Toshiba TV Service Manual CF-27A50 (pdf document) free file download at fliiby.com

"FILE NO. 020-200004 SERVICE MANUAL COLOR TELEVISION N0ES Chassis 27A50 (TAC0012) PRINTED IN U.S.A. Apr., 2000 U TABLE OF CONTENTS GENERAL ADJUSTMENTS CHAPTER 1 GENERAL ADJUSTMENTS SAFETY INSTRUCTIONS ........................................................................................................................................ 3 SET-UP ADJUSTMENT ............................................................................................................................................ 4 SERVICE MODE ...................................................................................................................................................... 8 DESIGN MODE ...................................................................................................................................................... 11 ELECTRICAL ADJUSTMENTS .............................................................................................................................. 12 CIRCUIT CHECKS ................................................................................................................................................. 16 CHAPTER 2 SPECIFIC INFORMATIONS SETTING & ADJUSTING DATA ............................................................................................................................. 17 SPECIFIC INFORMATIONS LOCATION OF CONTROLS ................................................................................................................................... 18 PROGRAMMING CHANNEL MEMORY ................................................................................................................. 20 CIRCUIT BLOCK DIAGRAM .................................................................................................................................. 21 CHASSIS AND CABINET REPLACEMENT PARTS LIST ...................................................................................... 22 PC BOARDS BOTTOM VIEW ................................................................................................................................ 31 TERMINAL VIEW OF TRANSISTORS ................................................................................................................... 34 SPECIFICATIONS .................................................................................................................................................. 37 APPENDIX: CIRCUIT DIAGRAM –2– CHAPTER 1 GENERAL ADJUSTMENTS GENERAL ADJUSTMENTS SPECIFIC INFORMATIONS SAFETY INSTRUCTIONS WARNING: BEFORE SERVICING THIS CHASSIS, READ THE “X-RAY RADIATION PRECAUTION”, “SAFETY PRECAUTION” AND “PRODUCT SAFETY NOTICE” INSTRUCTIONS BELOW. X-RAY RADIATION PRECAUTION 1. Excessive high voltage can produce potentially hazardous X-RAY RADIATION. To avoid such hazards, the high voltage must not be above the specified limit. The nominal value of the high voltage of this receiver is (A) kV at zero beam current (minimum brightness) under a 120V AC power source. The high voltage must not, under any circumstances, exceed (B) kV. Refer to table-1 for high voltage (A), (B). (See SETTING & ADJUSTING DATA on page 17.) 2. This receiver is equipped with a Fail Safe (FS) circuit which prevents the receiver from producing an excessively high voltage even if the B+ voltage increases abnormally. Each time the receiver is serviced, the FS circuit must be checked to determine that the circuit is properly functioning, following the FS CIRCUIT CHECK procedure in this manual. 3. The only source of X-RAY RADIATION in this TV receiver is the picture tube. For continued X-RAY RADIATION protection, the replacement tube must be exactly the same type tube as specified in the parts list. 4. Some part in this receiver have special safety-related characteristics for X-RAY RADIATION protection. For continued safety, parts replacement should be undertaken only after referring to the PRODUCT SAFETY NOTICE below. Each time a receiver requires servicing, the high voltage should be checked following the HIGH VOLTAGE CHECK procedure in this manual. It is recommended that the reading of the high voltage be recorded as a part of the service record. It is important to use an accurate and reliable high voltage meter. SAFETY PRECAUTION WARNING : Service should not be attempted by anyone unfamiliar with the necessary precautions on this receiver. The following are the necessary precautions to be observed before servicing this chassis. 1. An isolation transformer should be connected in the power line between the receiver and the AC line before any service is performed on the receiver. 2. Always discharge the picture tube anode to the CRT conductive coating before handling the picture tube. The picture tube is highly evacuated and if broken, glass fragments will be violently expelled. Use shatter proof goggles and keep picture tube away from the unprotected body while handling. 3. When replacing a chassis in the cabinet, always be certain that all the protective devices are put back in place, such as; non-metallic control knobs, insulating covers, shields, isolation resistor-capacitor network, etc. 4. Before returning the set to the customer, always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as antennas, terminals, screwheads, metal overlays, control shafts, etc. to be sure the set is safe to operate without danger of electrical shock. Plug the AC line cord directly into a 120V AC outlet (do not use a line isolation transformer during this check). Use an AC voltmeter having 5000 ohms per volt or more sensitivity in the following manner: Connect a 1500 ohm 10 watt resistor, paralleled by a 0.15 µF, AC type capacitor, between a known good earth ground (water pipe, conduit, etc.) and the exposed metallic parts, one at a time. Measure the AC voltage across the combination of 1500 ohm resistor and 0.15 µF capacitor. Reverse the AC plug at the AC outlet and repeat AC voltage measurements for each exposed metallic part. Voltage measured must not exceed 0.3 volts rms. This corresponds to 0.2 milliamp. AC. Any value exceeding this limit constitutes a potential shock hazard and must be corrected immediately. AC VOLTMETER 0.15µF Good earth ground such as a water pipe, conduit, etc. Place this probe on each exposed metallic part. 1500 ohm 10 watt PRODUCT SAFETY NOTICE Many electrical and mechanical parts in this chassis have special safety-related characteristics. These characteristics are often passed unnoticed by a visual inspection and the protection afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special safety characteristics are identified in this manual and its supplements; electrical components having such features are identified by the international hazard symbols on the schematic diagram and the parts list. Before replacing any of these components, read the parts list in this manual carefully. The use of substitute replacement parts which do not have the same safety characteristics as specified in the parts list may create shock, fire, X-ray radiation or other hazards. –3– WARNING: BEFORE SERVICING THIS CHASSIS, READ THE “X-RAY RADIATION PRECAUTION”, “SAFETY PRECAUTION” AND “PRODUCT SAFETY NOTICE” ON PAGE 3 OF THIS MANUAL. GENERAL ADJUSTMENTS SET-UP ADJUSTMENT (FOR 13", 14", 19", 20") s The following adjustments should be made when a complete realignment is required or a new picture tube is installed. Perform the adjustments in order as follows : 1. Color Purity 2. Convergence 3. White Balance Note: The PURITY/CONVERGENCE MAGNET assembly and rubber wedges need mechanical positioning. Refer to figure 1. Mounting position of the purity magnet assembly should fit to same position as old one because slightly difference to the position depend on a kind of tube. SPECIFIC INFORMATIONS * There are no adjustment of purity and convergence in some picture tube (unified with purity magnet). COLOR PURITY ADJUSTMENT NOTE : Before attempting any purity adjustments, the receiver should be operated for at least fifteen minutes. 1. Demagnetize the picture tube and cabinet using a degaussing coil. 2. Set the brightness and contrast to maximum. 3. Use a green raster from among the built-in test signals. 4. Loosen the clamp screw holding the yoke and slide the yoke backward or forward to provide vertical green belt (zone) in the picture screen. 5. Remove the Rubber Wedges. 6. Rotate and spread the tabs of the purity magnet (See figure 2.) around the neck of the picture tube until the green belt is in the center of the screen. At the same time, enter the raster vertically. 7. Slowly move the yoke forward or backward until a uniform green screen is obtained. Tighten the clamp screw of the yoke temporarily. 8. Check the purity of the red and blue raster. DEFLECTION YOKE TEMPORARY MOUNTING 14mm(13", 14") 19mm(19", 20") RUBBER WEDGE ADHESIVE PURITY/ CONVERGENCE MAGNET ASS'Y GLASS CLOTH TAPES DEFLECTION YOKE Figure 1. –4– 6-POLE MAGNETS 4-POLE MAGNETS ADJUST THE ANGLE (VERTICAL LINES) FIXED ROTATE TWO TABS AT THE SAME TIME (HORIZONTAL LINES) PURITY MAGNETS CONVERGENCE MAGNET ASSEMBLY ADJUSTMENT OF MAGNETS Figure 2. BLU RED RED/BLU GRN BLU RED RED/BLU GRN 4-POLE MAGNETS MOVEMENT 6-POLE MAGNETS MOVEMENT Center Convergence by Convergence Magnets BGR R G B B G R B G R RGB BGR RGB INCLINE THE YOKE UP (OR DOWN) R G B INCLINE THE YOKE RIGHT (OR LEFT) Circumference Convergence by DEF Yoke Figure 3. Dot Movement Pattern –5– SPECIFIC INFORMATIONS s CENTER CONVERGENCE ADJUSTMENT 1. Use the cross-dot pattern from among the built-in test signals. 2. Set the brightness and contrast for well defined pattern. 3. Adjust two tabs of the 4-Pole Magnets to change the angle between them (See figure 2.) and superimpose red and blue vertical lines in the center area of the picture screen. 4. Turn the both tabs at the same time keeping the angle constant to superimpose red and blue horizontal lines at the center of the screen. 5. Adjust two tabs of 6-Pole Magnets to superimpose red/ blue line and green one. Adjusting the angle affects the vertical lines and rotating both magnets affects the horizontal lines. 6. Repeat adjustments 3, 4, 5 keeping in mind red, green and blue movement, because 4-Pole Magnets and 6-Pole Magnets have mutual interaction and make dot movement complex. GENERAL ADJUSTMENTS CONVERGENCE ADJUSTMENTS NOTE: Before attempting any convergence adjustments, the receiver should be operated for at least fifteen minutes. s CIRCUMFERENCE CONVERGENCE ADJUSTMENT 1. Loosen the clamping screw of deflection yoke slightly to allow the yoke to tilt. 2. Temporarily put a wedge as shown in figure 1. (Do not remove cover paper on adhesive part of the wedge.) 3. Tilt front of the deflection yoke up or down to obtain better convergence in circumference. (See figure 3.) Push the mounted wedge into the space between picture tube and the yoke to fix the yoke temporarily. 4. Put other wedge into bottom space and remove the cover paper to stick. 5. Tilt front of the yoke right or left to obtain better convergence in circumference. (See figure 3.) 6. Keep the yoke position and put another wedge in either upper space. Remove cover paper and stick the wedge on picture tube to fix the yoke. 7. Detach the temporarily mounted wedge and put it in another upper space. Stick it on picture tube to fix the yoke. 8. After fixing three wedges, recheck overall convergence. Tighten the screw firmly to fix the yoke and check the yoke is firm. 9. Stick three adhesive tapes on wedges as shown in figure 1. WARNING: BEFORE SERVICING THIS CHASSIS, READ THE “X-RAY RADIATION PRECAUTION”, “SAFETY PRECAUTION” AND “PRODUCT SAFETY NOTICE” ON PAGE 3 OF THIS MANUAL. GENERAL ADJUSTMENTS (FOR 35", 36") s The following adjustments should be made when a complete realignment is required or a new picture tube is installed. Perform the adjustments in order as follows : 1. Color Purity 2. Convergence 3. White Balance Note: The PURITY/CONVERGENCE MAGNET assembly and rubber wedges need mechanical positioning. Refer to figure 1. Mounting position of the purity magnet assembly should fit to same position as old one because slightly difference to the position depend on a kind of tube. s There are no adjustment of purity and convergence in some picture tube (unified with purity magnet). COLOR PURITY ADJUSTMENT NOTE : Before attempting any purity adjustments, the receiver should be operated for at least fifteen minutes. 1. Evenly degauss the entire screen. 2. Set the CONTRAST and BRIGHTNESS Controls to the maximum. 3. Display built-in green raster using the TEST SIGNAL SELECTION function. 4. Loosen the clamp screw holding the deflection yoke (and remove the Rubber Wedges). 5. Slide the yoke forward or backward to provide vertical green belt (zone) in the picture screen. 6. Rotate and spread the tabs of the purity magnet (See figure 4.) around the neck of the picture tube until the green belt is in the center of the screen. At the same time, center the raster vertically by adjusting the magnet as shown below. Figure 1. SPECIFIC INFORMATIONS DEFLECTION YOKE 1-5/8” Xv Coil PURITY/ CONV. MAGNET RUBBER WEDGES Adhesive Green Belt 7. Move the yoke slowly forward or backward until a uniform green screen is obtained. Tighten the clamp screw of the yoke temporarily. 8. Check the purity of the red and blue raster. 9. Put four wedges into the space between the picture tube and the yoke to hold the yoke in the adjusted position. (See figure 2.) Do not tilt the yoke by excessive insertion of the wedge. 10. Remove cover paper of wedge and stick wedges on the tube to fix the yoke in the adjusted position. Fix the wedges with glass cloth tapes. DEFLECTION YOKE Figure 2. –6– FIXED ROTATE TWO TABS AT THE SAME TIME (HORIZONTAL LINES) ADJUSTMENT OF MAGNETS BLU RED RED/BLUE GRN Figure 4. BLU RED RED/BLUE GRN s SCREEN-CORNER CONVERGENCE When the misconvergence is still evident on corners even though the above adjustment is done, use the ferrite sheet (Part No. 23993622) to correct misconvergence. 1. Put ferrite sheets into the space under the yoke. Decide such position that misconvergence becomes minimum, watching picture screen. (See figure below.) 2. Remove cover paper of ferrite sheet to stick it in the place on the tube. Put adhesive tapes on ferrite sheets to fix. 4-POLE MAGNETS MOVEMENT 6-POLE MAGNETS MOVEMENT Center Convergence by Convergence Magnets Figure 3. s Xv COIL ADJUSTMENT Adjust the Xv coil (on the deflection yoke) to correct misconvergence at both sides on screen. Use a hexagonal tip stick (plastic) to adjust the core of coil. Clockwise Adjustment Counterclockwise Adjustment Clockwise Adjustment Counterclockwise Adjustment Ferrite Sheets Ferrite Sheets R B B R B R R B A For correcting misconvergence on the position A XV Cross Pattern View v –7– SPECIFIC INFORMATIONS s CENTER CONVERGENCE ADJUSTMENT 1. Display built-in cross-dot pattern using the TEST SIGNAL SELECTION function. 2. Adjust the BRIGHTNESS and CONTRAST Controls for well defined pattern. 3. Loosen the tightening ring and adjust two tabs of the 4-Pole Magnets to change the angle between them (See figure 4.) and superimpose red and blue vertical lines in the center area of the picture screen. (See figure 3.) 4. Turn the both tabs at the same time keeping the constant angle to superimpose red and blue horizontal lines at the centre of the screen. (See figure 3.) 5. Adjust two tabs of 6-Pole Magnets to superimpose red/ blue line with green one. Adjusting the angle affects the vertical lines and rotating both magnets affects the horizontal lines. 6. Repeat adjustments 3, 4, 5 keeping in mind red, green and blue movement, because 4-Pole Magnets and 6Pole magnets interact and make dot movement complex. 7. After completing the “CENTER CONVERGENCE ADJUSTMENT”, tighten the tightening ring to fix the magnets. PURITY MAGNETS PURITY/CONVERGENCE MAGNETS ADJUST THE ANGLE (VERTICAL LINES) GENERAL ADJUSTMENTS CONVERGENCE ADJUSTMENTS NOTE: Before attempting any convergence adjustments, the receiver should be operated for at least fifteen minutes. 6-POLE MAGNETS 4-POLE MAGNETS SERVICE MODE GENERAL ADJUSTMENTS 1. ENTERING TO SERVICE MODE 1) Press MUTE button once on Remote Control. 2) Press MUTE button again to keep pressing. 3) While pressing the MUTE button, press MENU button on TV set. S MUTE (Service mode display) 2. DISPLAYING THE ADJUSTMENT MENU 1) Press MENU button on TV. Service mode Adjustment mode Item S Press Press Data SPECIFIC INFORMATIONS 3. KEY FUNCTION IN THE SERVICE MODE The following key entry during display of adjustment menu provides special functions. A single horizontal line ON/OFF: Test signal selection : Selection of the adjustment items : Change of the data value : Adjustment menu mode ON/OFF : Initialization of the memory (QA02) : Initialization of the self diagnostic data: “RCUT” selection : “GCUT” selection : “BCUT” selection : “CNTX” selection : “COLC” selection : “TNTC” selection : Test audio signal ON/OFF (1kHz) : Self diagnostic display ON/OFF : TV (ANT)/VIDEO button (on TV) TV (ANT)/VIDEO button (on Remote) Channel s/t (on TV or Remote) Volume s/t (on TV or Remote) MENU button (on TV) RECALL+Channel (s) button on TV RECALL+Channel (t) button on TV 1 button 2 button 3 button 4 button 5 button 6 button 8 button 9 button –8– 4. SELECTING THE ADJUSTING ITEMS 1) Every pressing of CHANNEL s button in the service mode changes the adjustment items in the order of table-2. (t button for reverse order) Refer to table-2 for preset data of adjustment mode. (See SETTING & ADJUSTING DATA on page 17.) 5. ADJUSTING THE DATA 1) Pressing of VOLUME s or t button will change the value of data in the range from 00H to FFH. The variable range depends on the adjusting item. 6. EXIT FROM SERVICE MODE 1) Pressing POWER button to turn off the TV once. s INITIALIZATION OF MEMORY DATA OF QA02 After replacing QA02, the following initialization is required. 1. Enter the service mode, then select any register item. 2. Press and hold the RECALL button on the Remote, then press the CHANNEL s button on the TV. The initialization of QA02 has been completed. 3. Check the picture carefully. If necessary, adjust any adjustment item above. Perform “Programming Channel Memory” on the owner's manual. CAUTION: Never attempt to initialize the data unless QA02 has been replaced. 7. TEST SIGNAL SELECTION 1) Every pressing of TV/VIDEO button on the Remote Control in the service mode changes the built-in test patterns on screen in the following order. Normal picture Red raster Green raster Blue raster All black All white White and black Black cross-bar White cross-bar H signal (black) H signal (white) White cross-dot Black cross-dot White cross-hatch Black cross-hatch Black cross-bar on green raster Signals • Red raster • Green raster • Blue raster • All Black • All White • Black & White Picture • Black cross-bar • White cross-bar • Black cross-bar on green raster • Black cross-hatch • White cross-hatch 2) Press “8” button while any built-in test pattern to on the screen to output the 1 kHz sound. Press the button again to cut off the sound. Note: If the video cable is connected to the VIDEO1 INPUT jack, the built-in pattern signals are not displayed. • Black cross-dot • White cross-dot • H signal (white) • H signal (black) *The signals marked with are not usable to display in the test signal for some model. –9– SPECIFIC INFORMATIONS GENERAL ADJUSTMENTS GENERAL ADJUSTMENTS 8. SELF DIAGNOSTIC FUNCTION 1) Press “9” button on Remote Control during display of adjustment menu in the service mode. The diagnosis will begin to check if interface among IC’s are executed prope..."

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