Toshiba 21E88 Manual de usuario

SERVICE MANUAL

FILE NO. SM-CTV-O-081

COLOR TELEVISION

SERVICE MANUAL

MODELNO. 21E88

CHASSIS NO. CN-18EA

Please read this manual carefully before service.

SERVICE MANUAL

TABLE OF CONTENTS

SPECIFICATIONS........................................................................................................... 1

SAFETY INSTRUCTIONS AND MAINTENANCE....................................... 2

X-RAY RADIATION PRECAUTION ........................................................................................ 2

SAFETY PRECAUTION .......................................................................................................... 2

PRODUCT SAFETY NOTICE ................................................................................................. 3

SAFETY SYMBOL DESCRIPTION ......................................................................................... 4

MAINTENANCE ...................................................................................................................... 4

ADJUSTMENTS................................................................................................................ 5

SET-UP ADJUSTMENTS........................................................................................................ 5

CIRCUIT ADJUSTMENTS ...................................................................................................... 8

CONTROL BUTTONS................................................................................................. 23

CONTROL BUTTONS .......................................................................................................... 23

REMOTE CONTROL ............................................................................................................ 24

BASIC FUNCTIONS......................................................................................................... 25

STRUCTURE AND CHASSIS FUNCTION DESCRIPTION................ 28

STRUCTURE BLOCK DIAGRAM ......................................................................................... 28

BLOCK DIAGRAM FOR SUPPLY VOLTAGE SYSTEM ....................................................... 29

CHASSIS DESCRIPTION..................................................................................................... 30

SERVICE DATA.............................................................................................................. 31

TECHNICAL DATA OF KEY ICS .......................................................................................... 31

SERVICE DATA OF KEY ICS............................................................................................... 55

REPLACEMENT OF PARTS.................................................................................. 60

APPENDIX

1. CIRCUIT DIAGRAMS

2. FINAL ASSEMBLY DIAGRAMS

3. FIND WIRING DIAGRAMS

4. PRINTED CIRCUIT BOARD LAYOUTS

SERVICE MANUAL

SPECIFICATIONS

Model Number 21E88

Color system PAL, NTSC3.58, NTSC4.43

RF system

Sound system B/G, M, D/K, I

Video system PAL4.43, NTSC3.58, NTSC4.43 (50/60Hz)

Programs preset 236 (0-235)

Antenna input 75Ω(unbalanced)

Picture tube

Effective screen dimensions

(Approx.)

406×305mm

Audio output (THD≤7%) Main channel: 3W+3W

Power source 220V ~, 50Hz

Weight (Approx.) 23 Kg

Dimensions

(W×H×D) (Approx.)

585×457×484mm

Rated power consumption 87W

Designs and specifications are subject to change without notice.

SERVICE MANUAL

SAFETY INSTRUCTIONS AND MAINTENANCE

WARNING: BEFORE SERVICING THIS CHASSIS, READ THE

“

X-RAY RADIATION

PRECAUTION

”

“

SAFETY PRECAUTION

”

AND

“

PRODUCT SAFETY NOTICE

”

INSTRUCTION

BELOW.

X-RAY RADIATION PRECAUTION

1. The EHT must be checked every time the TV is serviced to ensure that the CRT does not emit

X-ray radiation as result of excessive EHT voltage. The maximum EHT voltage permissible in any

operating circumstances must not exceed the rated value. When checking the EHT, use the High

Voltage Check procedure in this manual using an accurate EHT voltmeter.

2. The only source of X-RAY radiation in this TV is the CRT. The TV minimizes X-RAY radiation,

which ensures safety during normal operation. To prevent X-ray radiation, the replacement CRT

must be identical to the original fitted as specified in the parts list.

3. Some components used in this TV have safety related characteristics preventing the CRT from

emitting X-ray radiation. For continued safety, replacement component should be made after

referring the PRODUCT SAFETY NOTICE below.

4. Service and adjustment of the TV may result in changes in the nominal EHT voltage of the CRT

anode. So ensure that the maximum EHT voltage does not exceed the rated value after service

and adjustment.

SAFETY PRECAUTION

WARNING: REFER SERVICING TO QUALIFIED SERVICE PERSONNEL ONLY.

1. The TV has a nominal working EHT voltage. Extreme caution should be exercised when working

on the TV with the back removed.

1.1 Do not attempt to service this TV if you are not conversant with the precautions and procedures for

working on high voltage equipment.

1.2 When handling or working on the CRT, always discharge the anode to the TV chassis before

removing the anode cap in case of electric shock.

1.3 The CRT, if broken, will violently expel glass fragments. Use shatterproof goggles and take

extreme care while handling.

1.4 Do not hold the CRT by the neck as this is a very dangerous practice.

2. It is essential that to maintain the safety of the customer all power cord forms be replaced exactly

as supplied from factory.

3. Voltage exists between the hot and cold ground when the TV is in operation. Install a suitable

isolating transformer of beyond rated overall power when servicing or connecting any test

equipment for the sake of safety.

SERVICE MANUAL

4. When replacing ICs, use specific tools or a static-proof electric iron with small power (below 35W).

5. Do not use a magnetized screwdriver when tightening or loosing the deflection yoke assembly to

avoid electronic gun magnetized and decrement in convergence of the CRT.

6. When remounting the TV chassis, ensure that all guard devices, such as nonmetal control buttons,

switch, insulating sleeve, shielding cover, isolating resistors and capacitors, are installed on the

original place.

7. Replace blown fuses within the TV with the fuse specified in the parts list.

8. When replacing wires or components to terminals or tags, wind the leads around the terminal

before soldering. When replacing safety components identified by the international hazard symbols

on the circuit diagram and parts list, it must be the company-approved type and must be mounted

as the original.

9. Keep wires away from high temperature components.

PRODUCT SAFETY NOTICE

CAUTION: FOR YOUR PROTECTION, THE FOLLOWING PRODUCT SAFETY NOTICE

SHOULD BE READ CAREFULLY BEFORE OPERATING AND SERVICING THIS TV SET.

1. Many electrical and mechanical components in this chassis have special safety-related

characteristics. These characteristics are often passed unnoticed by a visual inspection and the

X-ray radiation protection afforded by them cannot necessarily be obtained by using replacements

rated at higher voltages or wattage, etc. Components which have these special safety

characteristics in this manual and its supplements are identified by the international hazard

symbols on the circuit diagram and parts list. Before replacing any of these components read the

parts list in this manual carefully. Substitute replacement components which do not have the same

safety characteristics as specified in the parts list may create X-ray radiation.

2. Do not slap or beat the cabinet or CRT, since this may result in fire or explosion.

3. Never allow the TV sharing a plug or socket with other large-power equipment. Doing so may result

in too large load, causing fire.

4. Do not allow anything to rest on or roll over the power cord. Protect the power cord from being

walked on, modified, cut or pinched, particularly at plugs.

5. Do not place any objects, especially heavy objects and lightings, on top of the TV set. Do not install

the TV near any heat sources such as radiators, heat registers, stove, or other apparatus that

produce heat.

6. Service personnel should observe the SAFETY INSTRUCTIONS in this manual during use and

servicing of this TV set. Otherwise, the resulted damage is not protected by the manufacturer.

SERVICE MANUAL

SAFETY SYMBOL DESCRIPTION

The lightning symbol in the triangle tells you that the voltage inside this product may

be strong enough to cause an electric shock. Extreme caution should be exercised

when working on the TV with the back removed.

This is an international hazard symbol, telling you that the components identified by

the symbol have special safety-related characteristics.

FDA This symbol tells you that the critical components identified by the FDA marking have

special safety-related characteristics.

UL This symbol tells you that the critical components identified by the UL marking have

special safety-related characteristics.

C UL This symbol tells you that the critical components identified by the C-UL marking

have been evaluated to the UL and C-UL standards and have special safety-related

characteristics.

VDE

This symbol tells you that the critical components identified by the VDE marking have

special safety-related characteristics.

MAINTENANCE

1. Place the TV set on a stable stand or base that is of adequate size and strength to prevent it from

being accidentally tipped over, pushed off, or pulled off. Do not place the set near or over a

radiator or heat register, or where it is exposed to direct sunlight.

2. Do not install the TV set in a place exposed to rain, water, excessive dust, mechanical vibrations or

impacts.

3. Allow enough space (at least 10cm) between the TV and wall or enclosures for proper ventilation.

4. Slots and openings in the cabinet should never be blocked by clothes or other objects.

5. Please power off the TV set and disconnect it from the wall immediately if any abnormal condition

are met, such as bad smell, belching smoke, sparkling, abnormal sound, no picture/sound/raster.

Hold the plug firmly when disconnecting the power cord.

6. Unplug the TV set from the wall outlet before cleaning or polishing it. Use a dry soft cloth for

cleaning the exterior of the TV set or CRT screen. Do not use liquid cleaners or aerosol cleaners.

SERVICE MANUAL

ADJUSTMENTS

SET-UP ADJUSTMENTS

The following adjustments should be made when a complete realignment is required or a new picture

tube is installed.

Perform the adjustments in the following order:

1. Color purity

2. Convergence

3. White balance

Notes:

①The purity/convergence magnet assembly and rubber wedges need mechanical positioning.

②For some picture tubes, purity/ convergence adjustments are not required.

1. Color Purity Adjustment

Preparation:

Before starting this adjustment, adjust the vertical sync, horizontal sync, vertical amplitude and

focus.

1.1 Face the TV set north or south.

1.2 Connect the power plug into the wall outlet and turn on the main power switch of the TV set.

1.3 Operate the TV for at least 15 minutes.

1.4 Degauss the TV set using a specific degaussing coil.

1.5 Set the brightness and contrast to maximum.

1.6 Counter clockwise rotate the R /B low brightness potentiometers to the end and rotate the green

low brightness potentiometer to center.

1.7 Receive green raster pattern signals.

1.8 Loosen the clamp screw holding the deflection yoke assembly and slide it forward or backward to

display a vertical green zone on the screen. Rotate and spread the tabs of the purity magnet

around the neck of the CRT until the green zone is located vertically at the center of the screen.

1.9 Slowly move the deflection yoke assembly forward or backward until a uniform green screen is

obtained.

1.10 Tighten the clamp screw of the assembly temporarily. Check purity of the red raster and blue

raster until purities of the three rasters meet the requirement.

SERVICE MANUAL

Yok

Fig. 1

2. Convergence Adjustment

Preparation:

Before attempting any convergence adjustment, the TV should be operated for at least 15 minutes.

2.1 Center convergence adjustment

2.1.1 Receive dot pattern.

2.1.2 Adjust the brightness/contrast controls to obtain a sharp picture.

2.1.3 Adjust two tabs of the 4-pole magnet to change the angle between them and red and blue

vertical lines are superimposed each other on the center of the screen.

2.1.4 Turn both tabs at the same time keeping the angle constant to superimpose red and blue

horizontal on the center of the screen.

2.1.5 Adjust two tabs of the 6-pole magnet to superimpose red/blue line and green line.

2.1.6 Remember red and blue movement. Repeat steps 2.1.3～2.1.5 until optimal convergence is

obtained.

2.2 Circumference convergence adjustment

2.2.1 Loosen the clamp screw holding the deflection yoke assembly and allow it tilting.

2.2.2 Temporarily put the first wedge between the picture tube and deflection yoke assembly. Move

front of the deflection yoke up or down to obtain better convergence in circumference. Push the

mounted wedge in to fix the yoke temporarily.

2.2.3 Put the second wedge into bottom.

2.2.4 Move front of the deflection yoke to the left or right to obtain better convergence in

circumference.

2.2.5 Fix the deflection yoke position and put the third wedge in either upper space. Fasten the

SERVICE MANUAL

deflection yoke assembly on the picture tube.

2.2.6 Detach the temporarily mounted wedge and put it in either upper space. Fasten the deflection

yoke assembly on the picture tube.

2.2.7 After fastening the three wedges, recheck overall convergence and ensure to get optimal

convergence. Tighten the lamp screw holding the deflection yoke assembly.

Fig. 2

4-pole Magnet Movement 6-pole Magnet Movement

Center Convergence by Convergence Magnets

Incline the Yoke Up (or Down) Incline the Yoke Right (or Left)

Circumference Convergence by DEF Yoke

Fig.3

3. White Balance Adjustment

Generally, white balance adjustment is made with professional equipment. It’s not practical to get

good white balance only through manual adjustment. For TVs with I2C bus control, change the bus

data to adjust white balance.

SERVICE MANUAL

CIRCUIT ADJUSTMENTS

Preparation:

Circuit adjustments should be made only after completion of set-up adjustments.

Circuit adjustments can be performed using the adjustable components inside the TV set. For TVs with

I2C bus control, first change the bus data.

1. Degaussing

A degaussing coil is built inside the TV set. Each time the TV is powered on, the degaussing coil

will automatically degauss the TV. If the TV is magnetized by external strong magnetic field,

causing color spot on the screen, use a specific degausser to demagnetize the TV in the following

ways. Otherwise, color distortion will be shown on the screen.

1.1 Power on the TV set and operate it for at least 15 minutes.

1.2 Receive red full-field pattern.

1.3 Power on the specific degausser and face it to the TV screen.

1.4 Turn on the degausser. Slowly move it around the screen and slowly take it away from the TV.

1.5 Repeat the above steps until the TV is degaussed completely.

2. Confirmation and Adjustment for Voltage

Caution: +B voltage has close relation to high voltage. To prevent X-ray radiation, set +B voltage to

the rated value.

2.1 Make sure that the supply voltage is within the range of the rated value.

2.2 Connect a digital voltmeter to the voltage output terminal of the main PCB. Power on the TV and

set the brightness and sub-brightness to minimum. Ensure that the voltage from the main PCB

reads as follows.

2.3 Regulate voltage adjustment components on the power section until the +B the voltage reaches the

rated value.

Table 1

Test Point Voltage (V)

Negative of VD851 118V±2V

Negative of VD852 17V±1V

Negative of VD854 11V±1V

Negative of VD857 14V +1V

-1.5V

Positive of C874 9V±0.5V

Positive of C878 5V±0.5V

Positive of C800 5V±0.25V

Note:

It’s impossible to check the power part separately from the main chassis board as the part is

mounted on the main chassis board. The power components, etc. should be checked for burnout

when power-on. If burned out, do not power on the TV again until the cause is found out.

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