SHARP 26SL41M, 26SL71M, 29SL81M Service Manual

26SL41M, 26SL71M 29SL81M

SERVICE MANUAL

S80G526SL41M/

COLOR TELEVISION

Chassis No. SN-91A

POWER POWER

PUSH OPEN

MTS STEREO

MODELS

26SL41M, 26SL71M 29SL81M

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.

CONTENTS

Page

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

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

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

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

» CHASSIS LAYOUT.............................................................................................................................11

» BLOCK DIAGRAM..............................................................................................................................12

» SCHEMATIC DIAGRAMS...................................................................................................................15

» PRINTED WIRING BOARD ASSEMBLIES........................................................................................32

» REPLACEMENT PARTS LIST ...........................................................................................................36

» PACKING OF THE SET......................................................................................................................47

ELECTRICAL SPECIFICATIONS

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

POWER RATING

26SL41M.......................................................................... 120 W

26SL71M.......................................................................... 125 W

29SL81M.......................................................................... 130 W

PICTURE SIZE

26SL41M, 26SL71M ............................ 2,032 cm2 (315 sq inch)

29SL81M.............................................. 2,193 cm2 (340 sq 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

26SL41M......................................................... 1.5 W + 1.5 W

26SL71M, 29SL81M .............................................. 5 W + 5 W

(at 5% distortion and Dual CH Operate)

SPEAKER

SIZE .............................................................. 12 × 6 cm (2 pcs.)

VOICE COIL IMPEDANCE

26SL41M....................................................32 ohm at 400 Hz

26SL71M, 29SL81M .................................... 8 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.

SHARP CORPORATION

26SL41M, 26SL71M 29SL81M

Service work should be performed only by qualified service technicians who are throughly familiar with all safety checks and the servicing guidelines which follow:

IMPORTANT SERVICE SAFETY PRECAUTION

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 nonisolated (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 picture 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 .

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 Xradiation 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.

2 2

IMPORTANT SERVICE SAFETY PRECAUTION

1.5k ohm 10W

0.15µF

TEST PROBE

CONNECT TO KNOWN EARTH GROUND

TO EXPOSED METAL PARTS

VOLTMETER

(Continued)

26SL41M, 26SL71M 29SL81M

BEFORE RETURNING THE RECEIVER (Fire & Shock Hazard)

Before returning the receiver to the user, perform the following safety checks.

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 127 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 0.15µF 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.

• 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 nonpolarized 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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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 and 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.

234567890123456789012345678901212345678901234567890123456789012123456789012345678901234567890121

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.

26SL41M, 26SL71M 29SL81M

Front Panel

LOCATION OF USER'S CONTROL

POWER

Press → On. Press again → Off.

SENSOR AREA FOR REMOTE CONTROL

Basic Remote Control Functions

POWER

Press → On. Press again → Off.

REMOTE KEYP AD

Accesses any channel from keypad.

FLASHBACK

Returns to previous channel.

PERSONAL PREFERENCE

With the Personal Preference buttons, you can program your favorite programs by using the 4 categories A, B, C and D. The channels can be accessed quickly by using these buttons.

VOLUME UP/DOWN

(+) Increases sound. (–) Decreases sound.

• In menu mode, changes or selects the TV adjustments.

Press → Accesses MAIN MENU. Press again → Exits MAIN MENU.

TV-CATV MODE SELECT SWITCH

In TV position, sends power and channel select commands (Channel up/down and Random Access buttons) to the TV. In CATV position, sends power and channel select commands to a cable TV converter.

VCR CONTROL

POWER POWER

VOLUME UP/DOWN

(+) Increases sound. (–) Decreases sound.

POWER

VCR

1 2 3 4 5 6 7 8 9

FLASHBACK

PERSONAL PREFERENCE

B C D

VOL

—

MENU MUTE

REW PLAY FF

PAUSE

STOP REC

TV • VCR • CATV

VIDEO IN 2 L-AUDIO-R– VOL + CH MENU

DISPLAY

CATV

INPUT

ENTER

100

VOL

VCR CH

MTS STEREO

– VOL + CH MENU

CHANNEL UP/DOWN

) Selects next higher

(

channel.

(

) Selects next lower

channel.

VIDEO/AUDIO TERMINALS

IN 2

(VIDEO/AUDIO terminals are also provided on the rear.)

Press → Accesses MAIN MENU. Press again → Exits MAIN MENU.

Infrared Transmitter Window

DISPLAY

Press → Displays receiving channel for four seconds. Press again → Removes display.

• Temporarily displays receiving channel when in Closed Caption mode.

INPUT

Press → Switch to external video INPUT mode. Press again → Switch to TV mode.

ENTER

Used in some instances where a VCR or Cable Converter Box requires an “enter” command after selecting channels, when using the REMOTE KEYPAD button.

CHANNEL UP/DOWN

( ) Selects next higher channel.

( ) Selects next lower channel.

• Moves the “

” mark of the MENU

screens.

MUTE

Press → Mutes sound. Press again → Restores sound.

• CLOSED CAPTION appears when sound is muted.

Note:

• The above shaded buttons on the Remote Control glow in the dark. To use the glow-in-the-dark display on the remote control, place it under a fluorescent light or other lighting.

• The phosphorescent material contains no radioactive or toxic material, so it is safe to use.

• The degree of illumination will vary depending on the strength of lighting used.

• The degree of illumination will decrease with time and depending on the temperature.

• The time needed to charge the phosphorescent display will vary depending on the surrounding lighting.

• Sunlight and fluorescent lighting are the most effective when charging the display.

26SL41M, 26SL71M 29SL81M

INSTALLATION AND SERVICE INSTRUCTIONS

Note: (1)When performing any adjustments to resistor controls and transformers use non-metallic

screwdrivers or TV alignment tools.

(2)Before performing adjustments, the TV set must be on at least 15 minutes.

CIRCUIT PROTECTION The receiver is protected by a 5.0A fuse

(F701), mounted on PWB-A, wired into one side of the AC line input.

X-RADIA TION PROTECTOR CIRCUIT TEST

After service has been performed on the horizontal deflection system, high voltage system, B+ system, test the X-Radiation protection circuit to ascertain proper operation as follows:

1. Apply 127V AC using a variac transformer for accurate input voltage.

2. Allow for warm up and adjust all customer controls for normal picture and sound.

3. Receive a good local channel.

4. Connect a digital voltmeter to TP653 and make sure that the voltmeter reads 11.2 ± 0.6V.

5. Apply external 13.8V DC at TP653 by using an external DC supply, TV must be shut off.

6. To reset the protector, unplug the AC cord and make a short circuit between TP651 and TP652. Now make sure that normal picture appears on the screen.

7. If the operation of the horizontal oscillator does not stop in step 5, the circuit must be repaired before the set is returned to the customer.

HIGH VOL T AGE CHECK

High voltage is not adjustable but must be checked to verify that the receiver is operating within safe and efficient design limitations as specified checks should be as follows:

1. Connect an accurate high voltage meter between ground and anode of picture tube.

2. Operate receiver for at least 15 minutes at 127V AC line voltage, with a strong air signal or a properly tuned in test signal.

3. Enter the service mode and select the service adjustment "S19" and Bus data "01" (Y-mute on).

4. The voltage should be approximately, 28.7kV (26SL41M/71M)/29.7kV(29SL81M)(at zero beam). If a correct reading cannot be obtained, check circuitry for malfunctioning components. After the voltage test, make Y-mute off to the normal mode.

26SL41M, 26SL71M 29SL81M

For adjustments of this model, the bus data is converted to various analog signals by the D/A converter circuit.

Note: There are still a few analog adjustments in this series such as focus and master screen voltage.

Follow the steps below whenever the service adjustment is required. See "Table-B" to determine, if service adjustments are required.

1. Service mode

Before putting unit into the service mode, check that customer adjustments are in the normal mode. Use the reset function in the video adjustment menu to ensure customer controls are in their proper (reset) position.

2. Service number selection

Once in the service mode, press the Ch-up or Chdown button on the remote control unit or at the set. The service adjustment number will vary in increments of one, from "S01" to "OP2" (26SL41M)/ "M05" (26SL71M, 29SL81M). Select the item you wish to adjust.

3. Data number selection

Press the Vol-up or down button to adjust the data number.

DATA NUMBER

SERVICE ADJUSTMENT NUMBER

To enter the service mode and exit service mode.

While pressing the Vol-up and Ch-up buttons at the same time, plug the AC cord into a wall socket. Now the TV set is switched on and enters the service mode. To exit the service mode, turn the television off by pressing the power button.

CHANNEL

S01

Figure A.

55(085)

S01 D:00

26SL41M, 26SL71M 29SL81M

SERVICE

NUMBER

S01 PICTURE 55 00-7F S02 TINT 46 00-7F S03 COLOR 32 00-7F S04 BRIGHTNESS 40 00-7F S05 SHARPNESS 28/24 00-3F S06 VERTICAL PHASE 00 00-07 Must be set to "00" S07 HORIZONT AL PHASE 12 00-1F S08 RF-AGC 23 00-3F S09 VERTICAL AMP 20 00-3F S10 PIF VCO 2C 00-7F S11 R CUT-OFF 00 00-FF S12 G CUT -OFF 00 00-FF S13 B CUT-OFF 00 00-FF S14 G GAIN 7F 00-FF S15 B GAIN 7F 00-FF S16 TRAP 00/01 00 or 01 S17 BALANCE 20 00-3F Must be set to "20" S18 C.C. POSITION 17 00-7F S19 MUTE 00 00,01,03 "00"=Normal, "01"=No Y, "03"=No Vertical S20 ENERGY SAVE OFFSET 20 00-3F Must be set to "19" S21 INT. CYCLE TIMING 7A 00-1F Must be set to "7A" S22 00 00 No Setting S23 TUNER SETUP 00 00, 01 Must be set to "00" OP1 OPTION (Set to each model) 00 00-FF OP2 OPTION (Set to each model) 00 00-FF Must be set to "0C"=26SL41M, "0F"=26SL71M,

M01 INPUT LEVEL 0A 00-0F M02 ST VCO 20 00-3F M03 FILTER 1C 00-3F M04 WIDE BAND 20 00-3F M05 SPECTRAL 1B 00-3F

ADJUSTMENT ITEM

INITIAL VALUE

DATA

ADJUSTMENT CONTENTS

RANGE

Must be set to "28"(26SL41M/71M)/"24"(29SL81M)

Must be set to "00"(26SL41M/71M)/"01"(29SL81M)

Must be set to "E1"=26SL41, "E7"=26S71M, 29SL81M "8F"=29SL81M

Only for Models 26SL71M, 29SL81M

Table - A

Holding down both the CH-up/down buttons on the TV set at service mode for more than 2 seconds will automatically write the above initial values into IC2101.

PART REPLACED

IC2001

IC201 X

IC2101

CRT IC3001

ADJUSTMENT

NECESSARY

X X

UNNECESSARY

Data is stored in IC2101. The adjustment is needed to compensate for characteristics

of parts including IC201 and MTS level (M01).

Holding down both the CH-up/down buttons on the TV set in the service mode for more than 2 seconds will automatically write the above initial values into IC2101. Then perform a complete adjustment.

Adjust items related to picture tube only. Adjust items related to MTS only (M01~M05).

NOTES

Table - B

26SL41M, 26SL71M 29SL81M

SERVICE ADJUSTMENT

VCO Adjustment

1. Connect a digital voltmeter between pin (44) of IC201 and ground.

2. Receive a good local channel.

3. Enter the service mode and select the service adjustment "S10".

4. Adjust the data so that digital voltmeter reads 2.2V.

5. Adjustment is completed, remove the voltmeter, return to "normal" mode.

RF AGC Adjustment

1. Receive a good local channel.

2. Enter the service mode and select the service adjustment "S08".

3. Set the data value to point where no noise or beat appears.

4. Select another channel to confirm that no noise or beat appears. Note 1: You will have to come out of the service

mode to select another channel.

Note 2: Setting the data to "00" will produce a black

raster.

White Balance Adjustment

1. Receive a good local channel.

2. Enter the service mode and select the service adjustment "S03" and set to "00" (minimum color)(Record original data code under adjustment "S03" before changing). "S03" does not have to be adjusted, if you selected a B/W picture or monoscope pattern.

3. Alternately adjust the service adjustment data of "S14" and "S15" until a good grey scale with normal whites is obtained.

4. Select the service adjustment "S03" and adjust data to obtain normal color level.

Sub-Picture Adjustment

1. Receive a good local channel.

2. Make sure the customer picture control is set to maximum.

3. Enter the service mode and select the service adjustment "S01".

4. Adjust the data value to achieve normal contrast range.

Screen Adjustment

1. Connect a oscilloscope between TP854 and GND on the CRT Unit.

2. Receive a good local channel.

3. Enter the service mode and select the service adjustment "S03" and set the data value to "00" to set the color level to minimum. (Record original data code under adjustment "S03" before changing) You may skip this step, if you selected a B/W picture or monoscope pattern.

4. Select the service adjustment "S19" and adjust the data value to "01", this turn off the luminance signal (Y-mute).

5. Select the service adjustment "S04" and adjust data value to obtain 2.35 V on the oscilloscope screen.

2.35V GND

6. Adjust the master screen control until the raster darkens to the point where raster is barely seen.

7. Adjust the service adjustments "S11" red, "S12" green and "S13" blue to obtain a good grey scale with normal whites at low brightness level.

8. Select the service adjustment "S19" and reset data to "00". Select the service adjustment "S03" and reset data to obtain normal color level.

9. Remove oscilloscope and reset the master screen control to obtain normal brightness range.

Sub-Tint Adjustment

1. Receive a good local channel.

2. Set customer tint control to center of it's range.

3. Enter the service mode and select the service adjustment "S02".

4. Adjust "S02" data value to obtain normal flesh tones.

Sub-Color Adjustment

1. Receive a good local channel.

2. Make sure the customer color control is set to center position.

3. Enter the service mode and select service adjustment "S03".

4. Adjust "S03" data value to obtain normal color level.

26SL41M, 26SL71M 29SL81M

Sub-Brightness Adjustment

1. Receive a good local channel.

2. Make sure the customer brightness control is set to center position.

3. Enter the service mode and select the service adjustment "S04".

4. Adjust "S04" data value to obtain normal brightness level.

Vertical-Size Adjustment

1. Receive a good local channel.

2. Enter the service mode and select the service adjustment "S09".

3. While observing the top and bottom of the screen, adjust "S09" data value to proper vertical size.

Vertical Phase Adjustment

1. Enter the service mode and select the service adjustment "S06".

2. Adjust data value to "00".

Note: This must be set "00" when changed data retrace

line will appear.

3.58MHz Trap Adjustment

1. Receive a good local channel.

2. Enter the service mode and select the service adjustment "S16".

3. This is a two position adjustment, "00" is ON, "01" is OFF.

4. Adjust data value to "00"(26SL41M/71M)/"01" (29SL81M) for normal viewing.

Sharpness and Audio Balance Adjustments

1. Receive a good local channel.

2. Enter the service mode and select the service adjustments "S05" for sharpness and "S17" for audio balance.

» Sharpness Adjustment

3. Adjust data value to "28"(26SL41M/71M)/"24" (29SL81M)(center of data range) for sharpness adjustment.

» Audio Balance Adjustment

4. Adjust data value to "20"(center of data range) for audio balance adjustment.

Horizontal Position Adjustment

1. Receive a good local channel.

2. Enter the service mode and select the service adjustment "S07".

3. Adjust "S07" data value so that picture is centered.

Caption Position Adjustment (Horizontal)

1. Receive a good local channel.

2. Enter the service mode and select the service adjustment "S18".

3. A black text box appears on the screen. (see Figure B. below)

4. Adjust "S18" data value so that text box is positioned in the center of the screen.

Energy save offset Adjustment

1. Enter the service mode and select the service adjustment "S20".

2. Adjust data value to "19".

Note: This position is used to preset the level for the

energy save function.

Other Adjustments

1. Enter the service mode.

2. Adjust the following data values as listed below.

S21 "7A" INT. CYCLE TIMING S22 "00" No Setting S23 "00" TUNER SETUP

Figure B.

26SL41M, 26SL71M 29SL81M

MTS ADJUSTMENT

(Only for Models 26SL71M, 29SL81M)

MTS Level Adjustment

1. Feed the following monaural signal to pin (14) of IC3001.

Monaural signal : 300 Hz, 245 mVrms

2. Connect the rms voltmeter to pin (39) of IC3001.

3. Enter the service mode and select the service adjustment "M01".

4. Adjust the data so that the rms voltmeter reads 490 ± 10 mVrms.

MTS VCO Adjustment

1. Keep the unit in no-signal state.

2. Connect the frequency counter to pin (39) of IC3001.

3. Connect a capacitor (100µF, 50V) in between positive(+) side of C3005 and ground.

4. Enter the service mode and select the service adjustment "M02"

5. Adjust the data so that the frequency counter reads

62.94 ± 0.75 kHz.

Filter Adjustment

1. Feed the following stereo pilot signal to pin (14) of IC3001 . Stereo pilot signal: 9.4 kHz, 600 mVrms.

2. Enter the service mode and select the service adjustment "M03".

3. Adjust the data at the point where "OK" appears on the screen. The "OK" represents the approximate center of the adjustable range of the data.

Separation Adjustment

1. Connect the rms voltmeter to pin (39) of IC3001.

2. Receive the following composite stereo signal 1. Composite stereo signal: 30% modulation, left channel only, noise reduction on, 300 Hz

3. Enter the service mode and select the service adjustment "M04".

4. Adjust the data until the AC voltage reading of the rms voltmeter is minimum.

5. Receive the following composite stereo signal 2. Stereo signal: 30% modulation, left channel only, noise reduction on, 3 kHz

6. Enter the service mode and select the service adjustment "M05".

7. Adjust the data until the AC voltage reading of the rms voltmeter is minimum.

8. Take the above steps 1 thru 7 again for fine adjustment.

CHASSIS LAYOUT

26SL41M, 26SL71M 29SL81M

654321

26SL41M, 26SL71M 29SL81M

MODEL 26SL41M BLOCK DIAGRAM

654321

MODEL 26SL71M BLOCK DIAGRAM

26SL41M, 26SL71M 29SL81M

654321

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