Sharp 28JS-74SS Manuel utilisateur

28JS-74S

MODEL 28JS-74SS

PAL / SECAM BG SYSTEM COLOUR TELEVISION

SE0028JS74S00

SERVICE MANUAL

Issued :30th July 2002

This document has been published to

be used for after sales service only.

GA-200 CHASSIS

In the interests of user safety (required by safety

regulations in some countries) the set should restored

to its original condition and only parts identical to

those specified should be used.

CONTENTS

ELECTRICAL SPECIFICATIONS ................... 3

IMPORTANT SERVICING NOTES ................. 4

CONTROLS & TERMINALS ........................... 5

ADJUSTMENT PROCEDURES ...................... 7

LED FLASHING CODES ............................... 12

PRINTED WIRING BOARDS ........................ 13

COMPONENT LOCATION TABLES ............... 19

CHASSIS LAYOUT ......................................... 24

SCHEMATIC DIAGRAMS ............................... 26

BLOCK DIAGRAM ....................................... 38

TROUBLESHOOTING TABLES ..................... 39

ICs ADDITIONAL INFORMATION .................. 44

PARTS LISTING ............................................. 66

SERVICING NOTES.................................... 74

SOURCE OF DOCUMENTATION .................. 78

SHARP CORPORATION

28JS-74S

Use this page to keep any special servicing information as Technical Report (Bulletin), Technical Information, etc.

If only part number changes are required, just change part number directly the part number in the Parts Listing Section.

If you need more information, please refer to the Technical Report (Bulletin).

SERVICE MANUAL UPDATE LOG SHEET

Part No.

Technical Report No.

Technical Bulletin No. Cause / Solution Page No. Application

Data /Serial No.

28JS-74S

ELECTRICAL SPECIFICATIONS

•Focus ....................... High Bi-Potential Electrostatic

•Sweep Deflection ..................................... Magnetic

•Picture Intermediate Frequency................... 38.9MHz

•Sound Carrier Trap................................... 33.4MHz

•Adjacent Sound Carrier Trap ................... 40.4MHz

•Adjacent Picture Carrier Trap.................. 31.9MHz

•Aerial Input Impedance

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

•Tuning Ranges........... 48.25 MHz thru 855.25 MHz

VHF: E2-E12 CH / S1 - S41 CH (Hiperband)

UHF: E21 - E69 CH

CATV Special Channels

•White Level

Set brightness control to get total picture tube cathode current of 600 µA under no signal condition.

Maximum necessary correction of each picture tube cathode current to get 8550 degrees K+1 MPCD

screen temperature should not exceed 15% of its original value.

X=0.290 ± 0.015 Y=0.300 ± 0.015

WARNING

The chassis in this receiver is partially hot. Use an isolation transformer between the line cord plug

and power receptacle, when servicing this chassis.

To prevent electric shock, do not remove cover. No user-serviceable parts inside. Refer servicing to

qualified service personnel.

Specifications are subject to change without prior notice.

•Power Input .................... 220V-240 Volts AC 50Hz

•Power Consumption

Normal Operation (Method IEC60107) ............ 84W

Stand-by Operation ..........................................1.5W

•Audio Power Output Rating (MPO) / Impedance

Internal Left Speaker ................................. 10W, 7Ω

Internal Right Speaker ............................... 10W, 7Ω

•Speakers

Left / Right ................................................. 12 x 6cm

•Convergence (Maximum Misconvergence)

Static (Centre) between any two colours ... 0.08 cm

Dynamic after static equals zero

Within 10cm (4”) circle ....................... 0.12 cm

10-25cm (4-10” ) circle ...................... 0.20 cm

Everywhere else ................................ 0.28 cm

MODEL DIFFERENCES:

28JS-74S: Base model.

28JS-74SS: Silver Cabinet.

28JS-74S

IMPORTANT SERVICING NOTES

Only qualified service personnel are allowed to carry out maintenance and repair of this receiver.

Servicing of High Voltage System and CRT

It is important that the static charge is removed from the high voltage system when carrying out work on the

receiver. This can be achieved by connecting a 10K resistor (with a suitably insulated lead) from the CRT

cavity connector to the CRT ground tag. This must be carried out with the AC supply disconnected from the

receiver.

Note the following:

•The CRT in this receiver employs Integral Implosion Protection.

•If the CRT has to be changed it MUST be replaced with the correct type for continued safe working.

•DO NOT lift the CRT by its neck.

•When handing the CRT, ensure that shatterproof goggles are worn.

•Ensure that the CRT is discharge before handling.

X-Ray

This receiver is designed to keep any x-ray emission to an absolute minimum. Some fault conditions and

servicing procedures may produce potentially hazardous x-ray radiation levels. This is a problem when in

close proximity to the receiver for long periods of time. To reduce any risks associated with this, please

observe the following precautions:

1. When undertaking any servicing on this chassis, DO NOT increase the EHT to more than 30 KV, (at a

instantaneous beam current of 1500µA).

2. Ensure that during normal operation the EHT does not exceed 30KV (at a beam current of 1000µA). This

level has been preset in the factory. Always check that this level has not been exceeded after carrying out

any repair on the receiver.

3. DO NOT replace the CRT with any other type than that specified in the parts listing as this may cause

excessive x-ray radiation.

Before returning the receiver to the customer

In addition to the above checks, the following should also be carried out before returning the receiver to the

customer.

1. Inspect all the leads to ensure that they are dressed correctly and that they are not obstructed or pinched

by any other parts.

2. Ensure that all protective devices are in good condition. These will include nonmetallic control knobs,

insulating fish papers, cabinets backs, compartment covers or shields, mechanical insulators, etc.

28JS-74S

CONTROLS & TERMINALS

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28JS-74S

ADJUSTMENT PROCEDURES

All adjustments to this chassis, except for focus, are carried out in the Service Mode.

••

•SERVICE MODE

The Service Mode is provided to enable the engineer to correctly set up the receiver to the CRT fitted in the set.

Note that these adjustments may vary from one receiver to another.

To enter the Service Mode, carry out the following procedure.

1. Connect a test pattern to the antenna terminal.

2. Tune the receiver to this signal.

3. Turn the receiver off using the mains switch.

4. Press volume down and channel up buttons on the

front of the receiver at the same time.

5. Keeping these buttons pressed, turn the mains on.

6. When the set starts up it will be in Service Mode.

7. Release the two buttons.

••

•Use the channel up and down buttons to move between the options.

••

•Use the volume control buttons to change the data.

••

•To store the data, use the stand-by button on the remote control.

••

•To exit the Service Mode, turn the receiver off using the mains switch.

When the Service Mode is entered the following On Screen Display appears:

SERVICE SOFTWARE version ∗∗.∗∗

SW on: XXXX SW off: XXXX Hours ON: XXXX

The figures displayed in the “XXXX” locations are hexadecimal representations of the number of times that particular

function has been executed. For example if the hexadecimal number displayed after “SW ON” was “0E4A”, this would

correspond to the receiver being turned on 3658 times.

Adjustment menu:

The following adjustments can be carried out in the Service Mode.

•Horizontal Shift

• East West Width

• Pin Phase

• Pin Amp

• Upper corner correction

• Lower corner correction

• Extreme Corner Correction

• Vertical Linearity

• Vertical angle

• Vertical bow

• Vertical Amplitude

• S Correction

• Vertical Shift

• Red Cut Off

• Green Cut Off

• Blue Cut Off

• Alter NVM Pag (Page)

• Alter NVM Pos (Position)

• Alter NVM Val (Value)

• Teletext Mix Mode Contrast

• Teletext Contrast

• OSD Contrast

• DVCO Adjustment (Only PAL)

• DVCO Adjustment (Only NTSC)

• AGC Adjustment

• Auto Installation On/Off

Figure 1

28JS-74S

The following geometry adjustments can be carried out. Detailed instructions on how to execute these are given on the

following pages:

Horizontal

• Horizontal Shift

• East West Width

• Pin Phase

• Pin Amp

• Vertical angle

• Vertical bow

• Upper Corner Amplitude

• Lower Corner Symmetry

• Extreme Corner Symmetry

Vertical

• Vertical Amplitude

• S Correction

• Vertical Shift

• Vertical Linearity

Just in case the TV set requires a full geometry adjustment, please proceed first with Verti-

cal according to the above order, and after that, adjust Horizontal according to the above

order.

Horizontal Shift

Adjust the horizontal shift so that the picture is centred.

The effect of this adjustment is shown in figure 2.

•When the volume up button is pressed, the picture moves to the left.

•When the volume down button is pressed, the picture moves to the right.

•Press the stand-by button on the remote control to store.

East West Width

Adjust the East West Width so that 8% over-scan is achieved.

The effect of this adjustment is shown in figure 3.

•When the volume up button is pressed, horizontal scanning increases.

•When the volume down button is pressed, horizontal scanning decreases.

•Press the stand-by button on the remote control to store.

Pin Phase

Adjust the Pin Phase so that the picture is symmetrical top and bottom.

The effect of this adjustment is shown in figure 4.

•When the volume up button is pressed, side pincushion changes.

•When the volume down button is pressed, side pincushion changes.

•Press the stand-by button on the remote control to store.

Pin Amp

Adjust the Pin Amplitude so that the picture is centred.

The effect of this adjustment is shown in figure 5.

•When the volume up button is pressed, side pincushion changes from pincushion to

barrel shape.

•When the volume down button is pressed, side pincushion changes from barrel

shape to pincushion.

•Press the stand-by button on the remote control to store.

Figure 2

Figure 3

Figure 4

Figure 5

28JS-74S

Upper Corner Correction

Adjust the Upper Corner Correction so that the picture is centred.

The effect of this adjustment is shown in figure 6.

• When the volume up button is pressed, side pincushion changes from pincushion to

barrel shape.

•When the volume down button is pressed, side pincushion changes from barrel shape to

pincushion.

•Press the stand-by button on the remote control to store.

Lower Corner Correction

Adjust the Lower Corner Correction so that the picture is centred.

The effect of this adjustment is shown in figure 7.

• When the volume up button is pressed, side pincushion changes from pincushion to

barrel shape.

• When the volume down button is pressed, side pincushion changes from barrel shape to

pincushion.

• Press the stand-by button on the remote control to store.

Extreme Corner Correction

Adjust the Extreme Corner Correction so that the picture is centred.

The effect of this adjustment is shown in figure 8.

• When the volume up button is pressed, side pincushion changes from pincushion to

barrel shape.

•When the volume down button is pressed, side pincushion changes from barrel shape to

pincushion.

•Press the stand-by button on the remote control to store.

Vertical Linearity

Adjust the Vertical Linearity so that the upper and lower parts of the picture are symmetrical.

The effect of this adjustment is shown in figure 9.

• When the volume up button is pressed, the upper picture scanning decreases and the

lower picture scanning increases.

• When the volume down button is pressed, the upper picture scanning increases and the

lower picture scanning decreases.

• Press the stand-by button on the remote control to store.

Vertical Angle

Adjust the Vertical Angle so that the picture is centred.

The effect of this adjustment is shown in figure 10.

• When the volume up button is pressed, the vertical angle changes to right.

• When the volume down button is pressed, the vertical angle changes to left.

• Press the stand-by button on the remote control to store.

Figure 9

Figure 7

Figure 10

Figure 6

Figure 8

28JS-74S

Colour Adjustments

The following adjustments should only be carried out when the CRT or IC801 are replaced.

G2, Cut Off and Gain Adjustments

1. Follow the procedure below to set the G2

1.1 Tune the set to the output of a signal generator (cross hatch pattern).

1.2 In the user menu, set contrast to 80/100 and brightness to 40/100.

1.3 Connect the oscilloscope to the TP1801 and adjust G2 to read 135V on the sensor pulse as in the drawing:

Vertical Bow

Adjust the Vertical Bow so that the picture is centred.

The effect of this adjustment is shown in figure 11.

• When the volume up button is pressed, the vertical bow changes to left.

• When the volume down button is pressed, the vertical bow changes to right.

• Press the stand-by button on the remote control to store.

Vertical Amplitude

Adjust the Vertical Amplitude so that 8% over-scan is achieved.

The effect of this adjustment is shown in figure 12.

• When the volume up button is pressed, the vertical size of the picture increases.

• When the volume down button is pressed, the vertical size of the picture decreases.

• Press the stand-by button on the remote control to store.

S Correction

Adjust the S Correction so that the picture symmetrical between the top, centre and bottom.

The effect of this adjustment is shown in figure 13.

• When the volume up button is pressed, the top and bottom scanning decreases and the

centre scanning increases.

• When the volume down button is pressed the top and bottom scanning increases and the

centre scanning decreases.

• Press the stand-by button on the remote control to store.

Vertical Shift

Adjust the Vertical Shift so that the picture is centred.

The effect of this adjustment is shown in figure 14.

• When the volume up button is pressed, the picture moves up.

• When the volume down button is pressed, the picture moves down.

• Press the stand-by button on the remote control to store.

135 V

CH1 gnd

Figure 14

Figure 11

Figure 12

Figure 13

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