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1. SET FROM IK IN ON OFF CRT IC301 Y C JUNGLE TDAB172 STBY 5V 20615 CONTROLLER 57 521 8 SDA PIN 7 PROTECT 55 STANDBY TIMER LED TO CRT SELF DIAGNOSTIC SCREEN DISPLAY SELF DIAGNOSTIC igo IN BACKGROUND 2 O lt NUMERAL 0 MEANS NO FAULT 3 N A HAS BEEN DETECTED 4 5 1 NUMBER TIMES THIS PROBLEM 101 N A WAS RECORDED NUMBER OF TIMES STANDBY LED BLINKS SELF DIAGNOSTIC CIRCUIT CTV25J40 893 7 15 98 104
2. DEGAUSSING CIRCUITRY Y C JUNGLE IC TUNER AUDIO PROCESSOR DEGAUSSING IN STEREO MODELS COIL POWER ON COMMUNICATION BLOCK CTV25J24 877 8 11 98 60 Video Processing Block Tuner The Micro controls the tuner through the use of data and clock communi cations Both share in the TV station tuning functions TV Tuning Functions Tuner Uses input data to change the internal local oscillator frequency for station selection Outputs center of station AFT voltage Micro Data output identifies TV bands Low high VHF UHF Cable and TV channel Data output uses AFT feedback to fine tune the TV station Uses TV video sync to ID an active TV station auto programming Memorizes the location of active TV stations external memory IC Outputs TV video and audio signal Video Inputs In the 20 and smaller screen size BA 4 chassis video input selection is performed by the Jungle IC As many as three video inputs are available for the user to select from e Tuner video Video 1 composite or S video e Video 2 composite video only When the S video 1 jack is present in a model the composite video 1 input signal must pass through the S video jack The composite video 1 signal leaves the jack at the luminance Y line to the Jungle IC When S video 1 is input the round S video plug grounds the SW input to the Jungle IC so it knows to route the separate Y and C inpu
3. PIP B Y gt PIP R Y WIEN PIP Y USED Y UV SW TV TUNER C228 VIDEO gt TU101 18 nce VID Y 5 REAR FRONT VID VIDEO sN VIDEO J202 IN 201 TUNER TU101 5 R046 PULSES Q502C V PULSES VTIM 1C301 5 DATA CLK IC001 MICRO M37273MB SET 9V VDD ONLY IN PIP SETS IC301 Y C JUNGLE CXA2061S CO O XXX C316 R027 D004 R092 VIDEO INPUTS 70 X301 3 58MHz E C301 22 R OUT TO VIDEO BUFFERS Q392 G OUT gt 0393 0394 24 B OUT SIGNAL 21 bos FROM VIDEO D302 R OUTPUT C BD 5 1V Y Y DIGITAL M 7 CIRCUITRY NOT IN ALL C MODELS SERVICE MODE ST VIDEO ID NUMBERS 9v IDENTIFY 639i SET 9V WHEN USED 6 ON R324 R392 WM Q305 CEN NS R393 R394 RO25 jJ C020 CTV25J29 882 8 12 98 NOTES DIGITAL COMB FILTER COMPOSITE SOME VIDEO 1 MODELS S VIDEO JACK TO S VIDEO 1 JUNGLE T AL CATHODES VIDEO 2 INPUT SELECTION amp Y C 2 IK SENSE ABL PROTECT NOT USED IN ALL MODELS HP FROM VIDEO PROCESSING BLOCK CTV25J49 942 8 12 98 72 Video Output The video output stage utilizes the parts listed below to produce and control the picture Final Parts in the Video Output Stage Part Location Purpose Y C Jungle Main A board Separates video into Y amp IC 301
4. R5002 470k C5004 05004 5007 680 0 001 R5008 10k 470pF ts 7 05006 R5012 7 6Vdc D5007 1 5 6Vdc lk VDR5050 R5009 C5006 e 0 001 C5009 0 001 22 D5001 4 7 STBY 5Vde SOURCE STANDBY POWER SUPPLY 42 CTV25J28 881 8 19 98 NOTES STANDBY POWER SUPPLY REGULATION Stee ao eer B IC601 CONVERTER 12V AUDIO VCC DEGAUSS CIRCUITRY POWER SUPPLY BLOCK 27 MODELS amp LARGER CTV25J38 891 8 13 98 44 B Regulation 27 TV The primary purpose of this stage is to regulate the B voltage that out puts from power input transformer T603 The B voltage will remain ata stable 135Vdc because of this regulating circuit A soft start circuit is connected to this regulating stage to keep the B from rising above 135Vdc at power ON before the regulating circuit has had time to react Regulation Power Input Transformer T603 has several secondaries that output three different voltages for the TV to operate For regulation the output is used as a sample and the 12V output is used in the control The B voltage is sampled and used to control the converter oscillator frequency Changing the frequency of the oscillator in turn changes all the outputs from the T603 transformer including the B This regulation method allows the voltage from T603 s
5. VERTOUT C509 3ovp p 541 3 Tv 5 EUN Dore TMER LZ H DRIVE R320 604 STBY T501 N C313 sey 5 502 R310 ae H OUT 1k IC521 V 0574 NJM4558 Ed Q300 6 MICRO 7 N ae R585 0577 C575 R586 N CONTROLLER 33k 0 47 T 4 7k Y C JUNGLE 8 2V 2s CXA2061S R583 100k R584 PROTECTION CTV25J31 884 8 12 98 94 95 Troubleshooting The self diagnostic part of Micro IC001 causes the Timer Standby light to blink identifying a problem area This can be used as an aid in trouble Normal Operating Voltages Component Input Output D574 120Vp p at anode 109 2Vdc at cathode IC521 Pin 6 9 7Vdc Pin 7 1 34Vdc Pin 5 8 76Vdc Q300 Base 0 46Vdc Collector 3 4Vdc 5Vp p 9usec pulse Q571 B E voltage 0 52V dc Collector 7 9Vdc D581 0 88 Vdc at anode 0 46Vdc at cathode When the FBT voltage is excessive the TV is required to shutdown An excessive FBT voltage level will cause IC521 pin 7 to output a HIGH which will turn ON Q300 When Q300 saturates the 3 4volts from 1C301 pin 18 are grounded This ground immediately causes shutdown data to output IC301 pin 35 to the Micro The Micro receives this command and produces a HIGH at pin 6 to shut off the TV After the TV is shut OFF the Timer Standby light blinks two times pauses and repeats for as long as the set is plugged into 120Vac Excessive B current Failure Leakage in the Ho
6. support 11 Only the heater pins should have resistance All other pins have infinite resistance to each other and to either heater pins Highly used picture tubes that have a heater cathode leakage short have alow restoration success level Do not manually Degauss New 27 35 picture tubes are magnetically conditioned for optimum beam landing Strong manua degaussing will destroy this conditioning Applying disc magnets P I 1 452 094 00 to the bell of the picture tube is the only way to com pensate for lost magnetic conditioning The Sony manual degaussing tool can be used to degauss these tubes because of the reduced field intensity P N 7 700 781 01 RGB RAINBOW UNREPAIRABLE BLACK DUST SPOT ON THE PICTURE TUBE S APERTURE GRILL DISTANCE FOR IMPACT IS GRADUALLY INCREASED 6 IN MAXIMUM RUBBER MALLET SIDE VIEW DISLODGE THE DUST PARTICLES WITH A RUBBER MALLET 12 Picture Tube Handling and Vacuum Disposal Once you have determined that the CRT is inoperative air should be let into the tube This will reduce the risk of implosion caused by a sudden loss of vacuum There are two good methods of airing the tube A Puncture through the anode button B Break the thin glass seal at the neck The first method allows air to enter the tube gradually A Puncture through the anode button Air can be let in gradually by making a hole inside the high v
7. ENLARGED Z APERTURE GRILL BEHIND SCREEN I CTV25J3 802 827 98 Defective Picture Tube Symptoms Symptom Suspect Check Procedure Bright picture Grid 2 to Symptom is Reduce G2 screen with retrace high that all three voltage to the lowest lines and or voltage colors are setting poor focus Grid 3 bright Vary focus control to both leakage lim its several times Puton safety apparel Place the tube face down and lightly tap the neck to dislodge the particle Black spot on Dust Generate a Mark location and pull the screen lodged in white raster TV Follow safety see black the Inspect grill instructions spot aperture with Apply light im pact with diagram grill m agnifying rubber m allet see glass diagram RGB Aperture Rainbow of A loose aperture grill is Rainbow grill was colors can dangerous and may see rainbow unseated start at the cause tube im plosion picture in transit top or bottom Use all safety bottom precautions Do not jar rainbow set Transport face shown down Purity Beam The TV s Sam e color Do not manually landing is off degaussi blotches Degauss the picture ng circuit rem ain at that tubewith your strong did not area of the degaussing coil demagne screen Repair the TV s tize regardless of degaussing circuit The aperture picture screen thermistor is usually at grillmetal changes fault
8. 001 6 603 T603 OUTPUT OUTPUT DM 58 R699 CONVERTER OSCILLATOR FREQUENCY 470 OHMS B FDBK OSC T603 T602 7 FREQ OUTPUT FREQUENCY gt CTV25J51 945 8 11 98 B REGULATION 27 TV 46 Power ON Communications Block A number of processes occur when the power ON button is pressed Below is a list of the sequence of operation and their purpose Power ON Sequence Tuner Audio processor Block Operation Purpose 1 Press ON button Power ON Start command 2 Micro Degauss Degaussing Eliminate magnetized circuitry areas of the picture tube 3 Micro Regulator ON Switch ON the SET Switch Regulator 9Voltage to power the Jungle IC 4 Sw Reg Jungle IC Jungle power Vcc to jungle IC 5 Jungle IC Micro Vertical Interval Timing Vertical oscillator pulse signal output for data timing VTIM 6 Micro Memory IC Stored data retrieval from Pulls last active user memory information from memory 1 Last TV station 2 Input used 3 Picture settings 4 Volume levels 5 TV ID features 7 Micro Jungle IC Communications Data and clock are used to notify the other ICs to return to the former TV condition at power down 47 Data and clock communications signals are high rise time waveforms with harmonics To avoid communications interference with the picture the microprocessor only communicates with other ICs during the vertical interval time ab
9. 001 shuts OFF the TV to OSD BLK STBY 5V SET FROM IK IN 541 7 PROT ON OFF CRT IC301 V OUT IC001 L Y C JUNGLE TDA8172 MICRO STBY 5V Cath CXA2061S CONTROLLER 521 8 EDE M37273M8 Em PIN 7 PROTECT STANDBY TIMER LED TO CRT SELF DIAGNOSTIC SCREEN DISPLAY SELF DIAGNOSTIC IN BACKGROUND 2 O NUMERAL 70 MEANS NO FAULT 3 HAS BEEN DETECTED 4 0 5 1 NUMBER OF TIMES THIS PROBLEM 101 N A WAS RECORDED NUMBER OF TIMES STANDBY LED BLINKS SELF DIAGNOSTIC CIRCUIT CIV2540 893 7 15 98 102 protect itself The Timer Standby light blinks two times pauses repeats to indicate the failure If flyback FBT pulses were abnormally high perhaps as a result of an open resonate capacitor C508 in this set the TV would similarly shut down Higher than normal FBT pulses result in a high DC volt age that also grounds the horizontal pulses at IC301 pin 18 loss of horizontal pulses is detected and data is sent from IC301 pin 35 to 001 37 for the TV to shut OFF The Timer Standby light continues to blink two times pauses and repeats after the failure 3 White Balance Failure Jungle IC301 initiates CRT drive and moni tors CRT cathode current at pin 21 The amplitude of the three IK pulses that return to IC301 pin 21 represent the level of red green and blue CRT cathode emi
10. INSIDE BOTTOM 7 4 1 anu M M f 2 1110 1 4 4 41 WEEER A A A Wan YA DEFLECTION 1 AG ENLARGED LH ELECTRON GUN E SCREEN SLOTS PLATES N x INPUT ANODE SLOTTED APERTURE GRILL APERTURE GRILL BEHIND SCREEN TOP VIEW TRINITRON PICTURE TUBE CIV25J3 802 827 98 In diagram 6 you can see the slits have a more important purpose When all three beams are turned ON the narrow AG slots prevent adjacent electron beams from landing on the wrong color phosphor The aperture grill slots only allow electron beams to pass through and land on their corresponding color phosphor THREE ELECTRON BEAMS SWEEP ACROSS FROM ONE AG SLOT TO ANOTHER AG APERTURE GRILL E 7 EEN BLUE STRIPE PHOSPHOR PHOSPHOR PHOSPHOR STRIPE STRIPE STRIPE ELECTRON BEAM LANDING 3 COLORS WHITE 2 6 805 5 19 98 Phosphor Stripes Phosphor is a powder that becomes luminescent when bombarded by electrons The color and persistence of phosphor glow after electron bombardment is determined by using additional chemicals combined with the phosphor Three different color phosphors are painted in vertical strips that correspond to aperture grill slits The phosphor strips are sepa rated by carbon stripes that do not glow when struck by electrons These carbon stripes allow for manuf
11. ONLY IN STEREO VERSIONS OF THE BA 4 CHASSIS COMMUNICATIONS CTV25J18 871 8 11 98 58 Below is a chart showing the ID codes for the current BA 4 chassis ID Codes for the BA 4 Chassis Model ID 0 3 ID 1 ID 2 ID 3 ID 4 ID 5 ID 6 ID 7 KV Country Stereo 13M40 25 1 0 3 19 0 13M50 25 3 0 3 19 1 51 20M40 25 3 0 131 23 1 20540 25 3 1 131 23 1 41 20V80 25 19 13 131 31 1 27540 153 1 13 195 31 1 0 64 27545 153 27 13 195 31 1 1 64 27565 153 27 27 15 195 31 7 64 The Canadian version is a 9 instead of 25 and 129 instead of 153 Communications with other ICs After the memory IC003 information is stored in the working static memory inside the information is communicated to the Jungle IC301 Tuner TU101 and audio processor IC402 if used to set up all the operating parameters of the TV In this second scope shot the same data is shown expanded so you can see there is a space in the clock signal from 001 It also can be seen that the memory data and jungle data seem to be alike TV ON Active channel Channel 1 IC301 pin 5 VTIM Channel 2 001 36 Bi directional Data Channel 001 39 Clock Output to IC003 Channel 4 001 37 Bi directional Data All waveforms at 5V div Time base 200usec div 59 Channel UP Command This third scope shot shows that additional data and clock a
12. GND DECODER CXA2019Q G W3312 x BUFFER R B D 5 NI EY 9 P IC3303 PIP PROC SDA9288 a ay aK sr O MAN VE MAIN VP HP YUV_SW ND Y Y AT LK P HP PICTURE IN PICTURE CIV25 39 892 8 19 98 82 There are several sections to a TV s main horizontal and vertical Deflec Deflection Block tion stage Deflection Sections Name Sections Purpose Horizontal Y C Jungle Horiz oscillator Output Drive Horiz amplifier Output Horiz amplifier to drive the horizontal deflection yoke Pincushion Y C Jungle E W Hourglass shaped pictures occur in east west Pincushion yoke deflection angles 100 or more Amp This stage increases width at left and right sides to compensate High Voltage Horiz Output Makes primary drive signal Flyback Transformer Develops picture tube accelerating high FBT voltage Makes remainder of tube and vertical output voltages Horiz HP Horiz Output Compares huge horiz output pulses AFC Resistive Voltage HP and video sync for AFC lock of H Protection Dividers Transistors oscillator Jungle IC Excessive B current or FBT voltages Micro are detected by the Jungle IC Data transmitted to the Micro will shut OFF the TV ABL FBT Limits picture brightness by using tube current to reduce RGB drive Vertical Jungle IC Vertical Oscillator Vertical Output
13. IR DATA R649 I ON OFF R056 470 ce ROO7 R642 0611 459 N 9V POWER_ 9 CO14 SYq604 3 RELAY C627 7 47 Q606 H DRIVE HOLD gt DOWN Q501 B 4 5 B REDUCTION po 5292 CFOO1 8MHz POWER ON CTV25J15 868 8 11 98 54 NOTES PORER SET 9V SWITCH ON SWITCH REG DEGAUSSING CIRCUITRY TUNER AUDIO PROCESSOR IN STEREO MODELS DEGAUSSING COIL POWER ON COMMUNICATION BLOCK CTV25J47 940 8 11 98 56 Communications Before normal communications can begin start timing pulses are needed Then Data and Clock communications will run as long as the set is powered ON Start Once the TV is powered ON Set 9Vdc is available to the Y C Jungle IC301 at pin 44 Then IC301 s internal oscillator starts making horizon tal and vertical drive signals and a 60Hz Vertical Timing VTIM pulse from pin 5 This 60Hz VTIM pulse begins the communications by telling IC001 when to begin sending out Data and Clock signals Run Memory Retrieval Micro IC001 first communicates with the memory 003 TV settings were stored into memory IC003 the each time they are changed while the TV was ON At power ON IC001 sends out clock and data commu nications to Memory 003 to retrieve this information The return data is sent back to 001 on the same data line 001 36 003 5 and is supported by clock signal from 001 39 User Settings Transferred from
14. 001 17 After two seconds of missing pulses 001 will turn OFF the TV set and blink the Timer light four times Troubleshooting When the TV is shutdown and the Timer Standby light blinks four times the problem is in the vertical or horizontal section Start the TV by press ing the Power button You have two seconds to identify the missing signal with your scope or voltmeter before the TV shuts down again Here is a general checklist of items that will cause the TV to shutdown Some causes for the Timer Standby light to blink four times and repeat Some causes for the Tim er Standby light to blink four tim es and repeat e No Data Clock input IC301 pin 34 35 This causes NO IC301 pins 13 14 drive output Missing positive or negative 13 voltage to power IC541 at pins 2 or 4 This voltage comes from the FBT Loss of horizontal drive resulting in no FBT voltages e Loss of either or both vertical drive signals from IC301 pins 13 and or 14 e fbt boost output from 541 R562 0562 7504 9 13V SOURCE 1504 7 30Vp p PROTECT SET 001 17 ENDS 49V 1 001 2 IC541 V OUT 58Vp 9 VCC1 VCC2 DATA CLK IC301 FROM Y C JUNGLE CN501 MICRO CXA2061S PANE IC001 ERT VERT 120 J YOKE 4 7 OHMS d VERTICAL DEFLECTION 25 34 887 8 12 98 86 NOTES PINCUSHION WHEN USED HORIZ YO
15. 502 R310 ae H OUT 1k IC521 V 0574 NJM4558 Ed Q300 6 MICRO 7 N ae R585 0577 C575 R586 N CONTROLLER 33k 0 47 T 4 7k Y C JUNGLE 8 2V 2s CXA2061S R583 100k R584 PROTECTION CTV25J31 884 8 12 98 96 The normal voltage should be less than 0 5Vdc If it is less than 0 5Vdc before the TV turns OFF again there is a problem in the protection circuit at Q300 or IC301 Test Q300 for leakage or replace Move your DVM probe to IC301 pin 18 and turn ON the TV If this voltage stays below 2Vdc Q300 is leaky If above 2Vdc IC301 may be defective If the voltage at Q300 s base is HIGHER than 0 5Vdc the problem may be in 521 Q571 or in the circuitry Place your DVM at IC521 pin 7 and turn ON the TV The normal voltage should be less than 2Vdc If it is higher the problem is around 1C521 or there is excessive FBT voltage from an open safety capaci tor C508 or high B voltage Reduce the AC voltage and monitor the voltages at IC521 pins 5 amp 6 The voltage at IC521 pin 6 is fixed at the D573 zener voltage plus 0 6V D572 The normal voltage at pin 5 should never ex ceed 10Vdc If the voltage at 1C521 pin 5 is HIGHER than 10Vdc the problem is in the circuits safety capacitor or high B voltage If the voltage at 521 5 is Lower than 10Vdc the problem is about IC521 If none of the voltages around IC521 were high the problem must be around Q571 a defective horizontal output trans
16. CONTROL VAO 100k 0 001 WINDING C699 0 001 THIS SCHEMATIC L cs DIFFERS FROM THE T602 SERVICE MANUAL PRT CONVERTER CTV25J27 880 8 11 98 26 NOTES PRIMARY INPUT TRANSFORMER AUDIO VCC 13V 12V STBY 5V B 116VDC CONVERTER REGULATION POWER SUPPLY BLOCK 20 AND SMALLER CTV25J44 937 8 11 98 28 Converter Voltage Outputs Once the converter oscillator is running current is induced into the sec ondary windings to power the set Three voltages are derived from this converter power supply Audio Vcc 13Vdc B 12 Source Audio Vcc This fused 13Vdc is applied to power amplifier ICs The 27 TV uses one stereo power amplifier IC because all the 27 TVs are stereo Audio Vcc Destination TV Type Audio Output Package 1 Audio Output Package 2 13 and 20 Monaural IC400 13 and 20 Stereo 1 400 right IC401 left 27 1 401 stereo pkg B Two different T603 Power Input Transformers are used Power Input Transformers USA models TV Type T603 part number B Voltage Output 13 amp 20 1 431 674 11 115 116Vdc 2T 1 431 837 11 135Vdc D610 is a 150Vdc zener diode placed on the B line to guard against excessive B voltage D610 will short to prevent the horizontal output transistor and transformer load from seeing the excessive B voltage Unfortunately a prolonged short on the B
17. ON 1 7 seconds after power ON 2 2 seconds after power ON BRIDGE D601 DEGAUSS RELAY THP601 RY601 DEGAUSSING COIL STBY 5Vde AC BRIDGE RECT D601 R056 IC001 0 DGC Q601 14 MICRO N 37273 8 2 R050 001 eum s AT POWER ON DEGAUSSING CIRCUITRY CTV25J17 870 8 19 98 50 NOTES MEMORY Z DEGAUSSING aes CIRCUITRY DEGAUSSING POWER ON COMMUNICATION BLOCK CTV25J46 939 8 11 98 STBY 5V 12V POWER ON SWITCH SET 9V TUNER AUDIO PROCESSOR IN STEREO MODELS COIL 52 Power ON Power ON Once the Micro has received Standby 5Vdc at plug the external 8MHz crystal can run even while reset This 8MHz is used for all se quential digital based operations in IC001 and consequently is neces sary for any activity Now that the Micro is ready it can respond to a power ON command ON command can come from the front panel 5001 switch or the remote control Either input causes 001 to respond at the following outputs Micro Output at Power ON Purpose Activates the degaussing circuit Turns ON the Set 9V regulator Q605 Output 1 1 001 13 LOW 2 1 001 6 LOW The LOW output from IC001 pin 13 is applied to the degaussing circuitry It only remains LOW for 2 2 seconds each time the TV is turned ON This is more than enough time needed
18. Stee ao eer B IC601 CONVERTER 12V AUDIO VCC DEGAUSS CIRCUITRY POWER SUPPLY BLOCK 27 MODELS amp LARGER CTV25J38 891 8 13 98 38 Standby Power Supply This standby power supply is new to the consumer TV line It contains a FET based oscillator circuit that can operate over a wide range of input voltages but it must have a load Standby Oscillator Normal Operating Conditions TV 7 5 Load current Frequency Q5001 D ON 130 ma 42kHz OFF 30 ma 74kHz Standby 7 5Vdc output ma Dampened ringing at 79kHz not loaded load unplugged There are several stages that make up this oscillator circuit Basic oscillator Voltage regulator Current limiter Additional components Basic Oscillator For this oscillator to work FET Q5001 is turned ON and OFF with the aid of the standby transformer T5001 FET Q5001 ON FET Q5001 is turned ON when a positive voltage appears at its gate The voltage comes from fusible resistor R5001 and passes through T5001 pins 1 3 and R5003 to arrive at Q5001 s gate As the gate voltage in creases the FET drain to source resistance decreases Q5001 s cur rent flows from T5001 pin 1 3 through the drain to source of Q5001 thor ough R5011 to ground Initial Current Path to Ground Input Output T5001 SBT Pin 1 Pin 3 Q5001 Drain Source R5011 Ground 39 Current flowing thorough transformer SBT T5001 pins 1 3 induces v
19. TV station information and The TV operating parameters height width linearity OSD position etc Each time the user s preferences and channel are changed the Micro IC001 loads these changes into memory 003 Micro IC001 and Memory IC003 communications occur during these times Micro Memory Communications When Direction Purpose Plug In To Micro Load user and operating parameters into working RAM in IC001 User command To Memory Each time the user changes a preference like change volume or channel number 31 PRIMARY INPUT TRANSFORMER AUDIO VCC 13VDC CONVERTER LOW VOLTAGE 12V OUTPUT STBY 5V B 116VDC POWER SUPPLY BLOCK 20 AND SMALLER CIV25 25 878 8 11 98 32 B Regulation 13 amp 20 TV The primary purpose of this stage is to regulate the B voltage that out puts from power input transformer T603 Additional circuits are connected to this regulating stage to e Fine adjust the B voltage e Reduce T603 output at power OFF e Reduce picture blooming Regulation Power Input Transformer T603 has several secondaries that output three different voltages for the TV to operate For regulation the B output is used as a sample and the 12V output is used in the control The B voltage is sampled and used to control the converter oscillator frequency Changing the frequency of the oscillator in turn changes all the outputs from the T603 transformer
20. WINDING C699 0 001 THIS SCHEMATIC L cs DIFFERS FROM THE T602 SERVICE MANUAL PRT CONVERTER CTV25J27 880 8 11 98 20 A magnetic field is created when current flows through pins 1 2 of PRT transformer T602 This induces a negative voltage that outputs the trans former at T602 pin 3 This negative voltage is applied to the base of 601 2 turning it OFF At the same time a positive induced voltage from T602 pin 4 is applied to the base of IC601 1 This voltage is held there by capacitor C616 and coupled to the base via C611 The positive voltage drives IC601 1 into saturation ON The voltage at the collector of IC601 1 becomes zero by transistor action This zero volts also appears at T603 pin 6 because the inductance of T602 is small few windings Because C614 initially acts like a momentary short the full 167 supply voltage is applied to T603 s primary transformer windings pins 4 6 T603 s rising magnetic field is coupled into the secondary windings Top Transistor 601 2 Turns ON The conduction of the transistors in the IC601 package alternate when the magnetic field in T603 collapses Eventually C616 s charge leaks off so IC601 1 can no longer be held in conduction At this time current stops flowing through 601 1 and PIT T603 s primary winding The magnetic field that is built up in the primary winding of T603 now col lapses and current through the primary winding of T603 flows in t
21. When the TV set is turned OFF the load disappears This sudden change causes the B to rise instantaneously To prevent this increase 0603 receives a HIGH at the same time the TV is turned OFF Current flows D604 OUTPUT 1 Di 167VDC AC CONVERTER OSCILLATOR ee bt M gt SOURCE D610 cer T E R699 470 12 R626 SOURCE IC602 POWER CONTROL 4 kO O ADJ R632 R625 001 4 gt T ww C626 L 0 47 MA R629 P rj ON OFF gt ww Di r B osc reos sak 0619 T602 7 FREQ T603 OUTPUT OUTPUT 3 THIS CIRCUIT IS R628 CONVERTER NOT IN 13 47k OSCILLATOR MONO CHASSIS qe E Y STBY R637 R638 FREQUENCY gt gt 5V HESS 10k 0602 33k ABL H COMP FROM FBT gt MV N 7504 11 R634 25 R636 3 3k REGULATION 34 CTV25J19 872 8 11 98 through its emitter base junction R628 and C625 to ground Q603 turns ON increasing the voltage at error regulator 602 1 This results in a decrease in T603 output to offset the no load condition at power OFF Reduce picture blooming Picture blooming can occur when a bright scene is called for This scene causes the TV to draw the largest amount of power from the power sup ply at once When the power supply is delivering the maximum amount of current it is functioning
22. bright scene changes The focus is customarily adjusted for sharpness when snow no station is present The rapid changes from black to white when snow is dis played on the screen are the most taxing on the high voltage system Setting the focus under these dynamic conditions will insure a well fo cused picture within the normal viewing range Convergence Plates The Trinitron gun uses one gun which three electron beams pass through These three beams diverge as they pass out of the gun Electrostatic convergence plates bend the outer electron beams back so they land adjacent to the center electron beam on the corresponding red and blue phosphors Four convergence plates are used to bend the outer electron beams The two center plates are connected to the flyback generated high volt age The two outer plates are connected to a voltage a few hundred volts less than the high voltage A variable resistor CV external to the picture tube determines the exact voltage As the outer two electron beams pass through the convergence plates they are bent attracted inward toward the higher voltage plate Adjust ing the CV control changes the voltage to the outer convergence plates The deflection angle of the outer beams can be changed so they con verge and pass through the same aperture grill slot by the screen as the center green beam After the beams pass the aperture grill they diverge to land on their corresponding red green and blue pho
23. cathode Clipper Stage Q301 Q302 This IK signal is applied to a signal clipper stage to cut off low and high level parts of the waveform The clipper circuit consists of a voltage di vider and two transistors The voltage divider resistors R321 and R322 place the base of both transistors at a threshold voltage The IK signal is applied to both transistors emitters When the IK signal rises above this threshold both transistors conduct and pass only the signal above this voltage threshold Therefore this stage is said to clip the lower voltage components of the positive IK signal leaving the just the peaks In normal operation the IK line consists of the three IK pulses and the video signal from the picture tube cathodes Q301 passes the signal to the Y C Jungle IC301 so the IK pulses can be identified and used for cathode current balancing Zener D301 limits the signal input to the Y C Jungle IC301 pin 21 to a 5 volt maximum pulse Q302 is used to clip the larger amplitude signals Q302 operates similarly to Q301 but passes the IK signal to ground dividing the signal current As the signal amplitude becomes larger more current flows through R329 The additional voltage dropped by R329 turns Q302 ON harder than Q301 As Q302 turns ON harder the level of the video signal or any other volt age spike from the picture tube is reduced so it does not damage the Y C Jungle IC301 The following waveforms show the IK signal entering t
24. comes from the Micro and is sent to the Jungle IC as OSD voltages Since the Microprocessor needs to know exactly where to place these characters it is essential that horizontal HP and vertical VTIM timing pulses are input or there will be no OSD IK Sense Circuit The Jungle IC adjusts the levels of each R G and B signal to maintain a level of white balance The current drawn by each picture tube cathode is monitored as long as the TV set is ON The monitoring process results in three pulses that reside in the vertical blanking invisible area of the picture Each pulse corresponds to the three cathodes of the picture tube These IK cathode current sense pulses are separated by the Jungle IC and used to adjust the R G and B levels to maintain white balance ABL The Automatic Brightness Limiting input monitors the current drawn by the picture tube s high voltage If the picture gets suddenly bright this ABL voltage input to the Jungle IC causes a reduction in R G and B output levels Protection The protection circuitry monitors B current and flyback voltage If ei ther signal is excessive the Jungle IC sends data to the Micro to turn OFF the TV set 63 COMPOSITE VIDEO 1 S VIDEO JACK Y V Y ro Y DIGITAL COMB FILTER SOME MODELS Y C R TO S VIDEO 1 JUNGLE VIDEO PICTURE VIDEO 2 INPUT SELECTION amp Y C PROCESS ANT DATA CLK IK SENSE OSD TV VIDEO ABL PROTECT ud n AFT HP FROM FB
25. including the B This regulation method allows the B voltage from T603 s secondary winding to be main tained at a constant level Resistor R699 samples the B voltage from PIT T603 and applies it to a voltage divider R626 and R625 This reduced B voltage is applied to power control error regulator 602 1 The IC602 pin 3 output is in verted from the input so if the B voltage increased IC602 pin 3 s output decreases Therefore IC602 is a voltage error regulator Error regulator IC602 is used to control the converter oscillator frequency IC602 changes the current through PRT transformer T602 s control wind ing at pins 7 8 Current thorough the control winding reduces the effec tive inductance of this special transformer When the inductance of a resonate circuit decreases its oscillator frequency increases There fore current through the control winding of PRT transformer T602 sets the converter frequency The secondary output of the Power Input Transformer T603 is deter mined by the converter frequency input to its primary The converter oscillator develops a symmetrical square This waveform is applied to a tank circuit consisting of C614 and T603 which is resonate at about 60kHz in this TV set 33 The output at T603 is a bell shaped curve shown in the diagram below The oscillator frequency input to this tank circuit is above resonance at point A Therefore the output of T603 is not at maximum By changing the
26. into IC301 This analog input voltage at Jungle IC301 pin 29 is used to darken blank the main RGB picture signal at the instant the OSD character is 103 to appear and enable the OSD Since IC301 pin 29 is an analog input OVdc input leaves the main picture at normal brightness 2Vdc input reduces the picture to half brightness and 5Vdc blanks or mutes the picture Main Picture Brightness Control with OSD Voltage at IC301 pin 29 Brightness level 0 Vdc Normal 2Vdc Reduced to half 5Vdc Dark main picture muted The following waveform was taken with the self diagnostic page displayed on the TV The waveform shows that the YM OSD BLK signal is at an average level of 2 0 volts for the main picture brightness reduction There are peaks of the YM OSD BLK signal that rise to 5Vdc to mute the main picture These peaks correspond to the self diagnostic OSD characters By muting the main picture at this time the OSD letters appear on the TV screen without interference from the main picture 1 iy i L A CH2 Channel 1 IC301 pin 29 OSD signal 2V div Channel 2 1 301 31 OSD green signal input 0 5V div Time base 2msec div While the main picture is at half brightness the OSD self diagnostic page is displayed at normal brightness and appears as an overlay to the main picture OSD BLK STBY lt
27. no White balance failure weak repeats video picture tube or Low G2 voltage 2 Sound Continues to blink No or defective No reply from an IC data bus once a second Jungle IC301 is busy grounded or held communications HIGH The number of times the TV has failed is held in memory As long as there is failure information present the standby light will blink when the set is tuned OFF Unplugging the TV set will clear the memory informa tion and stop the blinking 99 Self Diagnostic On Screen Display A dormant intermittent problem is difficult to detect The BA 4 chassis Control Tuning System IC001 has a program to record the number of times the TV has failed in the first three categories listed above This information can be accessed and displayed on the TV screen as long as the set remains plugged in Self Diagnostic Access With the set OFF aim the remote at the TV and press the following re mote buttons in this sequence 1 Display 2 5 3 Volume Down 4 Power On The TV will power ON and display the self diagnostic page This self diagnostic display will overlay the TV or video picture At the left of the self diagnostic TV screen display are the numbers 2 4 and 5 These represent the number of times the Timer Standby light was blinking The numbers 3 and 101 are not used N A The column on the right side shows the number of failures that have occurred since the program was reset Up to 99 failure
28. problems is detected by the program is stored in 001 This number remains in IC001 s resident memory as long as the TV remains plugged into AC and is not manually cleared Inputs When the TV set is turned ON 001 monitors three TV conditions using two inputs at pins 37 and 17 These TV conditions are 1 Vertical Failure In normal operation Vertical Output IC541 s Ref pin 3 outputs a 30Vp p pulse 1msec pulse width This voltage is reduced by R549 and clamped to no higher than 5Vp p by 0001 These vertical pulses from IC541 pin 3 are monitored by Control Tun ing System IC001 at pin 17 A vertical drive failure causes no pulses to be generated If these vertical pulses are lost for two seconds 001 will turn OFF the TV to prevent the vertical deflection failure from damaging the CRT How ever the front panel Timer Standby light continues to blink four times pauses and repeats even though the set is OFF 2 Excessive Current Demand Excessive FBT pulse amplitude Y C Jungle IC301 monitors both of these conditions at input pin 18 Nor mally there are horizontal pulses applied to IC301 pin 18 when the TV is ON When there is excessive current being drawn by the FBT or Horizon tal Output Transistor the horizontal pulses are grounded out The Y C Jungle IC301 detects this loss from pin 18 almost immediately and sends data from IC301 pin 35 to IC001 pin 37 even in normal opera tion there is always data on this line
29. secondary winding to be main tained at a constant level Resistor R699 samples the B voltage from PIT T603 and applies it to power control error regulator IC603 pin 1 The IC602 pin 4 output is in verted from the input so if the B voltage increased IC602 pin 4 s output decreases Therefore IC603 is seen now as an error regulator Error regulator 603 is used to control the converter oscillator frequency IC603 changes the current through PRT transformer T602 s control wind ing at pins 7 8 Current thorough the control winding reduces the effec tive inductance of this special transformer When the inductance of a resonate circuit decreases its oscillator frequency increases There fore current through the control winding of PRT transformer T602 sets the converter frequency The secondary output of the Power Input Transformer T603 is deter mined by the converter frequency input to its primary The converter oscillator waveform is applied to a tank circuit consisting of C614 and 603 which is resonate at about 60kHz in this TV set T603 s output is a bell shaped power curve shown in the diagram The oscillator frequency input to this tank circuit is to the right of the resonance peak at point A 45 Therefore the output of T603 is not at maximum By changing the fre quency of the oscillator the secondary power output of the PIT T603 can be adjusted to provide sufficient load current while maintaining the same B voltage This is
30. small red green and blue input voltages to larger volt ages for the picture tube drive The voltage output of this video stage is applied to the picture tube cath odes This voltage varies from 200 volts for a dark picture to zero volts for a very bright picture Deflection When the Y C Jungle IC receives power and serial data its internal ver tical and horizontal oscillators operate and output These two VD and HD signals leave the IC to drive the external deflection amplifiers The output of the vertical deflection stage drives the vertical deflection coil of the yoke The purpose of the vertical yoke coil is to move or sweep the picture tube s electron beam downward to produce the picture The yoke and flyback transformer FBT use the output of the horizontal deflection stage The yoke uses this drive signal in the horizontal deflec tion coil to sweep the electron beam from left to right and back retrace to produce the picture The flyback transformer is a low current high frequency transformer that develops the remainder of the voltages the TV set needs to oper ate AUDIO OUT DEFLECTION FOCUS YOKE VOLTAGE VIDEO RGB OUT VIDEO R G B PICTURE TUNER OUTPUT TUBE I Y C SECONDARY gt JUNGLE VOLTAGES IC VD E VERTICAL DEFLECTION VIDEO HD HORIZONTAL DEFLECTION B MEMOR DATA CLOCK SET FOCUS 9V FBT VOLTAGE TRANSFORMER SECONDARY REG SW STBY REG SW VO
31. the TV could leave a spot of light at the center of the picture tube This is because the TV s magnetic deflection would collapse first being the most power hungry leaving residual beam current to produce a cen ter spot Q701 D700 D702 and D703 will drive the CRT harder depleting the beam current when AC is lost Normally with the TV ON Q701 is turned ON with bias from B via zener D700 Q700 s collector voltage is LOW When AC vanishes B is lost and Q700 s collector voltage rises to apply Set 9Vdc to IC701 pins 1 amp 2 via diodes This drives the blue and green beams full ON before deflection ceases depleting the power pro viding beam current The reduced beam current eliminates the possibility having a spot on the screen 180V IC301 Y C JUNGLE CXA2061S MIX BLK z SDA OSD R OSD G 3X 9 Go9G9G2 G E DECODER GAIN CONTROL R385 SET R713 R706 9V So BUFFERS R714 R707 0706 Ax 180V p osea N PICTURE TUBE R715 SCL OSD B R329 Q301 100 R304 C306 0 1 T Jessi ABL R534 B R533 0301 5 1V 1 e R322 10 J 6 8k CONTROL SET 9V gt TUNING SYSTEM 51 1 001 BOARD 50 0500 BLK CONTROL 521 7 520 HORIZ PULSE FROM H OUT C VID 76 D700 R701 82V R702 R703 EO OUTPUT 180V FEEDBACK SIGNAL SET 9V R705 Q701 SPOT SUPPRESS CTV25J3
32. the current flowing through R5011 rep resents the current in the FET If the current through R5011 drops 0 6Vdc Q5002 begins to conduct Its conduction reduces the FET gate voltage limiting its current so it does not overheat Current Path from T5001 s Collapsing Magnetic Field Parts Purpose Part Input Output D5005 R5009 C5008 Back up for voltage error regulator Prevents excessive T5001 Pin 3 C5006 standby voltage These parts limit the 7 5Vdc to 33 Vdc if D5003 Anode Cathode the main regulator path 05007 R5012 05006 C5003 opened T5001 1 D5004 R5008 Keeps Q5002 OFF at the start up of the next oscillator cycle Testing After replacing the Q5001 FET and checking for shorts increasing the AC voltage gradually is a good way to determine if there is an additional problem The standby power supply is still connected to the load during this test so you must monitor the 7 5Vdc output voltage and prevent it from being excessive The oscillator should start at about 35Vac The normal operating voltages are listed in the chart below Normal Standby Oscillator Characteristics KV27S45 AC Voltage R5001 Vdc Q5001 D Osc Freq Output Vdc 20Vac 8 5Vdc 0 0 0 40Vac 47Vdc 180Vp p 29 3kHz 7 4Vdc 60Vac 79Vdc 200Vp p 50 kHz 7 56V dc 80Vac 108Vdc 240Vp p 61 6 kHz 7 6Vdc 100Vac 136Vdc 270Vp p 69 6 kHz 7 6Vdc 120Vac 164Vdc 300Vp p 74 2 kHz 7 6Vdc MAIN BOARD
33. 0 883 8 19 98 Troubleshooting The IK circuit may keep the set in blanking because e The picture tube is old and the amplitude of the IK feedback pulses is too low to permit automatic cathode adjustment One or more of the IK pulses is not output to the CRT One or more of the IK pulses is not returned to the Jungle IC301 pin 21 Turning up the screen control will permit you to see if a color is missing If there is a color missing the problem is between the Jungle IC and the picture tube cathodes If all three colors are present the defect is in the IK return feedback line between 701 5 and Jungle IC301 pin 21 While the unit is blank ing use your scope to look for the three positive IK pulses from the Jungle IC301 pin 22 24 back to pin 21 77 IK SIGNAL PATH Component Signal In Signal Out Purpose IC301 pins Positive pulse Drive the 22 23 24 Blanked P ix picture tube 3 6Vp p IK signal cathode during the test Normal Pix 2Vp p interval Q392 Q394 Sam e as above Buffers 1C 701 Positive pulses Pins 7 9 Neg Am plify the Blanked Pix pulses 3 2Vp p IK test 3 2Vp p IK Blanked Pix i and ulse 0 2Vp p p E e Se 180Vp p IK pulses horizontal horiz pulses at Normal Pix signal to the the bottom 180Vp p of R G or Picture tube B signal with a N E Normal pix 120Vp p IK neg 2V p p pulse IC 701 Positive pulses Pin 5 Sup
34. 1 VDR602 All of the TV s power comes through C614 and T603 A bright scene accompanied by a surge in AC line can pass more current through C614 than normal More current means there would be a greater voltage drop across C614 If the capacitor s maximum voltage is exceeded it will short and damage the transformer VDR602 is placed across C614 for its protection VDR602 is a Voltage Dependant Resistor that only shows low resistance when there is a high voltage across it When good it measures like a small capacitor FROM 1603 F601 D601 R606 0614 KT 0 1 OHM 167VDC 0 056 AC R618 FROM 10 OHMS De PLUG 100k R612 0612 C610 1 OHM 3 5 0691 ue E cord 615 R692 0 22 100 C601 R610 C613 CONTROL VAO 100k 0 001 WINDING C699 0 001 THIS SCHEMATIC L cs DIFFERS FROM THE T602 SERVICE MANUAL PRT CONVERTER CTV25J27 880 8 11 98 22 Protection 2 D690 amp D691 The oscillator transistors IC601 are protected from a base to emitter failure A transistor s base to emitter junction can be punctured open or shorted By applying an 8 10 volt reverse b e bias voltage from a col lapsing magnet field to this junction the transistor will short C615 C616 and C613 prevent sharp high voltage spikes from leaving the trans former Diodes D690 and D691 prevent the transistor s base to em
35. 1 R610 IC602 1 Base Emitter Ground IC602 1 Collector Emitter Ground Resistors R608 R609 R611 and R610 form a voltage divider string from the 167Vdc supply to ground The base emitter junction of 1601 2 connects resistors R609 and R611 R610 is connected to ground by the base emitter junction of 1C601 1 The voltage at the junction of R609 and R611 is approximately half the supply voltage because the resistors in the voltage divider string are the same value Therefore before oscillation begins there are 167Volts 2 83 5Vdc at IC601 1 s collector At this time the TV set consumes 40ma AC C614 removed to stop oscillation Bottom Transistor IC601 1 Turns ON The second current path turns OFF transistor IC601 2 and turns ON tran sistor 1601 1 beginning the oscillator operation This path passes through several parts to ground Second Current Path to Ground Component Input Output R606 C614 T603 PIT Pin 4 Pin 6 T602 PRT Pin 1 Pin 2 R611 amp R610 R611 R610 IC601 1 Base Emitter Ground IC601 1 Collector Emitter Ground FROM 1603 F601 D601 R606 0614 KT 0 1 OHM 167VDC 0 056 AC R618 FROM 10 OHMS De PLUG 100k R612 0612 C610 1 OHM 3 5 0691 ue E cord 615 R692 0 22 100 C601 R610 C613 CONTROL VAO 100k 0 001
36. EQ T603 OUTPUT OUTPUT 3 THIS CIRCUIT IS R628 CONVERTER NOT IN 13 47k OSCILLATOR MONO CHASSIS qe E Y STBY R637 R638 FREQUENCY gt gt 5V HESS 10k 0602 33k ABL H COMP FROM FBT gt MV N 7504 11 R634 25 R636 3 3k REGULATION 36 CTV25J19 872 8 11 98 Power Supply Block 27 Models 13 and 20 Sony Electronics BA 4 chassis In the 13 and 20 Sony Electronics BA 4 chassis TV sets the converter oscillator runs when the set is plugged in Only the Set 9V is switched ON to turn ON the TV 27 Sony Electronics BA 4 chassis The 27 model of the BA 4 chassis is a bit more conventional Only the standby power supply is active when this TV is plugged in This standby 7 5 is regulated down to standby 5V Standby 5 voltage is used to power the Micro and Infrared receiver so it can respond to a power ON command from the user When the Micro receives a power ON command first the degaussing circuitry becomes active While this circuit operates the power relay is energized This relay delivers AC power to the converter stage which outputs B 12Vdc and audio Vcc 13Vdc to power the TV This standby power supply is new to the consumer TV line It contains a FET based oscillator that can operate over a wide range of input volt ages 37 STANDBY POWER SUPPLY REGULATION
37. Grid 2 be infinite remove video board short resistance 2 Apply 15 20Vdc between the between the G1 and G1 and G2 G2 pins to vaporize pins the short Current limit the power supply to 1 Amp Bright red Heater Remove the 1 Unplug TV amp remove green or blue Cathode Gor B the video board picture short video output 2 Apply 15 20Vdc One color OR transistor of between the pins that retrace lines Cathode that bright show resistance to may be to Grid 1 Color If that vaporize the short present short color is still Current limit the Retrace lines pig ht the external power supply are diagonal tube is bad to 1 Amp lines that run There should from lower be infinite left to the resistance upper right between any corner CRT pin to either Heater pin DEFLECTION FRAME PHOSPHOR STRIPES ON INSIDE OF GLASS SCREEN GETTER ASSEMBLY INSIDE BOTTOM SCREEN ELECTRON GU TOP VIEW SS HV INPUT M N DAMPER WIRES SLOTTED APERTURE GRILL GAA 9 TRINITRON PICTURE TUBE 10 SLOTS 3 WN NNNNNNNSK CNNNNNNNNNNNNNNNNNBSSZAA A CNNNNNNNNNNNNNNNNNNNNNXM Y
38. IC541 13Vdc power from FBT horiz drive failure 5 e Green buffer transistor Q393 open or shorted Loss of green e Protection diode D706 shorted signal to CRT amp 701 defective IC301 pin 21 e Picture tube socket not making contact e IK amplitude limiter Q302 or zener D302 damaged by picture tube arcing Once a second Jungle IC communications failure When the problem is intermittent you will have to probe further by moni toring the horizontal output transistor temperature and the TV s current consumption to see if it is high vibrate and possibly bake the set to force the intermittent failure to reveal itself Memory Clear Unplugging the TV from AC power resets the stored failure information and stops the blinking light The memory is cleared once standby 5Vdc is removed from the Control Tuning System Microprocessor ICOO1 It can also be manually cleared by first pressing 8 and then pressing EN TER while you are in the self diagnostic mode 101 Clearing the Self Diagnostic Memory Method Steps A Unplug the TV from AC Removing AC power clears the memory at any time Press buttons 8 then press ENTER B From the remote control Self Diagnostic Exit Shutting off power to the set retains the memory information and allows you to return to the TV picture Self Diagnostic Circuit The self diagnostic program is contained in the Control Tuning System 001 The number of
39. K VIDEO PROCESSING BLOCK CIV25 36 889 8 17 98 64 TV Reception Reception from Power ON Station Information At power ON TV station information is sent from the Memory IC003 to Micro 001 37 This information contains e The active TV stations e Each of the station s frequency and band locations e The last station watched at turn off Coarse Tuning TV station reception is performed using Micro IC001 and Tuner TU101 The last station watched with its frequency and band location informa tion is transmitted by data to the tuner TU101 pin 5 In TU101 the band and frequency data are used to tune to the desired station Fine Tuning An analog AFT voltage from the TU101 pin 4 is used to fine tune the station When the station is on frequency the Automatic Fine Tuning AFT voltage from TU101 pin 10 is 0 7Vdc If the station is off frequency this AFT voltage will be 0 volts or as high as 1 2Vdc The off frequency error is detected by Micro 001 34 001 sends frequency correc tion data from pin 37 to TU101 pin 5 The station s frequency is fine tuned and the AFT voltage is brought to 0 7Vdc Video Output 2Vp p of TV video is output the Tuner at pin18 buffered by 0205 and fed to the Jungle IC301 pin 43 Video Output Level Location DC Voltage Vp p TU101 pin 18 4 3Vdc 2Vp p Q205 em itter 5Vdc 2Vp p Q390 emitter 3 7V dc 2V p p 65 Channel Change audio mute By pressi
40. KE Y C JUNGLE GY ROTECTION Z FBT d VOLTAGE 77 FBT H OUT CURRENT HP PROTECT HV HEATER 13V 13V Z VERT YOKE PROTECT TO MICRO 13V DEFLECTION BLOCK czsso 943 8 12 98 88 Horizontal Deflection The horizontal deflection stage consists of several sections Horizontal Oscillator Horizontal Drive Horizontal Output AFC feedback Automatic Brightness Limiting ABL Protection Horizontal Oscillator When the TV is turned ON Set 9Vdc appears and is applied to Y C Jungle IC301 pin 33 Internally IC301 s horizontal oscillator starts and shapes this signal into a horizontal drive pulse that leaves pin 19 The pulse is 4Vp p with a positive width of 24usec The waveform stays LOW for 40usec after the pulse and repeats Horizontal Drive The horizontal signal from IC301 is amplified by IC501 The signal levels are shown in the following chart Horizontal Drive Location Amplitude Vdc IC301 pin 19 4Vp p 3Vdc Q501 base 3Vp p 0 7V dc Q501 collector 100Vp p 47Vdc Q502 base 2Vp p 0 03 Vdc 6Vp p w spikes In the KV20M40 model TV Q501 amplifies the horizontal drive signal to 100Vp p B 116Vdc The drive signal is reduced in voltage but increased in current by T501 The increased current at the secondary is necessary to drive the low gain higher power and horizontal output tran sistor Q502 89 Horizontal Output Q502 i
41. LTAGES MICRO IC ON OFF vo V1 gt TUNER AUDIO EXTERNAL AUDIO L gt N d REMOTE AUDIO DETECTOR VO PROCESS gt xc Load DECAUSS DEGAUSSING sien AUDIO DHL USER COIL RIGHT N 120VAC CIRCUIT AUDIO EXT gt AA I l D INPUT AUDIO 4 NUR 4 MODEL VARIATIONS POWER STBY 5V 12V SUPPLY AUDIO VCC OVERALL BLOCK DIAGRAM 4 CHASSIS crv25J42 903 8 11 98 16 Power Supply Block 20 TV amp smaller In the smaller BA 4 chassis TVs power is applied to most of the TV stages when the set is plugged into 120Volts AC Three stages develop and regulate the four voltages that leave the power supply 1 The converter stage 2 The voltage output stage 3 The power output control The Converter Stage The purpose of the converter stage is to change the low frequency 60Hz AC that is input to this stage into a high frequency AC signal that will output this stage To do this several operations take place within the converter stage The 120Volts AC input is rectified into DC and filtered This DC voltage powers a medium power high frequency oscillator An oscillator is used in this converter stage because its frequency is easily controllable and the high frequency output can pass through a small lightweight transformer This keeps the entire TV lightweight and efficient The high frequency AC output of the osc
42. M ELECTRON T G2 400V G3 APERTURE 21 300 21kV GRILL SCREEN GRID STRUCTURES crv25J2 801 5 15 98 Grid ring five is applied a very high voltage to accelerate the beam so it comes to a fine point some distance away at the center of the screen The ratio of voltages at G4 and G5 determines where the focus point is positioned This focus point forms an arc when the electron beam is swept from left to right by the deflection yoke SCREEN p ly Z ELECTRON BEAM FOCUS ARC CIV25M 902 6 24 98 Unfortunately the picture tube screen does not match this focus arc so the beam will only be in focus at the center of the screen To correct this physics problem the G4 focus grid voltage is modulated with a parabolic waveform shape is like a bowl at the horizontal rate The parabolic waveform moves the focus points forward so they match the screen In a TV high voltage drops during bright scenes because of heavy cur rent demands When the high voltage applied to grid five drops the G4 G5 focus voltage ratio changes This voltage change causes the focus point to change during the brightest spots One method to maintain the focus voltage ratio is to take both the focus voltage for G4 and high voltage for G5 from the same flyback secondary transformer winding If G5 s high voltage drops so does the G4 focus voltage The focus volt age ratio and picture focus are maintained during
43. Memory The user settings stored in memory will include TV station last station used CC channel block favorites e Input Selection Video 1 Video 2 or TV input e Picture settings Brightness color sharpness etc if not at default level e Volume level tone balance speaker ON OFF The waveform of the VTIM signal is shown preceding the IC003 memory data and clock signals 57 TV ON Active channel Channel 1 IC301 pin 5 VTIM Channel 2 001 36 Bi directional Data Channel 001 39 Clock Output to IC003 Channel 4 001 37 Bi directional Data All waveforms at 5V div Time base 2msec div ID Code Transferred from Memory In addition to the user data transferred from memory into IC001 operat ing parameters such as size gamma linearity and the TV s ID codes are also transferred These ID codes identify the model s features Having the wrong codes will permit the TV to display parts of a feature that does not exist in that model For instance a video 3 may appear on the OSD when there is no video 3 input These ID codes are accessible for check and correction from the service menu see the service manual for access information from the remote control ICO05 MEMORY ST24CO2FM6 SET 9V Y C JUNGLE 2 MICRO 20615 ROO M37273M8 IC402 AUDIO 21 PROCESSOR CXA2021S
44. R606 0614 KT 0 1 OHM 167VDC 0 056 AC R618 FROM 10 OHMS De PLUG 100k R612 0612 C610 1 OHM 3 5 0691 ue E cord 615 R692 0 22 100 C601 R610 C613 CONTROL VAO 100k 0 001 WINDING C699 0 001 THIS SCHEMATIC L cs DIFFERS FROM THE T602 SERVICE MANUAL PRT CONVERTER CTV25J27 880 8 11 98 24 What to Expect When Increasing the AC Voltage to the TV Observe Normal on a 20 BA 4 chassis TV AC Current degaussing coil Current will rise to 1 amp at about 12 Volts AC then unplugged drop down to 0 34Amps Oscillator s DC supply Will increase proportional to the AC voltage being voltage at R606 increased Collector of IC601 1 Must be half the DC voltage measured at R606 If not a part is still defective Normal Testing Results Below is a chart that shows the converter TV operation as AC is increased slowly to the TV that is OFF The Degaussing coil is unplugged during this test In the 27 BA 4 chassis the converter can be tested by temporarily jump ing the TV s ON OFF relay contacts and removing the load by unsoldering series inductor L504 Do not disconnect the B regulating stage IC603 DM 58 or the TV will draw an abnormally high current as the AC voltage is increased 25 When beginning to increase the AC voltage to the set under test the AC current will
45. SONY Training Manual Color Television BA 4 Chassis Circuit Description and Troubleshooting Course CTV 25R1 Introduction The Picture Tube The Trinitron Electron Gun Operation The Trinitron Screen Picture Tube Defect Symptoms Picture Tube Handling and Vacuum Disposal Overall Block Diagram Power Supply Communications Video Processing Deflection Power Supply 20 TV amp Smaller The Converter Stage The Voltage Output Stage The Power Output Control Converter The Rectifier The Oscillator Converter Voltage Outputs B Regulation 13 amp 20 TV Regulation Table of Contents 13 15 15 15 15 15 17 17 17 17 19 19 19 29 33 33 Additional Circuits Power Supply Block 27 Models Standby Power Supply Basic Oscillator Additional Components B Regulation 27 TV Regulation Soft Start Circuit Power On Communications Block Degaussing Circuitry Concept Circuit Operation Power ON Communications Start Run Video Processing Block Tuner Video Inputs Digital Comb Filter Video Output 33 37 39 39 41 45 45 45 47 49 49 49 53 57 57 57 61 61 61 61 63 TV Reception Reception from Power ON Channel Change Audio Mute Auto Station Programming Video Inputs Video Output Spot Elimination Circuit Troubleshootintg Video Block 27 With PIP Picture in Picture PIP Board Signal Flow Picture in Picture Processing Defle
46. T5001 winding collapses The reversed current flow applies a positive voltage to charge C5003 via D5003 41 Additional Components There are several additional components used in this circuit that have not been discussed Additional Components T5001 s collapsing magnetic field induces a LOW voltage that is output pin 4 to Q5001 gate This LOW insures that Q5001 turns OFF In this path C5003 is charged to about 300Vdc representing the crest of the oscillator waveform at Q5001 drain Voltage Regulator To maintain voltage regulation the following parts are used Parts Used for Voltage Regulation Part Purpose D5007 Rectifies T5001 sample voltage D5006 5 6V zener Keeps Q5002 OFF so Q5001 can begin oscillating Q5002 NPN Controls the voltage at the gate of Q5001 for regulation When the oscillator is running the voltage at T5001 pin 6 is sampled and rectified This sampled voltage passes through zener D5006 and is applied to error regulator Q5002 When the standby voltage is high more current is applied to Q5002 base Its increased conduction re duces the Q5001 gate voltage and the FET stays in conduction less This change in duty cycle decreases the power available at the SBT T5001 secondary and the voltage is reduced Current Limiter The current through Q5001 is limited by reducing its gate voltage Since Q5001 and R5011 are in series
47. The magnets within the speakers disturb the beam landing However the internal speaker s magnet is fully shielded to prevent this problem Electrical appliances that contain motors placed near the TV or turned OFF at the TV will also cause a purity problem In this case turning OFF the appliance magnetizes metal areas of the picture tube s aperture grill causing the purity problem The earth s terrestrial magnetism can also magnetize parts of the picture tube s aperture grill when the TV is moved The degaussing circuit elimi nates these magnetic effects on the aperture grill The purpose of this degaussing circuit is to demagnetize the aperture grill at plug in and each time the TV is powered ON This is done by passing AC through a coil of wire located at the bell of the picture tube The AC field created eliminates the magnetized areas of the aperture grill Circuit Operation Micro 001 controls the degaussing relay At plug in Micro 001 has received standby 5Vdc and a LOW at IC001 pin 30 for reset After the reset line goes HIGH IC001 can respond to the Power ON command Immediately the degaussing output line at IC001 pin 13 goes HIGH to start degaussing This HIGH is applied to Q601 s base turning the tran sistor ON Current flowing through Q601 also flows through the RY601 relay coil energizing the degaussing relay 49 AC current from the 120Vac line can pass through the relay into the degaussing coil The 120Vac i
48. The high voltage is used in the picture tube to accelerate electrons Larger picture tubes require a higher high voltage from the FBT to move the electrons a longer distance Control Grid One Electrons at the cathode are attracted to a positive potential The grid one ring is the next electrode structure in the electron gun In consumer TVs grid one is fixed at a OVdc potential for reference If a positive potential were placed on the cathode electrons would not be attracted to grid one At a 200Vdc potential electrons would not leave the cath ode If no electrons enter the gun the TV screen is dark The picture tube is said to be in cutoff On the other hand placing the cathode at the same potential as grid one OVdc is the same as if grid one were invisible The maximum amount of electrons is attracted toward the positive grid two structure resulting in maximum screen brightness By varying the voltage at the cathode from 0 Vdc to 200Vdc cutoff the amount of electrons available to the gun structure to produce screen brightness can be controlled Screen Grid Two The higher voltage at the second grid ring accelerates the electron beam This voltage is connected to the TV circuitry s screen control The screen control is adjusted to limit the maximum beam acceleration brightness This limit avoids over driving the tube which shortens the life of the cath odes and phosphors Acceleration Gr
49. Vertical Amplifier to drive the deflection yoke 83 MICRO DATA CLK PINCUSHION AMP WHEN USED HORIZ YOKE PROTECTION HP PROTECT toT VOLTAGE HV HEATER 13V FBT H OUT CURRENT 13V VERT YOKE PROTECT TO MICRO 13V DEFLECTION BLOCK 25 37 890 8 12 98 84 Vertical Deflection The vertical deflection stage consists of e Vertical oscillator e Vertical amplifier e Flyback generator Deflection yoke The purpose of this stage is to manufacture a magnetic field The mag netic field will bring the electron beam gradually from top to bottom ver tically and then quickly back to the top beam retrace of the screen to start over again Vertical Oscillator When the TV is turned ON Set 9Vdc appears at Y C Jungle IC301 pin 44 The internal horizontal oscillator begins and is counted down di vided to 60 Hz to become the vertical drive signal The drive signal is formed into a positive and negative ramp to be changed in amplitude and linearity by the serial data from Micro 001 If the data or clock signal were missing there would be NO vertical drive signal output IC301 pins 13 and 14 Vertical Amplifier A single package vertical amplifier and output IC541 generates sufficient amplitude and current to drive the deflection yoke It is powered with 13Vdc from the flyback transformer secondary Flyback Boost Generator The vertical waveform is used to generate
50. across the filter capacitor during a bright scene when there is a greater current demand This is shown in the chart below 60 Hz Ripple at Main Filter Capacitor C607 0 8Vp p across C607 4Vp p across C607 6Vp p across C607 TV Set OFF TV Set ON Dark screen TV Set ON Bright screen Oscillator The oscillator consists of two transistors a main transformer a PRT power regulator transformer PRT bias and protection resistors and capacitors When the oscillator runs it produces a 180Vp p square wave into the main Power Input Transformer PIT T603 pin 6 The two transistors IC601 alternately turn ON and OFF to develop the square wave The operation of the oscillator consists of three parts 1 A quiescent state 2 When the bottom transistor is ON and the top is OFF 3 When the bottom transistor is OFF and the top is ON 19 The Quiescent State The oscillator starts when DC voltage from fusible resistor R606 is ap plied to the oscillator stage Two initial current paths are taken toward ground within the oscillator stage The first current path places both transistors in the 601 package at the threshold of conduction to estab lish a quiescent state This state places 85Vdc at IC601 2 s emitter First Current Path to Ground Component Input Output R606 R608 amp R609 R608 R609 IC601 2 Base Emitter IC601 2 Collector Emitter R611 amp R610 R61
51. acturing tolerances when making the AG and painting the phosphor stripes Getter Assembly Electron emission efficiency and cathode life are greatly dependent upon clean environment inside the CRT After the air is pumped out of the CRT and sealed residual water vapor carbon dioxide and oxygen inevi tably remain A small cup attached to the gun assembly containing a barium com pound is placed inside the picture tube After sealing the glass picture tube the Getter is flashed with a high level of RF energy The barium compound heats up and evaporates combining with the residual unde sirable elements in the picture The resultant compounds that are cre ated coat the inside walls of the picture tube without consequence The result is a longer tube life because of the cleaner environment Picture Tube Defect Symptoms Several problems can occur in new picture tubes The bench technician can solve some problems and avoid a picture tube replacement Defective Picture Tube Symptoms Symptom Suspect Check Procedure Dark picture Heaters Apply 6Vdc to Clean the CRT pins and or one color Open the heater examine the socket for missing terminals corrosion Some heaters Apply 6Vdc to the CRT are connected heater pins looking for a in parallel glow in all 3 heaters others in Then if a heater s does series but all not glow replace the take 6Vdc picture tube Dark picture Grid 1 to There should 1 Unplug TV and
52. at the very top of the bell curve in the non linear region At this operating point the B regulation does not exist The picture may stretch disproportionately blooming as the B fluctu ates To avoid this Q602 monitors the ABL voltage from the flyback trans former secondary A bright scene causes this ABL voltage to decrease Q602 inverts this change and a positive going change is applied to the error regulator IC602 pin 1 This results in a reduction of T603 output shifting the operating point away from the top of the bell curve This reestablishes regulation at very bright scene levels Picture blooming as a result of no regulation is reduced If Q602 failed it would cause a negligible effect on the width of the pic ture This can be understood by observing that there are only small changes to the B voltage and converter frequency when Q602 is defec tive Results of Q602 Failure Q602 Converter Frequency B Voltage Shorted c e 68 8kHz 119Vdc Normal 71kHz 116Vdc Open c e 72 5kHz 111Vdc 35 D604 OUTPUT 1 Di 167VDC AC CONVERTER OSCILLATOR ee bt M gt SOURCE D610 cer T E R699 470 12 R626 SOURCE IC602 POWER CONTROL 4 kO O ADJ R632 R625 001 4 gt T ww C626 L 0 47 MA R629 P rj ON OFF gt ww Di r B osc reos sak 0619 T602 7 FR
53. com ponents when there is no external com b filter Uses the Y B amp W signal to adjust the RG B output voltage level Separates the C input into RGB voltages Adjusts RGB drive levels to m aintain preset cathode current Req IK feedback signal Amp IC701 C board Am plifies the RGB drive signal Picture tube Front cabinet Produce a color picture bezel Video signal Path Y C Jungle IC301 Within Y C Jungle IC301 the input signal is selected processed and converted to RGB The RGB signal undergoes some final processing before leaving the Jungle IC301 Later Processing Internal to IC 301 Processing Stage Operation Purpose Insert OSD or CC characters into the picture OSD Mixer The OSD characters replace the RGB signal Uses ABL signal from the FBT to reduce RGB drive voltage Blank gnd the RGB Output signaland instructs IC 001 to shut off the TV if there is a ground at IC 301 pin 18 Uses FBT high voltage to lim it the Blanking brightness of the picture Excessive FBT voltage or B current ill cause IC 30 1 pin 18 to be grounded 301 inform s IC 001 to protect the TV by turning the TV OFF Gain Control The gain and levelof the RGB signals is set by 1 communications data SDA before output Picture tube cathode current IK feedback is used to m aintain RGB levels Maintains good white balance Video Buffers Thes
54. ction Block Vertical Deflection Horizontal Deflection Protection Troubleshooting Self Diagnostic Timer Standby Light Self Diagnostic On Screen Display Self Diagnostic Circuit 65 65 65 65 69 73 75 77 79 79 81 83 85 89 93 95 99 99 99 101 Introduction Sony TV Models Covered by this Manual Purpose BA 4 Chassis Current Models Covered KV13M40 KV20M40 KV27S40 KV27V40 KV13M50 KV20M40 KV27S45 KV27V45 KV13M51 KV20S40 KV27S65 KV27V65 KV20S41 KV20V80 The purpose of this book is to Show through diagrams and explanation how the Sony Trinitron Picture tube now works because it has evolved since inception in 1968 Provide organized simplified diagrams that provide an insight to understanding the necessities of the circuit s operation This is an essential aid to rapidly determining the cause of a failure Explain the circuit operation and provide tips for troubleshooting where needed Some parts of the circuit are used only under certain conditions of operation It is important to know when these additional parts affect the main circuit during operation and how they affect the main circuits if they are defective Provide some voltages from a working production run set that are not supplied in the service manual These can be compared to the non working unit you are repairing to determine where the fault is Explain the new self diagnostic circuit 1 How to acc
55. cuit that changes the yoke current is called the pincushion stage Aperture Grill Construction The aperture grill AG is an aluminum panel located behind the picture tube screen with vertical slits cut out The aperture grill is welded to a steel frame that holds it completely flat in the vertical direction and curved in the horizontal direction Consequently the resultant picture tube face shape is like the front of a cylinder This flatter surface reflects less room light and therefore produces fewer glares from the ambient light This is another feature that sets the Trinitron apart from other picture tubes that are spherical in shape Although the grill is held flat it still can move slightly especially in larger tubes In larger tubes there are two horizontal wires that run across equidistant across the grill preventing the slots from vibrating or shifting These two wires found in the grill are called anti vibration damper wires Aperture Grill Purpose ep N In diagram 5 the slits in the aper ture grill allow the electron beam to l pass through and land on the phos phor The electron beam meant to land on the green phosphor is 1 shown 5 AG APERTURE GRILL a R G B R G B PHOSPHOR STRIPES ELECTRON BEAM LANDING GREEN PHOSPHOR STRIPES ON INSIDE OF GLASS SCREEN 7 TY al GETTER 104 4 p AY ASSEMBLY Z g
56. e white mixture The cap is fastened to a sleeve that houses a heating element filament This assembly is called a cathode There are three cathodes in the beginning part of the gun assembly by the pins of the CRT They all supply electrons in controlled amounts The center cathode on the Trinitron tube produces the amount of elec trons that correspond to the green color information These electrons will eventually land on the green phosphor if things go well on the jour ney The outer cathodes are angled slightly to send electrons through the gun structure Their final targets are the red and blue phosphor at the screen Next a voltage is connected to the cathode sleeve and a more positive voltage to the second grid two in the gun structure This difference in potential will pull the electrons from the cathode s Barium Carbonate surface into the gun structure The difference in potential volt age between the cathode and grid two will determine the amount of elec trons emitted More electrons landing on the phosphor screen will in crease the color spot intensity CATHODE ASSEMBLY G2 G3 G4 G5 400V 21kV 300V 21kV Lu d d n 2 BASE METAL BARIUM CARBONATE AN SLEEVE TRINITRON ELECTRON GUN 4 CONVERGENCE PLATES R _ ELECTRON G BEAMS S 710 SCREEN CTV25J4 803 8 11 98 Five Grid Structures The electron gun consist
57. e three buffer transistors provide current drive to sink the current from IC701 A short in one of these transistors would stop that color and activate blanking via the IK circuit An open transistor will cause that color to go to a high brightness with retrace lines CRT Amplifier This IC package amplifies the RGB signal from the buffers to a sufficient voltage to drive the cathodes of the picture tube Cathode Current Adjusting IK Circuit Concept As the picture tube ages the electron output of the three cathode struc tures will no longer be the same The cathode current IK circuit moni tors the current of each cathode and adjusts the electronic drive signal level to compensate for the differences due to aging As the tube is being used normal wear causes the cathodes to decrease in output at different rates When one cathode has dropped in output below the others white color no longer appears white White balance is now off Increasing one of the R G or B drive signal levels to the deficient cath ode increases that cathode s electron emission so its output will be like the others The picture quality can be automatically maintained with this circuit Circuitry The automatic cathode current adjusting circuit keeps the video and OSD blanked until the AKB circuit has finished The Y C Jungle IC301 gener ates the cathode drive pulse to begin the IK circuit operation Three horizontal lines in the vertical interval of the fie
58. emory When PIP is called for by the cus tomer the memory picture is converted from digital back to analog be fore leaving the PIP Processor IC3303 pins 7 9 as Y R Y V and B Y U PIP IC Operations IC Purpose Chroma Converts incoming video to Y V and U Decoder Alters outgoing V amp U signals to match the main IC3304 pix color using SCP video from Jungle IC301 PIP Uses H amp V to make the pix smaller Processor Stores the child pix into memory IC3303 E Analog to Digital for memory storage and reverse to PB Most of this child picture processing is done in IC3303 which makes troubleshooting simpler The other main IC is a chroma decoder 1C3304 that converts the incoming video into Y R Y and B Y for the PIP Proces sor IC3303 81 Processing The Picture in Picture circuit board needs the following signals to oper ate These signals are present all the time when the set is ON whether the Picture in Picture section is being turned on or not These signals are Serial data and clock signal at connector CN302 12 and 13 9V at CN302 1 which becomes 5Vdc on the board Input video signal at CN302 2 2Vp p The P board uses the child pictures sync to sample and store the child picture The main picture s vertical and horizontal pulses are used to determine where the beam is at any given moment so the Picture in Picture can be output for main picture insertion at the proper location Th
59. ese input timing signals are approximately 5Vp p The Y R Y and B Y signals that leave the P board when PIP is turned ON have to be switched into the main picture at the correct time That is the purpose of the YUV or PYS in several other sets signal that is out put at pin 17 when the child picture is simultaneously output This YUV signal to Jungle 1C301 36 selects the main picture when LOW and the Picture in Picture when HIGH Conceptionally the YUV signal cuts a hole in the picture in which the child picture is inserted 2 WH When Picture in Picture is called for from the remote control all four Picture in Picture inputs to the Jungle 1 301 9 10 11 and 12 will be active Signal Flow The video or child picture that enters the Picture in Picture board at CN302 2 is a 2Vp p video signal that is input to the Chroma Decoder IC 3304 IC3304 outputs the video as Y R Y and B Y labeled as Y V and U at 1C3304 18 19 and 20 The simpler labeling of Y V and U in place of Y R Y and B Y has been used in Europe for years The Picture in Picture processor IC3303 outputs child picture information when serial data SDA SCL is input and calls for that feature At that time only when PIP is turned ON does the child picture information out put from IC3303 s Y V and U output terminals SET 49Vdc 3502 5V REG 5Vdc CN302 1 CN3301 Q3301 BUFFER IC3304
60. ess it 2 How it works 3 When to use it 4 The circuits that support it Note This note is common to all schematics and block diagrams All capacitors are uf unless otherwise noted All resistors are ohms unless otherwise noted All voltages are dc unless otherwise noted The Trinitron Picture Tube The Cathode Ray Tube CRT has been slowly changing since its con ception about 50 years ago Since then the emitter accelerator and focus structures at the gun end have been added to the vacuum tube to shape and control the amount of electrons from the gun At the target end of the CRT the luminescent screen is made of a phos phor mixture Phosphor glows white when struck by electrons Phos phor brightness is directly proportional to the amount of electrons that strike the phosphor The CRT sport brightness was controllable with a gun and phosphor screen The electron beam produced a spot of light that was stationary on the phosphor screen Placing an electromagnetic field near the electron beam after it left the gun created movement The spot intensity and location were now controllable and the CRT became known as the pic ture tube To produce a color picture on the CRT screen three independent gun structures are used The electron guns produce different amounts of electrons targeted to their corresponding Red Green and Blue phos phors Red Green and Blue are the pri
61. extra current in the deflection yoke during the retrace period This extra current is used to quickly re turn the electron beam to the top of the picture The flyback generator stage within IC541 uses the vertical waveform to make a 30Vp p pulse needed during retrace time The retrace portion of the vertical drive waveform input IC541 pins 13 14 is extracted ampli fied and appears at pin 3 as a 30Vp p pulse It passes through C541 to 85 provide sufficient current to power 541 6 during retrace time Di ode D542 blocks this pulse and prevents it from increasing the 13 volt source The vertical flyback signal from IC541 pin is used in the protection circuit This 30Vp p signal from pin 3 is reduced to 5Vp p and monitored by Micro IC001 to prove the vertical stage is working Deflection yoke The deflection yoke translates the electrical current flowing through its coils into a magnetic field that positions the election beam vertically Current flowing through the deflection yoke coil is returned to ground through R544 The voltage developed across this resistor is fed back to the inverting input of IC541 pin 1 to improve linearity Protection loss of data vertical drive flyback generator signal or 13Vdc power will cause the protection circuit to shut OFF the TV The 30Vp p retrace pulse from IC541 pin 3 is used as an indication of vertical output opera tion This pulse is reduced to 5Vp p and monitored by Micro
62. for the degaussing operation The LOW output at 001 6 is applied to 0604 and 0605 It remains LOW as long as the set is ON The LOW is applied to the base of switch Q604 turning it OFF With Q604 turned OFF its collector voltage is allowed to rise to the zener voltage of D611 9Vdc The zener voltage comes from pull up resistor R649 connected to the 12 volt source The 9Vdc back at the zener diode s cathode is connected to the base of regulator Q605 The posi tive voltage will forward bias Q605 so its emitter will output Set 9V actually 8 4Vdc This Set 9V is the source of Vcc power for the Jungle IC to begin the TV set operation 53 Power OFF Additional circuits connected to 001 6 are used during power OFF to insure proper turn OFF This is because only the Set 9Vdc is re moved at power OFF while the remaining converter voltages are present to many circuits Circuits Used During Power OFF Transistor Name Purpose Q606 Horizontal Drive Hold Grounds the horizontal drive to Down assure no FBT secondary voltages Q603 B Reduction Prevents excessive B when there is no load at power OFF AUDIO VCC T603 PIT B SOURCE RECT 12V SOURCE B R690 IC002 REG DEGAUSS STBY CIRCUIT Q601 8 5V SOURCE ON OFF L002 SET 9V R641 TO JUNGLE IC301 STBY ICOO1 0038 N 0605 8 4 0 TUNER VIDEO PRE 5V MICRO 5 6V 5099 I DRIVERS M J
63. frequency of the oscillator the secondary power output of the PIT T603 will supply sufficient current to maintain the same B voltage de spite a changing load In summary variations in load current will occur with changing scene brightness 602 will cause a change to the con verter frequency to meet the current demand while maintaining a con stant B voltage The table below shows that there are changes to the converter frequency as the current demand changes Converter Frequency Changes to Meet TV Current Demands TV Control Voltage Converter B Voltage IC602 pin 3 Frequency White screen 10 4Vdc 71 55kHz 113 8Vdc Black screen 10 2Vdc 71 63 kHz 116 7Vdc TV OFF 8 09 Vdc 103 kHz 116Vdc Measured using a Sony model KV20M40 TV connected to 120Vac Additional circuits Additional circuits are connected to this regulating stage in order to e Permit fine adjustment to the B voltage via the service mode e Immediately reduce T603 output at power OFF e Reduce picture blooming Fine adjust the B voltage Micro 001 outputs an analog voltage from information stored in memory to fine tune the B This voltage is output IC001 pin 4 at turn ON and is coupled to the error regulator IC602 pin 1 stage using R633 and R632 This memory stored information can be accessed via the TV s service mode Removing R632 causes the B voltage to regulate at 110Vdc instead of 116Vdc T603 output reduction at power OFF
64. gher resolution than a standard digital comb filter by simulating detail and reduction of dot crawl The word Adaptive indicates that the digital processing is constantly analyzing and selecting the best algorithm available in the filter Digital 3 D Adaptive Comb Filter This filter is an improvement over the 2 D that only processed information within that field The 3 D filter analyzes information over frames to compare and eliminate noise interference and irregularities as well as separate the Y from the C Different digital filters are used in different models of Sony TVs 2 DIGITAL COMB FILTER COMPOSITE SOME VIDEO 1 MODELS S VIDEO JACK Y Y C TO PICTURE S dn JUNGLE G Ge CATHODES VIDEO 2 INPUT SELECTION amp Y C PROCESS ANT IK SENSE ABL PROTECT NOT USED IN ALL MODELS HP FROM FBK VIDEO PROCESSING BLOCK CTV25 36 889 8 17 98 62 Video Output The video processing continues from within the Y C Jungle to the picture tube The Y C jungle IC takes the composite video or S video and con verts this information into separate R G and B voltage levels These voltages are amplified by the video output stage and applied to the pic ture tube cathodes On Screen Display The TV s menu channel information and input selected are introduced into the video path in the last stages of the Jungle IC This alphabet character information is called On Screen Display information OSD It
65. gt HV FOCUS VOLTAGE x G2 VOLTAGE P PICTURE SCREEN TUBE R535 100k 777 CTV25J32 885 8 12 98 Automatic Brightness Limiting ABL The purpose of this circuit is to prevent sudden bright scenes from short ening the life of the picture tube It does this automatically by monitoring the picture tube s current and then using this voltage to limit the bright ness of the picture The flyback transformer T504 secondary supplies the picture tube s high voltage The ground end of the secondary at T504 pin 11 is current limited by a 100k ohm resistor R535 As the picture gets brighter the high voltage current increases causing a voltage drop across R535 This ABL voltage decreases with increasing brightness ABL Voltages Model KV20M40 Condition T504 pin 11 Voltage IC301 pin Voltage Black screen 6 2Vdc 6 2V dc generator Color bars 2 96Vdc 3Vdc W hite screen 2 1Vdc 2 1Vdc 91 Voltage divider R533 R534 and R532 bias this ABL line with a positive voltage that is applied to Jungle IC301 pin 3 A lower ABL voltage de creases the level and gain of the RGB waveform This is how ABL sec tion uses the Jungle IC to keep the brightness within a reasonable oper ating range OCP Protection One part of the protection circuit is shown here in block form The over current Protection OCP stage shuts OFF the TV during a fault Q571 is used to monitor the current flowing through the FBT and h
66. he op posite direction During the collapsing magnetic field current takes this path through 601 2 Collapsing Magnetic Field Current Path Component Input Output T603 pin 4 C614 R608 amp R609 R608 R609 IC601 2 base Emitter IC601 2 collector Emitter T602 2 1 T603 pin 6 Both IC601 transistors receive a change base bias While current is flowing through T602 pins 2 1 a positive voltage is induced and output T6502 pin This is coupled into the base of IC601 2 turning it ON At the same time a negative voltage is induced and output T602 pin 4 This turns IC601 1 OFF As a result of IC601 2 s conduction its emitter rises to 167Vdc 21 When the collapsing magnetic field in T603 has depleted its energy the cycle repeats starting with the charging of C614 The result is a square wave at the junction of the two IC601 transistors when they alternately turn ON and OFF The following waveform shows the oscillator s square wave output chan nel 2 at IC601 It is shown with IC601 1 base bias channel 3 and the sine wave at the junction of transformer T603 and C614 channel 1 Oscillator Stage TV ON 120Vac input Channel 1 T603 pin 4 50V div Channel 2 601 1 Collector 50V div Channel 3 601 1 Base 5V div Time base 2usec div Oscillator Stage Protection Protection
67. he signal clipper stage CH 1 and the signal leaving CH 2 Note that only the top half of the IK waveform is allowed to pass Vil Vi CH 1 ii I CH 2 Wm MM VL 75 Color bar pattern on TV screen Digital scope is set for peak waveform presentation The 3 IK pulses are difficult to see in this digital picture but are present to the right of the open vertical area The vertical lines in the waveform represent the horizontal scan lines Channel 1 CN301 pin 4 2v div Channel 2 D301 Cathode 1V div Time base 2msec div The output IK signal is applied to IC301 pin 21 Inside IC301 each one of the three IK pulses is measured and compared to technician set levels stored in memory These levels stored in memory are accessed from the service mode see the service manual The information is adjusted and used to set the gain of the RGB signals When the gain is within the automatic adjustment range the RGB signal is unblanked and leaves IC301 pins 22 24 with the IK pulses Transistor Voltages Color Bar Test Pattern Transistor Em itter Base Collector Q392 0 1 5Vdc 2 2Vdc Q393 0 1 5Vdc 2 1Vdc Q394 0 1 6Vdc 2 2Vdc Q300 0 0 46Vdc 3 4Vdc Q301 3 8Vdc 3 73V dc 0 78Vdc Q302 3 9Vdc 3 73V dc 0 Spot Elimination Circuit Since many cable boxes shut off power by removing AC when the TV is ON
68. id Three The very highest voltage in a TV from the flyback transformer is applied to the third grid ring This creates a large magnetic field to further accel erate the three electron streams from the cathodes Focus Grid Four and Acceleration Grid Five The lower voltage at focus grid ring four slows down the electron stream so they bunch up thickening the beams By varying the focus voltage applied to grid four the beam thickness is controlled A thicker beam means the electron stream will focus at a point closer to the gun before the screen When a very bright spot is called for more electrons are sent from the cathodes As a result the beam is at its thickest at the G4 focus ring In 8 small electron gun the G4 focus ring is closer to the thick beam than the single Trinitron gun where the focus ring is much larger Grid four s magnetic field is the strongest at the metal grid ring More peripheral electrons are attracted to the focus grid ring of the smaller electron gun Some of these peripheral electrons are lost from the stream as G4 grid current limiting beam thickness The limited beam thickness results in a shift in focus point This causes reduced focus during bright ness peaks in the smaller electron gun Therefore at high brightness levels it is advantageous to have a large G4 focus structure A wider dynamic focus range is achievable with the large single Trinitron gun FLUORESCENT SCREEN CATHODE ELECTRON BEA
69. illator is applied to the next stage for multiple voltage outputs The voltage output stage The purpose of this voltage stage is to provide multiple voltages to the TV The oscillator signal from the converter stage is applied to a trans former in the voltage output stage The transformer s secondary wind ings are used to make the four voltages The most important voltages are the standby 5V and the B voltage In the 13 and 20 BA 4 chas sis the B is 116Vdc In the 27 TV B equals 135Vdc e The standby 5V is used to power the microcomputer e The B is used to power the horizontal deflection and high voltage stages Variations in the voltage will cause the picture to change in width and brightness 17 The power output control The purpose of this stage is to maintain regulate the B voltage The input to the power control stage is the B voltage Variations in the B voltage will change the converter s oscillator frequency TRANSFORMER RESONANT FREQUENCY OSCILLATOR OPERATING POINT POWER ON TRANSFORMER SECONDARY OUTPUT POWER OFF 71kHz 103kHz FREQUENCY Transformer Operation Point Increasing the oscillator frequency results in a shift along the transformer s resonate frequency curve This results in a decrease in the transformer s primary to secondary transfer efficiency Therefore there is reduced secondary output until the has returned to normal Conversely dec
70. increase sharply until the B reaches the correct voltage for that set 116Vdc or 135Vdc and then drops gradually as AC voltage is increased The degaussing coil is unplugged during this test Peak AC Current Consumption Model AC Voltage AC Current KV20M40 12Vac 0 8 Amps KV27S45 11Vac 1 3 Amps Increasing Voltages with TV OFF Model KV20M40 Converter IC601 2 E AC DC at R606 Vp p Freq B 7 Vac 8 Vdc 20 Vp p 55kHz 22Vdc 11 Vac 11 Vdc 28 Vp p w 49kHz 108Vdc spikes 22 Vac 25 Vdc 35 Vp p 51kHz 116Vdc 40 Vac 50 Vdc 60 Vp p 54kHz 116Vdc 75 Vac 100 Vdc 100 Vp p 61kHz 116Vdc 110 Vac 150 Vdc 150 Vp p 78 SkHz 116Vdc 120 Vac 166 Vdc 170 Vp p 104kHz 116Vdc Above 12Vac the B has reached its maximum and the regulation stage changes the converter frequency to supply sufficient TV current to main tain a steady B voltage As the input AC is being increased toward 120Vac the current continues to drop toward the normal operating level This TV power supply can run unloaded but the regulation circuit must remain intact or the unit will damage the converter 601 and blow a fuse FROM 1603 F601 D601 R606 0614 KT 0 1 OHM 167VDC 0 056 AC R618 FROM 10 OHMS De PLUG 100k R612 0612 C610 1 OHM 3 5 0691 ue E cord 615 R692 0 22 100 C601 R610 C613
71. ion of this training manual T504 FBT R56 D561 Ow Em C562 I SOURCE B 13v SOURCE R549 FROM gt IQ VERT OUT ee 30Vp p 541 3 TV 54V ON orr 7 C313 Q604 B 0 01 PROTECT MICRO R585 33k C577 I css R586 I CONTROLLER 0 47 4 Y C JUNGLE d n CXA2061S PROTECTION CTV25J31 884 8 12 98 98 Self Diagnostic Self Diagnostic is new in the series BA 4 TV chassis It uses a blinking light or OSD to notify you if there is a failure caused by the following 1 Excessive flyback current or amplitude 2 No Vertical sweep or 3 No green automatic white balancing signal Timer Standby Light The number of times the Timer Standby light blinks indicates what failure is detected by the Control Tuning System Microprocessor IC001 IC001 will shut off or blank the TV set to protect itself The Standby Timer light will continue to blink as long as the TV is plugged into AC power Standby Timer Light Diagnosis Standby Light Blinks Symptom Problem 2 times pauses and Shutdown 1 Excessive B current repeats TV powers OFF demand or high FBT pulse amplitudes 2 No reply from Jungle IC301 4 times pauses and Set Turns OFF Vertical Failure may also be repeats Horizontal Failure since the vertical IC is powered by the FBT 5 times pauses and 1 Raster but
72. is the standby 5Vdc at plug in The middle waveform is the reset signal from IC002 and the bottom waveform channel 3 is the reset sig nal at IC001 pin 30 after a pi filter network The pi filter network insures no voltage spikes pass into the Micro Plug Into 120Volts AC Channel 1 002 5 2V div Channel 2 002 2 2V div Channel 3 IC001 pin 30 2V div Time Base 20msec div Capacitor C690 connected to 002 3 is used to extend the reset time to 60msec Without it the reset time is only 20msec T605 POWER INPUT TRANSFORMER PIT L200 N 25 N 50 IN 27 TV AUDIO VCC SOURCE TO OUTPUT 1C400 1 401 IC003 MEMORY 8 ST24C02FM6 B SOURCE des 116VDC 20 TV amp SMALLER RO65 RO66 CONVERTER 135VDC 27 TV amp LARGER IR DET 004 2 STBY 5V MICRO M37273MB 12V SOURCE TO 9V SW REG Q604 Q605 DEGAUSS 601 AUDIO UNMUTE Q203 CTV25J20 873 8 11 98 CONVERTER VOLTAGE OUTPUTS 30 IC001 Memory Data Retrieval After reset one of IC001 s first programs is to retrieve data from the external EEProm memory 003 Data and clock are output IC001 pins 36 and 38 to request a reading of all the memory information The memory information is serially output IC003 pin 5 and stored in Micro IC001 s resident memory internal RAM This memory information contains The user s picture and sound preferences The last active
73. is video is buffered by Q390 leaving its emitter for Q001 s base Q001 is a sync separator that passes just the sync tips of the video waveform into 001 16 It is these horizontal sync tips that are identified by 001 and the channel is logged as being active at this time For reference the DC voltages at sync separator 0001 are listed 5 1 5 5Vdc B 5Vdc Same as above C 20 7Vdc C 2 0 5 0 8Vdc On station Off station SET 9V di D650 5 6V C228 TV gt 0 Y C R253 mec ms JUNGLE C255 IC301 43 R254 AN sov 0205 AUDIO OUT ANT 77 TUNER 201 1 BTF W 411 SET 9V R390 ENABLE 22228 AUDIO OUT JACK S R242 1 AUDIO OUTPUT IC S STBY 5V IC301 STBY xia 34 35 001 M37273M8 1029 bras R021 m lt STBY CH A CH M VOL VOL 899 OO 29 TV RECEPTION CTV25J33 886 8 13 98 66 NOTES DIGITAL COMB FILTER COMPOSITE SOME VIDEO 1 MODELS TO OUTPUT CATHODES VIDEO 2 LE INPUT SELECTION 2 ABL PROTECT IK SENSE NOT USED IN ALL MODELS HP FROM FBk VIDEO PROCESSING BLOCK Crv25J48 941 8 11 98 68 The Jungle not only performs luminance Y and chroma pro cessing but input selection as well There are as many as seven inputs Video Inpu
74. istor or transformer Place your DVM at Q571 collector Turn the TV ON This voltage should not rise above 10Vdc If this voltage is HIGH suspect Q571 R571 and other resistors in the area If these protection parts test OK there is a heavy current demand on the B line The problem may be a short at the FBT secondary wind ings 97 Timer Standby light blinks four times A vertical deflection failure or horizontal drive failure is indicated 1 Test the horizontal section by using one of these tricks Place your scope probe by the FBT and turn ON the TV You will see the horizontal signal if the drive path from the Jungle IC to the FBT is OK Listening to the frying sound at the yoke is another indicator of horizontal signal arriving at the yoke 2 Test the vertical stage by using the scope probe to monitor the verti cal drive signal and the DVM to measure the positive and negative supply voltages to the vertical 541 at turn ON 3 Testthe Protection circuitry by placing your scope lead at the Vertical Output 541 You should see a 30Vp p pulse there If it is present this pulse is not getting to IC001 pin 17 Replace zener D001 if shorted Timer Standby light blinks five times This failure is caused by a problem in the video output IK circuit Turning up the screen control will let you see light on the screen so you can make an evaluation of the problem For more details see the Video Output sect
75. itter junction from being reversed Protection 3 C612 amp C699 A transistor s collector to emitter junction can be shorted if the maximum voltage across these terminals is exceeded Vce Although the typical maximum voltage for these transistors is 600volts it can still be exceeded when lightning brings in a much higher voltage The voltage spikes from a non direct lightning hit may be high in voltage but low in current small pulse width They are bypassed to ground with C612 and C699 If a very high current spike shorted 601 2 from collector to base current would also have flowed through C610 and R612 and they should be replaced IC601 Protection D690 D691 prevents 60175 E B junction from reverse bias damage C615 C616 C613 rounds off sharp spikes from rising and collapsing magnetic fields C612 C699 high voltage low current spikes circumvented by this capacitor This reduces the voltage to IC601 so the transistor s C E breakdown voltage specification is not exceeded R606 fusible resistor Protection from internal spikes causing immediate failure Protection from external spikes lightning Protection Thermal 23 Oscillator Frequency The oscillator frequency is predominately a function of T603 inductance and C614 capacitance forming a sine wave at the junction Since the inductance of T603 is changed with a load the frequenc
76. ld above the picture are used to test each cathode one at a time Each cathode is driven full ON starting with the Red output at pin 22 After the first pulse at pin 22 IC301 pin 23 sends a 10usec pulse to turn on the green cathode for the entire horizontal line After the pulse at IC301 pin 23 returns LOW pin 24 outputs the last pulse to turn on the blue cathode These 10usec width positive drive pulses are buffered by Q392 Q394 and amplified by 701 to be applied to the picture tube cathodes 180V 180V 1 LN R385 SET R713 R706 2 VIDEO T lt 9V 9 IC301 Y C JUNGLE CXA2061S BUFFERS 3 R714 707 G PICTURE R cz D706 180V b Q394 R384 CRT B GAIN AMP CONTROL Gh ii 2 R715 R708 0393 R383 6107Q D705 MIX BLK D qe B 180V Q392 FEEDBACK SIGNAL 229 SET 9V 100 R315 o DE 0301 CN301 5 1V CN702 D700 R701 8 2V Q701 R322 gt m c SPOT 10k SUPPRESS 6 8 CONTROL SET 9V R702 R703 gt TUNING SYSTEM 8 Icooi A BOARD C BOARD 59 Q300 BLK R304 CD CONTROL ABL e AY 1 521 7 C306 R532 R534 31 lt HORIZ B PULSE R533 FROM H OUT C CTV25J30 883 8 19 98 VIDEO OUTPUT 74 When the picture tube warms up and draws current these three pulses all appear next to each other at the common cathode IK 5 of IC701 The amplitudes represent the current of each
77. line will load down the con verter stage In the converter stage IC601 will short fail trying to supply current to maintain the voltage Therefore if you find a shorted con verter IC601 check the D610 zener as well After parts replacement test the converter stage by following the steps outlined in the Converter section of this book 29 12 Vdc Source 12Vdc is applied to several stages at plug in Purpose Applies 9Vdc to the Jungle IC to power ON the TV Permits the degaussing relay to operate at plug in TV power is OFF Insures audio mute at power OFF Powers and resets Micro IC001 See below Stage 0604 0605 switched 9V regulator RY601 Degaussing Relay Q203 Audio mute 10002 Standby 5Volt regulator IC001 Vcc Power At plug in Micro 001 is powered and reset using IC002 When 12Vdc is applied to IC002 pin 4 a regulated 5Vdc leaves pin 5 This is the Standby 5Vdc used to power the Micro 001 Memory 003 and the remote infrared receiver IC004 IC001 Reset 001 also needs to be reset when standby power is applied 001 30 is connected to 002 2 002 performs the reset operation by keeping its pin 2 LOW for 60msec at AC plug in After 60 msec reset ends when this line goes HIGH The HIGH permits the Micro to operate beginning with memory data retrieval This reset operation is shown in the following waveforms The top chan nel 1
78. mary colors for light In 1968 the Sony Trinitron picture tube was a departure from the tradi tional three gun color picture tube Three major changes to the old color tube created a distinctive Trinitron picture tube 1 Instead of three small electron guns focus was improved using one large electron gun structure that all three beams pass through 2 Electrostatic convergence plates were added to bend the outer elec tron beams so they would land on the corresponding red and blue color phosphor 3 continuous vertical slotted aperture grill at the screen end that Reduces the effects of terrestrial magnetism e Prevents adjacent and stray electrons from striking the wrong phos phor e Allows more electrons to pass increasing brightness without short ening life e Results in a flat screen This reduces annoying room light reflections glare The remainder of this document is divided into four sections explaining the construction of Trinitron tube as an aid to the service technician The Trinitron Electron Gun Operation The Trinitron Screen Picture Tube Defect Symptoms Picture Tube Handling and Vacuum Disposal The Trinitron Electron Gun Operation The Sony Trinitron electron gun consists of three cathode assemblies five grid structures and convergence plates Three cathode assemblies When heated electrons are given off from a Barium Carbonate BaCO surface deposited onto a cap cap serves as a holder for th
79. ng the channel or buttons on the front panel or remote control IC001 responds with data from pin 37 for the tuner to change a station At the same time Micro 001 5 outputs a 1 second positive pulse that is applied to TU101 pin 17 to mute just the audio This insures no audio noise is heard when changing stations The mute output from 001 5 also goes HIGH when the volume down button is pressed and the level has reached its lowest limit IC001 pin 5 also goes HIGH when the mute button is pressed This is summa rized in the following chart Audio Mute from IC001 pin 5 O peration Interval Channelchange 1 second Volum e all the way down Until volum e up is pressed Remains HIGH until TV is turned OFF Mute button pressed Auto Station Programming Station identification is used during the TV s auto station programming This is when all the cable or over the air active stations are selected over the inactive ones Each channel is polled one by one When there is horizontal sync received at that channel the station is deemed to be active This channel location is then stored in IC001 to be transferred to an external memory IC at power OFF When this feature is activated from the user s menu IC001 sends data to the tuner to tune to each channel to see if there is a station present If a station is present at the first channel location video will output the Tuner TU101 pin 18 Th
80. nput must first pass through several parts before reaching the degaussing coil Parts between the AC Line and the Degaussing Coil Part Purpose VDR601 Absorbs voltage spikes from the AC line C601 Reduces voltage spikes from the line and from the TV converter stage R620 Bleeder resistor for C601 T601 Common mode rejection transformer Cancels opposite polarity noise signals on the AC line THP601 Degaussing thermistor is 3 5 ohms cold in series with 3 5 ohms cold the degaussing coil It increases in resistance to 14kohms hot calculated almost turn OFF all the coil current within 2 seconds RY601 Controlled by IC001 to apply AC to the degaussing coil for 2 2 seconds Creates an AC field that erases magnetic effects of the aperture grill Coil 273 ohms Degaussing coil Approx 8 ohms Thermistor Operation When current flows through the degaussing coil it also flows through the THP601 thermistor Initially its resistance is 3 5 ohms but increases rapidly so that within two seconds there is only 8 5ma flowing through the degaussing coil This current develops a negligible magnetic field in the coil and is effectively OFF Shortly after the thermistor has reached its highest resistance the RY601 relay disconnects the degaussing coil from the AC line completely Degaussing Coil Current 10Amps momentary 8 5ma thermistor operation THD601 0 ma Power
81. o pass through the anode hole and not touch the anode button s outer metal rim 6 Being careful not to hit the glass with the hammer gently tap the tool further into the anode button The anode is made of a soft lead amalgam that will give inward 7 The hissing sound when the punch is wiggled out means that the tube is aired B Break the thin glass seal at the neck Method B for releasing the picture tube vacuum is to break the glass nub at the neck of the tube Read the procedure below first 1 Put on protective goggles gloves apron and shoes as specified in the picture tube safety precautions Check that there is still a metal implosion protection band about the panel of the 27 or larger picture tubes If the band has been re moved do not proceed with this vacuum disposal procedure There is a plastic keyway at the pins of the CRT Remove the plastic keyway by wiggling it off This exposes the glass nub that was sealed to maintain the vacuum With a pair of long nose pliers or diagonal cutters break this glass nub by squeezing it to shatter the glass The tube is aired 2 Picture Tube Safety Precautions Wear safety goggles even over glasses to prevent side glass entry Handle the picture tube with the correct size work gloves for your hands to avoid slipping Change to a thick long sleeve shirt to avoid exposing your skin to glass fragments Wear a thick rubber apron Wear shoes to protec
82. oblem Circuits Blinks 2 times pauses Shutdown Excessive B current demand or high FBT pulse amplitudes 4 times pauses and repeats Set Turns OFF Vertical Failure may also be Horizontal Failure since the vertical IC is powered by the FBT 5 times pauses and repeats 1 Raster but no video 2 Sound OK White balance failure weak picture tube or Low G2 voltage Continues to blink once a second No or defective Jungle IC301 communications No reply from an IC data bus is busy grounded or held HIGH Use the Timer Standby light to begin your troubleshooting Timer Standby light blinks two times The TV is shutting down because there is an excessive current drawn by the Horizontal Output Transformer or Transistor After checking for shorts in these stages test the protection trip circuitry Testing the Protection Circuitry 1 Locate Q300 base The collector lead of this surface mount transis tor is by itself If the collector is pointed up the base lead is at the left 2 Monitor the DC voltage with a DVM peak reading is preferred 3 Turn ON the TV T504 FBT R561 D561 gt AW ER gt 13V 135V mE I 0571 R572 13V SOURCE ale R549 FROM VERTOUT C509 3ovp p 541 3 Tv 5 EUN Dore TMER LZ H DRIVE R320 604 STBY T501 N C313 sey 5
83. oblem is a loss of vertical signal Unfortunately 13Vdc that powers the vertical IC541 comes from the horizontal stage FBT Therefore a horizontal failure will also cause the light to blink four times pause and repeat Excessive FBT Voltage An open safety capacitor C508 or high B voltage can cause the flyback transformer FBT to produce an undesirably high secondary voltage The FBT s secondary voltage at T504 pin 7 is monitored for excessive signal level This stage consists of T504 D574 IC521 Q300 IC301 001 Flyback pulses are rectified and compared to a reference voltage to de termine if they are excessive The 120Vp p T504 pin 7 pluses are recti fied by D574 into 109 2Vdc This voltage is reduced further to 8 76Vdc by voltage divider resistors R583 R582 and R584 and applied to the input of comparator 521 5 As long as the voltage at pin 5 is no higher than the 9 7Vdc at the negative input pin 6 the output of IC521 pin 7 will remain LOW 1 34Vdc The Jungle IC detects the comparator output The LOW from compara tor IC521 pin 7 is applied to Q300 base keeping it OFF as if it were not in the circuit This allows the horizontal pulses from Q502 collector and the internal voltage of 3 4Vdc to remain at Jungle IC301 pin 18 for nor mal operation T504 FBT R561 D561 gt AW ER gt 13V 135V mE I 0571 R572 13V SOURCE ale R549 FROM
84. olt ages into the other windings A positive voltage leaves T5001 pin 4 through C5004 to Q5001 s gate This positive voltage keeps the FET ON This second turn ON voltage is necessary because while Q5001 is in conduction the original turn ON voltage from R5003 has dropped to zero This waveform shows the gradual conduction of Q5001 drain voltage decreasing in channel 1 as its gate voltage increases channel 3 to about 2 3Vdc Model KV27S45 TV is OFF Channel 1 Q5001 Drain 100V div Channel 2 T5001 pin 4 10V div Channel 3 Q5002 collector 2V div Channel 4 Q5002 base 0 5V div Time base 2usec div FET Q5001 OFF At the beginning of the 1 cycle the positive voltage at Q5001 s gate decays This is because C5004 s charge has leaked off The reduced Q5001 s gate voltage begins to turn Q5001 OFF so its drain voltage rises MAIN BOARD R5002 470k C5004 05004 5007 680 0 001 R5008 10k 470pF ts 7 05006 R5012 7 6Vdc D5007 1 5 6Vdc lk VDR5050 R5009 C5006 e 0 001 C5009 0 001 22 D5001 4 7 STBY 5Vde SOURCE STANDBY POWER SUPPLY 40 CTV25J28 881 8 19 98 When FET 5001 is turned OFF its drain voltage rises above the 164Vdc supply voltage to about 300Vdc This is because magnetic energy stored in the SBT
85. oltage an ode The anode is located at the stronger bell part of the picture tube Read the procedure below first 1 Put on protective goggles gloves apron and shoes as specified in the picture tube safety precautions Check that there is still a steel implosion protection band about the panel of the 27 or larger picture tubes See the picture for the loca tion If it is not present do not air the tube Call for professional disposal Next the high voltage stored by the picture tube must be discharged The picture tube capacitor has two plates One plate is inside con nected to the HV anode button The other plate is outside con nected to ground The tube s outside conductive plate is a black graphite aquadag coating Use a high voltage probe self contained to gradually discharge the high voltage HV with the TV off Clip one end of a jumper wire to the chassis strap resting on the conductive black aquadag coating of the picture tube bell Connect the other end of the jumper wire to the anode terminal Leave the jumper there for about a minute to make sure the picture tube capaci tor is completely discharged During this time inspect the bottom area of the picture tube to make sure the ground strap is touching the black aquadag coating 2 13 5 Using a small screwdriver or center punch as a puncturing tool seat it into the center of the soft lead anode button cavity hole The puncturing tool must be able t
86. or 5 ABL voltage to IC301 pin 3 missing The picture blanking protection was explained in the video output docu ment of this training manual The remaining protection circuits shut the TV OFF They are shown here controlled by Micro 001 There are only three circuits that tell IC001 to turn OFF the TV Protection Circuits that turn the TV OFF Trigger Mechanism 001 Input Missing vertical pulses Loss of V pulses for 2 seconds at pin 17 Data into pin 37 Data into pin 37 Defective Stage Vertical Output FBT Output Excessive output voltage B Excessive current 93 Vertical Output Failure Pulses from the vertical output IC are monitored for activity by IC001 Two signals are output when the vertical output stage is receiving the drive signal and amplifying The main drive signal goes to the vertical deflection yoke The other signal is made inside the vertical Output IC541 s flyback generator and output pin 3 At pin 3 is a 30Vp p pulse that is reduced by R549 and limited by zener diode D001 to 5Vp p IC001 pin 17 receives and monitors this 5 volt vertical pulse to prove the Vertical stage is operating If IC001 detects a loss of these vertical flyback pulses for two seconds IC001 will turn the TV OFF As part of IC001 s diagnostic program after the set is turned OFF but not unplugged the Timer Standby light will blink four times pause and repeat This indicates the pr
87. orizontal out put transistor If the current becomes excessive Q571 conducts ground ing out the DC voltage from the Jungle IC301 pin 18 This ground causes IC301 pin 34 to send data to Micro 001 37 The data instructs 001 to shut OFF the TV allowing the horizontal output transistor to cool down DATA IC001 37 SET 9V 32 7501 Bt EO GO RISG C390 2 ct R347 C330 ON 680 275 0501 on OFF em EN R310 R318 HP PROTECT EU C313 IC301 R320 Y C JUNGLE CXA2061S Q571 OCP R532 C531 m S a HORIZONTAL DEFLECTION HV 92 Q502 H OUT C509 C508 135V 0502 8 R508 150 OHMS 3 E HORIZONTAL 507 YOKE pe 1504 FBT gt HV FOCUS VOLTAGE x G2 VOLTAGE P PICTURE SCREEN TUBE R535 100k 777 CTV25J32 885 8 12 98 Protection The TV s protection circuitry either blanks the video or turns the TV OFF Protection can be caused by a failure in one of these stages Failures Activating TV Protection Picture Blanking sound OK Shutdown TV OFF 1 Loss of R G or B drives from 1 Vertical Failure loss of boost pulse 01 IC541 pin 3 2 Ik signal from C board missing 2 Horizontal drive failure stops pulses powering the FBT The FBT stops powering vertical 1 541 3 Screen control misadjusted 3 Excessive FBT secondary voltage 4 Picture tube weak 4 Excessive B current to FBT and or H Output transist
88. ove the picture To locate this time the Micro uses the vertical timing VTIM signal from the jungle IC In previous Sony TV sets the 60Hz VTIM signal was crucial to the start ing operation of the microprocessor If there was no VTIM signal into the Micro there was no data or clock signal output and the TV would not work In the BA 4 chassis when there is no VTIM signals input serial data will still output the microprocessor As a result the TV will turn ON but the data and clock communications will be at a lower 50Hz frequency MEMORY STBY 5V 12V POWER ON SWITCH REG POWER ON SWITCH SET 9V VP NTIM DEGAUSSING CIRCUITRY Y C JUNGLE IC TUNER AUDIO PROCESSOR DEGAUSSING IN STEREO MODELS COIL POWER ON COMMUNICATION BLOCK CTV25J24 877 8 11 98 48 Degaussing Circuitry Concept The picture tube has three electron beams that are targeted to exact locations on the phosphor screen If a magnet were brought near the picture tube the electron beams would be attracted to it The electron beams would move out of place and not land on their correct phosphors When they strike the wrong phosphors a predominate color pattern ap pears at that portion of the screen near the magnet If only one electron beam is turned ON the TV screen will not display a pure single color screen This is called a purity problem Placing speakers next to the TV commonly causes purity problems
89. ply a Blanked Pix Blanked Pix 3Vp composite 3 2Vp p IK p horizontal pulses RGB output pulse 0 2Vp with a 0 7Vp p signal at pin 5 p of residual positive IK signal to horiz pulses at i the 3 5Vp p RGB Normal Pix signal with 110Vp p 2Vp p positive IK signal Q301 0302 Inputsame as Output Q301 C Clip the lower IC 70 1 5 Blanked Pix portion of the S EU f 0 4V p p of horiz signal with a 0 1Vp am plitude of p positive IK pulse the overall Normal P ix signal 1 5 Vp p RGB signal with a 0 2 positive IK pulse 1C 301 pin Same as E xtract IK 21 Q301 C pulses and use Output them to adjust RGB levels and unblank the video 180V 180V AN R385 R713 R706 R VIDEO IC301 Y C JUNGLE CXA2061S BUFFERS S R714 R707 G PICTURE TUBE 22 Q394 R384 0706 LL 180V p GAIN Ss CONTROL R715 AF Q393 16 180V FEEDBACK SIGNAL Q301 SET 9V R315 P aes D301 A er 5 1V D700 8 2V P R701 Q701 R322 K B K 2 5 10k R321 SUPPRESS 6 8k CONTROL SET 9V R702 R703 TUNING SYSTEM i IC001 A BOARD BOARD Q300 BLK R304 CONTROL ABL 521 7 R310 C306 R532 418 R534 HORIZ Lm B PULSE R533 FROM H OUT C CTV25J30 883 8 19 98 VIDEO OUTPUT 78 Video Block 27 with PIP An A V switch to accommodate
90. re added to the communications line when the channel up was pressed Similar data is present when other buttons such as video selection volume and display are pressed TV ON Remote Channel Up button pressed Channel 1 IC301 pin 5 VTIM Channel 2 001 36 Bi directional Data Channel 001 39 Clock Output to IC003 Channel 4 001 37 Bi directional Data All waveforms at 5V div Time base 2msec div Missing VTIM Timing Signals Unlike previous Sony TV sets in the BA 4 chassis if the VTIM timing signal from IC301 were missing data and clock would still output the Micro 001 5 36 39 and the set would appear to function normally except there would be no on screen display OSD The OSD needs vertical and horizontal timing pulses for positioning Without either pulse the OSD characters would not know where to appear The frequency of the data communications when this VTIM signal is miss ing is about 50Hz Normally the data and clock follow the 60Hz VTIM signal In the previous Sony TVs if the VTIM signal were missing nei ther data nor clock would output the Micro The symptom is that the set would remain blanked because there is no data to the Jungle IC This is no longer true starting with this year s BA 4 TV chassis MEMORY STBY 5V 12V POWER ON SWITCH REG POWER ON SWITCH SET 9V VP NTIM
91. reasing the oscillator frequency simultaneously increases the four voltages that leave the voltage output stage In this power con trol circuit the oscillator frequency stops changing when B has returned to 116Vdc or 135Vdc depending upon the set size This is how the power output control stage regulates the four voltages that leave the power supply PRIMARY INPUT TRANSFORMER AUDIO VCC 13VDC CONVERTER LOW VOLTAGE 12V OUTPUT STBY 5V B 116VDC POWER SUPPLY BLOCK 20 AND SMALLER CIV25J25 878 8 11 98 18 Converter In the past the word converter referred to a rotating machine consist ing of an electric motor driving an electric generator This system was used to change alternating current into direct current Changing AC to DC is also the purpose of this converter but itis done in an electronic manner The converter consists of two parts 1 The Rectifier 2 The Oscillator Rectifier The rectifier changes the 120Volts AC into DC using bridge rectifier D601 The output of D601 is a pulsating DC waveform commonly called the ripple The 60 Hz ripple has a crest high point and a trough low point C607 is the main filter capacitor that reduces the ripple amplitude by charging during a crest and discharging to fill a void during the trough However as the TV s current demand increases C607 cannot supply the additional current to the TV during the trough This is why there is a higher AC ripple
92. rizontal output transistor Q502 shorts in flyback trans former T504 or a short in a secondary winding would draw excessive current from the B line Excessive current drain will cause the TV to shut down allowing itself to cool off Components involved in this stage are R571 Q571 Q300 IC301 and 001 All the current from the B source flows through resistor R571 Transistor Q571 s emitter base junction is essentially placed across this resistor Resistors R574 R575 R572 and R573 pre bias Q571 C571 across Q571 b e prevents rapid scene changes from turning Q571 ON and triggering the protection circuit If R571 drops sufficient voltage to turn ON Q571 its conduction will ap ply a positive voltage through D581 into the base of Q300 turning it ON as well When Q300 turns ON the 3 4Vdc from IC301 pin 18 is grounded out This causes IC301 to send shutdown data from pin 34 to 001 37 001 responds by shutting OFF the TV set when 6 is brought HIGH After the TV is shutdown the Timer Standby light blinks two times pauses and repeats for as long as the set is plugged into 120Vac shooting Timer Standby Light During a failure that causes the TV to shutdown or go into blanking the Timer Standby light 0002 blinks pauses and blinks again The number of times it blinks identifies the defective stage Standby Timer Light Diagnosis and repeats TV powers OFF Standby Light TV Symptom Pr
93. s can be recorded Although the self diagnostic page will display the number of times a fail ure has occurred it will not be able to tell you exactly where the problem is only that it exists OSD BLK STBY 5V SET FROM IK IN 541 7 PROT ON OFF CRT IC301 V OUT IC001 L Y C JUNGLE TDA8172 MICRO STBY 5V Cath CXA2061S CONTROLLER 521 8 EDE M37273M8 Em PIN 7 PROTECT STANDBY TIMER LED TO CRT SELF DIAGNOSTIC SCREEN DISPLAY SELF DIAGNOSTIC IN BACKGROUND 2 O NUMERAL 70 MEANS NO FAULT 3 HAS BEEN DETECTED 4 0 5 1 NUMBER OF TIMES THIS PROBLEM 101 N A WAS RECORDED NUMBER OF TIMES STANDBY LED BLINKS SELF DIAGNOSTIC CIRCUIT CIV2540 893 7 15 98 100 Some of the reasons for the failure could be in this checklist Failure Checklist Times Standby Possible defect Light Blinks 2 1 Horizontal Output Transistor leaky shorted Excessive current 2 Flyback shorted or FBT amplitude 3 Flyback secondary load is shorted 4 Safety resonate capacitor opens C508 in this set 5 Sensing circuit defect IC521 Q571 and 0300 6 No reply from Jungle IC301 4 1 Vertical Output IC541 failure Vertical failure 2 Open R549 open foil path 3 Shorted D549 4 IC001 damaged by open D001 5 No vertical drive from IC301 pin 13 and 14 6 No vertical
94. s of the cathode and several metal rings called grids The grid name came from the controlling grids in a vacuum tube where the interelectrode elements were originally shaped like a screen mesh There is no structural resemblance between the picture and vacuum tube grids In the picture tube the grid rings are applied differ ent electrical potentials to focus shape and accelerate speed the elec trons from the cathodes Each part of the gun has a voltage applied to it for a specific purpose Trinitron Electron Gun Parts Name Purpose Applied Voltage Filament Heater Inside the cathode assembly Brings the cathode to emission temperature Test voltage 6 Vdc 0 64 Amp Actual voltage FBT pulse 6V rms Cathode assembly Houses the electron emitting chemical and the heater R G or B signal voltage 200V Cutoff No electrons output electrons output Grid 1 Control Grid Ground via current limiting resistor Reference potential for cathode emission Grid 2 Screen Grid Brightness limit 400Vdc approx Grid 3 Accelerating Accelerate stream HV from FBT Grid 4 Focus Sets focus point 300Vdc approx Focus Control range 200Vdc to 1kVdc Grid 5 Accelerating Post Accelerating HV from FBT FBT Flyback Transformer in consumer TVs Transformer is assembled with rectifiers in a doubler or tripler configuration to develop 25 35kV of DC
95. s on the screen If one were missing there would be no OSD or CC text The OSD characters generated from IC001 pins 50 52 are accompanied by switching signals applied to IC301 pin 29 These switching signals must go HIGH to displace the input video and enable the OSD R G and B that is input IC301 pin 30 32 Inside the Jungle IC the R G and B characters replace pieces of the video The level of voltage input to IC301 pin 29 determines if the input video is blanked or just reduced in brightness If IC301 pin 29 is brought to 5 volts the video will be blanked completely permitting the OSD to appear If IC301 pin 29 is brought to only 2 volts the video will appear at reduced brightness such as when the menu button is pressed The full 5 volt video blanking signal comes from 001 49 and the 12 brightness signal comes from 001 41 via R092 10Kohm The closed caption stage is within Micro 001 and only requires three signals for operation The H amp V sync information that is used by the OSD stage is also used in the CC circuits for positioning Video input IC001 pin 22 to extract the CC information from a line in the vertical inter val is the remaining signal necessary for operation Additional Signals necessary for the OSD and CC to function Input Location OSD Horizontal pulses Q502 collector Vertical pulses IC301 pin 5 CC CC video information Q305 emitter Horizontal pulses Vertical pulses
96. s the output transistor that drives two inductive loads and two circuits e The deflection yoke Develops a magnetic field in order to move the electron beam from left to right on the screen e The flyback transformer Develops high focus screen and 13Volts for the picture tube and TV s vertical section e AFC feedback circuit Used to monitor the frequency of the horizon tal oscillator AFC feedback A sample of the horizontal output signal from Q502 collector is used to keep the horizontal oscillator locked to the incoming video sync The high voltage pulse at Q502 collector is reduced by voltage divider C509 and C508 to 23Vp p and again by R318 and R320 to 5Vp p The 5Vp p signal passes through C313 and R310 to IC301 pin 18 Inside IC301 this horizontal output signal is compared to the incoming video sync and a correction voltage is developed The correction volt age is used to keep the frequency of the Jungle s horizontal oscillator in step with the incoming video This is the automatic horizontal frequency correction AFC DATA IC001 37 SET 9V 32 7501 Bt EO GO RISG C390 2 ct R347 C330 ON 680 275 0501 on OFF em EN R310 R318 HP PROTECT EU C313 IC301 R320 Y C JUNGLE CXA2061S Q571 OCP R532 C531 m S a HORIZONTAL DEFLECTION HV 90 Q502 H OUT C509 C508 135V 0502 8 R508 150 OHMS 3 E HORIZONTAL 507 YOKE pe 1504 FBT
97. sphors to produce a white dot An incorrect adjustment of this CV control causes the outer beams to pass through other slots in the aperture grill The outer beams will pro duce a red and blue dot near the green one instead of a single white dot There is no CV control in newer Sony TV sets The CV control end of the picture tube s high voltage resistor is grounded so there is still a differ ence in convergence plate potiential Plastic rings with tabs called V Stat control permit you to magnetically perform the same static conver gence as the CV control These plastic rings are located at the back of the yoke and contain a few small pieces of metal molded into the plastic This metal alters the yoke s magnetic field for beam convergance FOCUS CONVERGENCE G1 G2 G5 PLATES SSS CATHODES W WW A Hmm AN A d lt w EXTERNAL TO TUBE CTV25J1 800 5 15 98 CONVERGENCE PLATES The Trinitron Screen In front of the electron gun are the Deflection Yoke Aperture Grill AG Phosphor Stripes Getter Assembly Deflection Yoke The yoke consists of two coils of wire mounted on the glass bell of the picture tube in front of the internal convergence plates One coil gener ates a magnetic field to move the electron beams in the X axis and the other coil moves the beams in the Y axis Guided by the deflection yoke three electron beams first s
98. ssions Their amplitudes are used to white balance the picture while the TV is ON This IK circuit is designed to look for three IK pulses returned from the picture tube If IC301 detects a missing IK pulse within two sec onds after the set is turned ON the video is blanked muted The two seconds allow time for the picture tube to warm up This blanking state is relayed as data from IC301 pin 35 to 001 37 001 causes the Timer Standby light to blink five times pause and repeat The set remains ON during this video failure so the sound is still present When there are multiple failures the two blinking light failure has a higher priority over the four blinking light failure By the same logic the four blinking light failure has a greater priority than the five blinking light fail ure For example if multiple failures caused all of the two four and five blinking light failures to be stored in memory the Timer Standby light would blink two times pause and repeat when the TV shut down The number of failures has nothing to do with how many times the light blinks Display By using the TV s remote control you can access this failure information stored in memory Once 001 receives the self diagnostic access com mand at pin 12 001 powers ON the TV The failure information from 001 is sent to the Jungle IC301 as On Screen Display OSD video levels A OSD signal accompanies the OSD video levels from 001
99. t your feet Find a partner to help move or reposition the picture tube Your partner needs protective gear more than you do BUTTON lt NECK gt OUTER COATING gt __C0nWK I YRK ILOI IK I IIIIxII lt II lt II IINIIIOI IKU IeIII IIO I_II I I I I I I IO I I I I R I J III I 0 eK I III IV SUI IC WOYSI STEEL IMPLOSION BAND METHOD A VACUUM DISPOSAL 14 KEYWAY NUB UNDERNEATH METHOD B CTV25J10 859 5 26 98 Overall Block Diagram A TV set consists of several stages or blocks e Power Supply Power On Communications e Video Processing e Deflection Each stage has a purpose and is activated in sequence to properly power up the set Power Supply The purpose of the power supply is to convert the incoming 120Volts AC to some of the DC voltages required to operate the set the most impor tant of which is the Standby 5Vdc Standby 5Vdc is present when the set is plugged in and is used to power the Micro so it can respond toa TV power ON command from the user Power On Communications Three things occur when the power button is pressed Degaussing of the picture tube Application of power to the Jungle IC e Data communications When the TV is powered ON the Micro turns ON the degaussing circuit for 2 2 seconds Its purpose is to pass AC through the dega
100. the second tuner and the Picture in Pic ture PIP board are the only sections have been added into the 27 BA 4 chassis The video signal flow is the same as in the 20 BA 4 chassis A V Switcher Inputs Outputs Inputs Outputs V 1 is the main picture video to the Jungle IC Tuner 1 Tuner 2 optional V 2 is the video signal to the PIP board Video 1 Composite or S Video Video 2 optional Video 3 optional 79 Picture in Picture PIP Board Signal Flow PIP Board Input Outputs Input Output Video 1 from the A V switcher IC Luminance Y R Y V and B Y U PIP insertion signal YUV TUNER 1 TUNER 2 VIDEO CRT 2 VIDEO OUTPUT CATHODE U swt ea VIDEO 1 gee ot EKZ JUNGLE VIDEO 2 Y MONITOR DIGITAL COMB FILTER CONTROLLER FROM FBT CIRCUITRY VIDEO BLOCK 27 WITH PIP CTV25J35 888 7 29 98 80 Picture In Picture Processing Overview The purpose of the Picture in Picture circuitry on the small P board is to digitally compress the normal 525 line transmitted picture into a small picture 1 9 its original size To do this the PIP processor IC must first take the analog luminance and color information and convert it to digital format Then using the vertical and horizontal sync pulses this IC elimi nates information which makes the picture smaller The remaining infor mation is then stored into m
101. ts the Jungle IC can select from They are shown in the chart below Jungle IC Inputs Name IC001 Switch Access Pins Tuner 43 Data IC001 pin 35 Channel TV video buttons Video 1 2 amp 4 Data IC001 pin 35 TV video buttons Video 2 41 Data IC001 pin 35 TV video buttons OSD 30 32 5V positive pulses from Display or Menu IC001 pin 49 replace buttons pieces of video with OSD character pieces 2Vdc from 001 41 reduces video brightness menu Closed 30 32 5Vdc from 001 49 Select caption Caption blacks out video to form vision from the CC the CC text box and allow Menu CC does CC characters to appear not appear in most programs Y amp C 7 9 Data 001 35 Selected when from the the ID codes comb filter service adjustment mode identify the model with a comb filter Picture in 37 39 YUV sw into IC301 pin 36 PIP button on the Picture Switching pulse remote control High PIP picture Low Normal video input OSD On Screen Display of characters menu or channel numbers 69 OSD and Closed Caption Before the OSD circuit can function within IC001 it needs timing signals Horizontal pulses from the horizontal output transistor Q502 collector are applied to 001 17 Vertical timing signals from the Jungle IC301 are applied to IC001 pin 2 Both timing signals are necessary to position the OSD character
102. ts differently In the 27 screen BA 4 chassis there maybe an additional video input and video output jack Therefore a video switcher IC is used before entering the Y C Jungle IC as composite video or Y amp C S video 61 Digital Comb Filter Some TV models have a digital comb filter connected to the Y C Jungle IC These models must be identified to the Jungle IC so it knows to route composite video V out to the filter and receive luminance Y color C information from the filter as a departure from the internal video process ing path Data from the Micro identifies the presence of the external comb filter This data comes from ID codes found in the Micro and memory IC The technician can access them from the service mode further infor mation is in the service manual The purpose of a comb filter is to separate a composite video signal s luminance Y information from its color C information Digital comb filters have gone further There are currently four types of comb filters available on the TV market 1 Analog Comb Filter This type of filter will help increase the picture resolution to above 330 lines Digital Comb Filter This performs the same function but the sepa ration is done in the digital domain Digital 2 D Adaptive Comb Filter This filter employs a memory to analyze the picture information in two dimensions 2 D vertically and horizontally The result is not only Y C separation but also hi
103. ussing coil that surrounds the picture tube The AC field that is created erases re sidual magnetism collected by the tube s metal aperture grill Next the Micro IC turns the TV ON switching power from the power sup ply to the Y C Jungle IC The Jungle IC produces vertical VD and hori zontal HD pulses to create the remainder of the voltages necessary for the TV to operate This turns ON the TV see Deflection After the TV turns ON data and clock communications from the Micro IC are applied to the tuner and Jungle IC The tuner is instructed to tune to 15 the last station viewed and the Jungle IC is instructed to select the last video input used before the set was turned OFF The communications data and clock lines are always active when the TV is ON Video Processing The Y C Jungle IC selects a video signal from one of two external video inputs or the internal tuner video for processing Contrast brightness color level and hue are also controlled in this IC A change in level is received by the Micro IC stored in memory and communicated to this Y C Jungle IC thorough the data and clock inputs The final stage within this IC converts the information to individual red green and blue RGB output voltages The higher the voltage the greater the intensity of that color The three RGB voltages are applied to the video output stage The purpose of the video output stage is twofold 1 To invert the signal 2 To convert the
104. weep across the aperture grill along the X axis from left to right from the front as you would watch TV At the end of the horizontal sweep the beam retraces back to the left side of the screen Meanwhile the yoke s magnetic field moves the three beams down Y axis one line before the beams sweep horizontally across the aperture grill again This process then repeats Finally at the bottom right corner of the picture the beams are returned to the top left corner of the screen The deflection yoke has difficulty providing a magnetic field to sweep the beam so it matches the screen shape The yoke s magnetic field is stron ger at the corners of the picture then at the top bottom and sides X amp Y axis Improvements in deflection yoke construction have compensated for the reduced top bottom deflection Y axis Along the X axis the weaker magnetic field causes the picture to look like an hourglass This is be cause there is insufficient picture scan which produces a dark area at the left and right sides of the picture tube Increasing the current through the horizontal windings of the yoke com pensates for this hourglass picture The yoke current is then gradually increased line by line until the middle of the picture for maximum width the curve is reduced as the beam continues to scan downward The result is a straight picture This type of yoke distortion to the picture is called pincushion distortion The correction cir
105. why IC603 is labeled a power control device Soft Start Circuit The soft start circuit consists of Q608 C632 and the PRT transformer T602 Its purpose is to keep the B voltage initially low at power ON When the TV is turned ON the following devices energize the power relay supplying power to the converter oscillator TV Power ON Device State Micro 001 6 LOW Q604 OFF collector is 7 5Vdc Q670 ON collector is 0 3Vdc RY602 Energized contacts closed When power is applied to the converter oscillator voltage is output the secondaries of PIT T603 Current from 0606 and 0607 12V source takes the following path to ground Soft Start Path Part Input Output D606 amp D607 Anode Cathode band end R622 T602 PRT Q608 Emitter Base C632 Q608 Emitter Collector ground This path causes current to flow through T602 s control winding at pins 7 8 Current flow in this control winding causes the converter oscillator frequency to shift to a higher frequency at start up This keeps the B voltage low so it does not rise above 135Vdc at power ON 167VDC AC p an a o CONVERTER OSCILLATOR 7 5V gt ON OFF B RY602 SOURCE e Lee 135V L 4 A 135 622 10 5 12 SOURCE R673 7 5V gt w 0604 N R642 rH 47k 7 5 R674 22k
106. y of the oscilla tor will be different when the set is turned ON Oscillator Characteristics Resonate parts L T603 uH C610 C611 C614 C615 C616 Frequency 104 2 71 5 2 TV OFF no load TV ON Oscillator Testing After replacing parts in this stage check the following with ohmmeter before gradually applying power e Shorts in T603 secondary winding loads secondaries Check zener diode D610 first see Converter Voltage Output diagram below e Shorts in a flyback secondary winding loads Testing Procedure Steps 1 Plug the set into an isolated variable AC transformer must contain an AC ammeter and voltmeter and set to zero volts AC 2 Unplug the degaussing coil so the AC ammeter will only show the TV current consumption 3 Gradually increase the AC voltage to the TV while observing the fol lowing The AC current on the variable AC transformer The oscillator supply voltage DC at fusible resistor R606 The DC voltage at the collector of the bottom transistor IC601 1 Gradually increase the AC voltage The DC voltage at the collector of IC601 1 will always be half that of the oscillator supply voltage at R606 if the oscillator is OK This is true at any time even when the AC voltage is being increased The oscillator will start when there is about 5 6Vdc at R606 FROM 1603 F601 D601

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