Toshiba 3787DB User manual

TOSHIBA

SERVICE

MANUAL

COLOUR

TELEVISION

C8SS

Chassis

TABLE

OF

CONTENTS

aise

GENERAL

ADJUSTMENTS

SAFETY

INSTRUCTIONS

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SPECIFIC

INFORMATIONS

SETTING

&

ADJUSTING

DATA,

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CHASSIS

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CABINET

REPLACEMENT

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APPENDIX:

CIRCUIT

DIAGRAM

on

ttasmme

GENERAL

ADJUSTMENTS

SAFETY

INSTRUCTIONS

WARNING:

BEFORE

SERVICING

THIS

CHASSIS,

READ

THE

“X-RAY

RADIATION

PRECAUTION”,

“SAFETY

PRECAU-

TION’

AND

“PRODUCT

SAFETY

NOTICE”

INSTRUCTIONS

BELOW.

X-RAY

RADIATION

PRECAUTION

1.

Excessive

high

voltage

can

produce

potentially

hazard-

2.

The

only

source

of

X-RAY

RADIATION

in

this

TV

receiver

ous

X-RAY

RADIATION.

To

avoid

such

hazards,

the

high

is

the

picture

tube.

For

continued

X-RAY

RADIATION

pro-

voltage

must

not

be

above

the

specified

limit.

The

nominal

tection,

the

replacement

tube

must

be

exactly

the

same

value

of

the

high

voltage

of

this

receiver.is

@

kV

at

zero

type

tube

as

specified

in

the

parts

list.

beam

current

(minimum

brightness)

under

a

©

V

AC

power

3.

Some

part

in

this

receiver

have

special

safety-related

char-

source.

The

high

voltage

must

not,

under

any

circum-

acteristics

for

X-RAY

RADIATION

protection.

For

contin-

ued

safety,

parts

replacement

should

be

undertaken

only

stances,

exceed

©

kV.

:

after

referring

to

the

PRODUCT

SAFETY

NOTICE

below.

Each

time

a

receiver

requires

servicing,

the

high

voltage

should

be

checked

following

the

HIGH

VOLTAGE

CHECK

procedure

in

this

manual.

It

is

recommended

that

the

read-

ing

of

the

high

voltage

be

recorded

as

a

part

of

the

service

record.

It

is

important

to

use

an

accurate

and

reliable

high

voltage

meter.

SAFETY

PRECAUTION

WARNING

:

Service

should

not

be

attempted

by

anyone

unfamiliar

with

the

necessary

precautions

on

this

receiver.

The

following

are

the

necessary

precautions

to

be

observed

before

servicing

this

chassis.

1.

Anisolation

transformer

should

be

connected

in

the

power

line

between

the

receiver

and

the

AC

line

before

any

service

is

performed

on

the

receiver.

2.

Always

discharge

the

picture

tube

anode

to

the

CRT

conductive

coating

before

handling

the

picture

tube.

The

picture

tube

is

highly

evacuated

and

if

broken,

glass

fragments

will

be

violently

expelled.

Use

shatter

proof

goggles

and

keep

picture

tube

away

from

the

unprotected

body

while

handling.

3.

When

replacing

a

chassis

in

the

cabinet,

always

be

certain

that

all

the

protective

devices

are

put

back

in

place,

such

as;

non-

metallic

control

knobs,

insulating

covers,

shields,

isolation

resistor-capacitor

network

etc.

PRODUCT

SAFETY

NOTICE

Many

electrical

and

mechanical

parts

in

this

chassis

have

special

safety-related

characteristics.

These

characteristics

are

often

passed

unnoticed

by-a

visual

inspection

and

the

protection

afforded

by

them

cannot

necessarily

be

obtained

by

using

replacement

components

rated

for

higher

voltage,

wattage,

etc.

Replacement

parts

which

have

these

special

safety

char-

acteristics

are

identified

in

this

manual

and

its

supplements;

electrical

components

having

such

features

are

identified

by

the

international

hazard

symbols

on

the

schematic

diagram

and

the

parts

list.

Before

replacing

any

of

these

components,

read

the

parts

list

in

this

manual

carefully.

The

use

of

substitute

replacement

parts

which

do

not

have

the

same

safety

characteristics

as

specified

in

the

parts

list

may

create

shock,

fire,

X-ray

radiation

or

other

hazards.

WARNING:

BEFORE

SERVICING

THIS

CHASSIS,

READ

THE

“X-RAY

RADIATION

PRECAUTION”,

“SAFETY

PRECAU-

TION”

AND

“PRODUCT

SAFETY

NOTICE”

ON

PAGE

3

OF

THIS

MANUAL.

SET-UP

ADJUSTMENT

Bi

The

following

adjustments

should

be

made

when

a

complete

realignment

is

required

or

a

new

picture

tube

is

installed.

Perform

the

adjustments

in

order

as

follows

:

1.

Color

Purity

2.

Convergence

3.

White

Balance

Note:

The

PURITY/CONVERGENCE

MAGNET

assembly

and

rubber

wedges

need

mechanical

positioning.

Refer

to

figure

1.

”

pad

=

Lud

=

2]

pan)

pr)

Q

<t

wl

<<

oc

Lu

2

Lud

1]

*

There

are

no

adjustment

of

purity

and

convergence

in

some

picture

tube

(Unified

with

purity

magnet).

COLOR

PURITY

ADJUSTMENT

NOTE

:

Before

attempting

any

purity

adjustments,

the

receiver

5.

Remove

the

Rubber

Wedges.

should

be

operated

for

at

least

fifteen

minutes.

6.

Rotate

and

spread

the

tabs

of

the

purity

magnet

(See

fig-

1.

Demagnetize

the

picture

tube

and

cabinet

using

a

degauss-

ure

2.)

around

the

neck

of

the

picture

tube

until

the

green

ing

coil.

belt

is in

the

center

of

the

screen.

At

the

same

time,

enter

2.

Set

the

brightness

and

contrast

to

maximum.

the

raster

vertically.

3.

Use

a

green

raster

from

among

the

built-in

test

signals.

7.

Slowly

move

the

yoke

forward

or

backward

until

a

uniform

4.

Loosen

the

clamp

screw

holding

the

yoke

and

slide

the

green

screen

is

obtained.

Tighten

the

clamp

screw

of

the

yoke

backward

or

forward

to

provide

vertical

green

belt

yoke

temporarily.

(zone)

in

the

picture

screen.

8.

Check

the

purity

of

the

red

and

blue

raster.

TEMPORARY

DEFLECTION

MOUNTING

YOKE

29.1mm(28",

29")

|

25mm(25")

19mm(19",

20",

21")

ae

14mm(13",

14")

Int

~

oe

RUBBER

WEDGE

ADHESIVE

PURITY/

CONVERGENCE

DEFLECTION

MAGNET

ASS'Y

r

YOKE

GLASS

CLOTH

TAPES

Figure

1.

CONVERGENCE

ADJUSTMENTS

NOTE:

Before

attempting

any

convergence

adjustments,

the

receiver

should

be

operated

for

at

least

fifteen

min-

utes.

m@

CENTER

CONVERGENCE

ADJUSTMENT

.

Use

the

cross-dot

pattern

from

among

the

built-in

test

sig-

nals.

.

Set

the

brightness

and

contrast

for

well

defined

pattern.

.

Adjust

two

tabs

of

the

4-Pole

Magnets

to

change

the

an-

gle

between

them

(See

figure

2.)

and

superimpose

red

and

blue

vertical

lines

in

the

center

area

of

the

picture

screen.

4.

Turn

the

both tabs

at

the

same

time

keeping

the

angle

constant

to

superimpose

red

and

blue

horizontal

lines

at

the

center

of

the

screen.

5.

Adjust

two

tabs

of

6-Pole

Magnets

to

superimpose

red/

blue

line

and

green

one.

Adjusting

the

angle

affects

the

vertical

lines

and

rotating

both

magnets

affects

the

hori-

zontal

lines.

6.

Repeat

adjustments

3, 4,

5

keeping

in

mind

red,

green

and

blue

movement,

because

4-Pole

Magnets

and

6-Pole

Magnets

have

mutual

interaction

and

make

dot

movement

complex.

—

[cu

e)

4-POLE

MAGNETS

PURITY

MAGNETS

CONVERGENCE

MAGNET

ASSEMBLY

Figure

2.

BLU

RED

4-POLE

MAGNETS

MOVEMENT

ADJUST

THE

ANGLE

(VERTICAL

LINES)

CIRCUMFERENCE

CONVERGENCE

ADJUSTMENT

.

Loosen

the

clamping

screw

of

deflection

yoke

slightly

to

allow

the

yoke

to

tilt.

.

Temporarily

put

a

wedge

as

shown

in

figure

1.

(Do

not

remove

cover

paper

on

adhesive

part

of

the

wedge.)

.

Tilt

front

of

the

deflection

yoke

up

or

down

to

obtain

better

convergence

in

circumference.

(See

figure

3.)

Push

the

mounted

wedge

into

the

space

between

picture

tube

and

the

yoke

to

fix

the

yoke

temporarily.

.

Put

other

wedge

into

bottom

space

and

remove

the

cover

paper

to

stick.

.

Tilt

front

of

the

yoke

right

or

left

to

obtain

better

conver-

gence

in

circumference.

(See

figure

3.)

.

Keep

the

yoke

position

and

put

another

wedge

in

either

upper

space.

Remove

cover

paper

and

stick

the

wedge

on

picture

tube

to

fix

the

yoke.

.

Detach

the

temporarily

mounted

wedge

and

put

it

in

an-

other

upper

space.

Stick

it

on

picture

tube

to

fix

the

yoke.

.

After

fixing

three

wedges,

recheck

overall

convergence.

Tighten

the

screw

firmly

to

fix

the

yoke

and

check

the

yoke

is

firm.

.

Stick

three

adhesive

tapes

on

wedges

as

shown

in

figure

1.

ROTATE

TWO

TABS\\

AT

THE

SAME

TIME

(HORIZONTAL

LINES)

ADJUSTMENT

OF

MAGNETS

RED/BLU

GRN

RED/BLU

6-POLE

MAGNETS

MOVEMENT

Center

Convergence

by

Convergence

Magnets

INCLINE

THE

YOKE

UP

(OR

DOWN)

(INCLINE

THE

YOKE

RIGHT

(OR

LEFT)

Circumference

Convergence

by

DEF

Yoke

Figure

3.

Dot

Movement

Pattern

a5

SERVICE

MODE

1.

ENTERING

TO

SERVICE

MODE

1)

Press

¢X

button

once

on

2)

Press

eX

button

again

to

3)

While

pressing

the

2X

button,

Remote

Control.

keep

pressing.

press

MENU

button

on

TV

set.

[item

|

S

_——_——_

SUE

ao

(Service

mode

display)

n

E

=

Lu

=

a

n

=)

pr)

Q

{

owed

4

cc

Lu

Pad

uy

oO

2.

DISPLAYING

THE

ADJUSTMENT

MENU

1)

Press

MENU

button

on

TV.

Service

mode

Adjustment

mode

Item

s

___Press_

Data

Press

3.

KEY

FUNCTION

IN

THE

SERVICE

MODE

The

following

key

entry

during

display

of

adjustment

menu

provides

special

functions.

A

single

horizontal

line

ON/OFF:

-/--

button

(on

Remote)

or

-©

button

(on

TV)

:

Test

signal

selection

:

-©

button

(on

Remote)

Selection

of

the

adjustment

items

:

Channel

A/¥

(on

TV

or

Remote)

Change

of

the

data

value

:

Volume

<1

+/-

(on

TV

or

Remote)

Adjustment

menu

mode

ON/OFF

:

MENU

button

(on

TV)

Initialization

of

the

memory

(QA02)

:

CALL

+

Channel

button

on

TV

(A)

Reset

the

count

of

operating

protect

circuit

to

“OO”:

CALL

+

Channel

button

on

TV

(¥)

“RCUT”

selection

:

1

button

“GCUT”

selection

:

2

button

“BCUT”

selection

:

3

button

“CNTX”

(or

“SCNT”)

selection

:

4

button

“COLC’

selection

:

5

button-

-

Color

thickness

correction

“TNTC”

selection

:

6

button

note:

Displayed

differently

as

shown

below,

de-

Test

audio

signal

ON/OFF

(1kHz)

:

8

button

pending

on

the

setting

of

the

receiving

color

Self

diagnostic

display

ON/OFF

:

9

button

system.

COLP

(PAL)

COLC

(NTSC)

COLS

(SECAM)

CAUTION

:

Never

try

to

perform

initialization

unless

you

have

changed

the

memory

IC.

4.

SELECTING

THE

ADJUSTING

ITEMS

1)

Every

pressing

of

CHANNEL

&

button

in

the

service

mode

changes

the

adjustment

items

in

the

order

of

table-2.

(¥

button

for

reverse

order)

5.

ADJUSTING

THE

DATA

1)

Pressing

of

VOLUME

1

+/—

button

will

change

the

value

of

data

in

the

range

from

OOH

to

FFH.

The

variable

range

depends

on

the

adjusting

item.

6.

EXIT

FROM

SERVICE

MODE

1)

Pressing

POWER

button

to

turn

off

the

TV

once.

Mm

INITIALIZATION

OF

MEMORY

DATA

OF

QA02

After

replacing

QA02,

the

following

initialization

is

required.

.

Enter

the

service

mode,

then

select

any

register

item.

2.

Press

and

hold

the

CALL

button

on

the

Remote,

then

press

the

CHANNEL

A

button

on

the

TV.

The

initialization

of

QA02

has

been

complated.

3.

Check

the

picture

carefully.

If

necessary,

adjust

any

adjustment

item

above.

Perform

“Auto

search

Memory”

on

the

owner’s

manual.

CAUTION:

Never

attempt

to

initialize

the

data

unless

QA02

has

been

replaced.

=

7.

TEST

SIGNAL

SELECTION

1)

Every

pressing

of

©

button

on

the

Remote

Control

changes

the

built-in

test

patterns

on

screen

as

described

below

in

SERVICE

MODE.

*Redraster

—

Signal

off

——»

NTSC

signals

(14

patterns)

a

PAL

signals

(14

patterns)

*

All

Black

¢

All

White

¢

Black

&

White

¢

Black

cross-bar

«

White

cross-bar

©

Black

cross-bar

—

_ongreen

raster.

*

Black

cross-hatch

¢

White

cross-hatch

¢

Black

cross-dot

¢

White

cross-dot

*

H

signal

(white)

-

*

H

signal

(black)

*

The

signals

marked

with

are

not

usable

to

display

in

the

Test

signal

for

some

model.

”

-_

rd

i

=

f=

”

=]

pr]

oO

ft

=

<{

ea

uu

=

ud

a)

8.

SELF

DIAGNOSTIC

FUNCTION

1)

Press

“9”

button

on

Remote

Control

during

display

of

adjustment

menu

in

the

service

mode.

The

diagnosis

will

begin

to

check

if

interface

among

IC's

are

executed

properly.

2)

During

diagnosis,

the

following

displays

are

shown.

Indicated

color

of

mode

now

selected

:

Green

and

Red

<SELFE

CHECK>

Indicated

color

of

other

modes

:

White

2390****

Green

:

Normal

POWER

:

00

Red:

The

microcomputer

operates

to

provide

judgement

BUS

LINE

:

OK

of

no

video

signal.

The

red

color

is

still

indicated

BUS

CONT

:

OK

though

the

signal

is

input,

failure

may

exist

in

input

BLOCK

:

signal

line

including

QVO1.

QV01

:

In

case

of

indication

green

---Normal

In

case

of

indication

red

with

input

signal----

Failure

may

exist

in

output

line

including

QV01.

QOOOOO

2)

-

=

uu

=

-

2]

oe]

”

a)

f{

wl

ft

fc

ma

Pa

Lu

o

@

Part

number

of

microcomputer

(QA01)

@

Operation

number

of

protecting

circuit

----“O0”

is

nor-

mal.

When

indication

is

other

than

“O00”,

overcurrent

apts

to

flow,

and

circuit

parts

may

possibly

be

damaged.

@)

BUS

LINE

CHECK

----“OK”

is

normal.

“SDA1-GND”

-------------

SDA-GND

short

circuit.

“SCL1-GND”

--------------

SCL-GND

short

circuit.

“SCL1-SDA1”

---

-

SCL-SDA

short

circuit.

@

BUS

CONT

----“OK’

is

normal.

When

indication

shows

“Q

OOO

NG”,

the

device

with

the

number

may

possibly

be

damaged.

*

The

items

marked

with

“"

are

not

usable

to

display

in

the

SELF

DIAGNOST|C

FUCTION

for

some

model.

DESIGN

MODE

1.

ENTERING

TO

DESIGN

MODE

1)

Select

the

Service

mode.

2)

While

pressing

CALL

button

on

Remote

3)

Press

MENU

button

on

TV.

and

press

MENU

button

on

TV.

s

Press

~<—

ITEM

——____»

~<—

DATA

Press

(Design

mode)

(Adjustment

mode)

When

QA02

is

initialized,

items

“OPTO”

and

“OPT1”

of

DESIGN

MODE

are

set

to

the

data

of

the

representative

model

of

this

chassis

family.

Therefore,

because

ON-SCREEN

specification

remains

in

the

state

of

the

representative

of

model.

This

model

is

required

to

reset

the

data

of

items

“OPTO”

and

“OPT1”.

2.

SELECTING

THE

ADJUSTING

ITEMS

Every

pressing

of

CHANNEL

YW

button

in

the

design

mode

changes

the

adjustment

items

in

the

order

of

table-3.

3.

ADJUSTING

THE

DATA

Pressing

of

VOLUME

4A

or

¥

button

will

change

the

value

of

data.

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ELECTRICAL

ADJUSTMENTS

ADJUSTMENT

PROCEDURE

1.

Enter

the

service

mode,

then

select

any

register

item.

2.

Press

the

TV/VIDEO

button

on

the

Remote

until

the

black

cross-bar

pattern

ap-

pears

on

the

screen.

3.

Adjust

the

FOCUS

control

(on

T461)

for

well

defined

scanning

lines

on

the

picture

screen.

ITEM

FOCUS

VR

ADJ

1.

Set

CONTRAST

to

minimum,

and

BRIGHTNESS

to

center

by

adjusting

user

controls.

2.

Set

the

TV

in

service

mode

to

get

white

cross-bar

of

inside

pattern.

3.

Select

BRTC

(brightness

correction),

and

adjust

the

<1

—

/+

button

to

reduce

the

value

so

that

white

portion

of

inside

pattern

slightly

light.

4.

Adjust

1

-

/+

button

to

increase

the

data

value

of

BRTC,

and

set

it

just

before

the

difference

between

the

belt

of

vertical

retrace

and

the

border

of

black

Belt

of

vertical

retrace

portion

of

inside

pattern

is

visible.

After

that,

return

vertical

height

and

contrast.

.

Set

the

TV

in

service

mode,

and

get

black

or

white

cross-bar

signal

with

VIDEO

button

on

remote

hand

unit.

2.

Select

either

HPOS

(Horizontal

picture

phase)

or

VPOS

(Vertical

picture

phase)

with

CHANNEL

A,

¥

buttons,

and

adjust

horizontal

or

vertical

picture

position

in

the

center

of

screen

with

VOLUME

24

—

/+

buttons.

1.

Set

the

TV

in

service

mode,

and

get

black

or

white

cross-hatch

signal

with

VIDEO

button

on

remote

hand

unit.

The

first

2.

Select

HIT

(Vertical

amplitude)

with

CHANNEL

A,

¥

buttons,

and

adjust

vertical

amplitude

with

VOLUME

<1

—

/+

buttons

so

that

vertical

am-

plitude

lacks

a

little.

3.

Adjust

vertical

amplitude

with

VOL-

UME

1

—/+

buttons

so

that

the

first

bar

on

cross-hatch

signal

touches

edge

of

screen.

SUB-BRIGHTNESS

(BRTC)

Note:

Constrict

the

picture

height

until

the

vertical

retrace

line

appears

adjusting

the

item

HIT

(HEIGHT).

HORIZONTAL

POSITION

ADJUSTMENT

(HPOS)

VERTICAL

POSITION

ADJUSTMENT

(VPOS)

VERTICAL

AMPLITUDE

ADJUSTMENT

(HIT)

~10-

Toshiba 3787DB User manual

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