAT

button,

then

the

tape

will

automatically

be

reversed

and

the

tape

deck

will

be

set

to

forward

playback

when

the

“0000”

display

on

the

tape

counter

gives

way

to

"9999"

during

reverse

playback.

Be

sure

to

release

this

button

when

you

do

not

require

repeated

playback.

COUNTER

RESET

BUTTON

Push

this

button

to

reset

the

tape

counter

to

“0000"

LEVEL

METERS

These

allow

you

to

read

out

the

levels

during

recording

and

play-

back.

When

the

MONITOR

switch

is

set

to

SOURCE,

they

indicate

the

input

signal

level,

and

when

set

to

TAPE,

they

indicate

the

playback

output

level.

APSTAN

This

rotates

when

the

power

is

switched

on,

Together

with

the

pinch

roller,

it

keeps

the

tape

at

its

rated

speed.

PITCH

CONTROL

KNOB

You

can

use

this

to

make

the

tape

travel

6%

faster

or

slower

than

the

normal

tape

speed

during

playback.

When

set

to

the

central

position,

the

tape

speed

is

19cm/s

or

9.5cm/s

(standard

values).

Turn

the

control

to

the

left

and

the

speed

drops

and

the

musical

steps

are

lowered;

conversely,

turn

it

to

the

right,

and

the

speed

rises

and

the

musical

steps

are

raised.

This

control

cannot

be

used

during

recording.

RT-707

REC

MODE

SWITCHES

(L.

R)

Depress

these

switches

when

recording.

L:

Use

this

switch

for

L

(left)

channel

recording.

R:

Use

this

switch

for

R

(right)

channel

recording.

For

stereo

recording,

make

sure

that

you

depress

both

switches.

7

TAPE

DIRECTION

SELECTOR

BUTTONS

These

buttons

allow

you

to

select

the

direction

of

tape

play

during

playback.

When

depressed,

the

button’s

lamp

will

light

up

to

indicate

the

direction

of

tape

play.

Forward

playback:

The

tape

runs

from

left

to

right.

Reverse

playback:

The

tape

runs

from

right

to

left.

When

you

are

recording,

you

cannot

change

the

direction

of

tape

play

even

by

depressing

this

button.

The

tape

will

always

run

ina

forward

direction.

PAUSE

BUTTON

This

temporarily

stops

the

tape

during

tape

play.

When

pressed

during

recording

or

playback,

the

tape

merely

stops.

When

pressed

again,

the

tape

starts

to

run.

This

button

does

not

work

during

fast

forward

or

rewind.

FUNCTION

BUTTONS

44

REWIND:

This

cause

the

tape

to

be

wound

at

a

high

speed

from

the

right

to

the

left

reel.

>P

FAST

FORWARD:

This

causes

the

tape

to

be

wound

at

a

high

speed

from

the

left

to

the

right

reel.

PLAY:

For

tape

playback,

or

recording,

push

this

button.

REC:

To

record,

press

this

button

together

with

the

PLAY

button.

@™

STOP:

This

stops

the

tape

and

releases

the

other

function

buttons.

NOTE:

©

The

function

buttons

will

not

return

to

their

preset

positions

if

the

power

is

turned

off.

©

The

tape

will

always

run

in

a

forward

direction

when

the

POWER

switch

is

depressed

to

the

ON

position.

©

If

you

depress

both

the

PLAY

and

REC

buttons

with

the

tape

set

to

the

reverse

playback

direction,

then

the

tape

will

sometimes

move

slightly

backwards

and

then

start

to

run

forwards.

Therefore,

when

recording,

make

sure

that

you

set

the

DIRECTION

button

to

the

forward

playback

position.

©

There

is

no

need

to

press

the

(j™)

stop

button

if

you

want

to

change

over

from

one

function

to

another.

4.

BLOCK

DIAGRAM

HEADPHONE

Amp.

METER

DRIVE

Amp.

PB.

HEAD

>

(FWwO)

NOTE:

The

number

which

are

circled

in

the

block

diagram

indicated

the

points

which

are

to

be

measured

in

the

level

diagram.

@

HEAD

PHONES

ca

LINE

OUTPUT

o]

MIC

INPUT

DIN

LINE

INPUT

i

©

CONTROL

Ass'y

INDICATOR

a

ig

5

Ped

0

|

|

Su

Si2|

gp.

ac

‘“

Su-3

a

s

baa

io

Sto

q™

Seg

foe

ee

AC

120V

CF

sO

Hz

SWITCHES

St

Se

S3

Sa

Se

St

Se

Sa

Sis

Se:

:

POWER

:

SPEED

+

MONITOR

=

BIAS

Ss:

E.G

RECORD

LEFT

»

RECORD

RIGHT

:

REW

:

FWD

Sto

=

Sit

Sr:

Sa:

Su:

PLAY

REC

PAUSE

Fwo

REVERSE

REPEAT

SHUT

OFF

RELAIES

RY301

:

RY202

:

RY

en

RY

oz

:

LAMPS

Pu

Plz:

Pla:

Pla:

REC

LEFT

REC

RIGHT

:

PLAY

DIRECTION

:

LEVEL

METER

LEFT

LEVEL

METER

RIGHT

FwD

INDICATOR

REVERSE

\NDICATOR

RT-707

5.

LEVEL

DIAGRAM

NOTES:

OdBu=1V

Frequency:

1kHz

(PLAYBACK)

The

level

measurement

points

are

indicated

on

the

block

diagram.

dBy

a4

©

vaby

©

-7aBv

@-1468v

-2074

LEVEL

-

60

(RECORDING

}

©-10aBv

-20dBv

20

(©

-3048

-30

@

}OdBv

@-a1aBv

-40

®

-46dBv

LEVEL

~90

6.

CIRCUIT

DESCRIPTIONS

The

block

diagram

is

shown

on

page

7.

Model

RT-707

is

an

open

reel

tape

deck

charac-

terized

by

direct

drive

4-track

2-channel

configu-

ration,

3

motors,

4

heads

autoreverse

The

sensor

touch

pushbuttons

used

in

most

3-

motor

tape

decks

necessitate

a

relatively

large

num-

ber

Of

relays

in

the

transport

control

electronics;

the

RT-707,

however,

uses

locking

type

pushbut-

tons

which

permit

simplified

circuit

construction

and

also

facilitate

automatic

unattended

recording

in

conjunction

with

a

timer.

6.1

POWER

SUPPLY

When

the

power

switch

S,

is

switched

on,

AC100V

is

supplied

to

the

capstan

motor

from

the

secon-

dary

side

of

the

power

transformer,

and

the

motor

begins

to

rotate.

A

DC

voltage

rectified

in

Dgo,

D4o2,

stabilized

in

the

stabilizer

formed

by

Q4o1,

Q4o2

and

ZD4o,,

is

supplied

to

the

control

circuit

(Fig.

1).

6.2

CONTROL

CIRCUIT

The

control

circuit

is

shown

in

Fig.

2.

Table

1

indicates

the

transistor

states

for

the

different

transport

modes.

@

Play

Function

(Fig.

2)

1.

When

the

play

button

S,0-,

is

pushed,

ground

connection

of

R497

is

interrupted

and

the

base

circuit

of

Q4o,

is

opened.

No

current

can

flow

through

Q4o4,

and

it

enters

OFF

state.

2.

+B

voltage

causes

current

to

flow

along

the

route

Daos

>

Qaog

>

R413

>

Raio,

whereby

Qao5

is

turned

ON.

3.

As

R47

is

connected

between

base

and

emitter

of

Qos,

this

transistor

is

turned

ON.

The

collector

current

of

Qu4o9

activates

brake

solenoid

SL,,

pinch

solenoid

SL,

and

play

relay

RY...

4.

+B

current

also

flows

along

path

Dao;

>

Qyos

>

Rai

>Raio,

whereby

Q4o;

becomes

ON.

5.

As

Rais

is

connected

between

base

and

emitter

of

Q4i0

,

base

current

can

flow

and

the

tran-

sistor

becomes

ON.

Q4io

collector

current

activates

PAUSE

solenoid

SL;.

Operation

of

brake

solenoid

SL,

releases

the

brakes

of

the

supply

motor

(SM)

and

take-up

motor

(TM).

Operation

of

the

pinch

solenoid

SL,

causes

the

pinch

roller

ta

be

pressed

against

the

capstan.

Operation

of

the

play

relay

RY¢o;

enables

AC

70V

from

the

secondary

side

of

the

power

transformer

(see

Fig.

1)

to

be

applied

to

the

supply

and

take-up

motors

through

slide

resistors

R,

and

R;.

Power

switch

}

Si

|

ACI20V

-~

?

60Hz

;

a

Ry6o1-2

~

a

10

Fig.

1

@

Rewind

(&

Fast

Forward)

Function

(Fig.

2)

1.

When

the

rewind

button

S3_-;

is

pushed,

+B

cur-

rent

flows

along

the

path

brake

solenoid

SL,

>

Dao7

>

Ss-3,

and

SL,

operates,

releasing

the

supply

and

take-up

reel

brakes.

As

shown

in

Fig.

1,

AC100V

is

applied

to

the

supply

motor

via

F.F.

button

S,.,

and

Rewind

button

S,-,

,

and

tape

rewind

begins.

.

AC100V

also

flows

to

the

take-up

motor

via

F.F.

button

S,.,

>

rewind

button

S,.,

>

slide

resistor

R,

>

play

relay

RY¢o,

.

The

slide

resis-

tor

serves

to

apply

the

proper

amount

of

back

tension

to

the

take-up

motor

in

rewind

mode.

.

In

F.F.

mode,

on

the

other

hand,

AC100V

from

the

secondary

side

of

the

power

trans-

former

is

applied

to

the

take-up

motor

through

F.F.

button

So.,.

AC100V

also

flows

to

the

supply

motor

via

the

route

formed

by

S,.;

>

play

relay

RY¢o:

>

slide

resistor

R,.

The

slide

resistor

serves

to

apply

the

proper

amount

of

back

tension

to

the

supply

motor

in

fast

forward

mode.

RT-707

©

Solenoid

Voltage

Control

Circuit

(Fig.

2)

When

transport

functions

are

switched,

operating

current

of

the

solenoids

must

be

temporarily

in-

creased

to

effect

the

switching

action,

but

current

must

be

reduced

again

immediately

to

avoid

over-

heating

of

the

solenoids.

1.

When,

for

example,

the

play

button

is

pushed,

a

surge

of

charge

current

(base

current

from

Q407)

flows

to

Caog,

and

Qao7

is

turned

ON.

2.

Brake

solenoid

SL,,

pinch

solenoid

SL,,

play

relay

RY

go,

and

pause

solenoid

SL;

are

con-

nected

as

loads

to

Q4o3.

As

explained

under

PLAY

FUNCTION,

above,

these

solenoids

operate

in

play

mode,

whereby

the

Q4o7

emit-

ter

current

becomes

the

Q4os

base

current,

turning

Q4o3

ON.

8.

As

soon

as

C4og

has

been

charged,

bias

of

Qso7

returns

to

the

normal

operating

value

deter-

mined

by

stabilization

in

Rais;,

ZDao2-

Table

1

|

Transport

Mode

Transistors

in

ON

state

Transistors

in

OFF

state

|

STOP

Q4o4

Q403, Q405+ Qa06, Qa09s

Qaro

PLAY

Q403,

Qaos,

Qa06,

Q409,

Qaio_|

Qaoa

FF/REW

Qaos

Q4031 Q4051

Qa06

Qao9»

Qaio

PAUSE

Qaos;

Qaos,

Qaoss

Qsi0

Qsoa,

Qso9

Capstan

Motor

Solenoid

use

Solencid

Sle

:

Pir

RY¢o1:

Play

Relay

59.3

510-2

cal

t

Fig.

2

44