Sony DXA-H2750 User manual

Table of contents

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SERVICE

MANUAL

This

set

is

the

Amplifier,

cassette

deck

section

in

FH-E705C,

MHC-2750.

SONY-06187

DXA-H2790

US

Model

Canadian

Model

AEP

Model

UK

Model

E

Model

Australian

Model

Tourist

Model

Model

Name

Using

Similar

Mechanism]

TC-H2700/H3700

Tape

Transport

Mechanism

DECK

A|

TCM-190RA13A

Type

:

DECK

B|

TCM-19ORB22A

SPECIFICATIONS

Amplifier

Section

Continuous

RMS

power

output

US,

CND

model:

45

+

45

watts

(6

ohms

at

1

kHz,

5%

THD)

E,

EA,

AUS,

TR

model:

40.

+

40

watts

(6

ohms

at

1

kHz,

5%

THD)

AEP,

UK,

G,

IT

model:

35.

+35

watts

(6

ohms

at

1

kHz,

DIN)

Music

power

output

AEP,

UK,

G,

IT

model:

60

+

60

watts

(6

ohms

at

1

kHz,

10%

THD)

Peak

music

power

output

£,

EA,

AUS,

TR

model:

400

watts

inputs

DAT

IN

(phono

jacks):

sensitivity

450

mV,

impedance

47

kilohms

AEP,

UK,

G,

IT

model:

PHONO

IN

(phono

jacks):

sensitivity

5

mV,

impedance

47

kilohms

Except

AEP,

UK,

G,

IT

model:

VIDEO

IN

(phono

jacks):

sensitivity

450

mV,

impedance

47

kilohms

Outputs

HEADPHONES

(stereo

minijack):

accepts

headphones

of

8

ohms

or

more

SPEAKERS:

accepts

speakers

of

6

to

16

ohms

Cassette

Deck

Section

Recording

system

4-track

2-channel

stereo

Frequency

response

(DOLBY

NR

OFF)

40

—

13,000

Hz

(+3

dB),

using

TYPE

|

cassette

(Sony

HF-S)

40

—

14,000

Hz

(+3

dB),

using

TYPE

ii

cassette

40

—

15,000

Hz

(+3

dB),

using

TYPE

IV

cassette

Wow

and

flutter

0.1%

WRMS

+0.3%

(DIN)

Design

and

specifications

subject

to

change

without

notice.

STEREO

CASSETTE

DECK

AMPLIFIER

ONY.

DXA-H2750

|

SAFETY

CHECK-OUT

After

correcting

the

original

service

problem,

perform

the

following

safety

check

before

releasing

the

set

to

the

customer:

Check

theantenna

terminals,

metal

trim,

“metallized”

knobs,

screws,

and

all

other

exposed

metal

parts

for

AC

leakage.

Check

leakage

as

described

below.

LEAKAGE

TEST

The

AC

leakage

from

any

exposed

metal

part

to

earth

ground

and

from

ail

exposed

metal

parts

to

any

exposed

metal

part

having

a

return

to

chassis,

must

not

exceed

0.5mA

(500

microampers).

Leakage

current

can

be

measured

by

any

one

of

three

methods.

1.

A

commercial

leakage

tester,

such

as

the

Simpson

229

or

RCA

WT-540A.

Follow

the

manufacturers’

instructions

to

use

these

instru-

ments.

Ne

A

battery-operated

AC

milliammeter.

The

Data

Precision

245

digital

multimeter

is

suitable

for

this

job.

3.

Measuring

the

voltage

drop

across

a

resistor

by

means

of

a

VOM

or

battery-operated

AC

volt-

meter.

The

“limit”

indication

is

0.75V,

so

analog

meters

must

have

an

accurate

low-

voltage

scale.

The

Simpson

250

and

Sanwa

SH-63Trd

are

examples

of

a

passive

VOM

that

is

suitable.

Nearly

all

battery

operated

digital

multimeters

that

have

a

2V

AC

range

are

suitable.

(See

Fig.

A)

To

Exposed

Metal

Parts

on

Set

AC

0.15

nF

voltmeter

jo

3)

(0.75

V)

=

Earth

Ground

Fig.

A.

Using

an

AC

voltmeter

to

check

AC

leakage.

MODEL

IDENTIFICATION

—

Model

Number

Label

—

SONY

movetno.

pxa-H2750

STEREO

CASSETTE

DECK

AMPLIFIER

WML

US

model:

AC:

120V

60Hz

105W

CND

model:

AC:

120V

60Hz

115W

AEP

model:

AC:

220-—230V~50/60Hz

UK

model:

AC:

240V~50Hz

E,

EA,

TR

model:

AC:

120/220/230~-240V~50/60Hz

110W

G,

1T

model:

AC:

220—230V~50Hz

AUS

model:

AC:

240V~50Hz

110W

@CND:

Canadian

model

e@

AUS:

Australian

model

eG:

Germany

model

elT:

italian

model

@EA:

Saudi

Arabia

model

e@TR:

Tourist

model

SAFETY-RELATED

COMPONENT

WARNING!!

COMPONENTS

IDENTIFIED

BY

MARK

A

OR

DOTTED

LINE

WITH

MARK

A

ON

THE

SCHEMATIC

DIAGRAMS

AND

IN

THE

PARTS

LIST

ARE

CRITICAL

TO

SAFE

OPERATION.

REPLACE

THESE

COMPONENTS

WITH

SONY

PARTS

WHOSE

PART

NUMBERS

APPEAR

AS

SHOWN

IN

THIS

MANUAL

OR

IN

SUPPLEMENTS

PUB-

LISHED

BY

SONY.

ATTENTION

AU

COMPOSANT

AYANT

RAPPORT

A

LA

SECURITE!

LES

COMPOSANTS

IDENTIFIES

PAR

UNE

MARQUE

/(\

SUR

LES

DIAGRAMMES

SCHEMATIQUES

ET

LA

LISTE

DES

PIECES

SONT

CRITIQUES

POUR

LA

SECURITE

DE

FONCTIONNEMENT.

NE

REMPLACER

CES

CCM-

POSANTS

QUE

PAR

DES

PIECES

SONY

DONT

LES

NUMEROS

SONT

DONNES

DANS

CE

MANUEL

9U

DANS

LES

SUPPLEMENTS

PUBLIES

PAR

SONY.

|

DXA-H2750

TABLE

OF

CONTENTS

Section

Title

Page

Section

’

Title

Page

1.

GENERAL

5.

DIAGRAMS

j-l.

Part

Identification

.............-..

02.

e

eee

ee

ee

eee

ee

3

5-1.

Semiconductor

Lead

Layouts

................660.

13

5-2.

Ciaucuit

Boards

Location

....................006-

14

2.

DISASSEMBLY

5-3.

Printed

Wiring

Boards

—Deck

Section—..........

16

2-1.

Front

Panel

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

cece

cece

e

eee

eee

eaee

4

5-4.

Schematic

Diagram

—Deck

Section—

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

19

2-2.

Control

Board,

HP

Board

.....................05.

4

5-5.

Schematic

Diagram

—Main

Section—

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

24

2-3.

Cassette

Lid

Assy

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

cece

eee

e

centre

eee

5

5-6.

Printed

Wiring

Boards

—Main

Section—

........

29

2:4,

MD

Bl0ck®

occ

cen

secvanivdeae

ern

eaienldse

ai

aciiens

5

5-7.

Printed

Wiring

Boards

—-Panel

Section—

........

34

2:5..

“Back

Panel:

tee

.cneia

ce

cexiwints

alee

evse

Uieeet

e

6

5-8.

Schematic

Diagram

—Panel

Section—

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

37

2-6.

Power

Transformer

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

cece

e

scence

eeees

6

2-7.

TC

Main

Board

............0cc

ccc

ce

cece

ne

ee

ences

7

6.

EXPLODED

VIEWS

2-8.

Joint

(Upper)

...........

0.

cee

cece

e

eee

eens

7

6-1.

Cabinet

Section

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

sche

NE

dep

Wa

ae

Bh

ch

ane

42

2-9.

Capstan/Reel

Motor

.............-..

sees

eee

eee

eee

8

6-2.

Chassis

Section............0ccc

cece

ee

eee

n

cea

eeeee

43

2-10.

Head

Base

ASSY...........

sce

e

eee

e

ee

eee

eee

eens

8

6-3.

Cassette

Holder

Section.................

cee eee

44

6-4.

Mechanism

Deck

Section

1]

.................00005

45

3.

MECHAINICAL

ADJUSTMENTS

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

9

6-5.

Mechanism

Deck

Section

2

..............0:e

sees

46

4.

ELECTRICAL

ADJUSTMENTS

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

9

7.

ELECTRICAL

PARTS

LIST

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

47

LD

CD

ALD

DAL

AED

AP AD

EP

AED MEE AED

AED

E>

D>

AER

ECD»

AED

AD

ALD

AEP

ED

ARES»

RE E>

NEED

D>

AED» AEE:

A>

AED»

E>

AEG

AE

D>

ERED:

AEG»

ID

AED AED

AEE

AGS

Ds

AED

AE

AR

AE

AED

ALES

AED

ARORA

AS

SECTION

1

GENERAL

1-1.

-_PARTS

IDENTIFICATIONS

This

section

is

extracted

from

instruction

manual.

(1)

HEADPHONES

jack

(stereo

minijack)

[2]

SYSTEM

POWER

switch

and

STANDBY

indicator

The

indicator

remains

lit

as

long

as

the

AC

power

cord

is

connected

to

a

wall

outlet.

[3]

DISPLAY

button

@

[4]

DIRECT

button

and

indicator

@

(5)

FUNCTION

button

and

function

indicators

@ @

[6]

PRESET

button

@

VOLUME

control

@

TOTAL

EFFECT

CONTROL

—/+

buttons

@

[8]

Cassette

holder

(Deck

B)

EJECT

&

button

(Deck

8B)

[13]

Tape

operation

buttons

(for

Deck

8)

Q:

Stop

button

(>:

Forward

play

button

and

indicator

<]:

Reverse

play

button

and

indicator

<4

p>:

Fast

winding

buttons

PAUSE

[f:

button

and

indicator

REC

@:

button

and

indicator

[12]

DOLBY

NR

(Dolby

Noise

Reduction)

switch

@

[3]

CD

SYNCHRO

button

@ @

TAPE

DUBBING

buttons

@

NORMAL

SPEED

button

HIGH

SPEED

button

[is]

DIRECTION

mode

selector

@

@

Tape

operation

buttons

(for

Deck

A)

©:

Stop

button

>:

Forward

play

button

and

indicator

<j:

Reverse

play

button

and

indicator

<4

p>:

Fast

winding

buttons

EJECT

&

button

(Deck

A)

Cassette

holder

(Deck

A)

DXA-H2750

|

Note

:

Follow

the

disassembly

procedure

in

the

numerical

order

given.

SECTION

2

DISASSEMBLY

2-1.

FRONT PANEL

@

Connector

CN956

N80

te

}

©

Connectors

CN953

@

Connectors

}CN109

CN104

O

Claws

@

BVTP

2.6x8

2-2.

CONTROL

BOARD,

HP

BOARD

@

CN505

BVTT

3X6

Control

board

@

Knob

(VOL)

assy

2-3.

CASSETTE

LID

ASSY

2-4.

MD

BLOCK

BVTP

2.6X8

|

DXA-H2750

DXA-H2750

|

2-5.

BACK

PANEL

BD

CN952

(US,

Canadian)

>

BVTP

3X10

BVTP

3x10

@

Back

panel

D

BVTP

3x10

2-6.

POWER

TRANSFORMER

@

Bracket

(heat

sink)

B

Heat

sink

@

BVTT

3x6

Power

tranfomer

2-7.

TC

MAIN

BOARD

@TC

main

board

@CN601

@

CN603

2-8.

JOINT

(UPPER)

@

BVTP

2.6x8

@

Joint

(upper)

@

BVTP

2.6x8

|

DXA-H2750

DXA-H2750

|

2-9.

CAPSTAN/REEL

MOTOR

@

PTPWH

2x23

@

fitting

base

@

Claws

@

When

installing,

pull

the

FR

belt

and

put

arround

claws.

©

When

installing,

pull

the

capstan

belt

and

put

arround

claws.

@

connectors

@

capstan

motor

ground

plate’

connector

@B2.6x3

@

Claws

@

MD-A

board

MD-B

board

@

reet

motor

belt

(FR)

@

P2.6X2.8

2-10.

HEAD

BASE

ASSY

@

Claw

@

head

basd

assy

os

@

torsion

spring

hy:

9:

@

lever

(pinch

lever

REV)

assy

lever

(pinch

lever

FWD)

assy

—8—

SECTION

3

MECHANICAL

ADJUSTMENTS

PRECAUTION

1.

Clean

the

following

parts

with

a

denatured

alcoholmois-

tened

swad:

record/playback

head

erase

head

pinch

roller

rubber

belts

capstan

idlers

2.

Demagnetize

the

record/playback

head

with

a

head

demagnetizer.

(Head

demagnetizer

do

not

approach

for

the

erase

head.)

3.

Do

not

use

a

magnetized

screwdriver

for

the

adjustment.

4.

After

the

adjustments,

apply

suitable

locking

compound

to

the

parts

adjusted.

.

5.

The

adjustments

should

be

perfomed

with

the

rated

power

supply

voltage

unless

otherwise

noted.

Torque

Measurement

Meter

reading

30

to

65g

*

cm

CQ-1020

(0.42

to

0.90

02

«

inch)

Forward

1

to

6g*cm

CR

1ee

(0.014

to

0.0802

+

inch)

30

to

65g

*

cm

©0-102RC

(0.42

to

0.9002

«

inch)

Reverse

1

to

6g

*

cm

back

tension

€Q-102RC

(0.014

to

0.0802

*

inch)

Forward,

70

to

120g

>

cm

Reverse

€Q-201B

(0.98

to

1.67

oz

«

inch)

|

DXA-H2750

SECTION

4

ELECTRICAL

ADJUSTMENTS

PRECAUTION

1.

The

adjustment

should

be

performed

in

the

publication.

(Be

sure

to

make

playback

adjustment

at

first.)

2.

The

adjustment

and

measurement

should

be

performed

for

both

L-CH

and

R-CH.

@

Switch

position

DOLBY

NR

switch:

OFF

3.

Perior

to

electrical

adjustments,

short

the

connector

TP401

(test

mode).

Test

Tape

[Tape

|

__—Contents

[|

Use

P-4-A100

10kHz,

—10dB

Azimuth

Adjustment

P-4-L300

315Hz,

0dB

Level

Adjustment

WS-48B

3kHz,

0dB

Tape

Speed

Adjustment

Record/Playback

Head

Azimuth

Adjustment

Procedure

:

1.

Forward

Playback

Mode

test

tape

P-4-A100

(10kHz,

—10dB)

TP201

(LINE

OUT)

2.

Turn

the

adjustment

screw

for

the

maximum

output

levels.

If

these

levels

do

notmatch,

turn

the

adjustment

screw

until

both

of

output

levels

match

together

within

1dB.

L-CH

peak

within

1dB

R-CH

screw

Peak

position

L-CH

RCH

~

—

peak

peak

er

DXA-H2750

|

3.

Playback

Mode

test

tape

P-4-A100

(10kHz,

—10dB)

L-CH

47kQ

in

phase

45°

good

4.

Change

the

reverse

playback

mode

and

repeat

the

steps

1

to

3.

5.

After

the

adjustment,

lock

the

adjustment

screw

with

suitable

locking

compound.

Adjustment

Location

:

—record/playback

head—

azimuth

cover

+

Removing

the

azimuth

cover.

§

Unlock

the

stoppers

of

the

azimuth

cover

using

a

L-shaped

wrench

in

order

to

adjust.

Tape

Speed

Adjustment

Procedure

:

—Forward

Playback

Mode—

test

tape

WS-48B

(3kHz,

0dB)

frequency

counter

TP201

(LINE

OUT)

Perform

high

speed

adjustment

before

normal

speed

adjust-

ment.

(High speed

adjustment)

1.

Turn

on

the

power

and

put

the

deck

A

into

the

FWD

mode.

2.

Press

the

HIGH

SPEED

switch.

3.

Adjust

RV72A

(H)

of

the

deck

A

so

that

a

reading

on

the

frequency

counter

meets

the

adjustment

value.

4,

Adjust

the

RV72B

(H)

of

deck

B

performing

steps

1

to

3

as

deck

A.

(Norma!

speed

adjustment)

1.

Put

the

set

into

the

FWD

playback

mode.

2.

Press

the

NORMAL

SPEED

switch.

3.

At

this

time,

adjust

RV71A

(L)

of

the

deck

A

and

RV71B

(L)

of

the

deck

B

so

that

a

reading

on

the

frequency

counter

meets

the

adjustment

value.

Adjustment

Limits

:

Frequency

Counter

Reading

6,000

+

20Hz

3,000

+

10Hz

Frequency

difference

between

the

beginning

and

the

ead

of

the

tape

should

be

within

3%.

Frequency

difference

between

deck

A

and

deck

B

the

begin-

ning

of

the

tape

should

be

within

1.5%.

Adjustment

Location:

MD-A

Board,

MD-B

Board