RCA 8TS30 Istruzioni per il montaggio

271

|p

rcaVictor

TELEVISION

RECEIVER

MODEL

§1530

Chasils

No,

KCS

20J-1

(60

cycles)

and

KCS

20K-2

(50

cycles)—

Mh,

No,

274

Service

data

—

1948

No.

T1

—

RADIO

CORPORATION

OF

AMERICA

RCA

VICTOR

DIVISION

Model

STS30

CAMDEN,

N.

J.,

U.

S.

A.

Walnut,

Mahogany

or

Toasted

Mahogany

GENERAL

DESCRIPTION

Model

8TS30

is

a

thirty-tube,

direct-viewing,

10"

table

model,

Television

Receiver.

The

receiver

is

complete

in

one

unit

and

is

operated

by

the

use

of

seven

front-panel

controls.

Features

of

the

receiver

include:

Full

thirteen

channel

coverage;

F-M

sound

system;

Improved

picture

brilliance;

A-F-C

horizontal

hold;

Stabilized

vertical

hold;

Two

stages

of

video

amplifica¬

tion;

Noise

saturation

circuits;

Three

stage

sync

separator

and

clipper;

Four

me.

band

width

for

picture

channel,

and

Re¬

duced

hazard

high

voltage

supply.

ELECTRICAL

AND

MECHANICAL

SPECIFICATIONS

PICTURE

SIZE

.

GVa"

x

8Vi"—-2"

radius

at

comer

R-F

FREQUENCY

RANGES

Picture

Sound

Receiver

Channel

Carrier

R-F

Osc.

Number

Freq.

Me.

Freq.

Me.

Freq

Me.

Freq.

Me.

1.

.44-50.

.45.25.

.49.75.

.71

2.

.54-60.

.55.25.

.59.75.

.81

3.

.....60-66.

.61.25.

.65.75.

.87

4

.

.66-72.

.67.25.

.71.75.

.93

5.

.76-82.

.77.25.

.81.75.

.103

6.

.82-88.

.83.25.

.87.75.

.109

7..........

...174-180.......

.175.25.

.179.75..

.201

8.

...180-186.

.181.25.

.185.75.

.207

9..........

...186-192.

.187.25.

.191.75.

.213

10.

...192-198.

.193.25.

.197.75.

.219

11

.

...

1

9

8-204

.

.199.25.

.

203.75

.

.225

12

..........

...

204

-

210

.......

.....

205

.

2

5

........

......

209

.75.

.

..

.231

13

.

...210-216.

.211.25.

.215.75.

.237

F’WE

TUNING

RANGE

Plus

and

minus

approximately

300

kc

on

channel

1

and

plus

and

minus

approximately

750

kc

on

channel

13.

POWER

SUPPLY

HATING

KCS

20J-1

.115

volts,,

60

cycles,

320

watts

KCS

20K-2

.115

volts,

50

cycles,

320

watts

AUDIO

POWER

OUTPUT

RATING

Undistorted

...

2.5

watts

Maximum

.

4

watts

LOUDSPEAKER

(92573-2)

Typo

..

5x7

inch

Permanent

Magnet

Dynamic

Voice

Coil

Impedance

.

3.2

ohms

at

400

cycles

WEIGHT

Chassis

with

Tubes

in

Cabinet

(less

Kinescope)

.

80

lbs.

Shipping

Weight

.

93

lbs.

RECEIVER

ANTENNA

INPUT

IMPEDANCE.

.300

ohms

balanced

DIMENSIONS

(inches)

Length

Height

Depth

Cabinet

(Outside

...

26

14

Vi

19

Chassis

Base

(Outside)

.

19

Vi

3

Vi

15

Vi

Chassis

Overall

.

21

3

/i

11%

16

V4

RCA

TUBE

COMPLEMENT

Tube

Used

Function

(1)

RCA

6J6

...

R-F

Amplifier

(2)

RCA

6J6

.

R-F

Oscillator

(3)

RCA

6J6

.

Converter

(4)

RCA

6BA6

.

1st

Sound

I-F

Amplifier

(5)

RCA

6BA6

.

2nd

Sound

I-F

Amplifier

(6)

RCA

6AU6

.

3rd

Sound

I-F

Amplifier

(7)

RCA

SALS

...

Sound

Discriminator

(8)

RCA

6AT6

.

1st

Audio

Amplifier

(9)

RCA

6K6GT

...

Audio

Output

(10)

RCA

6AG5

.

1st

Picture

I-F

Amplifier

(11)

RCA

6AG5

...

2nd

Picture

I-F

Amplifier

(12)

RCA

6AG5

.

3rd

Picture

I-F

Amplifier

(13)

RCA

6AG5

..

4th

Picture

I-F

Amplifier

(14)

RCA

6AL5

.

Picture

2nd

Detector

and

D-C

Restorer

(15)

RCA

6AU6

.

1st

Video

Amplifier

(16)

RCA

6K6GT

.

2nd

Video

Amplifier

(17)

RCA

6SK7

.

1st

Sync

Amplifier

(18)

RCA

6SH7

.

Sync

Separator

(19)

RCA

6SN7GT

.

2nd

Sync

Amplifier

and

Horizontal

Discharge

(20)

RCA

6J5

.Vertical

Sweep

Oscillator

and

Discharge

(21)

RCA

6K6GT

.

Vertical

Sweep

Output

(22)

RCA

6AL5

.,...

Horizontal

Sync

Discriminator

(23)

RCA

6K6GT

..

Horizontal

Sweep

Oscillator

(24)

RCA

6AC7

.

Horizontal

Sweep

Oscillator

Control

(25)

RCA

8BG6G

...

Horizontal

Sweep

Output

(26)

RCA

5V4G

.

Horizontal

Reaction

Scanning

(27)

RCA

1B3-GT/8016

....

High

Voltage

Rectifier

(28)

RCA

5U4G

.

Power

Supply

Rectifiers

(2

tubes)

(29)

RCA

10BP4

...

Kinescope

Specifications

continued

on

page

2

1

272

8TS30

ELECTRICAL

AND

MECHANICAL

SPECIFICATIONS

(Continued)

PICTURE

I-F

FREQUENCIES

Picture

Carrier

Frequency

.

25.75

Me.

Adjacent

Channel

Sound

Trap

.

27.25

Me.

Accompanying

Sound

Traps

.

21.25

Me.

Adjacent

Channel

Picture

Carrier

Trap

..

19.75

Me.

OPERATING

CONTROLS

(front

panel)

Channel

Selector

(

Fine

Tuning

(

.

Picture

i

Sound

Volume

and

On-Off

Switch

|

.Dual

Control

Knobs

.Dual

Control

Knobs

SOUND

I-F

FREQUENCIES

Sound

Carrier

Frequency

..

21.25

Me.

Sound

Discriminator

Band

Width

between

peaks)

.

350

kc

Picture

Horizontal

Hold

Picture

Vertical

Hold

.Dual

Control

Knobs

Brightness

Single

Control

Knob

VIDEO

RESPONSE

.

To

4

Me.

FOCUS

......

...

Magnetic

SWEEP

DEFLECTION

.

Magnetic

SCANNING

.

Interlaced,

525

line

HORIZONTAL

SCANNING

FREQUENCY

.

15,750

cps

VERTICAL

SCANNING

FREQUENCY

.

60

cps

FRAME

FREQUENCY

(Picture

Repetition

Rate)

.

30

cps

NON-OPERATING

CONTROLS

not

including

r-f

&

i-f

adjust¬

ments)

Horizontal

Centering

.

rear

chassis

adjustment

Vertical

Centering

.

rear

chassis

adjustment

Width

.

rear

chassis

screwdriver

adjustment

Height

.

rear

chassis

adjustment

Horizontal

Linearity

.

top

chassis

screwdriver

adjustment

Vertical

Linearity

.

rear

chassis

adjustment

Horizontal

Drive....

rear

chassis

adjustment

Horizontal

Oscillator

Frequency

.

rear

chassis

adjustment

Horizontal

Oscillator

Phase

.

bottom

chassis

adjustment

h’oeus

.

rear

chassis

adjustment

Focus

Coil

.

top

chassis

wing

nut

adjustment

Ion

Trap

Magnet

.

top

chassis

thumb

screw

adjustment

Deflection

Coil

.

top

chassis

wing

nut

adjustment

HIGH

VOLTAGE

WARNING

OPERATION

OF

THIS

RECEIVER

OUTSIDE

THE

CABINET

OR

WITH

THE

COVERS

REMOVED,

INVOLVES

A

SHOCK

HAZARD

FROM

THE

RECEIVER

POWER

SUPPLIES.

WORK

ON

THE

RECEIVER

SHOULD

NOT

BE

ATTEMPTED

BY

ANYONE

WHO

IS

NOT

THOROUGHLY

FAMILIAR

WITH

THE

PRECAUTIONS

NECES¬

SARY

WHEN

WORKING

ON

HIGH

VOLTAGE

EQUIPMENT.

DO

NOT

OPERATE

THE

RECEIVER

WITH

THE

HIGH

VOLTAGE

COMPARTMENT

SHIELD

REMOVED.

KINESCOPE

HANDLING

PRECAUTIONS

DO

NOT

OPEN

THE

KINESCOPE

SHIPPING

CARTON,

INSTALL,

REMOVE

OR

HANDLE

THE

KINESCOPE

IN

ANY

MANNER

UNLESS

SHATTERPROOF

GOGGLES

AND

HEAVY

GLOVES

ARE

WORN.

PEOPLE

NOT

SO

EQUIPPED

SHOULD

BE

KEPT

AWAY

WHILE

HANDLING

KINESCOPES.

KEEP

THE

KINESCOPE

AWAY

FROM

THE

BODY

WHILE

HANDLING.

The

kinescope

bulb

encloses

a

high

vacuum

and.

due

to

its

large

surface

area,

is

subjected

to

considerable

air

pressure.

For

these

reasons,

kinescopes

must

be

handled

with

more

care

than

ordinary

receiving

tubes.

I

he

large

end

of

the

kinescope

bulb

particularly

that

part

at

the

rim

of

the

viewing

surface—must

not

be

struck,

scratched

or

sub¬

jected

to

more

than

moderate

pressure

at

any

time.

In

installation,

if

the

tube

sticks

or

fails

to

slip

smoothly

into

its

socket,

or

de¬

flecting

yoke,

investigate

and

remove

the

cause

of

the

trouble.

Do

not

force

the

tube.

Refer

to

the

Receiver

Installation

section

for

de¬

tailed

instructions

on

.kinescope

installation.

All

RCA

kinescopes

are

shipped

in

special

cartons

and

should

be

left

in

the

cartons

until

ready

for

installation

in

the

receiver.

Keep

the

carton

for

possible

future

use.

2

273

OPERATING

INSTRUCTIONS

8TS30

The

iollowing

adjustments

are

necessary

when

turning

the

receiver

on

for

the

first

time.

1.

Turn

the

receiver

"ON"

and

advance

the

SOUND

VOL¬

UME

control

to

approximately

mid-position.

2.

Set

the

STATION

SELECTOR

to

the

desired

channel.

3.

Turn

the

PICTURE

control

fully

counter-clockwise.

4.

Turn

the

BRIGHTNESS

control

clockwise,

until

a

glow

appears

on

the

screen

then

counter-clockwise

until

the

glow

just

disappears.

5.

Turn

the

PICTURE

control

clockwise

until

a

glow

or

pat¬

tern

appears

on

the

screen.

6.

Adjust

the

FINE

TUNING

control

for

best

sound

fidelity

and

SOUND

VOLUME

for

suit¬

able

volume.

7.

Adjust

the

VERTICAL

hold

control

until

the

pattern

stops

vertical

movement.

8.

Adjust

the

HORIZONTAL

hold

control

until

a

picture

is

ob¬

tained

and

centered.

9.

Adjust

the

PICTURE

control

for

suitable

picture

con¬

trast.

10.

After

the

receiver

has

been

on

for

some

time,

it

may

be

necessary

to

readjust

the

FINE

TUNING

control

slightly

for

improved

sound

fidelity.

11.

In

switching

from

one

station

to

another,

it

may

be

necessary

to

repeat

steps

number

6

and

9.

12.

When

the

set

is

turned

on

again

after

an

idle

period,

it

should

not

be

necessary

to

re¬

peat

the

adjustments

if

the

posi¬

tions

of

the

controls

have

not

been

changed.

If

any

adjust¬

ment

is

necessary,

step

number

6

is

generally

sufficient.

13.

I

f

the

positions

of

the

con¬

trols

have

been

changed,

it

may

be

necessary

to

repeat

steps

number

1

through

9.

NOTE:

If

any

difficulty

is

ex¬

perienced

with

steps

number

7

or

8,

turn

the

PICTURE

control

Vi

turn

counterclockwise

and

re¬

peat

those

adjustments.

Figure

1—Receiver

Operating

Controls

INSTALLATION

INSTRUCTIONS

The

Model

8TS30

television

receiver

is

shipped

complete

in

one

carton

except

for

the

10BP4

kinescope.

The

kinescope

is

shipped

in

a

special

carton

and

should

not

be

unpacked

until

ready

for

installation.

UNPACKING—To

unpack

the

receiver,

tear

open

the

carton

bottom

flaps,

pick

the

receiver

up

from

under

the

bottom

of

the

cabinet

and

lift

it

out

of

the

shipping

carton.

The

cabinet

safety

glass

front

panel

is

packed

in

a

cardboard

box.

Remove

the

box

and

unpack

the

panel.

Take

off

the

cabinet

top

and

back.

The

operating

control

knobs

are

packed

in

a

paper

bag

which

is

tied

to

the

inside

of

the

cabinet

brace.

Remove

the

bag.

Remove

the

protective

cardboard

shield

from

the

5U4G

recti¬

fier.

Make

sure

all

tubes

are

in

place

and

are

firmly

seated

in

their

sockets.

Loosen

the

two

kinescope

cushion

adjustment

wing

screws

and

slide

the

cushion

toward

the

rear

of

the

chassis.

Loosen

the

deflection

yoke

adjustment,

slide

the

yoke

toward

the

rear

of

the

chassis

and

tighten.

See

Figure

2

for

the

location

of

the

cushion

and

yoke

adjustments.

\

FRONT

MAGNET

GAP

ON

THIS

SIDE

AND

EVEN

WITH

REAR

MAGNET

GAP

Figure

2—Yoke

and

Focus

Coil

Adjustments

From

the

front

of

the

cabinet,

look

through

the

deflection

yoke

and

check

the

alignment

of

the

focus

coil

with

the

yoke.

If

the

focus

coil

is

not

in

line,

loosen

the

three

focus

coil

adjust¬

ment

wingnuts

and

raise,

lower,

or

rotate

the

coil

until

align¬

ment

is

obtained.

Tighten

the

wingnuts

with

the

coil

in

this

position.

Loosen

the

two

lower

kinescope

face

centering

slides,

and

set

them

at

approximately

mid

position.

See

Figure

3

for

loca¬

tion

of

the

slides

and

their

adjustment

screws.

TO

INSTALL

CABINET

FRONT

PANEL,

INSERT

THESE

SCREWS

SLIDES

SCREWS

Figure

3—

Cabinet,

Front

View

KINESCOPE

HANDLING

PRECAUTION—Do

not

open

the

kine¬

scope

shipping

carton,

install,

remove,

or

handle

the

kinescope

in

any

manner,

unless

shatterproof

goggles

and

heavy

gloves

are

worn.

People

not

so

equipped

should

be

kept

away

while

handling

the

kinescope.

Keep

the

kinescope

away

from

the

body

while

handling.

The

shipping

carton

should

be

kept

for

use

in

case

of

future

moves.

3

274

8TS30

INSTALLATION

INSTRUCTIONS

INSTALLATION

OF

KINESCOPE—The

kinescope

second

anode

contact

is

a

recessed

metal

well

in

the

side

of

the

bulb.

The

tube

must

be

installed

so

that

this

contact

is

approximately

on

top.

The

final

orientation

of

the

tube

will

be

determined

by

the

position

of

the

ion

trap

flags.

Looking

at

the

kinescope

gun

structure,

it

will

be

observed

that

the

second

cylinder

from

the

base

inside

the

glass

neck

is

provided

with

two

small

metal

flags,

as

shown

in

Figure

4.

The

kinescope

must

be

installed

so

that

when

looking

down

on

the

chassis,

the

two

flags

will

be

seen

as

shown

in

Figure

2.

Figure

4—loti

Trap

Flags

Insert

the

neck

of

the

kinescope

through

the

deflection

and

focus

coils

as

shown

in

Figure

5

until

the

base

of

the

tube

protrudes

approximately

two

inches

beyond

the

focus

coil.

If

the

tube

sticks,

or

fails

to

slip

into

place

smoothly,

investi¬

gate

and

remove

the

cause

of

the

trouble.

Do

not

force

the

tube.

Early

production

receivers

employed

an

EM

type

of

ion

trap

magnet

like

that

in

the

model

630TS

receiver.

Late

production

receivers

employed

a

PM

type

magnet

as

shown

in

Figure

2.

If

an

EM

type

of

magnet

is

applied,

slip

the

assembly

over

the

neck

of

the

kinescope

with

the

coils

down

and

the

large

coil

towards

the

base

of

the

tube.

Tighten

the

magnet

ad¬

justment

thumbscrews

sufficiently

to

hold

it

in

position

but

still

free

enough

to

permit

adjustment.

If

the

PM

type

is

employed,

slip

the

assembly

over

the

neck

of

the

kinescope

with

the

large

magnet

towards

the

base

of

the

tube

and

with

the

arrow

on

the

assembly

up

as

shown

in

Figure

2.

The

front

magnet

is

movable

on

the

assembly.

The

correct

position

of

the

front

magnet

is

with

the

gap

on

the

left

side

(from

the

rear

of

the

cabinet)

and

even

with

the

gap

of

the

rear

magnet.

Connect

the

kinescope

socket

to

the

tube

base.

Insert

the

kinescope

until

the

face

of

the

tube

protrudes

approximately

one-quarter

of

an

inch

outside

the

front

of

the

cabinet.

Ad¬

just

the

four

centering

slides

until

the

face

of

the

kinescope

is

in

the

center

of

the

cabinet

opening.

Tighten

the

four

slides

securely.

Wipe

the

kinescope

screen

surface

and

front

panel

safety

glass

clean

of

all

dust

and

finger

marks

with

a

soft

cloth

moistened

with

the

Drackett

Co's

"Windex"

or

similar

cleaning

agent.

Install

the

cabinet

front

panel

as

indicated

in

Figure

3.

To

install

the

front

panel

place

the

lip

on

the

bottom

of

the

panel

in

the

recess

below

the

kinescope

opening

and

push

the

top

in.

Insert

the

two

screws

from

the

bag

with

the

knobs

into

the

back

of

panel

as

shown

in

Figure

3.

Slip

the

kinescope

as

far

forward

as

possible.

Slide

the

kinescope

cushion

firmly

up

against

the

flare

of

the

tube

and

tighten

the

adjustment

wing

screws.

Slide

the

deflection

yoke

as

far

forward

as

possible.

Connect

the

high

voltage

lead

to

the

kinescope

second

anode

socket.

The

antenna

and

power

connections

should

now

be

made.

Turn

the

power

switch

to

the

"on"

position,

the

brightness

control

fully

clockwise,

and

picture

control

counter-clockwise.

ION

TRAP

MAGNET

ADJUSTMENT—The

ion

trap

rear

magnet

poles

should

be

approximately

over

the

ion

trap

flags

as

shown

in

Figure

2.

Starting

from

this

position

adjust

the

mag¬

net

by

moving

it

forwards

or

backwards

at

the

same

time

ro¬

tating

it

slightly

around

the

neck

of

the

kinescope

for

the

brightest

raster

on

the

screen.

Reduce

the

brightness

control

setting

until

the

raster

is

slightly

above

average

brilliance.

Adjust

the

focus

control

(R184

on

the

chassis

rear

apron)

until

the

line

structure

of

the

raster

is

clearly

visible.

Readjust

the

ion

trap

magnet

for

maximum

raster

brilliance.

The

final

touches

on

this

adjustment

should

be

made

with

the

brightness

control

at

the

maximum

position

with

which

good

line

focus

can

be

maintained.

FOCUS

COIL

ADJUSTMENTS—Turn

the

centering

controls

R181

and

R211

to

mid

position.

See

Figure

6

for

location

of

these

rear

apron

controls.

If

a

corner

of

the

raster

is

shadowed,

it

indicates

that

the

electron

beam

is

striking

the

neck

of

the

tube.

Loosen

the

focus

coil

adjustment

wing

nuts

and

rotate

the

coil

about

its

vertical

and

horizontal

axis

until

the

entire

raster

is

visible,

approximately

centered

and

with

no

shadowed

corners.

Tighten

the

focus

coil

adjustment

wing

nuts

with

the

coil

in

this

posi¬

tion.

Figure

6—Rear

Chassis

Adjustments

DEFLECTION

YOKE

ADJUSTMENT—If

the

lines

of

the

raster

are

not

horizontal

or

squared

with

the

picture

mask,

rotate

the

deflection

yoke

until

this

condition

is

obtained.

Tighten

the

yoke

adjustment

wing

screw.

PICTURE

ADJUSTMENTS—It

will

now

be

necessary

to

obtain

a

test

pattern

picture

in

order

to

make

further

adjustments.

See

steps

2

through

9

and

the

note

of

the

receiver

operating

in¬

structions

on

page

3.

CHECK

OF

HORIZONTAL

OSCILLATOR

ALIGNMENT—Turn

the

horizontal

hold

control

to

the

extreme

counter-clockwise

position.

The

picture

should

remain

in

horizontal

sync.

Mo¬

mentarily

remove

the

signal

by

switching

off

channel

then

back.

Normally

the

picture

will

pull

into

sync.

Turn

the

horizontal

hold

control

to

the

extreme

clockwise

position.

The

picture

should

remain

in

sync.

Momentarily

remove

the

sig¬

nal.

Again

the

picture

should

normally

pull

into

sync.

If

the

receiver

passes

the

above

checks

and

the'

picture

is

normal

and

stable,

the

horizontal

oscillator

is

properly

aligned.

Skip

"Alignment

of

Horizontal

Oscillator

and

proceed

with

'FOCJJS'

adjustment."

4

275

INSTALLATION

INSTRUCTIONS

8IS30

ALIGNMENT

OF

HORIZONTAL

OSCILLATOR—If

in

the

above

check

the

receiver

failed

to

hold

sync

with

the

hold

control

at

either

extreme

or

failed

to

pull

into

sync

after

momentary

removals

of

the

signal,

make

the

adjustments

under

"Slight

Retouching

Adjustments.’'

If,

after

making

these

retouching

adjustments,

the

receiver

fails

to

pass

the

above

checks

or

if

the

horizontal

oscillator

is

completely

out

of

adjustment,

then

make

the

adjustments

under

"Complete

Realignment."

Slight

Retouching

Adjustments—Tune

in

a

Television

Station

and

adjust

the

fine

tuning

control

for

best

sound

quality.

Sync

the

picture

and

adjust

the

picture

control

for

slightly

less

than

normal

contrast.

Turn

the

horizontal

hold

control

to

the

extreme

position

in

which

the

oscillator

fails

to

hold

or

to

pul

in.

Momentarily

remove

the

signal.

Turn

the

T10$

fre¬

quency

adjustment

on

the

chassis

rear

apron

until

the

oscil¬

lator

pulls

into

sync.

Check

hold

and

pull-in

for

the

other

extreme

position

of

the

hold

control.

Complete

Realignment—Tune

in

a

Television

Station

and

ad¬

just

the

fine

tuning

control

for

best

sound

quality.

Turn

the

T108

frequency

adjustment

on

rear

apron

until

the

picture

is

synchronized.

Adjust

the

picture

control

so

that

the

picture

is

somewhat

below

average

contrast

level.

Turn

the

T108

phase

adjustment

screw

(under

chassis)

until

the

blanking

bar,

which

may

appear

in

the

picture,

moves

to

the

right

and

off

the

raster.

The

range

of

this

adjustment

is

such

that

it

is

possible

to

hit

an

unstable

condition

(ripples

in

the

raster).

The

screw

must

be

turned

clockwise

from

the

unstable

position.

The

length

of

stud

beyond

the

bushing

in

its

correct

position

is

usually

about

V

2

inch.

Turn

horizontal

hold

to

the

extreme

counter-clockwise

position.

Turn

T108

frequency

adjustment

clockwise

until

the

picture

falls

out

of

sync.

Then

turn

it

slowly

counter-clockwise

to

the

point

where

the

picture

falls

in

sync

again.

Readjust

T108

phase

adjustment

so

that

the

left

side

of

the

pic¬

ture

is

close

to

the

left

side

of

the

raster,

but

does

not

begin

to

fold

ever.

Turn

horizontal

hold

to

the

extreme

clockwise

position.

The

right

side

of

the

picture

should

be

close

to

the

right

side

of

the

raster,

but

should

not

begin

to

fold

over.

If

it

does,

readjust

the

phase

control.

Momentarily

remove

the

signal.

When

the

signal

is

re¬

stored,

the

picture

should

fall

in

sync.

If

it

doesn't,

turn

T108

frequency

adjustment

counter-clockwise

until

the

picture

falls

in

sync.

Turn

horizontal

hold

to

the

extreme

counter-clockwise

position.

Remove

the

signal

momentarily.

When

signal

is

restored,

the

picture

shuuld

fall

in

sync.

NOTE:

If

the

picture

does

not

pull

in

sync

after

momentary

removals

of

the

signal

in

both

extreme

positions

of

horizontal

hold,

the

pull-in

range

may

be

inadequate,

though

not

neces¬

sarily.

A

pull-in

through

%

of

the

hold

control

range

may

still

be

satisfactory.

There

is

a

difference

between

the

pull-in

range

and

hold-in

range

of

frequencies.

Once

in

sync,

the

circuit

will

hold

about

50%

to

100%

more

variation

in

frequency

than

it

can

pull

in.

The

range

of

the

horizontal

hold

control

is

only

ap¬

proximately

equal

to

the

pull-in

range,

considerable

variation

may

be

found

due

to

variations

in

the

cut-off

characteristic

of

the

horizontal

oscillator

control

tubes,

V124.

FOCUS—Adjust

the

focus

control

R184

for

maximum

definition

of

tho

vertical

wedge

of

the

test

pattern.

HEIGHT

AND

VERTICAL

LINEARITY

ADJUSTMENTS—Adjust

the

height

control

(R169

on

chassis

rear

apron)

until

the

picture

fills

the

mask

vertically

(6

3

/s

inches).

Adjust

vertical

linearity

(R178

on

rear

apron),

until

the

test

pattern

is

symmetrical

from

top

to

bottom.

Adjustment

of

either

control

will

require

a

read¬

justment

of

the

other.

Adjust

vertical

centering

to

align

the

picture

with

the

mask.

WIDTH

AND

HORIZONTAL

LINEARITY

ADJUSTMENTS—Turn

the

horizontal

drive

(R187

on

rear

apron)

clockwise

as

far

as

possible

without

causing

crowding

of

the

right

of

the

picture.

This

position

provides

maximum

high

voltage

to

the

kine¬

scope

second

anode.

Adjust

the

width

control

(LI96

on

rear

chassis)

until

the

picture

just

fills

the

mask

horizontally

(8

V

2

inches).

Adjust

the

horizontal

linearity

control

L201

(see

Fig¬

ure

6)

until

the

test

pattern

is

symmetrical

left

to

right.

A

slight

readjustment

of

the

horizontal

drive

control

may

be

necessary

when

the

linearity

control

is

used.

Adjust

horizontal

centering

to

align

the

picture

with

the

mask.

If

repeated

adjustments

of

drive

width

and

linearity

fail

to

give

proper

linearity,

it

may

be

necessary

to

move

the

tap

on

R209,

which

is

located

in

the

high

voltage

compartment.

Adjust¬

ments

of

drive,

width

and

linearity

must

then

be

repeated.

Check

to

see

that

all

cushion,

yoke,

focus

coil

and

ion

trap

magnet

thumb

screws

are

tight.

Replace

the

cabinet

back

and

top.

Make

sure

that

the

back

is

on

tight,

otherwise

it

may

rattle

at

high

volume.

CHECK

OF

R-F

OSCILLATOR

ADJUSTMENTS—With

a

crystal

calibrated

test

oscillator

or

heterodyne

frequency

meter,

check

to

see

if

the

receiver

r-f

oscillator

is

adjusted

to

the

proper

frequency

on

all

channels.

If

adjustments

are

required,

these

should

be

made

by

the

method

outlined

in

the

alignment

pro¬

cedure

on

page

8.

The

adjustments

for

channels

1

through

5

and

7

through

12

are

available

from

the

front

of

the

cabinet

by

removing

the

station

selector

escutcheon

as

shown

in

Figure

7.

Adjustments

for

channels

6

and

13

are

under

the

chassis.

VIDEO

PEAKING

LINK—A

video

peaking

link

is

provided

(see

Figure

6)

to

permit

changing

the

video

response.

If

the

pictures

from

the

majority

of

stations

look

better

with

the

link

closed,

(2-3

position)

then

the

link

should

be

placed

in

that

position.

However,

if

transients

are

produced

on

high

contrast

pictures

then

the

link

should

be

left

open

(1-2

position).

Figure

7

—

R-F

Oscillator

Adjustments

ANTENNA

TRAP—In

some

instances

interference

may

be

en¬

countered

from

FM

stations

that

are

on

the

image

frequency

of

a

television

station.

In

other

instances

interference

between

two

television

stations

may

be

observed.

Assume

that

two

television

stations

in

a

city

are

operating

on

channels

6

and

10.

When

the

receiver

is

tuned

to

channel

6,

a

small

amount

of

the

oscillator

voltage

(109

me.)

is

present

on

the

r-f

amplifier

grid.

This

109

me.

voltage

beats

with

the

channel

10

picture

carrier

and

produces

an

84.25

me.

signal.

This

signal

falls

within

the

channel

6

range

and

interferes

with

the

reception

of

channel

6.

A

similar

case

occurs

be¬

tween

channels

5

and

7.

A

series

resonant

trap

across

ther-f

amplifier

grid

circuit

is

employed

to

remove

theoscillator

voltage

from

the

grids

and

thus

eliminate

this

type

of

interference.

To

adjust

the

trap

in

the

field,

tune

in

the

station

on

which

the

interference

is

observed.

Tune

both

cores

of

the

trap

for

minimum

interference

in

the

picture.

See

Figure

8

for

the

lo¬

cation

of

the

trap.

Keep

both

cores

approximately

the

same

by

visual

inspection.

Then,

turn

one

core

V

2

turn

from

the

original

position

and

repeak

the

second

for

maximum

rejec¬

tion

Repeat

this

process

until

the

best

rejection

is

obtained.

For

shop

alignment

of

the

trap

see

the

alignment

procedure

on

page

11.

In

severe

cases

of

interference,

it

may

be

necessary

to

reduce

the

signal

from

the

interfering

station

by

reorienting

the

an¬

tenna

or

by

connecting

a

half

wave

stub

of

transmission

line

across

the

receiver

antenna

terminals.

The

end

of

the

stub

should

be

terminated

by

a

47

ohm,

non

inductive

resistor.

5

276

8TS30

CHASSIS

TOP

¥1EW

\

R\BZ

&R10MTNB

SS

CONTROL

sm

VERTICAL

MOLD

CONTROL

WIGM

VOLTAGE

COMPARTMENT

(SHOWN

WITH

SUIELO

REMOVED)

BOTTOM

VIEW

8TS30

R

!

B

2

Figure

9—Chassis

Bottom

View

278

ALIGNMENT

PROCEDURE

8

fS30

TEST

EQUIPMENT

—To

properly

service

the

television

chassis

of

this

receiver,

it

is

recommended

that

the

following

test

equipment

be

available:

R-F

Sweep

Generator

meeting

the

following

requirements;

(a)

Frequency

Ranges

18

to

30

me.,

1

me.

sweep

width

40

to

90

me.,

10

me.

sweep

width

170

to

225

me.,

10

me.

sweep

width

(b)

Output

adjustable

with

at

least

.1

volt

maximum.

(c)

Output

constant

on

all

ranges.

(d)

"Flat”

output

on

all

attenuator

positions.

Cathode-ray

Oscilloscope,

preferably

one

with

a

wide

band

vertical

deflection,

an

input

calibrating

source,

and

a

low

ca¬

pacity

probe.

Signal

Generator

to

provide

the

following

frequencies.

(a)

I-F

frequencies

19.75

me.

adjacent

channel

picture

trap

21.25

me.

sound

i-f

and

sound

traps

21.8

me.

converter

transformer

22.3

me.

second

picture

i-f

transformer

23.4

me.

fourth

picture

i-f

coil

25.2

me.

third

picture

i-f

coil

25.3

me.

first

picture

i-f

transformer

25

75

me.

picture

carrier

27.25

me.

adjacent

channel

sound

trap

(b)

R-F

frequencies

Picture

Sound

Channel

Carrier

Number

Freq.

Me.

Freq.

Me.

1

.

..

45.25

.

49.75

2

.

..

55.25

.

59.75

3

.

..

61.25

.

65.75

4

.

..

67.25

.

71.75

5

.

..

77.25

.

81.75

6

.

..

83.25

.

87.75

7

.

..

175.25

.

179.75

8

.

..

181.25

.

185.75

S

.

..

187.25

.

191.75

10

.

..

193.25

.

197.75

11

.

..

199.25

.

203.75

12

.

..

205.25

.

209.75

13

.

...

211.25

.

215.75

(c)

Output

on

these

ranges

should

be

adjustable

and

at

least

.1

volt

maximum.

Heterodyne

Frequency

Meter

with

crystal

calibrator

if

the

sig¬

nal

generator

is

not

crystal

controlled.

Electronic

Voltmeter

of

Junior

"VoltOhmyst"

type

and

a

high

voltage

multiplier

probe

for

use

with

this

meter

to

permit

measurements

up

to

10

kv.

Service

Precautions—If

necessary

to

remove

the

chassis

from

cabinet,

the

kinescope

must

first

be

removed.

See

Figures

3

and

5.

If

possible,

the

chassis

should

then

be

serviced

without

the

kinescope.

However,

if

it

is

necessary

to

view

the

raster

during

servicing,

the

kinescope

should

be

inserted

only

after

the

chassis

is

turned

on

end.

The

kinescope

should

never

be

allowed

to

support

its

weight

by

resting

in

the

deflecting

yoke.

A

bracket

should

be

used

to

support

the

tube

at

its

viewing

screen.

By

turning

the

chassis

on

end

with

the

power

transformer

down,

all

adjustments

will

be

made

conveniently

available.

Since

this

is

the

only

safe

position

in

which

the

chassis

will

rest

and

still

leave

all

adjustments

accessible,

the

trimmer

location

drawings

are

oriented

similarly

for

ease

ol

use.

CAUTION:

Do

not

short

the

kinescope

second

anode

lead.

Its

short

circuit

current

is

approximately

3

ma.

This

repre¬

sents

approximately

9

watts

dissipation

and

a

considerable

overload

on

the

high

voltage

filter

resistor

R235.

Adjustments

Required—Normally,

only

the

r-f

oscillator

line

will

require

the

attention

of

the

service

technician.

All

other

circuits

are

either

broad

or

very

stable

and

hence

will

seldom

require

re-adjustment.

Due

to

the

high

frequencies

at

which

the

receiver

operates

the

r-f

oscillator

line

adjustment

is

critical

and

may

be

affected

by

a

tube

change.

The

line

can

be

adjusted

to

proper

frequency

on

channel

13

with

practically

any

6J6

tube

in

the

oscillator

socket.

However,

it

may

not

then

be

possible

to

adjust

the

line

to

frequency

on

all

of

channels

7,

8,

9,

10,

11

and

12.

To

be

satisfactory

as

an

oscillator

tube,

it

should

be

possible

to

adjust

the

line

to

proper

frequency

with

the

fine

tuning

control

in

the

middle

third

of

its

range.

It

may

therefore

be

necessary

to

select

a

tube

for

the

oscillator

socket.

In

replac¬

ing,

if

the

old

tube

can

be

matched

for

frequency

by

trying

several

new

ones,

this

practice

is

recommended.

At

best,

however,

it

will

probably

be

necessary

to

completely

realign

the

oscillator

line

when

changing

the

tube.

Tubes

which

cannot

be

used

as

oscillator

will

work

satisfac¬

torily

as

r-f

amplifier

or

converter.

ORDER

OF

ALIGNMENT—When

a

complete

receiver

align¬

ment

is

necessary,

it

can

be

most

conveniently

performed

in

the

following

order;

Sound

discriminator

Sound

i-f

transformers

Picture

i-f

traps

Picture

i-f

transformers

R-F

and

converter

lines

R-F

oscillator

line

Retouch

picture

i-f

transformers

Antenna

trap

adjustment

Sensitivity

check

SOUND

DISCRIMINATOR

ALIGNMENT—

Set

the

signal

generator

for

approximately

.1

volt

output

at

21.25

m

e.

and

connect

it

to

the

third

sound

i-f

grid.

Detune

T113

secondary

(bottom).

Set

the

"VoltOhmyst”

on

the

10

volt

scale.

Connect

the

meter

in

series

with

a

one

megohm

resistor

to

the

junction

of

diode

resistors

R219

and

R220.

Do

not

remove

the

discriminator

shield

to

make

connection

to

R219

and

R220.

Connection

can

be

easily

made

by

fashioning

a

hook

on

the

1

meg

resistor

lead

and

making

connection

to

the

transformer

lug

"C"

through

the

hole

provided

for

the

adjusting

tool.

Adjust

the

primary

of

T113

(top)

for

maximum

output

on

the

meter.

Connect

the

"VoltOhmyst"

to

the

junction

of

R236

and

C205.

Adjust

T113

secondary

(bottom).

It

will

be

found

that

it

is

pos¬

sible

to

produce

a

positive

or

negative

voltage

on

the

meter

de¬

pendent

upon

this

adjustment.

Obviously

to

pass

from

a

posi¬

tive

to

a

negative

voltage,

the

voltage

must

go

through

zero.

T113

(bottom)

should

be

adjusted

so

that

the

meter

indicates

zero

output

as

the

voltage

swings

from

positive

to

negative.

This

point

will

be

called

discriminator

zero

output.

Connect

the

sweep

oscillator

to

the

grid

of

the

third

sound

i-f

amplifier.

8

ALIGNMENT

PROCEDURE

8TS30

Adjust

the

sweep

band

width

to

approximately

1

me.

with

the

center

frequency

at

approximately

21.25

and

with

an

output

of

approximately

.1

volt.

Connect

the

oscilloscope

to

the

junction

of

R236

and

C205.

The

pattern

obtained

should

be

similar

to

that

shown

in

Figure

16A.

If

it

is

not.

adjust

the

T113

(top)

until

the

wave

form

is

symmetrical.

The

peak

to

peak

bandwidth

of

the

discriminator

should

be

approximately

350

kc.

and

it

should

be

linear

from

21.75

me.

to

21.325

me.

SOUND

I-F

ALIGNMENT—

Connect

the

sweep

oscillator

to

the

second

sound

i-f

amplifier

grid.

Connect

the

oscilloscope

to

the

third

sound

i-f

grid

return

(terminal

A

T112)

in

series

with

a

33,000

ohm

isolating

resistor.

Insert

a

21.25

me.

marker

signal

from

the

signal

generator

into

the

second

sound

i-f

grid.

Adjust

T112

(top

and

bottom)

for

maximum

gain

and

sym¬

metry

about

the

21.25

me.

marker.

The

pattern

obtained

should

be

similar

to

that

shown

in

Figure

16B.

The

output

level

from

the

sweep

should

be

set

to

produce

approximately

.3

volt

peak-to-peak

at

the

third

sound

i-f

grid

return

when

the

final

touches

on

the

above

adjustment

are

made.

It

is

necessary

that

the

sweep

output

voltage

should

not

exceed

the

specified

values

otherwise

the

response

curve

will

be

broadened,

permitting

slight

misadjustment

to

pass

unnoticed

and

possibly

causing

distortion

on

weak

signals.

Connect

the

sweep

and

signal

generator

to

the

top

end

of

the

trap

winding

of

T2

(on

top

of

the

chassis).

Adjust

Till

(top

and

bottom),

for

maximum

gain

and

symmetry

at

21.25

me.

Reduce

the

sweep

output

for

the

final

adjustments

so

that

approximately

.3

volt

peak-to-peak

is

present

at

the

third

sound

i-f

grid

return.

The

band

width

at

70%

response

from

the

first

sound

i-f

grid

to

the

third

i-f

grid

should

be

approximately

200

kc.

PICTURE

I-F

TRAP

ADJUSTMENT—

Turn

the

receiver

picture

control

for

-3

volts

on

the

picture

i-f

grids.

Set

the

channel

switch

to

channel

13.

Connect

the

"VoltOhmyst"

across

the

picture

second

detector

load

resistor

R137.

Connect

the

output

of

the

signal

generator

to

the

junction

of

C14

and

R6.

This

connection

is

available

on

a

terminal

lug

through

a

hole

in

the

side

apron

of

the

chassis,

beside

the

r-f

unit.

This

hole

is

normally

down

when

the

chassis

is

in

the

recommended

position.

Connection

can

be

easily

made,

how¬

ever,

by

allowing

the

receiver

to

hang

over

the

edge

of

the

test

bench

by

a

few

inches.

Set

the

generator

to

each

of

the

following

frequencies

and

tune

the

specified

adjustment

for

minimum

indication

on

the

"VoltOhmyst."

In

each

instance

the

generator

should

be

checked

against

a

crystal

calibrator

to

insure

that

the

gen¬

erator

is

exactly

on

frequency

21.25

m

e.—T2

(top)

21.25

me.—T105

(top)

27.25

me.—T103

(top)

27.25

m

e.—T102

(bottom)

19.75

me.-

1

T104

(top)

Note—On

some

sets,

T102

bottom

adjustment

is

omitted.

PICTURE

I-F

TRANSFORMER

ADJUSTMENTS—

Set

the

signal

generator

to

each

of

the

following

frequencies

and

peak

the

specified

adjustment

for

maximum

indication

on

the

"VoltOhmyst,"

21.8

me.—T2

(bottom)

25.3

me.—T103

(bottom)

22.3

me.—T104

(bottom)

25.2

me.—T’02

(top

of

chassis)

23.4

me.—LI85

(top

of

chassis)

If

T104

(bottom)

required

adjustment,

it

will

be

necessary

to

reset

T104

(top)

for

minimum

response

at

19.75

me.

Picture

I-F

Oscillation—If

the

receiver

is

badly

misaligned

and

two

or

more

of

the

i-f

transformers

are

tuned

to

the

same

frequency,

the

receiver

may

fall

into

i-f

oscillation.

I-F

oscilla¬

tion

shows

up

as

a

voltage

in

excess

of

3

volts

at

the

picture

detector

load

resistor.

This

voltage

is

unaffected

by

r-f

signal

input

and

sometimes

is

independent

of

picture

control

setting.

If

such

a

condition

is

encountered,

it

is

sometimes

possible

to

stop

oscillation

by

adjusting

the

transformers

approximately

to

frequency

by

setting

the

adjustment

stud

extensions

of

T2,

T103,

T104,

T105,

TT102,

and

L185

to

be

approximately

equal

to

those

of

another

receiver

known

to

be

in

proper

alignment.

If

this

does

not

have

the

desired

effect,

it

may

now

be

possible

to

stop

oscillation

by

increasing

the

grid

bias.

If

so,

it

should

then

be

possible

to

align

the

transformers

by

the

usual

method.

Once

aligned

in

this

manner,

the

i-f

should

be

stable

with

reduced

bias.

If

the

oscillation

cannot

be

stopped

in

the

above

manner,

shunt

the

grids

of

the

first

three

pix

i-f

amplifiers

to

ground

with

1000

mmf.

capacitors.

Connect

the

signal

generator

to

the

fourth

pix

i-f

grid

and

align

LI85

to

frequency.

Pro¬

gressively

remove

the

shunt

from

each

grid

and

align

the

plate

coil

of

that

stage

to

frequency.

If

this

does

not

stop

the

oscillation,

the

difficulty

is

not

due

to

i-f

misalignment

as

the

i-f

section

is

very

stable

when

prop¬

erly

aligned.

Check

all

i-f

by-pass

condensers,

transformer

shunting

resistors,

tubes,

socket

voltages,

etc.

R-F

AND

CONVERTER

LINE

ADJUSTMENT—

Connect

the

r-f

sweep

oscillator

to

the

receiver

antenna

ter¬

minals.

If

the

sweep

oscillator

has

a

50

ohm

single-ended

output,

it

will

be

necessary

to

obtain

balanced

output

by

connecting

as

shown

in

Figure

10.

Figure

10—Unbalanced

Sweep

Cable

Termination

Connect

the

oscilloscope

to

the

junction

of

C14

and

R6

(in

the

r-f

tuning

unit)

through

a

10,000

ohm

resistor.

By-pass

the

first

picture

i-f

grid

to

ground

through

a

1000

mmfd.

capacitor.

Keep

the

leads

to

this

by-pass

as

short

as

possible.

If

this

is

not

done,

lead

resonance

may

fall

in

the

r-f

range

and

cause

an

incorrect

picture

of

the

r-f

response.

Turn

the

picture

control

for

—1.5

volts

on

the

r-f

grids.

Connect

the

signal

generator

loosely

to

the

receiver

antenna

terminals.

Turn

the

antenna

trap

L81

and

L82

cores

fully

counterclock¬

wise

so

that

the

trap

will

not

affect

the

channel

6

r-f

response.

Since

channel

7

has

the

narrowest

response

of

any

of

the

280

ALIGNMENT

PROCEDURE

8TS30

high

frequency

channels,

it

should

be

adjusted

first.

Set

the

receiver

channel

switch

to

channel

7

(see

Figure

15

for

switch

shaft

flat

location

versus

channel).

Set

the

sweep

oscillator

to

cover

channel

7.

Insert

markers

of

channel

7

picture

carrier

and

sound

carrier

175.25

me.

and

179.75

me.

Adjust

L25,

L26,

L51

and

L52

(see

Figure

17)

for

an

approxi¬

mately

flat

topped

response

curve

located

symmetrically

be¬

tween

the

markers.

Normally

this

curve

appears

somewhat

overcoupled

or

double

humped

with

a

10

or

15%

peak

to

val¬

ley

excursion

and

the

markers

occur

at

approximately

90%

re¬

sponse.

See

Figure

17,

channel

7.

In

making

these

adjust¬

ments,

the

stud

extension

of

all

cores

should

be

kept

approxi¬

mately

equal.

Check

the

response

of

channels

8

through

13

by

switching

the

receiver

channel

switch,

sweep

oscillator

and

marker

oscillator

to

each

of

these

channels

and

observe

the

response

obtained.

See

Figure

17

for

typical

response

curves.

It

should

be

found

that

all

these

channels

have

the

proper

shaped

re¬

sponse

with

the

markers

above

70%

response.

It

the

markers

do

not

fall

within

this

requirement

on

one

or

more

high

fre¬

quency

channels,

since

there

are

no

individual

channel

ad¬

justments,

it

will

be

necessary

to

readjust

L25,

L26,

L51

and

L52,

and

possibly

compromise

some

channel

slightly

in

order

to

get

the

markers

up

on

other

channels.

Normally

however,

no

difficulty

of

this

type

should

be

experienced

since

the

higher

frequency

channels

become

comparatively

broad

and

the

markers

easily

fall

within

the

required

range.

Channel

6

is

in

the

same

manner.

Set

the

receiver

to

channel

6.

Set

the

sweep

oscillator

to

cover

channel

6.

Set

the

marker

oscillator

to

channel

6

picture

and

sound

car¬

rier

frequencies.

Adjust

L11,

L12,

L37

and

L38,

for

an

approximately

flat-topped

response

curve

located

symmetrically

between

the

markers.

Check

channels

5

down

through

channel

1

by

switching

the

receiver,

sweep

oscillator

and

marker

oscillator

to

each

chan¬

nel

and

observing

the

response

obtained.

In

all

cases,

the

markers

should

be

above

the

70%

response

point.

If

this

is

not

the

case,

LI

I,

L12,

L37

and

L.38

should

be

retouched.

On

final

adjustment,

all

channels

must

be

within

the

70%

spec¬

ification.

Coupling

between

r-f

and

converter

lines

is

augmented

by

a

link

between

LI2

and

L37.

This

link

is

adjusted

in

the

factory

and

should

not

require

adjustment

in

the

field.

On

channel

6

with

the

link

in

the

minimum

coupling

position,

the

response

is

slightly

overcoupled

with

approximately

a

10%

excursion

from

peak-to-valley.

With

the

coupling

at

maximum,

the

response

is

somewhat

broader

and

the

peak-to-valley

ex¬

cursion

is

approximately

40%.

The

amount

of

coupling

per¬

missible

is

limited

by

the

peak-to-valley

excursion

which

should

not

be

greater

than

30%

on

any

channel.

R-F

OSCILLATOR

LINE

ADJUSTMENT—

The

r-f

oscillator

line

may

be

aligned

by

adjusting

it

to

beat

with

a

crystal

calibrated

heterodyne

frequency

meter,

or

by

feeding

a

signal

into

the

receiver

at

the

r-f

sound

carrier

fre¬

quency

and

adjusting

the

oscillator

for

zero

output

from

the

sound

discriminator.

In

this

latter

case

the

sound

discriminator

must

first

have

been

aligned

to

exact

frequency.

Either

method

of

adjustment

will

produce

the

same

results.

The

method

used

will

depend

upon

the

type

of

test

equipment

available.

Regardless

of

which

method

of

oscillator

alignment

is

used,

the

frequency

standard

must

be

crystal

controlled

or

calibrated.

If

the

receiver

oscillator

is

to

be

adjusted

by

the

heterodyne

frequency

meter

method,

the

calibration

frequency

listed

under

R-F

Osc.

Freq.

must

be

available.

If

the

receiver

oscillator

is

adjusted

by

feeding

in

the

r-f

sound

carrier

frequency,

the

frequencies

listed

under

sound

carrier

Freq.

must

be

available.

Receiver

R-F

Sound

Channel

R-F

Osc.

Carrier

Number

Freq,

Me.

Freq.

Me.

1

.

71

.

49.75

2

.

81

.

59.75

3

.

87

.

65.75

4

.

93

.

71.75

5

.

103

.

..

81.75

6

.

109

.

87.75

7

.

201

.

179.75

8

.

207

.

..

185,75

9

.

213

.

191.75

10

.

219

.

197.75

11

.

225

.

..

203.75

12

.

231

.

209.75

13

.

237

.

215.75

If

the

heterodyne

frequency

meter

method

is

used,

couple

the

meter

probe

loosely

to

the

receiver

oscillator.

If

the

r-f

sound

carrier

method

is

used,

connect

the

"Volt-

Ohmyst"

to

the

sound

discriminator

output

(junction

of

R236

and

C205.

Connect

the

signal

generator

to

the

receiver

antenna

terminals.

The

order

of

alignment

remains

the

same

regardless

of

which

method

is

used.

Since

lower

frequencies

are

obtained

by

adding

steps

of

inductance,

it

is

necessary

to

align

channel

13

first

and

con¬

tinue

in

reverse

numerical

order.

Set

the

receiver

channel

switch

to

13.

Adjust

the

frequency

standard

to

the

correct

frequency

(237

me.

for

heterodyne

frequency

meter

or

215.75

me.

for

the

signal

generator).

Set

the

fine

tuning

control

to

the

middle

of

its

range

while

mak¬

ing

the

adjustment.

Adjust

L77

and

L78

for

an

audible

beat

on

the

heterodyne

frequency

meter

or

zero

voltage

from

sound

discriminator.

The

core

stud

extensions

should

be

maintained

equal

by

visual

inspection.

Switch

the

receiver

to

channel

12.

Set

the

frequency

standard

to

the

proper

frequency

as

listed

in

the

alignment

table.

Adjust

L76

for

indications

as

above.

Adjust

the

oscillator

to

frequency

on

all

channels

by

switch¬

ing

the

receiver

and

the

frequency

standard

to

each

channel

and

adjusting

the

appropriate

oscillator

trimmer

for

the

speci¬

fied

indication.

It

should

be

possible

to

adjust

the

oscillator

to

the

correct

frequency

on

all

channels

with

the

fine

tuning

control

in

the

middle

third

of

its

range.

After

the

oscillator

has

been

set

on

all

channels,

start

back

at

channel

13

and

recheck

to

make

sure

that

all

adjustments

are

correct.

RETOUCHING

OF

PICTURE

I-F

ADJUSTMENTS—

The

picture

i-f

response

curve

varies

somewhat

with

change

of

bias

and

for

this

reason

it

should

be

aligned

with

approxi-

10

RCA 8TS30 Istruzioni per il montaggio

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