Hitachi C2117T Manuale utente

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HITACHI

ne

CAUTION:

Before

servicing

this

chassis,

it

is

important

that

the

service

technician

read

the

“Safety

Precautions”

and

“Product

Safety

Notices”

in

this

service

manual.

NE

ot

4

ig rs

+32

:

be

aieied

pa

ot

ch

Pn

ct

cased

i

ate

eed

Bue

Reale

Data

contained

within

this

Service

manual

is

subject

to

alteration

for

improvement.

*

This

Model

has

NO

Production

Plan

-

Circuits

&

Parts

List

are

not

included

in

this

Service

Manual

No.

SM0Q0008

eine

|

BES

Ee

Be

ane

BBE

|

HITA-02931

ee

ere

gre

naa

re

eines

TECHNICAL

SPECIFICATIONS

Aerial

input

impedance

75

ohm

unbalanced

Picture

tubes

2117.

.

bs

hansen:

....

51

omtype

TV

Standard

..

....-.

0.00

wes

625

lines,

Programme

Selectors

10

key

buttons

on

the

C

Models

......

..

....

.STANDARD

I

remote

control,

with

UP/DOWN

Mains

Voltage

..

.....

220V~240V

50

Hz

CP

Models......

....

..

STANDARD

BG

buttons

on

the

front

of

TV

CS

Models

.

..

STANDARD

BG/DK

FUSE

bated

ve

eee

TS.

1T5AL

Type

All

above

525

lines

NTSC

4

43

MHz

Power

Consumption

DAVE

seh.

.

2

eh.

Tees

“SO

VY

Focusing

Se.

San

et

dads

Electro

static

Channel

coverage

....

.

UHF

Channels

(UK)

UHF/VHF

Hyper

band

(Export)

1997

SAFETY

PRECAUTIONS

WARNING:

The

following

precautions

should

be

observed

.

1.

Do

not

instail,

remove,

or

handle

the

picture

tube

in

any

manner

unless

shatter

proof

goggles

are

worn.

People

not

so

equipped

should

be

kept

away

while

picture

tubes

are

handled.

Keep

the

picture

tube

away

from

the

body

while

handling.

2.

When

service

is

required,

an

isolation

transformer

should

be

inserted

between

the

power

line

and

the

receiver

before

any

service

is

performed

on

the

chassis.

3.

When

replacing

the

chassis

in

the

cabinet,

ensure

all

the

protective

devices

are

put

back

in

place.

4,

When

service

is

required,

observe

the

original

lead

dressing.

Extra

precaution

should

be

taken

to

ensure

correct

lead

dressing

in

the

high

voltage

circuitry

area.

5.

Always

use

the

manufacturer’s

replacement

component.

Always

replace

original

spacers

and

maintain

lead

lengths.

Especially

critical

components

are

indicated

thus

A

on

the

parts

list

and

should

not

be

replaced

by

other

makes.

Furthermore,

where

a

short

circuit

has

occurred,

replace

those

components

that

indicate

evidence

of

overheating.

6.

Before

returning

a

serviced

receiver

to

the

customer,

the

service

technician

must

thoroughly

test

the

unit

to

be

certain

that

it

is

completely

safe

to

operate

without

danger

of

electrical

shock,

and

be

sure

that

no

protective

device

built

into

the

instrument

by

the

manufacturer

has

become

defective,

or

inadvertently

damaged

during

servicing.

Therefore,

the

following

checks

are

recommended

for

the

continued

protection

of

the

customers

and

service

technicians.

INSULATION

Insulation

resistance

should

not

be

less

than

10M

ohms

at

500V

DC

between

the

main

poles

and

any

accessible

metal

parts.

Also,

no

flashover

or

breakdown

should

occur

during

the

dielectric

strength

test,

applying

3kV

AC

or

4.25kV

DC

for

two

seconds between

the

main

poles

and

accessible

metal

parts.

HIGH

VOLTAGE

High

voltage

should

always

be

kept

at

the

rated

value

of

the

chassis

and

no

higher.

Operating

at

higher

voltages

may

cause

a

failure

of

the

picture

tube

or

high

voltage

supply,

and

also,

under

certain

circumstances

could

produce

X-radiation

levels

moderately

in

excess

of

design

levels.

The

high

voltage

must

not,

under

any

circumstances,

exceed

29kV

on

the

chassis.

X-RADIATION

TUBES:

The

primary

source

of

X-radiation

in

this

receiver

is

the

picture

tube.

The

tube

utilised

for

the

above

mentioned

function

in

this

chassis

is

specially

constructed

to

limit

X-radiation.

For

continued

X-radiation

protection,

replace

tube

with

the

same

type

as

the

original

HITACHI

approved

type.

PRODUCT

SAFETY

NOTICE

Many

electrical

and

mechanical

parts

in

HITACHI

television

receivers

have

special

safety

related

characteristics.

These

characteristics

are

often

not

evident

from

visual

inspection,

nor

can

the

protection

afforded

by

them

necessarily

be

obtained

by

using

replacement

components

rated

for

higher

voltage,

wattage,

etc.

Replacement

parts

which

have

these

special

safety

characteristics

are

identified

by

marking

with

a

A

on

the

schematics

and

the

replacement

parts

list

contained

in

this

service

manual.

The

use

of

a

substitute

replacement

component

which

does

not

have

the

same

safety

characteristics

as

the

HITACHI

recommended

replacement

one,

shown

in

the

parts

list

of

this

service

manual,

may

create

electrical

shock,

fire,

X-radiation,

or

other

hazards.

Product

Safety

is

continuously

under

review,

and

new

instructions

are

issued

from

time

to

time.

For

the

latest

information,

always

consult

the

current

HITACHI

service

manual.

A

subscription

to,

or

additional

copies

of

HITACHI

service

manuals

may

be

obtained

at

a

nominal

charge

from

your

HITACHI

SALES

CORPORATION.

CE

MARK

Some

of

these

models

may

contain

the

CE

mark

on

the

rating

plate.

This

illustrates

that

the

T.V.

contains

parts

that

have

been

specifically

approved

to

provide

electromagnetic

compatability

to

designated

levels.

Therefore,

when

replacing

any

part

in

this

T.V.,

please

use

only

the

correct

part

itemized

in

the

parts

list

of

this

service

manual

to

ensure

this

standard

is

maintained.

Also,

take

care

to

replace

lead

dressing

to

its

original

state,

as

this

can

also

have

a

bearing

on

the

electromagnetic

radiation/immunity.

TUBE

DISCHARGE

The

line

output

stage

can

develop

voltages

in

excess

of

25k\V;

if

the

E.H.T.

cap

is

required

to

be

removed,

discharge

the

anode

to

chassis

via

a

high

value

resistor,

prior

to

its

removal

from

the

tube.

CIRCUIT

DESCRIPTION

Tuner

and

I.F.

Stages:

The

tuner

used

on

this

chassis,

is

powered

by

the

+5V

supply.

The

CP,

CL

and

CS

models

cover

the

VHF-L,

VHFH

and

UHF

bands

whilst

the

‘C’

models

cover

UHF

only.

During

tuning,

the

mark/space

ratio

output

from

pin

1

of

ICO001

changes.

This

is

applied

to

the

base

of

Q001

via

RO39,

and

the

resultant

voltage

at

the

collector

is

filtered

and

applied

to

the

VT

terminal

of

the

tuner.

Signal

recognition

is

performed

by

|C201

in

conjunction

with

IC001,

and

is

explained

later

in

the

Remote

Control

and

Tuning

Circuit

description.

Band

switching:

CP

and

CS

models

IC001

performs

the

necessary

band

switching

in

conjunction

with

Q100.

“High”

or

“Low”

outputs

are

obtained

from

pins

11

and

12

of

1C001,

then

applied

to

pins

3

and

4

of

the

tuner

terminals.

These

select

the

UHF

or

VHF-H

bands.

When

VHF-L

band

is

selected,

pins

11

and

12

of

IC001

will

both

go

“Low”.

Q100

will

then

turn

off,

and

approximately

+5v

is

applied

to

the

VHF-L

terminal

of

the

tuner

via

R106.

Therefore,

which

of

the

tuner

terminals

BU, BH,

or

BL

has

a

+5v

applied

to

it

depends

on

these

“High”

or

“Low”

outputs.

UHF

only:

‘C’

Models

A

+5V

is

applied

via

R105

to

the

UHF

(pin

3)

terminal

of

the

tuner

only.

The

I.F.

output

from

the

tuner

is

applied

to

pins

45

and

46

of

IC201

via

the

SAW

filter

CP201.

Sound

I|.F.

stages:

C

and

CP

models

The

sound

stages

consist

of

!C201,

which

basically

performs

the

required

demodulation,

and

!C401,

which

is

the

output

amplifier.

The

|.F.

signal

from

the

tuner

is

fed

via

saw

filter

CP201,

and

applied

to

1C201

at

pins

45

and

46.

The

composite

signal

available

from

pin

7

of

I1C201

is

applied

to

the

filter

network

of

MF422,

via

L401A

etc.,

then

fed

to

pin

5

of

1C201

via

Q421

and

C422.

Demodulation

is

then

performed

within

the

IC,

with

the

sound

output

being

obtained

from

pin

50.

Sound

I.F.

stage:

CS

models

The

sound

stages

consist

of

1C4001,

which

performs

the

change

from

|.F.

to

intercarrier,

1C201

which

demodulates

the

signal

and

!C401

which

is

the

output

amplifier.

The

I.F.

signal

from

the

tuner

is

fed

via

the

sawfilter

MF4003,

and

applied

to

IC4001

at

pin

1.

The

resultant

intercarrier

is

available

at

pin

12

of

IC4001

and

fed

via

the

filter

network

consisting

of

MF422

(5.5MHz

intercarrier)

and

MF421

(6.5MHz

intercarrier)

and

Q421

to

Pin

5

via

C422.

Demodulation

is

then

performed

within

the

IC,

with

the

sound

output

being

obtained

from

pin

50.

Audio

From

pin

50

of

!1C201

it

is

then

applied

to

pin

3

of

1C401

via

Q401,

C421

and

R413,

amplified,

then

output

to

the

speaker

from

pins

6

and

8.

Should

C417

on

pin

2

of

1C401

or

its

output

go

short

circuit

the

base

of

Q440

will

become

“Low”,

and

it

will

turn

on.

A

voltage

will

then

be

applied

to

the

base

of

Q705,

which

then

turns

off

Q952,

and

as

a

result

the

+12v

supply

is

removed,

thus

preventing

damage

occurring

to

1C401.

How

the

+12v

is

removed

will

be

described

in

more

detail

later

during

the

horizontal

circuit

description.

Volume

control

is

performed

by

the

DC

voltage

applied

to

pin

5

of

IC201.

This

is

determined

by

the

Pulse

Width

Modulated

output

from

pin

2

of

IC001,

which

is

then

fed

to

IC201

after

filtering

via

RO17/R028

etc.

Under

no

signal

conditions,

or

when

the

“SEARCH”

routine

is

initiated,

pin

4

of

1C201

(ident)

will

go

“Low”.

When

this

happens,

internal

circuits

in

|C201

prevent

any

sound

output

from

being

obtained.

Demodulated

sound

is

also

available

at

pin

1

of

IC201.

It

is

then

connected

to

pins

1

and

3

of

the

21

pin

Euro

socket,

via

Q453

network

for

gain

and

impedance/level

matching.

If

desired,

this

output

can

then

be

applied

to

external

equipment

via

an

appropriate

connecting

plug.

Audio

signals

from

external

equipment

can

be

applied

to

the

21

pin

Euro

socket

at

pins

2

and

6

and

these

will

be

fed

via

R403/R404

and

C452

to

Pin

6

of

IC201.

Audio

signals

can

also

be

applied

to

the

front

phono

sockets

and

these

will

be

applied

to

pin

6

of

IC201

via

L151,

R406

and

C452.

A

separate

switching

voltage

is

also

applied

to

pin

16

of

1C201

when

external

equipment

is

connected.

The

external

sound

signal

applied

to

pin

6

will

then

be

switched

to

the

output

of

1C201

{pin

50).

This

is

then

further

amplified

by

IC401,

as

previously

described.

Volume

control

of

the

external

audio

signal

is

obtained

in

the

same

way

as

for

internal

sound,

i.e.,

by

the

voltage

level

at

pin

5

of

IC201.

(How

the

switching

voltages

are

obtained

for

IC201,

will

be

explained

in

the

Tuning

and

Contro!

Circuit

description).

Vision

I.F.

Stages:

The

|.F.

signal

from

CP201

is

applied

to

pins

45

and

46

of

IC201.

These

pins

supply

an

internal

amplifier

consisting

of

three

stages

whose

gain

is

controlled

by

the

A.G.C.

circuit.

The

speed

of

response

from

this

internal

A.G.C.

stage

is

determined

by

C205,

connected

to

pin

48.

The

output

from

the

internal

amplifier

is

then

input

to

a

quasi

synchronous

demodulator

stage,

where

the

signal

is

multiplied

by

its

own

carrier,

i.e.

the

reference

signal.

This

reference

signal

is

obtained

from

the

input

signal

using

the

tank

circuitry

of

L202

etc.

connected

between

pins

2

and

3

of

the

I.C.

The

reference

signal

is

limited

by

a

clamping

circuit,

and

is

then

applied

to

the

demodulator.

A

control

voltage

from

pin

47

of

IC201

determines

the

RF

A.G.C.

of

the

tuner.

The

tuner

take

over

point

is

determined

by

the

voltage

applied

to

pin

49,

which

is

governed

by

the

setting

of

VR202.

The

composite

video

finally

emerges

at

pin

7

of

1C201.

Luminance

Circuitry

The

composite

video

signal

from

pin

7

of

|C201

via

buffer

transistor

Q501,

is

applied

to

the

sound

rejection

filter

MF501,

(6.0MHz,

‘C’

model)

(5.5MHz

CP

and

CS

models)

and

on

the

CS

models

there

is

an

additional

filter

in

parallel

with

MF501

marked

MF502

which

is

for

frequency

6.5MHz

as

this

model

has

dual

sound.

The

resulting

internal

luminance

signal

is

then

applied

to:-

a:

Pin

19

of

the

Euro

socket,

from

where

it

can

be

output

to

external

equipment

if

desired.

b:

Pin

13

of

1C201

via

Q301

buffer,

for

colour

decoding

and

deflection

synchronisation.

c:

Pin

23

of

IC001

via

RO68/RO69

divider

network

for

TEXT.

The

luminance

signal

is

added

internally

to

the

RGB

matrix

circuits

of

1C201,

and

will

be

controlled

by

the

brightness,

contrast,

and

blanking

stages

of

the

I.C.

The

luminance

signal

finally

emerges

with

the

RGB

signals

from

pins

18,

19

and

20

of

C201.

The

voltages

which

contro!

the

contrast

and

brightness

levels

are

output

from

pins

5

and

6

of

IC001,

then

applied

to

pins

25

and

17

of

IC201.

An

automatic

beam

current

limit

circuit

is

employed

on

this

chassis.

Should

the

beam

current

start

to

rise,

the

voltage

at

pin

4

of

the

flyback

transformer

will

fall.

This

fall

is

fed

to

Q752,

tuning

the

transistor

on

and

pulling

its

emitter

voltage

low.

This

fall

in

voltage

is

applied

to

pin

25

of

IC201

via

D709/R723

and

R527,

effectively

reducing

the

contrast

level,

and

hence

the

beam

current.

Video

signals

from

external

equipment

can

be

connected

to

pin

20

of

the

21

pin

Euro

socket

where

they

will

be

applied

via

Q460

and

Q461

to:-

a:

Pin

15

of

1C201

via

C311.

b:

Pin

24

of

ICO01

for

TEXT.

External

video

signals

from

the

front

phono

socket

can

also

be

applied

via

Q460

and

Q461

to

the

above.

The

switching

voltage

at

pin

16

of

|C201,

ensures

that

only

the

external

signals

are

processed

by

IC201.

How

the

switching

voltages

are

obtained

will

be

explained

in

the

Remote

Control

and

Tuning

Circuit

description:

Chrominance

Circuitry:

1C201

is

designed

to

demodulate

PAL

and

NTSC.

On

CS

models

an

additional

SECAM

colour

system

is

used.

On

models

operating

in

the

PAL

mode

the

demodulated

R-y

and

B-y

colour

signals

are

made

available

from

pins

30

and

31

of

1C201,

then

fed

to

pins

14

and

16

of

IC501,

which

is

a

switch

capacitor

delay

line.

The

signals

at

pins

14

and

16

are

clamped,

then

fed

via

an

internal

buffer

stage

to

delay

lines,

which

are

driven

by

a

clock

signal

of

3MHz

to

obtain

a

delay

period

of

64uS.

This

internal

clock

is

generated

from

a

6MHz

voltage

controlled

oscillator,

and

line

locked

by

the

sandcastle

pulse

input

at

pin

5.

Low

pass

filters

after

the

delay

line

stages

suppress

the

unwanted

clock

signals.

The

undelayed

and

the

delayed

signals

are

then

added,

with

the

resulting

R-y

and

B-y

signals

being

output

from

pins

11

and

12.

These

are

then

fed

to

IC201

at

pins

28

and

29.

IC201

contains

clamping

circuits,

and

a

DC

colour

saturation

control,

the

level

of

which

is

set

by

the

voltage

applied

to

pin

26

from

pin

4

of

ICO01.

The

signals

are

then

applied

to

a

MATRIX

circuit,

and

finally

emerge

from

pins

18,

19

and

20

as

the

blue,

green,

and

red

signals.

On

models

(CS)

capable

of

receiving

SECAM

transmissions,

the

R-y

and

B-y

signals

from

pins

30

and

31

are

also

connected

to

pins

9

and

10

of

IC502.

This

IC

will

then

produce

control

voltages

from

pins

1

and

16.

These

are

applied

to

pins

32

and

27

of

IC201,

and

condition

the

|.C.

to

process

the

SECAM

signals,

thereby

producing

blue,

green,

and

red

outputs

from

pins

18,

19

and

20.

The

sandcastle

pulse

is

also

connected

to

pin

15

of

IC502

to

control

its

operation.

If

NTSC

signals

are

received

on

a

CS

model

pin

34

(R

model),

pin

30

(T

model)

of

|C001

goes

“low”.

This

turns

Q014

off,

which

then

causes

Q013

to

turn

off,

and

the

voltage

level

at

pin

27

of

IC201

will

fall

to

a

voltage

between

0-5V

originating

from

the

hue

control,

pin

3

of

IC001

via

RO63,

RO78,

R116

and

L052.

If

now

the

signal

received

is

SECAM

or

PAL

the

reverse

will

occur

finally

leaving

pin

27

of

IC201

high

with

a

voltage

of

approximately

6V.

For

C

and

CP

models

pin

27

is

held

at

3V

by

the

divider

network

R528/R529

for

PAL

and

NTSC

reception

with

fixed

hue

setting

for

NTSC.

Remote

Control

and

Tuning

Circuitry:

The

remote

control

receiving

unit

U001,

contains

an

infra

red

amplifier.

This

is

powered

by

the

standby

+5v

supply,

which

is

obtained

from

the

+12v

supply

via

Q957,

and

stabilised

by

ZDO06.

The

output

from

pin

3

of

the

infra

red

amplifier

is

applied

to

pin

35

of

ICO01

(‘R’

models,

non

text),

pin

45

of

ICO01

(‘T’

models).

This

I.C.,

performs

channel

selection,

UP/DOWN

analogue

control,

on-screen

display,

search

tuning,

and

also

controls

inputs

and

outputs

to

and

from

the

external

input

sockets.

IC002

is

the

memory

|.C.,

which

stores

all

data

relating

to

the

above

functions,

then

transfers

that

information

to

IC001

when

required.

IC001

and

IC002

are

both

powered

by

the

standby

+5v

supply.

X001,

C026

and

C027,

connected

between

pins

31

and

32

(‘R’

models)

or

pin

41

and

42

(‘T’

models)

supply

|CO001

with

a

basic

clock

frequency

to

control

all

operating

mode

requirements.

IC001

must

be

initially

reset

from

switch

on,

and

this

is

achieved

by

Q004.

As

the

+5v

supply

begins

to

rise

from

switch

on,

pin

33

(R’

models)

or

pin

43

(‘T’

models)

of

IC001

is

held

“High”

via

R075,

thus

resetting

the

I.C.

The

“High”

is

removed

from

this

pin

when

C002

becomes

charged

via

RO15

and

DOO3,

causing

Q004

to

switch

on,

thus

releasing

the

reset

condition.

When

the

search

routine

has

been

initiated

and

a

signal

has

been

located,

pin

4

of

1C201

will

become

“High”.

This

is

applied

to

pin

41

(‘R’

models)

or

pin

5

(‘T’

models)

of

‘(C001’

and

informs

the

I.C.

that

a

signal

is

present.

The

search

routine

then

stops,

and

the

I.C.

will

monitor

the

AFC

signal

present

at

pin

9

to

obtain

the

optimum

signal.

Contrast,

colour,

brightness,

hue,

sharpness

and

volume,

are

all

controlled

from

the

remote

contro!

handset

(can

also

be

adjusted

by

the

+

and

-

buttons

on

the

front

of

the

T.V.),

and

will

produce

DC

level

changes

from

pins

2

-

7

of

|C001.

These

changes

are

then

applied

to

the

relevant

pins

of

IC201.

Pins

36

to

38

(‘R’

models)

or

pins

46

to

48

(‘T’

models)

form

the

in

and

out

matrix

for

the

front

control

operations.

Pins

39

to

40

(‘R’

models)

or

pin

49

and

50

(‘T’

models)

provide

clock

and

data

information.

These

are

connected

to

the

memory

IC002.

,

When

external

equipment

connected

to

the

21

pin

Euro

socket

is

turned

on,

+12v

is

output

from

pin

8

of

the

socket

to

DOO6.

The

diode

then

becomes

forward

biased,

and

applies

approximately

+5v

to

pin

10

of

ICO01

via

potential

divider

RO35,

RO36.

From

pin

15

of

IC001

an

output,

“high”

is

then

applied

to

the

base

of

Q007

turning

it

hard

on

and

pulling

its

collector

“low”.

As

a

result

Q005

will

turn

off,

thereby

supplying

approximately

8V

to

pin

16

of

|C201

via

the

potential

divider

network

of

RO24/R103.

This

ensures

IC201

will

process

only

the

external

inputs

applied

to

pins

6

and

15.

If

the

external

equipment

does

not

have

an

equivalent

21

pin

Euro

connector,

or

if

the

external

inputs

are

applied

via

the

phono

sockets

on

the

front

of

the

T.V.,

then

the

AV

button

on

the

remote

contro!

has

to

be

pressed

to

select

the

external

mode.

This

will

then

produce

the

required

“High”

from

pin

15

(ICQ01)

to

achieve

the

necessary

switching

voltages.

When

a

command

requiring

an

on-screen

display

is

received

by

|C001,

a”High”

is

made

available

at

pin

25

(‘R’

model)

pin

35

(‘T’

model).

This

is

applied

via

DO39A

to

pin

21

of

IC201,

and

blanks

out

a

portion

of

the

picture.

The

on-screen

display

information

is

then

inserted

into

this

portion,

thus

resulting

in

a

clear

display.

‘R’

models

The

components

L024,

C024,

and

C013,

on

pins

28

and

29,

determine

the

display

oscillator

frequency,

whilst

the

horizontal

and

vertical

inputs

at

pins

26

and

27

determine

the

actual

position

of

the

on-screen

display.

‘T’

models

The

character

display

is

generated

from

the

text

character

set,

whilst

the

horizontal

and

vertical

inputs

at

pins

36

and

37

determine

the

actual

position

of

the

on

screen

display.

Timer

and

Standby

When

the

“OFF”

timer

mode

has

been

set,

and

the

time

input

has

elapsed,

pin

20

of

IC001

outputs

a

“Low”.

This

removes

the

drive

supplied

to

the

base

of

Q952,

and

as

a

result

the

+9v

supply

from

IC951

disappears.

This

places

the

T.V.

into

its

standby

mode

of

operation

by

shutting

down

the

E.H.T.

generation

stages

of

1C201.

Also,

pin

19

of

!C001

is

taken

‘low’

causing

the

illumination

level

of

DOO1

to

increase.

This

sequence

also

applies

when

putting

the

TV

into

standby

mode

via

the

handset.

Deflection

Circuits:

The

deflection

circuitry

of

|1C201

contains

a

sync.

separator

stage,

horizontal

oscillator

and

output

stages,

a

vertical

countdown

and

output

stage.

Horizontal

Stage:

An

internal

composite

video

signal

from

pin

7

of

IC201

is

returned

to

pin

13

or

an

external

signal

from

the

21

pin

Euro

socket

is

applied

to

pin

15

of

|C201

as

previously

explained.

One

of

these

inputs,

pin

13

or

15

via

the

internal/external

switch

of

IC201

is

applied

to

the

internal

sync.

separator

stages

of

the

IC.

An

internal

phase

detector

stage

is

provided

with

a

sawtooth

waveform,

generated

from

the

line

pulse

input

to

pin

38.

The

phase

detector

then

compares

this

sawtooth

waveform

to

the

sync.

pulse.

Should

any

frequency

drift

occur,

a

corrective

output

will

be

applied

to

the

horizontal

oscillator,

thereby

maintaining

the

desired

phase

relationship.

The

components

connected

to

pin

40

form

a

filter

network

for

the

phase

detector,

and

VR701

connected

to

pin

39

provides

manual

phase

control.

The

horizontal

output

emerges

at

pin

37

and

is

then

applied

to

the

base

of

line

drive

transistor

Q701.

T701

couples

Q701

to

the

line

output

transistor

Q702.

Both

these

transistors

are

powered

by

the

+B

(H.T.)

supply.

A

line

pulse

available

at

pin

1

of

the

flyback

transformer

is

rectified

by

D701,

smoothed

by

C716,

and

provides

approximately

200v

to

drive

the

video

output

transistors

Q801,

Q802,

and

Q803

on

the

C.R.T.

base.

Under

certain

fault

conditions,

i.e.

increased

H.T.

supply,

or

low

line

oscillator

frequency

etc.,

an

excess

of

E.H.T.

could

be

developed.

To

prevent

this

happening,

the

rectified

voltage

of

D701

is

fed

via

potential

divider

R715,

R716,

and

applied

to

pin

3

of

the

comparator

1C701.

Should

the

E.H.T.

rise

excessively,

the

voltage

level

at

pin

3

of

IC701

will

exceed

the

threshold

level

determined

by

ZD704

(5v1

Zener)

at

pin

2.

When

this

happens,

the

output

at

pin

1

of

IC701

becomes

“High”,

causing

Q705

to

conduct

and

pulling

pin

20

of

IC001

low.

After

a

short

period

of

time,

the

low

at

pin

20

of

IC001

causes

the

|.C.

to

latch

into

its

standby

mode,

and

a

“Low”

will

be

applied

to

the

base

of

Q952,

turning

the

transistor

off.

Consequently,

Q953

is

turned

off,

and

the

+9v

supply

to

IC201

will

be

removed,

thereby

shutting

down

the

deflection

stages

of

the

|.C.

and

preventing

further

E.H.T.

generation.

Excessive

beam

current

can

also

occur

under

certain

fault

conditions,

so

this

is

prevented

in

the

following

manner.

The

H.T.

current

to

the

horizontal

output

stages

is

measured

by

R727.

Should

the

current

rise,

the

increased

voltage

drop

across

R727

will

cause

Q704

to

be

turned

on,

and

a

voltage

will

be

applied

to

the

base

of

Q705

via

R729.

This

will

then

prevent

further

E.H.T.

generation

as

previously

described.

Vertical

Stages:

The

internal

vertical

sync.

of

[C201

is

fed

to

a

triggered

vertical

divider

stage,

which

counts

down

the

horizontal

frequency

to

obtain

the

vertical

frequency.

This

eliminates

the

need

for

a

conventional

oscillator

circuit,

and

has

the

added

advantage

that

no

external

frequency

control

is

required.

C601/C601A

at

pin

42

of

the

I.C.

are

used

for

ramp

generation,

producing

the

required

sawtooth.

The

vertical

output

from

pin

43

of

1C201

is

applied

to

pin

4

of

1C601

via

R604.

The

components

D601

and

C605

determine

the

flyback

generation

time,

and

the

vertical

output

to

drive

the

deflection

coils

is

made

available

from

pin

2.

A

supply

of

+25v

is

required

for

|C601.

This

is

obtained

from

pin

6

of

the

flyback

transformer,

rectified

by

D702/D702A,

smoothed

by

C719,

then

applied

to

pin

6

of

IC607.

The

deflection

current

that

occurs

at

the

junction

of

C609/R609

is

added

to

the

feedback

from

R607/C608

etc,

and

the

result

is

applied

to

pin

41

of

IC201.

The

values

of

R607

and

C608

determine

the

linearity,

whilst

VR601

sets

the

vertical

height.

When

the

16:9

ratio

format

is

selected,

a

“High”

is

made

available

from

pin

16

of

1C001.

This

is

applied

to

Q015

via

R121,

turning

the

transistor

off.

This

effectively

removes

R125

from

pin

42

of

1C201,

thus

reducing

the

current

and

changing

the

vertical

ramp

output.

In

this

way,

the

vertical

height

is

corrected

to

suit

the

16:9

wide

screen

format.

Power

Supply

Circuit:

The

AC

input

is

rectified

by

D901

-

04,

and

produces

approximately

300v

at

the

collector

of

Q903.

Current

flowing

through

R901,

causes

Q903

to

initially

turn

on.

Secondary

voltages

are

then

induced

in

T901,

and

a

feedback

voltage

is

obtained

via

D905,

L903

etc.,

and

applied

to

Q903

base,

maintaining

the

transistors

operation.

This

circuitry

self

oscillates

at

a

frequency

determined

by

the

inductance

of

the

transformer,

the

AC

mains

voltage,

and

load

conditions

etc.

The

secondary

voltage

induced

in

the

S1

-

S2

winding

is

rectified

by

D951

to

produce

the

+B

(H.T.),

which

is

smoothed

by

C952.

The

S3-S4

winding

produces

+12v

via

D952,

and

this

is

smoothed

by

C954.

It

is

then

applied

to

Q953,

and

in

conjunction

with

IC951

produces

the

chassis

+9v

supply.

Q951

stage

controls

the

H.T.

regulation.

The

base

of

Q951

is

set

to

a

pre-determined

level

by

the

resistor

network

R952,

VR951,

and

R951.

Should

the

H.T.

rise,

the

base

current

fed

to

Q951

will

increase,

turning

the

transistor

on

harder.

This

causes

more

current

to

flow

through

the

opto-coupler

IC901.

An

output

is

then

produced

from

pin

5

of

the

opto-coupler,

which

is

applied

to

the

transistor

network

Q901,

Q902.

As

these

transistors

control

the

on

time

of

the

power

transistor

Q903,

a

constant

and

regulated

H.T.

level

is

maintained.

ZD952

offers

protection

to

the

H.T.

circuits

should

the

voltage

level

rise

excessively.

When

the

standby

mode

is

selected,

pin

20

of

I1C001

will

go

“Low”,

removing

the

drive

to

Q952.

As

a

result,

Q953

is

turned

off,

and

the

+9v

to

IC201

disappears,

therefore

shutting

down

the

deflection

stages

of

the

1C201.

E.H.T.

generation

will

then

cease

for

as

long

as

the

standby

condition

exists.

PICTURE

AND

CONTROL

ADJUSTMENTS

H.T.

Adjustment

(+B):

1.

Switch

TV.

on,

receive

Philip’s

circle

test

pattern,

and

set

contrast

and

brightness

levels

to

maximum.

2.

Connect

a

voltmeter

between

the

+ve

leg

of

C709

and

Ground.

3

Adjust

VR951

so

that

meter

reads

as

follows:-

51cm

models

112v

+

Ov2

A.F.C.

Alignment:

(L202

Adjustment)

1

Switch

on

the

TV.

and

apply

an

I.F

signal

(88

9MHz)

with

a

level

between

10

and

0

dBm,

to

pin

1

of

CP201

2

OnCS

models

only,

set

the

standard

selection

to

AUTO

in

the

Installation

menu.

(see

operating

guide

for

Installation

menu

examples).

3

Connect

an

oscilloscope

and

a

voltmeter

to

pin

44

of

IC201.

4,

Adjust

L202

until

fast

rate

of

change

is

seen

on

the

oscilloscope,

then

carefully

adjust

L202

until

voltmeter

reads

4

Ov

+

0.2v

AGC

Adjustment:

1.

Switch

TV

on

and

allow

to

warm

up

for

at

least

two

minutes

2.

Receive

a

signal

with

a

level

of

-47dBm

3

Connect

a

voltmeter

to

the

AGC

terminal

of

the

tuner

unit.

4

Adjust

VR202

until

meter

reads

2v5

+/-

Ov2

Horizontal

Phase/Vertical

Centre/Vertical

Amplitude:

Receive

Philip’s

circle

test

pattern.

Set

brightness

and

contrast

levels

to

maximum,

then

face

the

television

to

the

North

or

South.

Adjust

VR701

to

centralise

circle

pattern.

Connect

the

removable

plug

on

E601

to

the

pins

which

achieve

the

best

vertical

centre

position.

Adjust

VR601

to

obtain

the

required

vertical

height

Return

brightness

and

contrast

levels

to

their

previous

levels

AARON

Focus

Adjustment:

1.

Receive

Philip’s

circle

test

pattern

setting

colour

level

to

minimum,

and

contrast

and

brightness

levels

to

maximum

2

Adjust

contrast

so

that

the

first

two

bars

of

the

colour

bar

display

become

black

3.

Adjust

brightness

so

that

the

3rd

and

4th

bars

of

the

grey

scale

bar

display

are

the

same

colour

black

as

in

step

2

4

Adjust

the

focus

control

(upper

control

on

flyback

transformer)

to

obtain

the

best

overall

focus.

COMPOSITION

OF

TEST

CARD

PROVIDED

BY

PHILIPS

PM5644

COLOR

PATTERN

GENERATOR

Colorless

(R

Yb

signal

Border

castellations

for

check

of

picture

Colorless

(8-Y)

signal

for

check

af

decoding

centre

and

atpact

ratia

for

check

of

decoding

Cigitally

derived

circle

for

chack

of

scanning

linearity

ou

E

Burst

gata

—>

check

250

kHz

squarewave

of

75%

contrast

white

and

black

refarence

level

for

calor

bar

NS

NS

SS

NWN

AVG

g

g<

ERG

Check

of

subcarrier

jockin:

N

NXVL

QV

QR

MAR

EAS

NN

Color

difference

signats

Color

ditterance

signals

for

check

of

decoding

for

check

of

decoding

CUT

OFF

AND

SCREEN

ADJUSTMENT

PREPARATION

(i)

(ii

Preset

the

red,

green

and

blue

background

controls

on

the

C.R.T.

base

to

the

positions

shown.

(Approximately

mid.

point).

Component

Side

Set

the

customer

controls

as

follows:-

Contrast

=

0

Colour

=

0

Brightness

=

middle

of

scale

(iii)

Receive

horizontal

white

line,

or

red

raster

pattern

from

a

Philip’s

pattern

generator.

METHOD:

1.

Adjust

screen

control

(lower

control

on

the

flyback

transformer)

until

the

horizontal

line

is

just

visible

and

its

colour

can

be

seen.

2.

Do

not

touch

the

background

control

of

the

colour

that

is

most

prominent

on

the

screen,

but

adjust

the

other

two

background

controls

until

a

reasonable

white

line

is

obtained

Connect

an

oscilloscope

probe

to

each

of

the

R.G.B.

cathodes

in

turn

and

leave

connected

to

the

one

with

the

highest

level.

4.

Set

customer

brightness

so

that

the

cathode

value

is

no

greater

than

140v

as

shown

below.

Peak

white

wow...

:

si

wee

veoevand

AAOV

5.

Disconnect

oscilloscope,

and

set

screen

control

so

that

the

white

horizontal

line

is

just

visible

once

more.

WHITE

BALANCE

PREPARATION:

(i)

(ii)

Set

the

customer

controls

as

follows:-

Contrast

=

0

Colour

=

0

Receive

the

white

raster

pattern.

(iii)

Obtain

and

set

up

a

combined

colour

analyser

and

light

meter,

e.g.

MINOLTA

CA100.

METHOD:

1.

Adjust

brightness

customer

control

so

that

the

light

output

from

the

white

raster

reads

Y

=

1

—

2

cdm’*

on

the

light

meter.

Next

adjust

the

red

and

blue

background

controls

to

obtain

the

colour

chromaticity

co-ordinates

of

x

=

283

y

=

299

representing

a

colour

temperature

of

9300k

(models

C,

CS

and

CP/481/381).

For

colour

temperature

of

7400k

the

red

and

blue

background

controls

will

have

to

be

adjusted

to

obtain

the

colour

chromaticity

co-ordinates

of

x

=

304

y

=

320

(for

all

CP

models

other

than

shown

above).

PROTECTION

CHECKS

High

Voltage

Limit

Check:

1.

2.

Switch

T.V.

on

and

set

contrast

and

brightness

levels

to

maximum.

For

models

34cm

and

41cm,

connect

a

1M4

resistor

in

parallel

with

R715

and

ensure

that

the

picture

and

sound

disappear

instantly.

N.B.

On

51cm

models,

resistor

value

should

be

1MO

and

on

59cm

models

it

should

be

1M2.

Switch

T.V.

off,

remove

resistor,

and

wait

10

~

15

seconds.

Switch

T.V.

on

again,

check

that

normal

operation

is

resumed,

then

return

contrast

and

brightness

levels

to

their

original

levels.

Anode/Focus

s/c

Check:

1

ee

Switch

T.V.

on

and

set

contrast

and

brightness

levels

to

maximum.

Connect

a

270R

(20

-

30

Watt)

resistor

from

pin

9

of

the

flyback

transformer

to

ground.

N.B.

Use

a

470R

resistor

for

51cm/59cm

models.

Check

that

picture

and

sound

disappear

instantly.

Switch

T.V.

off,

remove

resistor,

and

wait

10

-

15

seconds.

Switch

T.V.

on

again,

and

check

that

normal

operation

is

resumed,

then

return

contrast

and

brightness

levels

to

their

original

levels.

POSITION

OF

ADJUSTMENT

CONTROLS

ON/OFF

switch

[|

E601

e

eee

VOLTAGE

MEASUREMENTS

IC001

P83C055

(‘R’

models)

PIN

VOLTAGE

PIN

|

VOLTAGE

IC002

ST24C04

PIN

|

VOLTAGE

en

voce

1

varies

with

tuning

1

2

OV-5v

(varies

with

volume)

2

3

Ov-5v

(varies

with

hue)

3

4

Ov-5v

(varies

with

colour)

-

4

5

Ov-5v

(varies

with

contrast)

4v8

5

6

Ov-5v

(varies

with

brightness)

4v5

6

7

Ov-5v

(varies

with

sharpness)

2v8

ig

8

not

used

2v8

8

9

1.8v

not

used

Ov

(5v0

with

direct

scart

input)

2v5

Ov

VHF-L

and

VHF-H

(5v0

UHF)

3v0

Ov

VHF-L

and

UHF

(5v0

VHF-H)

Ov

eee

tune

OV

1v1

(5v0

NTSC

signals)

PIN

OV

(1v7

RGB

mode)

5v0

Ov

(5v2

AV/RGB

modes)

4v5

1

Ov

(5v0

16:9

selection)

4v7

2

Ov

(Ov7

system

L’)

5v2

3

Ov

(6v0

system

L)

5v2

4

3.4v

(Ov

in

standby

mode)

5v2

5

3v8

(Ov

in

standby

mode)

5v5

6

Ov

5v0

Fé

8

9

IC001

SAA529X

PIN

VOLTAGE

PIN

VOLTAGE

PIN

VOLTAGE

‘

varies

with

tuning

3v4

(Ov

in

standby

mode)

2

OV-5v

(varies

with

volume)

3v8

(Ov

in

standby

mode)

3

Ov-5v

(varies

with

hue)

N/C

4

Ov-5v

(varies

with

colour)

Ov

5

Ov-5v

(varies

with

contrast)

2v7

6

Ov-5v

(varies

with

brightness)

Ov6

rf

Ov-5v

(varies

with

sharpness)

2v3

8

Ov

(B6)

5v

(Dk)

2V6

9

1.8v

Ov

Ov

(5v0

with

direct

scart

input)

Ov

Ov

VHF-L

and

VHF-H

(5v

UHF)

N/C

Ov

VHF-L

and

UHF

(5v

VHF-H)

1v1

(5v

NTSC

Signals)

OV

4v7

OV

(1v7

RGB

mode)

Ov

Ov

(5v2

AV/RGB

modes)

Ov

Ov

(5v0

16:9

selection)

Ov

Ov

(Ov7

system

L’)

Ov

Ov

IC201

TDA836

1

AND

2

VOLTAGE

PIN

|

VOLTAGE

PIN

|

VOLTAGE

VOLTAGE

IN

14

3v0

27

|

8v0

(0-5v

NTSC

signals)*|

40

15

4v2

41

16

|

Ov

(7v8

AV/RGB

mode)

42

17

3v0

43

18

2v0

44

19

2v0

45

20

2v1

46

21

Ov3

47

22

3v4

48

23

3v4

49

24

3v4

50

25

2v3

51

26

1v2

52

OONOORWDNM

—

NOTE:

Pins

5,

17,

25,

and

26

will

vary

depending

on

the

level

of

brightness

etc.

set

by

the

customer.

Pin

27

is

the

Hue

control

in

NTSC

signals.

*

ALSO

PAL

FOR

C

&

CP

MODELS

10