X-ray PF21GB30 service manual

COLOR TELEVISION

SERVICE MANUAL

MODEL NO. PF21GB300

CHASSIS NO. ETE-3

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Please read this manual carefully before service.

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CONTENTS

Part I. Safty instructions and maintenance

1.1 X-Ray Radiation precaution..................................................... 3

1.2 Safety Precaution.......................................................................3

1.3 Product Safety Notice…………………………………………3

1.4 Safety Symbol Description……………………………………4

1.5 Maintenance………………………………………………….. 5

Part II. Adjustments

2.1 Set-up Adjustments…………………………………………... 5

2.1.1 Color Purity Adjustment……………………………….. 5

2.1.2 Convergence Adjustment………………………………. 6

2.1.3 White Balance Adjustment………………………………8

2.2 Circuit Adjustments……………………………………………8

2.2.1 Degaussing……………………………………………….9

2.2.2 Confirmation and Adjustment for Voltage………………9

2.2.3 High Voltage Inspection………………………………..10

2.2.4 Lian grid, focus of the adjustment

and white balance adjust…………………………………11

2.2.5 Service Mode…………………………………………....12

PartIII. Struction and Chassis Function Description

3.1 Structure Block Diagram…………………………………….18

3.2 Chassis Description…………………………………………..18

3.2.1 General Description…………………………………….18

3.2.2 The ICs and Assemblies the Chassis mainly uses……...19
PartIV. Service Data

4.1 TV Signal Processor TDA111XX series……………………...20

4.1.1 General Description……………………………………..20

4.1.2 Features of TV processor………………………………..20

4.2 TFA9842AJ……………………………………………………24

4.2.1 General Description

……………………………………..24

4.2.2 Features………………………………………………….24

4.2.3 Block diagram of TFA9842AJ…………………………..25

4.2.4 Pining…………………………………………………….25

4.2.5 Pin Description…………………………………………..26

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4.3 Vertical Scan Output Stage Circuit………………………….26

4.3.1 Features..........................................................................26

4.3.2 General Description………………………………….27

4.3.3 Block Diagram of TDA4864AJ……………………...27

4.4 EEPROM AT24C16…………………………………………28

4.4.1 Features………………………………………………28

4.4.2 Pin Description……………………………………….28

4.4.3 Memory Organization………………………………..29

4.4.4 Block Diagram……………………………………….29

4.5 Switch-mode Power Supply IC FSCQ0765RT…………….30

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1. SAFETY INSTRUCTIONS AND MAINTENANCE
WARNING: Before serving the chassis, please read the “x-Ray radiation

precaution”, “safety precaution” and “product safety notice” instruction
below.

1.1 X-RAY RADIATION PRECAUTION

1.1.1 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.

1.1.2 The only source of X-RAY radiation in this TV is the CRT. The TV

minimizes X-RAY radiation, which ens ures safety during normal operation. To
prevent X-ray radiation, the replacement of CRT must be identical to the
original fitted way as specified in the parts list.

1.1.3 Some components used in this TV hav e char acteristics concerni ng saf ety

to prevent the CRT from emitting X-ray radiation. For continued safety,
replacement component should be made after referring the PRODUCT SAFETY
NOTICE below.

1.1.4 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.

1.2 SAFETY PRECAUTION
WARNING: Refer servicing to qualified service personal only.

1.2.1 The TV has a nominal working EHT voltage. Extreme caution should be

exercised when working on the TV with th e back remov ed.

Do not attempt to service this TV if you are not conversant with the

precautions and procedures for working on high voltage equipment.

When handling or working on the CRT, always discharge the anode to the

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TV chassis before removing the anode cap in case of electric shock.

The CRT, if broken, will violently expel glass fragments. Use shatterproof

goggles and take extreme care while handling.

Do not hold the CRT by the neck as this is a v ery dangerous practice..

1.2.2 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.

1.2.3 When replacing ICs, use specific tools or a static-proof electric iron with

small power (below 3 5W).

1.2.4 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.

1.2.5 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.

1.2.6 Replace blown fuses within the TV with the fuse specified in the parts

list.

1.2.7 When replacing wires or components to terminals or tags, wind the

leads around the terminal before soldering. When re pl acing saf ety
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 original.

1.3 PRODUCT SAFETY NOTICE

WARNING: For your protection, the following product safety notice should

Be read carefully before operating and servicing this TV set.

1.3.1 Many electrical and mechanical components in this chassis h ave speci al

safety-related characteristics. Co mponents whi ch have these sp ecial s afety
characteristics in this manual and its supplements are identified by the

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international hazard symbols on the circuit diagram and parts list. Before
replacing any of these components please 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.

1.3.2 Do not slap or beat the cabinet or CRT, since this may result in fire or

explosion.

1.3.3 Never allow the TV sharing a plug or socket with other large-power

equipment. Doing so may result in too large load or cause fire.

1.3.4 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.

1.3.5 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.

1.3.6 Service personnel should observe the SAFETY INSTRUCTIONS in this

manual during use and servicing of this TV set. Otherwise, the resulting
damage is not protected by the manufacturer.

1.4 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-rel ated ch aracteristics.

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

marking have special safety-related char acteristi cs.

VDE or TUV This symbol tells you that the critical components identified

by the VDE/TUV marking have special safety-rel ated char acteristics .

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1.5 MAINTENANCE

1.5.1 Do not place the set near or over a radiator or heat register, or where

it is exposed to direct sunlight.

1.5.2 Do not install the TV set in a place exposed to rain, water, excessive

dust, mechanical vibrations or impacts.

1.5.3 Allow enough space (at least 10cm) between the TV and wall or

enclosures for proper ventilation.

1.5.4 Please power off the TV set and disconnect it from th e wall im mediately

if any abnormal condition is met, such as bad smell, belching smoke, sparkling,
abnormal sound, no picture/sound/raster. Hold the plug firmly when
disconnecting the power cord.

1.5.6 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.

2. ADJUSTMENTS

2.1 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:

Color purity

Convergence

White balance

2.1.1 Color Purity Adjustment
Preparation:

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

vertical amplitude and focus.

Measures:

•Face the TV set north or south.

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•Connect the power plug into the wall outlet and turn on the main power

switch of the TV set. •Operate the TV for at least 15 minutes.

•Degauss the TV set using a specific degaussing coil.

•Set the brightness and contrast to maximum.

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

rotate the green low brightness potentiometer to center.

•Receive green raster pattern signals.

•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. •Slowly move the
deflection yoke assembly forward or backward until a uniform green screen is
obtained.

•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.

2.1.2 Convergence Adjustment
Preparation: Before attempting any convergence adjustment, the TV should

be operated for at least 15 minutes.

Measures:

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•Center convergence adjustment.

•Receive dot pattern.

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

•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.

•Turn both tabs at the same time keeping the angle constant to superimpose red

and blue horizontal on the center of the scre en.

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

line.

•Remember red and blue movement. Repeat steps 2.1.3 2. 1.5 until optimal

convergence is obtained.

•Circumference convergence adjust ment.

•Loosen the clamp screw holding the deflection yoke assembly and allow it

tilting.

•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.

•Put the second wedge into bottom.

•Move front of the deflection yoke to the left or right to obtain better

convergence in circumference.

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

Fasten the deflection yoke assembly on the picture tube.

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

the deflection yoke assembly on the picture tube.

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

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

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2.1.3 White Balance Adjustment

For TVs with I2C bus control, change the bus data to adjust wh ite balan ce.

2.2 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 w ith 2 I C bus con trol, first change th e
bus data.

2.2.1 Degaussing

A degaussing coil is built inside the TV set. Each ti me the TV is powered

on, the degaussing coil will automatically degauss the TV. If the TV is

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