TOSHIBA 14AR21 - Service Manual Immediate Download

TOSHIBA

FILE NO.050-2001

SERVICE MANUAL

COLOR TELEVISION

14AR21

DOCUMENT CREATED IN JAPAN, OCT., 2001

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COLOR TELEVISION

Chassis No. MSA

In the interests of user-safety (Required by safety regulations in some countries) the set should be restored to its

original condition and only parts identical to those specified should be used.

ELECTRICAL SPECIFICATIONS ......................................................................................................... 1

IMPORTANT SERVICE SAFETY PRECAUTION ................................................................................. 2

LOCATION OF USER'S CONTROL .....................................................................................................4

INSTALLATION AND SERVICE INSTRUCTIONS ................................................................................ 5

CHASSIS LAYOUT ............................................................................................................................. 13

BLOCK DIAGRAM .............................................................................................................................. 14

DESCRIPTION OF SCHEMATIC DIAGRAMS .................................................................................... 15

PRINTED WIRING BOARD ASSEMBLIES ........................................................................................ 19

REPLACEMENT PARTS LIST ............................................................................................................ 22

PACKING OF THE SET ...................................................................................................................... 27

Page

CONTENTS

MODEL

POWER INPUT ........................................ 110-220 V AC 50/60 Hz

POWER RATING .................................................................... 53 W

PICTURE SIZE ........................................... 574cm2 (88.97sq inch)

CONVERGENCE ............................................................. Magnetic

SWEEP DEFLECTION .................................................... Magnetic

FOCUS ............................................... Hi-Bi-Potential Electrostatic

INTERMEDIATE FREQUENCIES

Picture IF Carrier Frequency ..................................... 45.75 MHz

Sound IF Carrier Frequency ...................................... 41.25 MHz

Color Sub-Carrier Frequency .................................... 42.17 MHz

(Nominal)

AUDIO POWER

OUTPUT RATING ................................ 0.9W (at 10% distortion)

ELECTRICAL SPECIFICATIONS

SPEAKER

SIZE ...................................................................... 8 cm (Round)

VOICE COIL IMPEDANCE ............................. 32 ohm at 400 Hz

ANTENNA INPUT IMPEDANCE

VHF/UHF ..................................................... 75 ohm Unbalanced

TUNING RANGES

VHF-Channels ............................................................... 2 thru 13

UHF-Channels ............................................................ 14 thru 69

CATV Channels ........................................................... 1 thru 125

Specifications are subject to change without

prior notice.

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IMPORTANT SERVICE SAFETY PRECAUTION

Ë Service work should be performed only by qualified service technicians who are thoroughly

familiar with all safety checks and the servicing guidelines which follow:

X-RADIATION AND HIGH VOLTAGE LIMITS

1. Be sure all service personnel are aware of the

procedures and instructions covering X-radiation.The

only potential source of X-ray in current solid state

TV receivers is the picture tube. However, the picture

tube does not emit measurable X-Ray radiation, if

the high voltage is as specified in the "High Voltage

Check" instructions.

It is only when high voltage is excessive that X-

radiation is capable of penetrating the shell of the

picture tube including the lead in the glass material.

The important precaution is to keep the high voltage

below the maximum level specified.

2. It is essential that servicemen have available at all

times an accurate high voltage meter.

The calibration of this meter should be checked

periodically.

3. High voltage should always be kept at the rated value

-no higher. Operation at higher voltages may cause

a failure of the picture tube or high voltage circuitry

and;also, under certain conditions, may produce

radiation in exceeding of desirable levels.

4. When the high voltage regulator is operating properly

there is no possibility of an X-radiation problem. Every

time a color chassis is serviced, the brightness should

be tested while monitoring the high voltage with a

meter to be certain that the high voltage does not

exceed the specified value and that it is regulating

correctly.

5. Do not use a picture tube other than that specified or

make unrecommended circuit modifications to the

high voltage circuitry.

6. When trouble shooting and taking test measurements

on a receiver with excessive high voltage, avoid being

unnecessarily close to the receiver.

Do not operate the receiver longer than is necessary

to locate the cause of excessive voltage.

WARNING

1. For continued safety, no modification of any circuit

should be attempted.

2. Disconnect AC power before servicing.

3. Semiconductor heat sinks are potential shock

hazards when the chassis is operating.

4. The chassis in this receiver has two ground systems

which are separated by insulating material. The non-

isolated (hot) ground system is for the B+ voltage

regulator circuit and the horizontal output circuit.The

isolated ground system is for the low B+ DC voltages

and the secondary circuit of the high voltage

transformer.

To prevent electrical shock use an isolation

transformer between the line cord and power

receptacle, when servicing this chassis.

SERVICING OF HIGH VOLTAGE SYSTEM

AND PICTURE TUBE

When servicing the high voltage system,

remove the static charge by connecting a

10k ohm resistor in series with an insulated

wire (such as a test probe) between the pic-

ture tube ground and the anode lead. (AC

line cord should be disconnected from AC

outlet.)

1. Picture tube in this receiver employs integral

implosion protection.

2. Replace with tube of the same type number for

continued safety.

3. Do not lift picture tube by the neck.

4. Handle the picture tube only when wearing

shatterproof goggles and after discharging the high

voltage anode completely.

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SAFETY NOTICE

Many electrical and mechanical parts in television

receivers have special safety-related characteristics.

These characteristics are often not evident from visual

inspection, nor can protection afforded by them be

necessarily increased by using replacement components

rated for higher voltage, wattage, etc.

Replacement parts which have these special safety

characteristics are identified in this manual; electrical

components having such features are identified by "å"

and shaded areas in the Replacement Parts Lists and

Schematic Diagrams.

IMPORTANT SERVICE SAFETY PRECAUTION

(Continued)

1. Inspect all lead dress to make certain that leads are

not pinched or that hardware is not lodged between

the chassis and other metal parts in the receiver.

2. Inspect all protective devices such as non-metallic

control knobs, insulating materials, cabinet backs,

adjustment and compartment covers or shields,

isolation resistor-capacity networks, mechanical

insulators and etc.

3. To be sure that no shock hazard exists, check for

leakage current in the following manner.

· Plug the AC cord directly into a 110~220 volt AC

outlet, (Do not use an isolation transformer for this

test).

· Using two clip leads, connect a 1.5k ohm, 10 watt

resistor paralleled by a 0.15

µF capacitor in series with

all exposed metal cabinet parts and a known earth

ground, such as electrical conduit or electrical ground

connected to earth ground.

· Use an AC voltmeter having with 5000 ohm per volt,

or higher, sensitivity to measure the AC voltage drop

across the resistor.

1.5k ohm

10W

0.15

µF

TEST PROBE

TO EXPOSED

METAL PARTS

CONNECT TO

KNOWN EARTH

GROUND

For continued protection, replacement parts must be

identical to those used in the original circuit. The use of

substitute replacement parts which do not have the same

safety characteristics as the factory recommended

replacement parts shown in this service manual, may

create shock, fire, X-radiation or other hazards.

BEFORE RETURNING THE RECEIVER

(Fire & Shock Hazard)

Before returning the receiver to the user, perform

the following safety checks.

· Connect the resistor connection to all exposed metal

parts having a return to the chassis (antenna, metal

cabinet, screw heads, knobs and control shafts,

escutcheon and etc.) and measure the AC voltage

drop across the resistor.

AII checks must be repeated with the AC ine cord

plug connection reversed. (If necessary, a non-

polarized adapter plug must be used only for the

purpose of completing these check.)

Any current measured must not exceed 0.5 milliamp.

Any measurements not within the limits outlined

above indicate of a potential shock hazard and

corrective action must be taken before returning the

instrument to the customer.

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LOCATION OF USER'S CONTROL

Infrared Transmitter Window

INPUT

Press

Switch to external video input

mode.

Press again

Switch to TV mode.

CHANNEL UP/DOWN

( ) Selects next higher channel.

( ) Selects next lower channel.

· Moves the "

CT-818

" mark of the MENU

screen.

Press

Accesses MAIN MENU.

Press again

Exits MAIN MENU.

DISPLAY

Press

Displays receiving channel for

4 seconds.

Press again

Removes display .

· Temporarily

displays

receiving

channel when in Closed Caption

mode.

Front Panel

CHANNEL UP/DOWN

( ) Selects next higher channel.

( ) Selects next lower channel.

VOLUME UP/DOWN

( )Increases sound.

( )Decreases sound.

POWER

Press

On.

Press again

Off.

Basic Remote Control Functions

POWER

Press

On.

Press again

Off.

REMOTE KEYPAD

Accesses any channel from keypad.

RET UR N

Returns to previous channel.

VOLUME UP/DOWN

(+) Increases sound.

() Decreases sound.

· In menu mode, changes or selects

the TV adjustments.

MUTE

Press

Mutes sound.

Press again

Restores sound.

· CLOSED CAPTION appears when

sound is muted.

Press

Accesses MAIN MENU.

Press again

Exits MAIN MENU.

SENSOR AREA FOR

REMOTE CONTROL

VIDEO/AUDIO TERMINALS

(VIDEO/AUDIO terminals are also

provided on the rear.)

RE TU RN

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