Sony TC-730 User manual

Power

Requirements:

Power

Consumption:

Track

System:

Ree!

Size:

Tape

Speed:

Recording

Time:

(with

1,800

ft.

tape)

Frequency

Response:

Signal-to-Noise

Ratio:

Flutter

and

Wow:

Harmonic

Distortion:

Recording

Bias

Frequency:

Inputs:

SPECIFICATIONS

AC

100, 110, 120,

127,

220

or

240

V

50/60

Hz

AC

120W

4—track

2—channel

stereo

and

mono

7°

(48

cm)

or

smaller

7

\/2

ips

(19

cm/s),

3

3/4

ips

(9.5

cm/s),

1

7/g

ips

(4.8

cm/s)

Tape

speed

4-—track

stereo

4—track

mono

vd

Vo

ips

1.5

hrs

3

hrs

(19

cm/s)

3

3/4

ips

3

hrs

6

hrs

(9.5

cm/s)

(with

SONY

SLH

tape)

20

~

30,000

Hz

at

71/2

ips

(19

cm/s)

20

~

20,000

Hz

at

33/4

ips

(9.5

cm/s)

(with

standard

tape}

20

~

25,000

Hz

at

71/2

ips

(19

cm/s)

20

~

17,000

Hz

at

34/4

ips

(9.5

cm/s)

30

~

9,000

Hz

at

17/g

ips

(4.8

cm/s)

56

dB

(with

SLH

tape)

53

dB

(with

standard

tape)

0.06

%

at

71/2

ips

(19

cm/s)

0.1%

at

39/4

ips

(9.5

cm/s)

0.2%

at1

’/gips

{4.8

cm/s)

1.2%

Approx.

160

kHz

Two

MIC

Inputs

Impedance

Maximum

sensitivity

:

low

impedance

:

—72

dB

(0.2

mV)

Outputs:

Maximum

Power

Output:

Built-in

Speaker:

Semiconductors:

Dimensions:

Weight:

Two

AUX

Inputs

Impedance

Maximum

sensitivity

REC/PB

connector

Input

impedance

Input

level

Two

LINE

Outputs

Load

impedance

Output

level

HEADPHONE

Output

Load

impedance

Output

level

REC/PB

connector

Output

impedance

Output

level

Two

EXT

SPKR

Load

impedance

Output

level

E

Model

STEREO

TAPECORDER

:

100

kQQ

:

—22

dB

(62

mV)

10kQ

:

—33

dB

(17.4mvV)

:

100

kQ2

:

OdB

(0.775

V)

BQ

:

—36

dB

(12.3

mV)

at

LEVEL’*1”

—28

dB

(30.8

mV)

at

LEVEL’

“2”

:

10kQ2

:

OdB

(0.775

V)

:8Q

:

17

dB

(5.6

V)

3.7

W

x

2

with

built-in

speakers

15

Wx

2

with

external

speakers

4x6

(10x

15cm)

x2

impedance

32

(2

51

transistors,

25

diodes

and

1

integrat

€d

circuit

21

(W)

x

19

5/g

(H)

x

8

15/46"

(D)

(533

x

498

x

227

m)

51

Ib

13

oz

(23.5

kg)

‘SERVICE

MANUAL,

Section

N

GENERAL

DESCRIPTION

1-1.

1-2,

1-3.

TABLE

OF

CONTENTS

Title

Specifications

..........

Block

Diagram

.........

Major

Parts

Locations

......

Switch

Location.

........

CIRCUIT

DESCRIPTION

Record

Amp

Circuit

Muting

Circuit

System

Control

3-1.

3-2.

3-3.

3-4,

3-5.

Ac’Servo

Circuit

4-1.

Priciple.

ace.

4.5

See

Bo

SS

4-2.

Servo

Amplifier

Operation.

...

4-3.

Motor

Speed

Deviation

from

Intended

Value

.........

Sequence

of

Switch

Operation.

.

DISASSEMBLY

2-1.

Cabinet

Removal...

......

2-2.

Head

Deck

Removal.

......

2-3.

Record

Equalizer

Circuit

Board

Removal.

..........

2-4.

Reverse

Switch

Circuit

Board

Brake

Solenoid

PM602

.....

Reel

Motor

Circuit...

.....

Pinch

Roller

Solenoid

PM601

..

.

Solenoid

Operating

Voltage

....

Removal

ADJUSTMENT

PROCEDURES

3-1.

3-2.

Mechanical

Adjustments.

...

.

Electrical

Adjustments

.....

Section

Title

4.

DIAGRAMS

4-1.

4-1-1.

4-1-2.

4-2.

4-2-1.

4-2-2.

4-2-3.

4-2-4,

4-2-5.

4-2-6.

4-2-7.

4-2-8.

4-2-9.

4-2-10.

4-2-1].

4-2-12.

4-3.

5.

ELECTRICAL

PARTS

LIST

Schematic

Diagram

.......

Audio

Amp

and

Bias

OSC

Circuits

3.05

oe

Ea

System

Control

Circuit

.....

Mounting

Diagram.

.......

Record

Amp

Circuit

Board

Speaker

Selector

Switch

Circuit

Board

..........

Tone

Control

Circuit

Board

...

Power

Amp

Circuit

Board...

.

Relay

Circuit

Board

.......

Power

Supply

Circuit

Board.

.

Servo

Control

Circuit

Board.

.

Reverse

Switch

Circuit

Board

..

.

68

Level

Diagram

6.

EXPLODED

VIEWS

6-1.

6-2.

6-3.

6-4.

6-5.

6-6.

6-7.

6-8.

6-9.

7.

HARDWARE

Cabinet

—

top

view

~—

Head

Deck

—topview—

....

Amplifier

Chassis

Panel

—topview-

..........

Amplifier

Chassis

—

top

view

—

.

Chassis

—

topview—-(1).....

Chassis

—

top

view

—

(2)...

..

Chassis

—

top

view

—(3).....

Chassis

~

bottom

view—-

....

PaCkKin

gw

ao

in2kt

Ge

eos

e

esa

al

Hardware

Nomenclature.

....

When

ordering

replacement

parts,

you

should

use

PART

NUMBER

listed

on

the

Parts

Lists

or

shown

in

the

EXPLODED

VIEW.

The

reference

number

should

not

be

used

for

ordering

purposes.

.

39

.

39

.

41

.

43

.

43

Record

Equalizer

Circuit

Board

. .

46

Playback

Amp

Circuit

Board.

.

Bias

OSC

Circuit

Board

.....

SOS/ECHO

Circuit

Board

...

.

48

.51

.

54

“55

.

56

.

58

.

60

.

63

.

66

67

.

70

77

279

.

81

.

83

.

85

.

87

.

88

.

89

.

90

941

.

91

SECTION

1

GENERAL

DESCRIPTION

BLOCK

DIAGRAM

1-1.

JINOHdGV3H

{om}

770d

Lon

|

a

AW

[:

|

‘

.

Azu

iN0D

4

Aviad

dd

zogwd

|

2

€

togau

[><]

tat

TS

Fale

1o9Wd

Ee

e

TJ

A001

|S}

sayO"

YOUId

SI

II'>

aad

|

mee

Re

oO

¥

mM

rere

=

39VLIOA

cor

4ayeads

d

urying

AIH

NON

dS

2

euiatiee

(2198)

I

q

:

AlddNS

4IMOd

60L0

YIZIMNEVLS

80L7~

1020

dWVY

Y3MOd

Z0S

“1090

2s0

svia

ANOHdOV

3H

voir

oO

90ED

ONILNW

SO0ED

dWY

YILIN

Hd

®@

INOHdQV3H

~~

ATH

gots

Au

,

FOuNOS

OE

‘E0E0

Hd

dNVY

INIT

~

GMs

4NO

3NIT

coir

OHIH/SOS

ZO

“L010

dWV

JIN

SOt

‘vOt

“E010

dWY

934

NI

XNW

1-2.

MAJOR

PARTS

LOCATIONS

Cabinet

—

Top

View

—

X-34980-81

X-34970-46

reel

panel

knob

ass’‘y,

ass

‘y,

complete

AUTO

REV

|

X-34970-47

cover

assy,

h@ad

-

rr

X-34970-46

knob

assy,

1-5

14-867

switch,

slide;

TAPE

SELECT

(S108)---~-----—-—

1-514-768

switch,

lever;

HEADPHONE

LEVEL

(S109)-------

1-507-282

jack,

binaural;

:

HEADPHONE

(J104)

ack

:

Fen

R(J202)

|

at

t

igieaditt

\

X-34970-50

AUX-L

——--—

|

knob

(A)

ass‘y,

i

|

control

AUX-R

-

:

|

i

of

;

i

{

|

M

Si

oe

J

}

1-524-082-11

EME

|

meter,

VU

R(ME2)

———--—________-—

{

j

L

(S105)

R

($205)

1-5

14-836

switch,

MONITOR

Cabinet

—

Side

Views

—

EXT

SPKR

171-536-309

push

terminal,

—

4P

(35701)

1-507-142

Jack,

AUX

IN

(J101,

201)

171-509-359

connectors,

REC/PB

3-497-237

terminal,

GND

171-507-142

tack,

LINE

OUT

(S703,

203)

1-514-868

switch,

lever

ECHO/SSOS

(S110)

‘

VOLUME

__

1-§14-869

switch,

lever;

~

MIC-R

X-34980-01

“cabinet

assy

SOS/ECHO

X-34980-02

TREBLE

knob

(B)

ass'y,

contro!

BASS

knob

(A)

ass’y,

control

-

ees

X-34970-50

SPKR

SELECT

(S702)

X-34580-22

knob

ass’y,

selector

1-514-866

switch,

seesaw;

POWER

AMP

(S701)

1-507-282

jack,

binaural;

HEADPHONE

(J702)

AUX-R

\

X-34970-50

knob

(A)

ass’y,

control

~R

x.34970-45

button

ass’y,

REC

_.

1-533-048

holder,

fuse

1-509-427

socket,

power

voltage

selector

(VS6071)

UNSWITCHED-

-300W--

171-509-341

—-

connector,

AC

i

OUTLET

(CNJG071}

1-534-487

cord,

power

Chassis

—

Top

View

—

X-34970-26

reel

table

ass’y

1-454-075

;

solenoid

plunger;

—_—__7al

pinch

roller

(PM601)

j

8-829-142-20

———

head,

playback

(PP102-4202)

8-828-629-20

head,

record/erase

{ERP102-2902)

3-497-207

pinch

roller

1-222-497

resistor,

variable;

AUX

30

kQ.(D)

(R136)

1-222-498

1-524-082-11

resistor,

variable;

meter,

VU

(ME7,

2)

MIC

10

k82(D)

(R135)

Chassis

—

Bottom

View

—

1-441-730

8-833-012-01

transformer,

power

motor,

fan

(T601)

(1S-024A]}

8-836-624-07

motor,

reel

(UC-624K)

X-34980-51

mounted

circuit

board,

tone

control

X-34980-52

mounted

circuit

——-——

board,

power

amp

X-34980-56

mounted

circuit

board,

speaker

selector

switch

1-454-074

solenoid,

plunger;

direction

(PM603)

X-34970-61

X-34970-64

mounted

circuit

mounted

circuit

board,

record

amp

_

board,

bias

osc

8-828-629-20

head,

record/erase

(ERP

102-2902)

171-221-910

S<—

resistor,

variable

50

kQ.(C)

(ECHO/SOS)

171-221-917

"

ggrl-

resistor,

va-iable

50

kKQ.

(A)

TREBLE

p

1-221-917

42

resisotr,

variable

50

k82.(A}

BASS

1-222-499

resistor,

variable

500

k82

BALANCE

gael

1-221-917

resistor,

variable

50

k82.

(A)

VOLUME

Y-20410-12-9

counter,

tape

index

—*1-514-870

switch,

rotary;

MODE

1-222-497

resistor,

variable,

AUX

30

k91{D)

(R236)

1-222-498

resistor,

variable,

MIC

10

k§2(D)

(R235)

1-454-074

solenoid,

plunger;

brake

(PM602)

8-836-624-07

motor,

reel

(UC-624K)

X-34970-66

mounted

circuit

board,

relay

X-34970-68

mounted

circuit

board,

servo

control

X-34980-53

mounted

circuit

board,

power

supply

8-836-214-01

motor,

capstan

(UC-214G)

-

X-34970-62

mounted

circuit

board,

record

equalizer

mounted

circuit

board,

playback

amp

1-3.

SWITCH

LOCATION

S614

(upper

side)

PLAY,

FF-STOP

switch

(4)

S605

(lower

side)

PLAY,

FF-STOP

switch

(2)

S610

(upper

side)

PLAY,

FF-STOP

switch

(3)

S613

i

.__.§602

(lower

side)

te”

PLAY,

FF-STOP

switch

(1)

S604

(upper

side)

S620

—~-

PLAY-FF,

STOP

switch

(1)

.

PLA

Y-FF,

STOP

S612

{lower

side)

switch

(4)

PLAY-FF,

STOP

switch

(2)

=

S609

S618

AUTO

SHUT-OFF

switch

AUTO

OFF

swit

OFF

switch

S616

S607

PLAY

switch

(3)

FF

switch—

PLAY

switch

(2)

-

S608

PLAY

switch

(1)

~~

S606

STOP

switch

woes

SHIT

FF

switch

(2)

S619

(upper

side)

FWD-REV

switch

(2)

S607

(lower

side)

FWD-REV

switch

(1)

;

3

E

|

!

i

CIRCUIT

DESCRIPTION

The

following

describes

operation

of

main

circuit:

1.

RECORD

AMP

CIRCUIT

First

stage

of

the

record

amplifier

comprises

NPN

and

PNP

type

transistors

connected

in

parallel.

This

circuit

improves

linearity

characteristics

of

record

amplifier

for

MIC

jack

input

signals.

Approximately

50

dB

linearity

can

be

obtained.,

Therefore,

can

record

signals

with

greater

input

level

(approximately

—10

dB,

0.25

V

to

MIC

jack)

with

low

distortion.

Linearity

for

conventional

circuit

which

has

only

one

transistor

is

approximately

30

dB.

2.

MUTING

CIRCUIT

During

direction

change

of

tape

transport

(about

three

seconds),

from

the

time

when

tape

stops

moving

until

tape

motion

reverses

and

recoveres

to

normal

tape

speed,

B

+

voltage

of

bias

oscillator

is

cut

off

in

record

mode

and

the

muting

circuits

(Q306

and

Q406)

of

playback

amplifier

are

activated

in

playback

mode.

When

turning

POWER

switch

ON,

the

multivibrator

(Q504

and

Q505)

is

kept

stable

as

follows:

POWER

switch

is

turned

ON.

Initial

current

through

C505

turns

0505

ON.

Decreased

collector

voltage

of

0505

turns

Q504

OFF.

After

C505

has

been

charged,

Q505

base

bias

is

applied

through

R507.

0505

is

kept

ON.

Decreased

collector

voltage

Decreased

collector

voltage

of

Q505

keeps

0306

and

of

0505

keeps

O506

OFF.

Q406

OFF.

Playback

amplifier

normal-

O503

is

kept

ON

and

sup-

ly

works.

plies

B+

voltage

to

bias

oscillator.

When

changing

the

unit

from

FWD

mode

to

REV

mode

or

vice

versa,

this

circuit

acts

as

follows:

FWD—

REV

—

FWD

Negative

trigger

pulse

Positive

trigger

pulse

through

D614

turns

through

D613

turns

Q505

OFF.

Q504

ON.

Increased

collector

voltage

of

0505

turns.0504

ON.

Collector

voltage

of

Q504

decreases.

Current

flows

through

R506

and

through

R507

and

C505.

C505

discharges

for

about

three

seconds.

During

the

discharge,

Q505

is

turned

OFF

by

decreased

base

bias.

Increased

collector

voltage

of

O505

turns

Q506

ON.

Increased

collector

voltage

of

Q505

turns

Q306

and

Q406

ON.

Q306

and

Q406 Q503

turns

OFF

ground

audio

and

cut

off

B+

signals.

voltage

to

bias

oscillator.

After

the

discharge,

current

stops

flowing

through

R507

and

C505.

Q505

is

turned

ON

by

increased

base

bias.

0504

is

turned

OFF.

:

j

E

é

:

Bt

From

power

supply

circuit

Q503

Q306

(0406)!

o

UPLAY

S614

Muting

circu

Collector

voltage

of

Q505

rises

for

sTopo

PLAY

FF

a

=p

S103-2

about

three

seconds

when

the

meade

switch

is

changed,

and

then

306

(Q406)

turns

ON.

D604

Fig.

7.

3.

SYSTEM

CONTROL

3-1.

Brake

solenoid

PM602

When

FWD

button

is

pushed,

S608

turns

ON.

Then

high

voltage

(about

170

volts

dc)

rectified

by

D604

is

applied

to

PM602

through

S605.

PM602

is

energized.

3-2.

Reel

motor

circuit

The

motor

current

flows

as

follows:

46

V

or

80

V

terminals

of

power

transformer

——»

$612

———»

R609

————-contacts

of

relay

RY602-———

reel

motors

M2,

M3

—»

$610

————~-

0

V

terminal

of

power

transformer

3-3.

Pinch

roller

solenoid

PM601

When

S602

is

turned

ON

by

solenoid

PM602,

high

voltage

(about

170

volts

dc)

rectified

by

D604

is

applied

to

PM601

through

S604.

PM601

is

energized.

Bt

To

bias

osc

circuit

ral”

V

(in

FWD

mode)

OV

lin

REV

mode)

RY601

Muting

circuit

3-4.

Solenoid

operating

voltage

Solenoids

(for

brake,

pinch

roller,

and

tape

direction)

are

energized

by

high

voltage

(about

170

volts

dc)

and

kept

energized

by

low

voltage

(about

30

volts

dc).

3-5.

S612

This

switch

supplies

a

high

reel-motor-driving

voltage

(80

volts

ac)

to

make

strong

tape

tension

in

a

starting

moment,

because

of

tape

slack

elimination.

When

pressing

FWD

or

REV

button,

$612

supplies

80

volts

ac

for

about

one

second

unitl

pinch

roller

solenoid

PM601

actuates

S612.

After

solenoid

PM601

has

actuated

S612,

S613

supplies

46

volts

ac

for

normal

tape

tension.

FF,

STOP

REW

right

reel

motor

self-locking

{Turns

ON

when

contacts

of

\FWD

button

is

pushed,

RY602

S607

Turns

ON

when

FF

or

REW

button

is

pushed

RY602

FF

relay

Fig.

2.

Reel

motor

circuit

4.

AC

SERVO

CIRCUIT

The

Model

TC-730

employs

ac

servo

amplifier

circuit

and

keeps

tape

speed

constant.

4-1.

Principle

See

block

diagram

in

Fig.

3.

Motor

speed

determined

by

voltage

Em

can

be

changed

by

voltage

Er.

E

(fixed)

=

Em

+

Er

When

motor

speed

becomes

faster

or

slower

than

intended

speed

according

to

external

disturb-

ances,

the

intended

motor

speed

can

be

obtained

again

by

changing

voltage

Er,

or

by

changing

resistance

R.

The

frequency

generator

FG

in

the

motor

detects

motor

speed

deviation.

Servo

amplifier

changes

resistance

R

according

to

the

deviation.

TC-730

uses

impedance

R

between

collector

and

emitter

of

tran-

sistor

Q901

instead

of

resistance

R

as

shown

in

Fig.

4.

Impedance

R

can

be

changed

by

the

base

voltage.

The

motor

speed

can

be

kept

stable

by

controlling

the

base

voltage

for

the

motor

speed

deviation.

The

bridge

type

rectifier

comprising

four

diodes

makes

current

flow

through

transistor

Q901

in

the

direction

shown

by

the

arrow

in

Fig.

4.

Efconstant)

SERVO

AMP

Fig.

3.

Servo

control

system

block

diagram

SERVO

AMP

Fig.

4.

Q9017

instead

of

resistance

R

Outline

of

IC

(CX-032})

Q2

Fig.

5.

Servo

amplifier

outline

Ac

4-2.

Servo

amplifier

operation

Servo

amplifier

which

changes

impedance

R

operates

as

follows:

See

Fig.

5

and

Fig.

6.

1)

2)

3)

4)

Sine

wave

signal

generated

by

frequency

ge-

nerator

FG

is

transfered

to

bases

of

Q1

and

Q?2.

Since

base

bias

voltages

of

Q1

and

Q2

are

set

to

saturation

region,

sine

wave

signal

is

waveshaped

to

square

wave

signal

shown

by

(A)

in

Fig.

6.

Square

wave

signal

from

Q2

is

amplified

by

Q3,

Q4

and

QS.

It

is

transfered

to

differentiating

circuit

comprising

Cl

and

R1

and

is

wave-

shaped

to

pulse

shown

by

(B)

in

Fig.

6.

Then

it

is

transfered

to

base

of

Q6.

De

voltage

Vs

stabilized

by

Q12

is

divided

by

R3

and

R4.

Then

it

is

transfered

to

base

of

Q8

and

keeps

the

emitter

voltage

Ek

of

Q8

(also

that

of

Q7)

constant.

Vs

also

charges

C2

according

to

the

time

constant

decided

by

C2

and

R2.

The

charged

voltage

is

applied

to

collector

of

Q6.

When

pulse

shown

by

(B)

in

Fig.

6

is

transfered

to

base

of

Q6,

Q6

repeats

ON

and

OFF

states.

C2

discharges

while

Q6

makes

current

flow

as

shown

by

the

arrow

(1)

in

Fig.

5.

Thus

sawtooth

wave

signal

shown

by

(C)

in

Fig.

6

is

obtained

at

collector

of

Q6.

—10—

5)

6)

4-3.

1)

The

sawtooth

wave

signal

is

supplied

to

base

of

Q7.

Since

the

emitter

voltage

Ek

is

kept

con-

stant,

Q7

turns

ON

only

when

the

peak

value

of

sawtooth

wave

signal

is

greater

than

Ek.

When

Q7

turns

ON,

the

negative

pulse

shown

by

(D)

in

Fig.

6,

appears

at

collector

of

Q7.

This

pulse

is

amplified

by

Q9,

Q10

and

Q11,

and

its

polarity

is

inverted.

The

positive

pulse

is

transfered

to

the

integrator

comprising

R5

and

C3,

and

is

waveshaped

as

shown

by

(E)

in

Fig.

6.

After

being

amplified

by

Q13

and

Q14,

it

is

transfered

to

base

of

Q901.

And

this

base

voltage

changes

impedance

between

collector

and

emitter

of

Q901

and

controls

motor

speed.

Motor

speed

deviation

from

intended

value

When

motor

speed

becomes

faster

(Fig.

7);

Switching

speed

of

Q6é

becomes

faster

since

frequency

of

frequency

generator

FG

increases.

Collector

voltage

of

Q6

is

grounded

before

it

becomes

greater

than

emitter

voltage

Ek

(con-

stant)

because

of

short

charging

time

for

C2.

The

peak

value

of

the

sawtooth

wave

signal

at

base

of

Q7

is

less

than

Ek.

Thus

Q7

turns

OFF,

and

base

voltage

of

Q901

decreases

since

the

pulse

is

not

supplied

to

base

of

Q9.

When

2)

3)

impedance

R

becomes

greater,

motor

voltage

Em

decreases

and

motor

speed

decreases

to

the

intended.

When

motor

speed

becomes

slower

(Fig.

8)

;

Switching

speed

of

Q6

becomes

slower

since

frequency

of

frequency

generator

FG

decreases.

Collector

voltage

of

Q6

is

grounded

after

it

becomes

greater

than

emitter

voltage

of

Q7

because

of

sufficient

charging

time

for

C2.

The

peak

value

of

the

sawtooth

wave

signal

at

base

of

Q7

is

higher

than

Ek.

Thus

Q7

turns

ON

for

T

seconds,

and

base

voltage

of

Q901

increases

since

the

pulse

is

supplied

to

base

of

Q9,

when

impedance

R

becomes

less,

motor

voltage

Em

increases,

and

motor

speed

increases

to

the

intended

speed.

Thus

by

changing

the

time

T

motor

speed

is

controlled.

.

Time

T

is

determined

by

charging-time

of

C2

(the

inclination

of

the

sawtooth

wave).

In

this

ac

servo

circuit,

the

time

constant

(C2

x

R2)

for

charging

time

is

determined

by

R2

for

the

specified

tape

speed.

Circuit

operation

when

motor

starts

running;

Just

after

the

power

switch

is

turned

ON,

Q6

is

still

turned

OFF

since

signal

is

not

supplied

from

the

frequency

generator

(motor.

is

not

running).

C2

is

charged

rapidly,

and

greater

voltage

than

Ek

is

applied

to

base

of

Q7.

When

base

voltage

of

Q901

increases,

ac

voltage

is

FG

output

signal

approx.

900

Hz

at

19

cm/s

(7

%

ips)

collector

of

Q2

base

of

Q6

collector

of

O6

collector

of

Q7

base

of

Q901

Fig.

6.

|

Waveform

at

each

point

qe:

applied

to

the

motor

and

the

motor

starts

running

rapidly.

In

the

FF

mode,

the

servo

circuit

does

not

work

and

ac

voltage

is

applied

to

the

motor

directly.

Then

motor

rotates

at

full

speed.

FG

output

signal

(short

cycle)

collector

of

Q2

base

of

O6

(short

cycle)

|

base

of

Q7

Ek

LAA

(peak

value

lower

than

Ek}

no

pulse

collector

of

Q7

at

base

of

Q907

(decreases)

Fig.

7.

When

motor

speed

becomes

faster

(long

cycle)

collector

of

Q2

base

of

Q6

(long

cycle)

base

of

Q7

(peak

value

base

of

Q901

(increases)

Fig.

8.

When

motor

speed

becomes

slower

FG

output

signal

higher

than

Ek}

collector

of

Q7

SEQUENCE

OF

SWITCH

OPERATION

Note:

The

number

in

circle

shows

the

sequence

of

switch

operation

when

the

mode

is

changed.

FWD

Button

Is

Pushed

@

S615

turns

ON.

@

S608

turns

ON.

In

the

REV

play

mode,

the

tape

Brake

solenoid

(PM602)

is

energized.

direction

relay

(RY601)

and

solenoid

(PM603)

are

energized

(FWD

play

mode)

@®

$602

turns

ON.

®

S610

turns

ON.

Pinch

roller

solenoid

(PM601)

is

energized,

Reel

motors

start

to

rotate.

@®

$605

is

changed

to

FF,

PLAY

@

S614

turns

ON.

position.

The

voltage

across

B+

voltage

for

bias

osc

circuit

brake

solenoid

(PM602)

de-

is

not

supplied

yet

because

creases.

S613

turns

OFF.

©

S618

turns

ON.

If

the

POWER

MAIN

switch

is

set

to

AUTO

OFF,

the

machine

turns

off

automatically

at

the

end

of

the

tape.

©

S620is

changed

to

PLAY

position.

®

S613

ischanged

to

PLAY

position.

Dummy

resistor

R611

in

B+

circuit

B+

voltage

is

supplied

to

bias

osc

is

cut

off

by

S620.

circuit.

©

S604

is

changed

to

PLAY

position.

@

S612

is

changed

to

PLAY

position.

The

voltage

across

pinch

roller

solenoid

(PM601)

decreases.

(After

one

second

since

S604

is

changed

to

PLAY

position

(6)).

FF

Button

Is

Pushed

®

S611

is

changed

to

FF

position.

@

$607

turns

ON.

FF

relay

(RY602)

is

energized

(FF

position).

The

motor

circuit

is

changed

to

supply

the

rated

voltage

to

each

reel

motor.

@®

Self-locking

contact

(1)

of

FF

relay

@

Contact

(2)

of

RY602

is

closed.

@

Contacts

(3)

and

(4)

of

RY602

are

RY602)

i :

(

02)

is

closed

Brake

solenoid

(PM602)

is

energized.

closed.

Pinch

roller

solenoid

(PM601)

is

de-energized.

AC

rated

voltage

is

supplied

to

reel

motors.

@®

S602

turns

ON.

@

$610

turns

ON.

Reel

motors

start

to

rotate.

These

actions

@

are

not

@®

S605

is

changed

to

FF

position.

@®

S614

turns

ON.

FF

operation.

The

voltage

across

brake

solenoid

(PM602)

decreases.

—12—

Sony TC-730 User manual

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