Sharp 28JW-74H Manuel utilisateur

28JW-74H

MODEL 28JW-74H

PAL I SYSTEM COLOUR TELEVISION

SE0028JW74H00

SERVICE MANUAL

Issued:21st June 2002

This document has been published to

be used for after sales service only.

GA-20 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

POSTCODE RESET ...................................... 11

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

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

CHASSIS LAYOUT ......................................... 19

ICs ADDITIONAL INFORMATION .................. 21

SCHEMATIC DIAGRAMS ............................... 36

TROUBLESHOOTING TABLES ..................... 49

PARTS LISTING ............................................. 52

SOURCE OF DOCUMENTATION .................. 60

PACKING OF THE SET & ACCESSORIES ... 61

SHARP CORPORATION

28JW-74H

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.

28JW-74H

ELECTRICAL SPECIFICATIONS

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

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

•Picture Intermediate frequency................... 38.9MHz

•Sound Carrier Trap................................... 32.9MHz

•Adjacent Sound Carrier Trap ................... 40.9MHz

•Adjacent Picture Carrier Trap.................. 30.9MHz

•Aerial Input Impedance

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

•Tuning Ranges........... 45.75 MHz thru 855.25 MHz

VHF: IR A - J / S1 - S41 CH (Hiperband)

UHF: I21 - I69 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 8900 degrees K-20 MPCD

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

X=0.290 ± 0.015 Y=0.284 ± 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) ............ 80W

Stand-by Operation ............................................ 3W

•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 ....................... 0.12cm

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

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

28JW-74H

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 32.0 KV, (at a

instantaneous beam current of 1500µA).

2. Ensure that during normal operation the EHT does not exceed 29.5KV±1.5KV (at a beam current of

1650µA). 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.

28JW-74H

HOW TO OPEN THE DOOR

Press the top of the door, opening it slightly

hook your finger inside and pull open.

Behind the door

10. Headphone Socket (3.5mm / 16 600 ohms)

11. S-Video input terminal

12. Video Input Terminal (PAL/SECAM/NTSC)

13. Audio Input Terminal (left)

14. Audio Input Terminal (right)

REAR TV

21-pin In/O t

1. 21-pin Audio/Video (AV-2)

With PAL/SECAM/NTSC Video Input

2. 21-pin Audio/Video (AV-1)

With PAL/SECAM/NTSC/S-Video Input

3. 21-pin Euro SCART (RGB)

With PAL/SECAM/NTSC Video Input

RF Inp t

4. Aerial terminal

2 3 4 1

L/S/G/I R/D/D/D

AUDIO

S-VIDEO VIDEO

FRONT

REAR

WOOFER

AV-2

AV/TERMINAL

AV-1

AV/TERMINAL

RGB

SCART

PERI TELEVISION

2 3

CONTROLS & TERMINALS

■FRONT TV

Main power button

Power indicator

Remote control sensor

Volume DOWN button

Volume P button

Channel DOWN button

Channel P button

Door

2 3 4 5 6 7 1 8

Behind the door

S-VIDEO input terminal

VIDEO input terminal (PAL/SECAM/NTSC)

A DIO input terminal (left)

A DIO input terminal (right)

Headphone jack (3.5mm / 16~600 ohms)

■REAR TV

21-pin In/Out

21-pin Audio/Video (AV-2)

With PAL/SECAM/NTSC Video Input

21-pin Audio/Video (AV-1)

With PAL/SECAM/NTSC/S-Video Input

21-pin Euro SCART (RGB)

With PAL/SECAM/NTSC Video Input

RF Input

Aerial terminal

28JW-74H

REMOTE CONTROL

TV 1. Stand-by button (TV)

Video 2. Power button (VCR)

TV 3. 0 ~ 9 digit buttons

4. Flash back button

Teletext 5. GREEN button

6. RED button

TV 7. Volume DOWN button

8. MENU button

Teletext 9. REVEAL button

10. LIST button

11. STORE button

12. CANCEL button

13. HALF PAGE button

TV 14. RESET button

Video 15. Rewind/picture search reverse

16. Play button

17. Pause/Still button

18. Stop button

TV 19. TV/VIDEO button

20. Channel Call button

21. Single/Double entry button

Teletext 22. YELLOW button

23. BLUE button

TV 24. Channel UP button

25. Volume UP button

26. Channel DOWN button

27. Wide mode button

TV /Teletext 28. CLOCK button

TV 29. Sound mode button

Teletext 30. HOLD button

TV 31. Sound Mute button

Teletext 32. TEXT/MIX/PICTURE button

33. INDEX button

Video 34. Channel UP button (VCR)

35. Fast forward/picture search forward

36. Channel DOWN button (VCR)

37. Record button

1. 19.

23.

21.

24.

25.

26.

2 .

28.

29.

30.

31.

32.

34.

3 .

36.

35.

33.

22.

20.

10.

11.

12.

13.

15.

18.

1 .

16.

14.

28JW-74H

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 ∗∗−∗∗x∗∗

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.

The figure displayed in the “ ∗∗−∗∗x∗∗ ” location is the EPROM version.

Adjustment menu:

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

•Horizontal Shift

• East West Width

• Pin Phase

• Pin Amp (Amplitude)

• Corner Amplitude

• Corner Symmetry

• Vertical Linearity

• Vertical Angle

• Vertical Bow

• Vertical Amplitude

• S Correction

• Vertical Shift

• Red Gain

• Green Gain

Note that the receiver should be set to FULL MODE before carrying out any geometry adjustments. This can be achieved

by pressing the widescreen mode button on the remote control until FULL MODE appears on the OSD. This can only be

done out of the Service Mode.

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

following pages.

• Blue Gain

• 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

28JW-74H

Horizontal

• Horizontal Shift

• E-W Width

• Pin Phase

• Pin Amp

• Corner Amplitude

• Corner Symmetry

Just in case the TV set requires a full geometry adjustment, please proceed first with Vertical according to the above

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

Vertical

• Vertical Amplitude

• Vertical Shift

• Vertical Bow

• Vertical Angle

• S Correction

• Vertical Linearity

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 right.

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

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

E-W Width

Adjust the E-W 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 decreases.

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

•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 Amp 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.

Corner Amplitude

Adjust the Corner Amplitude so that the picture is centred.

The effect of this adjustment is shown in figure 6.

Note: This adjustment affects to upper and lower sides.

• 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

Figure 6

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28JW-74H

Corner Symmetry

Adjust the Corner Symmetry so that the picture is centred.

The effect of this adjustment is shown in figure 7.

Note: This adjustment affects to upper and lower sides.

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

pincushion.

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

barrel shape.

• 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 8.

• 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 9.

• 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.

Vertical Bow

Adjust the Vertical Bow 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 bow changes to right.

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

• 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 11.

• 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 12.

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

centre scanning decreases.

Figure 8

Figure 12

Figure 11

Figure 10

Figure 9

Figure 7

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28JW-74H

Colour Adjustments

The following adjustments should only be carried out when the CRT or IC850 are replaced.

G2 (screen), R-G-B 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 (monoscope pattern).

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

1.3 Select FULL MODE.

1.4 Enter the Service Mode.

1.5 Select RED GAIN in Service Mode.

1.6 Adjust SCREEN VR so that the OSD value (indicated on Figure 14) reaches 50h ± 8h.

2. Follow the procedure below to set the Cut Off.

2.1 Adjust G2.

2.2 Tune a white pattern.

2.3 Adjust colour to minimum.

2.4 Position colorimeter in the centre of screen.

2.5 Adjust brightness and contrast to obtain a luminance of ≈ 3 NITS.

2.6 Operate in Service Mode and select location RED CUT OFF, GREEN CUT OFF and BLUE CUT OFF, to obtain

colour coordinates:

X=0.290 ± 0.015 Y=0.284 ± 0.015

To increase press volume-up button and to decrease press volume down button.

RED CUT OFF alter «X» coordinate.

GREEN CUT OFF alter «Y» coordinate.

BLUE CUT OFF alter «X» and «Y» coordinate.

3. Follow the procedure below to set the GAIN.

3.1 Using brightness and contrast buttons, select a luminance of ≈100 NITS.

3.2 Operate in Service Mode and select location RED GAIN, GREEN GAIN and BLUE GAIN, to obtain colour

coordinates:

X=0.290 ± 0.015 Y=0.284 ± 0.015

To increase press volume-up button and to decrease press volume down button.

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

the centre scanning increases.

• 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 13.

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

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

• Press the stand-by button on the remote control to store. Figure 13

Figure 14

RED GAIN XX

XX XX XX XX

XX 50 XX XX

Adjust value

to 50h ± 8h

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