CHASSIS CTU-AA SERVICE MANUAL - Page de test
Contents
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6. XO XO XO XO LO XO XO OY 7 CN CY CY 00 QN CY Ox LO LO XO XO XO 00 CY ANN ANN ANN HK H 1 m 1 15 Hi d i p d m O0 O0 O f fu f CO CO CO CO IB 2 HiHRmJgummmuoudammoommrmnammmsk I Ey BS 1 2 x St CN LO XO QO 7 00 n 0 e CON SP XO eA CON CO SP LO XO e e CO 00 OY CN 00 sf 10 XO 00 OY XO 0 e dn lt lt XO sr L0 D 00 OY QO QN 0 10 XO 00 O dn CO lt c n n CO QI 00 00 OY OY OY QO QO QO QO cm O OY Oy O OY OY O O QO QO QO QO str XO XO c n O O rm mn n d OI OI OQ QO QO QO O FA n mn mnH e c COIOJ OL OY CO OI QI 00 00 0 00 00 0 CO Q Q QO QO QO QO QO QO QO QO QO QO QO rm rm m rmn rm m CN C CN CO CO ON 00 00 00 00 00 00 00 00 00 00 00 st lt SP SP SP XO XO XO XO XO XO XO XO CO QOO QO QO QO O n d CN CN CX COL COL NNN NNN NNN 00 00 00 00
7. Vert sync separator It is an internal integrator to separate frame sync pulses from CVBS Vertical divider system The divider system uses a counter that delivers the timing for the vertical ramp generator in the geometry processor The clock is derived from the horizontal line oscillator Mode used is automatic 50 60Hz identification with 50Hz priority Vertical sawtooth generator pin 25 26 A reference current of 100mA is realized at pin 25 by means of an internal reference voltage 3 9V and resistor R3341 This 100mA reference current is used to derive 16mA current to charge C2340 pin 26 during vertical scan The charge current can be adjusted with the bus control VERT SHIFT The external capacitor is discharged during vertical retrace by the vertical divider system Vertical geometry processor The saw tooth signal that is derived from the sawtooth generator can be controlled by bus Control adjustments are 5 VERT SLOPE VERT AMP and VERT SHIFT See chapter 8 Vert output stage pins 21 22 The vertical geometry processor has a differential current output to drive a DC coupled frame deflection 7401 EHT compensation pin 36 A voltage inversely proportional of beam current proceeding of pin 8 of line transformer 5545 diagram D is applied to pin 36 to stabilize vertical amplitude from EHT variations Vertical guard input pin 50 A vertical retrace pulse proceeding from pin 8 of
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9. 7401 is added to cut off voltage at pin 50 this pin has 2 separated functions cut off function see chapter 7 1 5 If there is not pulse or its level is not correct should be above 3 65V 0 8msec the set goes to standby mode See chapter 7 7 1 Protections 7 1 8 Microcontroller Text Following there is an explanation of the different functions of the microcontroller indicating pins number assigned Tuning pin 4 The unit has a VST Voltage Synthesized Tuning system This system works by tuning to a station on the tuner through a linear variation of the tuning voltage V VARI from OV to 33V applied on pin 2 of the tuner It is generated on pin 4 of the and converted to an adequate level for the tuner using T7605 While searching are always reading internally AFC Automatic Frequency Control and video identification signals When video signal is identified uC stops searching and do a fine tuning to reach a right AFC value Control key 5 Pin 5 is activated by a DC voltage When control keys not activated a voltage of 3V3 is produced by R3618 If one control key is activated this pin is connected to ground directly or by a resistor R3665 R3667 Diagram C decreasing its voltage There 3 voltage levels depending of the key used for MENU 1V for P and 1 9V for Mute output pin 6 This pin is 3 state output used to control the sound amplifier see chapter 7 4 States are OV open an
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11. also has an embedded microcontroller The CTU AA chassis is designed to accept 2 different ICs in the position 7015 TDA9350 for TXT models and TDA9380 for no TXT The associated circuitry is the same The small signal includes IF detection video processing chroma decoder RGB sync processor and sound decoder mono sets It is fully controlled by the embedded microcontroller The microcontroller contains an specific program that assures all the functions of the appliance including 2 menus one to control the set see Instructions Manual and another for Service Mode see Service Instruct chapter 8 For stereo models sound decoder IC 7101 is controlled also for IC 7015 by 12 bus The IC for TXT sets TDA9350 contains a teletext decoder including the following functions TXT on off reveal freeze temporary cancellation clock subcode zoom index flof page X 26 and 8 30 packet decoding station identification and start up page z z oio S 2 S a EN bs gt lt Ko a a 4 c gt u gt a oo
12. gt AAA d OSSA EAE 2095 95 6 CAE CAE qN52S0 25 696 LS 8 7996 092 BESS NITTWLX d 1xs iNI atc ec L 5996 ETS CO 092 6L9T _ LnO IVIX 1oqv 1 d dtt 65 9 azz Sud sau 6595 989 uod co GHVOSASM 1296 1998 09 5 8196 00 WEAE 52 NOZZ 292 2200 819 096 0192 1192 gt OST MST 1 XOT 1098 19 Acc 9096 ava dene 69 2LI8Wd 096 0196 atoe 2196 096 lt 091 oa 8296 oot Baas 29 B EET 2099 1 4 SAT SAT 198 9 1d 2096 tose 5 9 z B HWIOHLNOOOHOIN V ZAZ ZAZ 9 l ls lt 1 0011 cgoe 0896 2896 HOSSHOOHd 8292 guis j ea lt EAE STOL N Ny lt 9695 Dl 3103 18 6 Electrical Diagram A B COMPONENTS RGB amp DISPLAY DISPLAY y 200 6201 33 L6 200 6216 200 6229 7200 TDAG107Q 6 2 21 BAV21 1 2202 2204 22
13. pin 1 switch to low level to make Power Supply in burst mode see stand by 7 5 3 OSD outputs The RGB and fast blanking signals used for On Screen Display OSD and also for TXT are internally inserted to RGB outputs pins 51 52 53 Oscillator pins 58 59 A 12 MHz oscillator is determined by a 12 MHz crystal 1679 between pins 58 and 59 pin 60 Power on reset POR is internal activated when the set is switched on If the shows abnormal behaviour it is advisable to reset it switching off on the set Reset can be done also by a short circuit between pins 60 and 61 RC5 pin 62 The commands transmitted by the remote control handset are received by infrared receiver 1685 and passed to the microcontroller for decoding EEPROM pins 63 and 64 The microcontroller is connected to non volatile memory 177685 EEPROM via bus 2 The following information are stored in the memory Channel data including tuning voltage and band of all the channels Personal preferences PP menu mix and child lock on user menu All settings included on Service Menu 7 1 9 Supplies and decoupings Small signal analog supply pins 14 39 The same 8V supply coming from line deflection is connected to pins 14 and 39 for small signal processing A separated supply C2036 feeds video and sound traps circuit If 8V supply is not present at pin 39 or 14 during the first 4 seconds after switch ON the TV set the micropr
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15. 49 decreases PWL This circuit is an internal detection circuit which comes into action if the difference between measurement DC level and white level exceeds approximately 2 6V Then a current of 200 is internally produced to discharge 2298 and Vpin 49 decreases RGB output circuit pins 51 52 53 RGB outputs are drived to RGB amplifier Diagram B Continuous Cathode Calibration CCC pin 50 This circuit is an auto tuning loop which stabilizes the black level offset as well as the cathode drive level gain of each gun Pulses in 3 consecutive lines R G and B pins 51 52 53 at the end of frame blanking are used on alternating fields one field for black level following for cathode drive level Cathode currents of 8mA for black level and 20mA for cathode drive level are stabilized Cathode current is present at pin5 of 1C7200 Diagram B and measured on pin 50 RGB outputs are adapted to keep cathode currents measured for example when VG2 voltage is adjusted DC level of RGB outputs is automatically corrected Warm up detection circuit pin 50 At the start up a DC voltage of 2 5V is present in the RGB outputs pins 51 52 53 As soon as beam current is detected on pin 50 RGB circuit starts in normal operation If RGB circuit is damaged or grid 2 is low the RGB circuit could not start black picture due to current is not detected 7 1 6 Horizontal synchro Start up The horizontal oscillator starts is commanded by mic
16. CVBS 0 2 2V RMS 6 10K 18 CVBS L 0V5 RMS 61K 19 CVBS 1Vpp 75W 20 CVBS 1Vpp 75W 21 Earthscreen L 0V2 2V RMS 010K 0V7pp 75W 0 2V int 10 12V ext 0V7pp 75W Head phone 0V7pp 75W c 8 to 6000 Mono 25mW at 320 0 4 int 1 3V ext 75W Stereo 2 6mW at 320 3 5 0 3 Mechanical instructions For the main carrier two service positions are possible 3 1 A For faultfinding on the component side of the main carrier B For de soldering activities on the copper side of the main carrier Position A can be reached by first removing the mains cord from it s fixation then loosen the carrier lips 1 and then pulling the carrier panel 2 for approximately 10cm Position B can be reached from position A after disconnecting the degaussing cable Put the carrier on the line transformer side Fig 3 1 Fig 3 2 4 Oscillograms mm J Y TES aD TP10 11 D fF 5 0 TP6 D 100 7 DC D 3 4 DC TP8 D gt 13 4 DC
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18. RF signal amplitude 1mV Adjust the value of AGC start item 6 of Service menu so that voltage at pin 1 of the Tuner 1001 is 3 7V 8 4 White D 8 4 1 Manual cut off Item 8 of adjusting values should be 00 see table 8 1 that means set is in automatic cut off However it is possible that RGB do not start black picture due to grid 2 is not adjusted In this case we recommend to change to Manual cut off Item 8 01 pre adjust grid 2 to have a good picture and change to automatic cut off Item 8 0 before continue adjusting see warm up detection circuit in 7 1 5 8 4 2 Grid 2 Connect a white pattern generator Adjust contrast at 00 and brightness at 36 00 and 24 in the service menu because hexadecimal values are used Put parameter 1 of the service menu ADJUST VG2 1 An arrow will be displayed on the left upper corner Adjust VG2 potentiometer in line transformer till the arrow will be transformed to a square In a few seconds arrow will be disappear and ADJUST VG2 parameter will be come back to 00 8 4 3 White checking Connect pattern generator containing grey scale Adjust the set to normal operation and reduce the saturation control to minimum Allow the set to warm up about 10 minutes and check visually if the grey scale has correct colour f not enter to Service menu and adjust G and B gain items 14 and 15 until a desired grey is obtained In the case that adjusting is difficult start again wit
19. disabled in this case the vertical guard blanks the RGB outputs but TV does not enter in Standby mode To disable Vguard item 8 of Service menu MANUAL C O should be 01 See chapter 8 1 Due to a change in MANUAL C O is difficult to do if the set switch to Standby Vguard can be disabled also connecting a diode 1N4148 in series with a 2K2 resistor between pins 10 and 7 of IC7015 Anode at 10 Be careful to disconnect this network after the set is repaired 7 7 2 Protections 7514 Diagram D Pin 1 Primary current is sensed by an internal resistor for the IC If this current is increased to 5A peak supply works in a intermittent way ON and OFF That can be provoked for a short circuit on secondary outputs Pin 3 If Vpin3 is lower than 9V the under voltage protection stops the supply If Vpin3 is higher than 32V over voltage protection limits output voltage 8 ELECTRICAL ADJUSTMENTS 8 1 Service mode The signal processor 7015 is fully controlled by 12C so that the most of adjustments of the set can be made by Service menu Enter in Service mode Select program 75 and press at the same time OSD key on RC and MENU key on local key board during 4 seconds Service mode is indicated by a S symbol on the down left corner of the screen Note Controls volume contrast brightness and saturation will be pre adjusted to the mid position Display Service Menu When the set is in service mode it i
20. flash over protection Continuous Cathode Calibration pins 50 This circuit is auto tuning loop which stabilizes the black level offset as well as the cathode drive level gain of each gun Pulses in 3 consecutive lines R G and B pins 51 52 53 at the end of frame blanking are used on alternating fields one field for black level following for cathode drive level Cathode currents Cathode current feedback pin 5 Cathode current used in Continuous Cathode Calibration circuit See 7 1 5 is obtained at this pin and feedback to pins 50 of IC7015 Diagram A White adjustment Gain and cut off point of RGB amplifiers can be adjusted by 12 in the service menu See chapter 8 Anti spot circuit When the set is switched off the capacitor 2208 keeps charged and a negative voltage is put at VG1 of the tube 7 3 DEFLECTION Diagrams A D 7 3 1 Frame deflection Diagrams A Full bridge vertical deflection output performed by the integrated circuit TD8357J 7401 Frame supplies pins 3 6 There are 2 supply voltages 12V pin 3 is the main supply and 45 6 is used to supply the output stage during flyback time Vertical inputs pins 1 2 pins 21 22 The output currents proceeding from pins 21 22 of IC7015 are converted to voltages by resistors R3411 12 in such a way that 2 inverted sawtooth are present in the differential inputs of amplifier pins 1 2 Vertical outputs pins 4 7 Verti
21. in its original condition The cabinet should be checked for defects to avoid touching by the customer of inner parts The insulation of the mains lead should be checked for external damage The mains lead strain relief should be checked onits function The cableform and EHT cable are routed correctly and fixed with the mounted cable clamps in order to avoid touching of the CRT hot components or heat sinks The electrical resistance between mains plug and the secondary side is checked This check can be done as follows Unplug the mains cord and connect a wire tween the two pins of the mains plug Switch on the TV with the main switch Measure the resistance value between the pins of the mains plug and the metal shielding of the tuner or the aerial connection on the set The reading should be between 4 5 M and 12 M Switch off the TV and remove the wire between the two pins of the mains plug Thermally loaded solder joints should be oldered This includes components like LOT the line utput transistor fly back capacitor Maintenance Instructions It is recommended to have a maintenance inspection carried out periodically by a qualified service employee The interval depends on the usage conditions When the set is used in a living room the recommended interval is 3 to 5 years When the set is used in the kitchen or garage this interval is 1 year During the maintenance inspection the above mentioned safety ins
22. is necessary for SIF demodulator By means of a 200mA current generator at pin 8 a 2V reference voltage is produced at pin 7 7 7 5 If TV does not start or it switches to stand by try to start again in few minutes and if problem remains check protection pins explained following 7 7 1 Protections in 7015 Diagram A Pins 14 39 If 8V supply is lower than 6V 39 or pin 14 during the first 4 seconds after switch ON the TV set the microprocessor goes to Standby mode See also chapter 7 1 9 Pin 50 If the vertical retrace pulse at this pin is not correct should be above 3 65V 0 8msec during the first 4 seconds after switch ON the TV set the vertical guard blanks the RGB outputs and the TV switch to Standby See also chapter 7 1 7 This protection operates in the following situations When the vertical deflection fails and there is no pulse When the vertical retrace pulse is higher than 0 9msec for example vertical amplitude is too high An extra protection is obtained when there is too much current in the CRT for example 200 supply is missing because in this case DC level of pulse is lower by means of cut off signal See fig 7 7 1 6v 3 65v 3 65v 2 8v Correct Vertical 3 2v Failure Deflection 0 8v 0 mS 20 mS 0 mS 20 mS Fig 7 7 1 Vertical guard protection To repair the set more easily Vguard protection can be
23. made by a capacitor on pin 29 De emphasis and audio out pin 28 De emphasis is made by 2102 at pin 28 The signal at this pin is drived to the euroconnector sound output see Diagram C by transistor 7104 External audio in pin 35 External audio proceeding of pins 2 6 of euroconnector is applied to this pin Selection between internal or external is done by an internal switching controlled by I2C see INT EXT chapter 7 6 Audio out pin 44 After a volume control by 12C this output is drived to the input of the final sound amplifier 7187 Diagram C Stereo sets SIF signal pin 38 Video signal containing sound signal is drived to sound stereo processor IC7101 see chapter 7 6 and diagram E 7 1 3 Video processing Video switches pins 40 42 The internal CVBS signal proceeding of pin 38 is now fed to pin 40 of 7015 External CVBS proceeding from pin 20 of Euroconnector is present on pin 42 of 7015 The IC switches between internal and external are controlled by I2C bus see INT EXT chapter 7 1 8 The selected CVBS signal is internally supplied to the synchronization teletext acquisition circuits and the video identification circuit for IF ident Luminance processor CVBS is also internally applied to luminance processor which is composed of chrominance trap filter luminance delay line and peaking circuits Sharpness control modifies peaking by 2 7 1 4 Chroma processing This circuit is an internal
24. no pins associated automatic decoder for Pal and NTSC systems commanded by 12 bus ACC and chroma filter Video signal coming from video switches is supplied to PAL NTSC chroma bandpass filter via a variable gain amplifier which is controlled by ACC and ACL detection circuits The dynamic range of the ACC is 26dB and detects only the burst amplitude The ACL is a chroma amplitude detector and is active when the chroma burst ratio exceeds approximately 3 It ensures that CVBS signal to chroma bandpass filter is limited for large PLL DCO Chroma PLL is integrated and it operates during the burstkey period the DCO digital controlled oscillator generates a subcarrier signal Fsc in phaselock with the incoming burst signal The reference signal for the DCO Fref is derived from the crystal oscillator 1679 Different colour frequencies are internally switched by The hue control rotates the DCO reference phases H90 from 40 10 40 degrees for NTSC signal bus PAL NTSC demodulation The 0 amp 90 signals are supplied to the burst demodulator circuits to obtain B Y and R Y respectively Chroma delay lines used in demodulators are internal 7 1 5 RGB processor External RGB inputs pins 46 47 48 RGB inputs coming from euroconnector see diagram C are AC coupled C2291 92 93 and converted internally in YUV signals Then are switched with internal YUV YUV SWITCH by fast blanking Fast blanking external pi
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27. 3XX block diagram 7 1 1 IF detection IF detection is intercarrier type that means sound and picture are detected in the same circuit PIF IF amplifier pins 23 24 IF signal coming from pin 11 of the tuner 1001 is filtered by the IF SAW filter 1015 and applied to IF amplifier of IC7015 by means of 23 and 24 input The IF bandpass characteristic is determined by the SAW Surface Acoustic Wave filter PLL demodulator pins 37 58 59 The IF signal is demodulated with the help PLL detector which is used to regenerate the IF reference signal Reference signal is determined by the PLL loopfilter pin 37 and calibrated by microcontroller x tal pins 58 59 It is alignment free Demodulation is achieved by multiplying reference signal with the incoming IF signal AGC pin 27 The IF AGC time constant is internally fixed The tuner AGC voltage pin 27 is applied to pin 1 of the tuner and adjusted by microcontroller see chap 8 4 Video output pin 38 This baseband CVBS signal with 2 5Vpp sync inclusive of nominal amplitude contains the FM intercarrier sound signal Sound is filtered out by a ceramic trap 1032 or 1033 which frequency can be different depending on the system 5 5 MHz for Pal BG and 6 0 MHz for Pal 7 1 2 Sound processor Mono sets FM demodulation pins 31 29 FM sound is filtered from CVBS pin 38 by a loopfilter pin 31 and demodulated Decoupling sound demodulator is
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29. SERVICE MANUAL CHASSIS CTU AA 1 Technical specifications CHASSIS CTU AA Mains voltage Power cons at 220 Aerial input impedance Min aerial input VHF Min aerial input UHF Max aerial input VHF UHF Pull in range colour sync Pull in range horizontal sync Pull in range vertical sync Picture tube range 4 TV Systems Indications VCR programs Tuning and operating system UV1315A IEC VST 01343 IEC VST Local operating functions 220 240 V 10 AC 50 Hz 5596 35 W 147 50W 207 21 Stand By 75 coax 400V 180mV 300Hz 600 Hz 5 Hz 14 20 21 Mono 25 1W 147 16 2W 20 21 Stereo 2 16 2x4W 217 PAL BG PAL I PAL BG SECAM BG DK PAL BG I SECAM BG L On screen display OSD green and menu 1 LED red in ON and blinking red in stand by 99 vst VHFa 48 168 MHz VHFb 175 447 MHz UHF 455 855 MHz UHF 455 855 MHz Vol Prog contrast colour brightness and sharpness and hue on program AV with NTSC signal 2 Connection facilities Euroconector 3 4 2 3 E 4 2o 5 Blue o 9 6 o 7 Blue o 5 8 5 9 4 229 10 0 9 11 Green 12 5 5 13 Red 14 15 lt gt 16 RGB status Audio C Audio Audio Audio 4 Audio CVBS status 1 R 0V5 RMS 6 1K 17
30. T V 258 223 1159 armaa 0952 4 E ever ES oco 2 27 WIT 8656 pL 0001 7 4 4017 2555 Cet ALP 5 6 jp vise ES 723 14405 4 723 62 249 6269 Y f oal NT l 0162 SIIN Sd 5 t d nee 1992 554 001 TLSE 6 WOT SLGL or POSE EAE 11 74 74 spe 2 2 8456 US ee io m ne s34 Zak 2166 n T 8 8082 082 Sako CV k V S Lar oesz P 6 5 a p S Thos Lco TS V WS TOTH Cc 1066 228 05 055 bess PEE 2088 WES ESV H ooss P 5 0 95255 sau V HVZI 70 lt 6 Em oTo g GOST L 056 E cud V zz 052 ssnwoad V Led sea 2 9ASO Re lt 6199 Ry Ry m S 8 SLYE 15558 G 4 MZ T 06 L ead L 004 28 9 5 AS 1 8E7E M S 6 y 0579 OSHE Sect e OMS MOT 8PIPTT 14123 248 0099 azz an sos veh tr Cms 90576 T V 012 ESPZ L 5 1 9 Svo 4 0499 n 2509 0196 O V NLD V v 52
31. cal output is DC coupled to deflection coil That means linearity adjustment is not necessary HF loop stability is achieved by a damping resistor R3413 Feedback input pin 9 A voltage proportional to current deflection is present in R3415 16 and a feedback to pin 9 Vertical flyback This signal is internally added to vertical output pin 7 using supply voltage at pin 6 VGUARD circuit pin 8 This circuit generates a high level during flyback period and is used to protect the TV set in case of a vertical failure See protections chapter 7 7 7 3 2 Line deflection Diagram D The final line transistor is driven by the transformer 5441 whose primary winding is driven by the transistor T7440 connected to the line drive output of IC7015 33 The horizontal deflection stage is carried out in a conventional way with the deflection transistor T7445 and line transformer 5445 Beam current info is present at C2460 There are the following supply voltages obtained from line transformer 5545 Frame supply 12B Main frame supply present at capacitor C2455 Flyback frame supply 45 Flyback frame supply present at capacitor C2455 48V stabilizer 8 for small signal is made from 12 C2454 by 06474 and T7478 5V stabilizer And additional voltage of 5V for small signal is made also from 12V C2454 06479 and T7479 Stereo supply only stereo models 12 from C2454 is drived to 7702 Diagram E to s
32. d Vcc 3 3V INT EXT input pin 7 The set can switch to external AV on the screen by remote control selecting program 0 or by rise edge at pin 8 of euroconnector see diagram C The IC switches internally video and audio to external In both cases the user can switch to internal changing the channel Band switching pin 8 11 There are 2 outputs for band switching 11 for VHFI and pin 8 for VHFIII The uC controls the channel band in the tuner by a voltage of 5 at the correspondent output UHF band is controlled by means of transistor 7601 If the set is in VHF one of the pins 8 or 11 are high and transistor conducts in such a way the UHF voltage is OV If the set is in UHF pins 8 and 11 are low transistor is cut and the set is in UHF LED pin 10 The LED D6663 diagram C lights up with a low current when the television set is ON and with a high current when the set is on Standby While the set is receiving a remote control signal the led is blinking Picture controls brightness contrast colour sharpness are processed internally by 12 bus Sound controls pins 2 3 Mono sets Sound controls are processed internally by 12 bus Stereo sets All information necessary to control stereo functions including sound controls are processed by a communication 12 bus between the and the stereo decoder IC 7101 pins 4 5 Standby pins 1 33 When the set is switched to stand by line stops pin 33 In addition to this
33. eep the same type of chassis setting correctly the chassis options 8 8 Error messages The microcomputer also detects errors in circuits connected to the I C Inter IC bus These error messages are communicated via OSD On Screen Display Error message Error description Component F2 Eprom communication error 7685 uC internal error RA IC7015 uC F4 Internal bus communication IC7015 FS SDA2 SCL2 bus wrong communication 1 7101 stereo sound SDA2 SCL2 bus no communication 7101 stereo F6 Eprom data error IC7685 F7 Not allowed options Item 21 22 service menu F8 Vertical guard pin 50 1 7015 If SYS OPTIONS or MENU OPTIONS not possible in this chassis the uC change to allowed options and first time TV set is switch on F7 message is displayed Options should be checked see 8 7 9 Safety instructions maintenance instructions warning and notes Safety Instructions for Repairs Warnings 1 Safety regulations require that during a repair 1 In order to prevent damage to IC s and transistors any flash over of The set should be connected to the mains via an isolating transformer Safety components indicated by the symbol should be replaced by components identical to the original ones When replacing the CRT safety goggles must be worn 2 Safety regulations require also that after a repair The set should be returned
34. h into protection mode see description of the SMPS 2 Do not use heatsink as earth reference 3 The direct voltages and waveforms should be measured relative to the nearest earthing point on the printed circuit board 4 Voltages and oscillograms in the power supply section have been measured for both normal operation and in the stand by mode D As an input signal a colour bar pattern has been used 5 The picTure tube PWB has printed spark gaps Each spark gap is connected between and electrode of the picture tube and the Aguadog coating
35. h the setting values of table 8 1 items 9 10 13 14 15 8 6 Geometry Connect a circle pattern generator with the controls at nominal conditions and enter to service menu Adjust to have picture centred in vertical position by service menu item 16 Horizontal shift Adjust to have picture centred in horizontal position by service menu item 18 Vertical amplitude Adjust picture height to cover the screen by service menu item 19 Adjustments only if necessary TXT Shift Vertical and horizontal shift of OSD or TXT can be adjusted by items 3 and 4 of service menu Vertical slope When item 17 is selected only upper part of the screen can be seen Vertical slope is adjusted when centre line of the pattern is just visible Vertical S correction S correction can be adjusted by item 20 of service menu 8 7 Options The type of chassis is defined by items 21 and 22 of service menu The following alternatives are available SYSTEM OPTIONS 21 MENU OPTIONS Item 22 VALUE PALB G lO 16 Languages menu 00 222222 11 without languages Important note the chassis have identification sheet when the chassis type is indicated Cod service SXXMXX where SXX means the option of system and MXX means the option of menu Example 501 00 means system 01 Pal 1 and menu 00 13 Languages menu When the chassis or the EEPROM 1C7685 have to be replaced be careful to k
36. hWYmumoaomnadgouniuu 2 mi Hl ix P5 5 O Bl B F5 Hl H1 65 HH BIO B O HT HO o MC HH 00 LO XO c L0 E L0 QI s CO sif Oy CN SI LO e 00 SP LO e QO n QO L0 00 O srt 00 e Od LO sif OY O 0 sr 00 SO COL CO LO D D D lt lt lt lt lt OO CO CN DOO 00 00 00 XO CO QO c4 OI ON OY ON 00 00 sf SP SPD e e O0 sr p LO LO LO LO lt lt SP SP SP SP LO LO UO LO LO SP SP SP SP SP SP SP SP SP LO L0 L0 L0 UU 10 L0 UU 10 UO t L0 L0 UO SP SP SP SP LO UO L0 LO UU LO SP SP SP SP UO L0 L0 t L0 0 tw 0 9 LO LO LO LO LO LO LO LO LO LO LO LO XO XO XO XO XO XO XO XO XO XO XO XO XO XO tO XO D P 00 0 0 OV ON ON ON Oh XO LO Sf LO LO St CO e 00 XO XO LO Sr L0 D L0 XO 0 00 00 SP ON ON SP sr 00 XO D 0 CON E XO lt CO SP CN OV ON CX OS 10 00 1010 XO LO LO CO OY st 0 e srt 0 0 lt o 0 m t mrmroanoaoammaooccdnrmsrimnunu uoornmnunumuunmumummuunmntfhtft eg j 111 00010140 0 061 1 amp 4 IT b ud J m CN sf LO XO 00 O cj 00 SP 40 00 SF 10 XO SP LO e OI 00 sif
37. his case pin 6 of 7015 is open T7659 conducts by resistor divider T7657 are cut MODE voltage is 5 5V Operating mode Vmode 0 5V Sound output present normal operation In this case Vmute 3V3 both transistors conduct mute signal is low Sound output OUT OUT Amplified sound is drived to the loudspeakers Mono sets Headphones output has been connected in such a way that when headphones are connected loudspeakers are switched off Stereo sets Headphones output are coming directly from pins 57 and 58 of stereo decoder IC7101 see chapter 7 6 and diagram E 7 5 POWER SUPPLY Diagram D Mains isolated switched mode power supply SMPS controlled in variable frequency mode 7514 KA5Q075RT includes control circuit and output MOSFET Output feedback is done by means of an optocoupler 7515 Switching behaviour The switching period is divided in on time when energy is extracted from the mains into the primary winding 8 12 of 5525 off time when energy in the transformer is supplied to the loads via secondary windings of 5525 and dead time when no energy is extracted or supplied Standby mode Output voltages are present when the set is in stand by Standby is done cutting line deflection and making the supply in burst mode in such a way that power consumption is very low 7 5 1 Degaussing and Rectifier Degaussing R3501 is a dual PTC 2 PTC s in one housing After switch on set PTC is cold so low ohmic a
38. in pins 33 34 External audio R and L proceeding of pins 6 and 2 of euroconnector Diagram C is applied pins 33 and 34 of IC7101 and digitalized by an ACD circuit Selection between internal or external is done from the 107015 by 2 bus see INT EXT chapter 7 6 External audio out pins 47 48 Signal at these pins are drived directly to the euroconnector sound outputs see Diagram C 5V stabilizer 5V supply for stereo processor is obtained from 12V C2454 diagram D D6702 and 7478 This voltage comes to supply voltages of IC1701 pins 59 15 64 Digital supplies pins 15 64 5V supplies at pins 15 and 64 are used for digital circuits of stereo processor Power ON reset pin 16 When the set starts C2754 is slow charged by an internal 50K resistor to 5 When digital supplies are present and oscillator is working reset is done if pin 16 is low Vpin16 1 5 V Analog supply voltage pin 53 59 There is a 5V supply for analog outputs DACs and operational amplifiers at pin 59 50 reference voltage 2 5V for these circuits is present at pin 53 ADC supply voltage pins 38 39 40 46 A 3 3V supply voltage is obtained internally and decoupled on pin 38 by C2758 Positive and negative reference voltage for ADC is present at pins 39 and 40 5096 reference voltage 1 65V for ADC is present at pin 46 Front end supply pins 7 8 11 A separated 3 3V supply voltage decoupled on pin 7 by C2750
39. m sz gt f m 1096 5 Hn 882 222 Ee 9699 RGAE S 99 a Ez toot D soi a 24 due S 1076 C E 22257 gt 1962 Secr L les gg 2 In zhe 1955 12 D 1095 1092 28192 hs 2315 lt Lm n 11 2095 CA 5096 996 Y zat E 296 629i 7552 Ezd B bes TIE 9696 1 7 1098 siscL 1 2 9 ene Ee 2 1129 797 8298 5 8296 Lt 0192 IR 0 8 SJ ULL db lt sese 196 sm ale 0606 iu L Hoge poem 3 0 rm S894 7395 7506 2992 P V6 0916 2092 7276 1 Z mu mm 8 5 7896 25 1413 506 vo6e 6 2066 196 0065 2916 69225892 8916 6916 3104 7 3291 2 3292 2 3293 2 3294 2 3295 2 18 1001 277 1015 76 1032 2 1033 2 1679 C3 2001 CY CY CY CY XO OO XO CN CY XO 00 LO CX X
40. n 45 When fast blanking is high external RGB is displayed only if TV is in external AV program 0 Fast blanking can switch signals for full screen by a DC voltage or for a part of the screen by a pulse voltage Matrix After switching YUV signals are converted to R Y G Y and B Y in the internal MATRIX circuit Saturation control is received by 12 bus Black stretcher Internally the luminance signal is connected to the YUV select circuit and via the input clamps it is supplied to the black stretcher The black stretcher circuit fully integrated extends the grey signal level This extension is dependent upon the difference between actual black level and the darkest part of the incoming video RGB adder RGB signals are obtained in this circuit by adding R Y G Y and B Y proceeding from matrix and Y proceeding from black stretcher RGB OSD RGB inputs for OSD and TXT are internally inserted to RGB signals Fast blanking used is also internal 45 Beam current limiter pin 49 The beam current limiter circuit functions as an average beam current limiter BCL as well as peak white limiter PWL Both functions reduce the contrast and brightness of RGB signals Contrast reduction begins when 49 lt 3 1V and brightness reduction begins when 49 lt 1 8V BCL Average beam current present at pin8 of 5445 Diagram D is feedback to pin 49 When beam current is high voltage of C2462 is lower D6462 conducts and Vpin
41. nd so degaussing current is very high After degaussing PTC is heated so high ohmic so in normal operation degaussing current is very low Rectifier Mains voltage is filtered by L5500 full wave rectified by diodes D6502 D6505 and smoothed by C2505 300V DC for 220V AC mains 7 5 2 Regulation Power MOSFET pin 1 Power stage is done by an internal MOSFET between pin1 and ground Current is sensed by an internal resistor and limited to 5A peak See chapter 7 7 2 Protections Start up and supply pin 3 When the set is switched on a current via R3527 and R3528 is applied to pin 3 When C2514 is charged to 15V the power supply starts and the internal MOSFET conducts A voltage across transformer windings is built up The voltage across winding 4 2 is rectified by diodes D6523 25 and used to supply the IC on pin 3 Voltage of pin3 depends on the output voltage and is about 28V If Vpin3 is lower than 9V supply stops and if it is higher than 32V output voltage is limited See chapter 7 7 2 Protections Sync pin 5 A pulse voltage proceeding from winding 4 2 is applied to this pin A delay is added by means of C2524 R3522 and R3526 to synchronize starts conduction of MOSFET at minimum Vds voltage Secondary feedback pin 4 Line supply feedback is obtained at pin 4 by divider R3531 34 19 the differential amplifier 7533 and the optocoupler 1C7515 Voltage at this pin is about 1 1V Output regulation 1C7514 stabilizes output vol
42. ocessor goes to Standby mode See chapter 7 7 Protections Digital supply pins 54 15 3V3 supply is used for digital circuit of TV processor 54 A decoupling capacitor for this supply is present at pin 15 C2301 Pin 54 is used also to supply the uC Bandgap decoupling pin 19 The bandgap circuit provides a very stable and temperature independent reference voltage of 4 0 V which one is used specially in the analogue video processor part uC supplies pins 54 56 61 The uC has several 3V3 supplies Pin 54 Analogue supply Oscillator ADC Pin 56 Digital supply touC core Pin 61 Supply to all output ports of When the set is in stand by the uC switch to stand by mode only 3V3 supplies are present but consumption is reduced 7 2 RGB AMPLIFIERS diagram The RGB signals available at pins 51 52 and 53 of 7015 Diagram A must be amplified and inverted in order to reach the level required for driving the tube The integrated circuit IC7200 TDA6107 is used for this purpose RGB inputs pins 2 3 1 These signals are connected to negative inputs of internal operational amplifiers There is and internal reference voltage of 2 5V for the amplifiers Negative feedback of amplifiers are internal resistors RGB outputs pins 8 7 9 These outputs are applied to the RGB cathodes of the tube Clamping diodes to 200 6201 6216 6229 and 1K5 series resistors 3203 3216 3229 are added for
43. r analog and digital multichannel sound systems in TV sets In the stereo chassis the sound part in the 107015 TDA9350 is disabled All sound signal analog and digital is processed in 1 7101 9875 The TDA9875A decodes NICAM signals B G and standard and two carrier FM modulation A2 signals B G standard Control bus pins 4 5 Stereo is fully controlled for the uC of IC7015 Diagram A via I2C bus Status information present in internal registers of 1 7101 is read by uC to determine whether any action is required Control is exercised by the uC also writing in other internal registers of IC7101 This control includes volume balance bass treble pseudo stereo spatial and Automatic Volume Level AVL Oscillator pins 18 19 The circuitry of the crystal oscillator is fully integrated only a external 24 576 MHz crystal is needed SIF input 12 SIF signal is filtered from video signal coming from pin 38 of IC7015 Diagram by a passband 5 5MHz to 6 5Mhz filter C2740 41 42 and L5741 AGC ADC SIF is passed through an AGC circuit and then digitized by an 8 bit ADC operating at 24 576 MHz The gain of the AGC amplifier is controlled from the ADC output Then signal is separated in 2 ways one for FM and other for NICAM FM demodulation FM signal is fed via a band limiting filter to a demodulator If signal is stereo A2 decoder recovers the left and right signal channels from the demodulated sound ca
44. rocontroller During start up circuit provides a softer operating horizontal output with a higher frequency Hor sync separator Fully integrated sync separator with a low pass filter slicing level at 5096 of the synchronized pulse amplitude Horizontal Phi 1 detector pin 17 This circuit locks the internal line frequency reference on the CVBS input signal It is composed of a phase comparator and an internal VCO of 25MHz 1600 15625 The free running frequency is stabilized using the 12 MHz reference of the X tal oscillator Phi 1 detector filter is made by external components at pin 50 Phi 1 time constant is automatically controlled by software for broadcasting signals For video signals AV and program 99 constant is always fast to prevent top bending on the screen LBF pin 34 Line Fly Back input is obtained by the network R3456 55 Diagram D and R3371 T7372 Sand Castle pin 34 Sand Castle output obtained at this pin is used only internally Levels of sandcastle pulse are 5 3V for burst detection 3V for line blanking and 2V for frame blanking Horizontal Phi 1 detector pin 16 The flyback position respect line blanking on TRC cathode is controlled by this circuit Phi 1 detector filter is made by C2305 pin 16 Horiz shift can be adjusted by 12 see chapter 8 HOUT pin 33 Horizontal output is an open collector which one drives the horizontal driver stage T7440 diagram 7 1 7 Vertical synchro and vertical drive
45. rriers A stereo identification signal is sent to the uC NICAM demodulation NICAM signal is transmitted in a DQPSK code at a bit rate of 728 kbit s NICAM demodulator performs DQPSK demodulation and feeds the resulting bitstream and clock signal onto the NICAM decoder A timing loop controls the frequency of the crystal oscillator to lock the sampling rate to NICAM decoder The device performs all decoding functions in accordance with the 728 specification Audio processing After demodulation digital signal is selected FM 2 or NICAM and processed according pC control Following functions are provided Forced mono stereo channel swap channel 1 channel 2 spatial effects Automatic Volume Level AVL volume balance bass and treble pins 54 55 Then signals are transformed to analog by DACs and sent to the outputs Post filter capacitors for DACs are at pins 54 and 55 Sound outputs pins 60 61 After a volume control by 12C sound outputs MAIN and MAIN L are drived to the inputs IN pins 12 and 6 of the final sound amplifier 7187 Diagram C Headphone outputs pins 57 58 Headphone outputs are drived by followed emitters 7780 and 7781 to the headphones These outputs are independent of loudspeakers outputs and controls are separated External audio out pins 47 48 Signal at these pins are drived directly to the euroconnector sound outputs see Diagram C External audio
46. s possible to display Service Menu by OSD key on RC Using P keys of remote control the different items can be displayed see table 8 1 Value Value Description Hexa 14 G GAIN 20H eem 5 Jecsme p 7 Reserves 5 jwwuco T peemess re jpwmer 8 Table 8 1 Service menu Settings are hexadecimal values Pre setting values When E2PROM is replaced values indicated on table 8 1 are stored by the uC see 8 7 2 Adjust by Service Mode When item is selected using V V keys of remote control it can be adjusted Items 2 5 23 and 24 have fixed values pre setting values rest of items see 8 2 to 8 6 Remove service menu There are 2 ways to remove service menu Saving the new settings Using OSD MENU or INSTALL keys on RC Keeping the old settings Switching the TV to stand by Service mode continues active Remove Service Mode Switching off the TV 8 2 Power supply and focusing Power supply voltage Adjust brightness and contrast controls at minimum Connect a DC voltmeter across C2530 Diagram D Adjust R3534 for a required voltage depending on the model and the TRC used see table 11 page 23 Focusing Adjust with the potentiometer placed on the line output transformer 8 3 Adjustment Connect pattern generator to the aerial input with
47. st C 00 00 O L0 LO O 00 00 E CN SP 10 O R 5 5 1mmuoozzzommmacotmnn OO CN SP LO 00 XO sr e 00 sri o O0 r si Sr LO LO LO LO LO LO LO SP SP 00 e ce SP SP SP ST 10 XO XO 00 00 00 00 00 O O 10 OO OO OO OO OO OO CO OO CO XO XO OO OO OO CO XO XO XO XO XO tO LF OY OS 0 stt 7 10 00 00 00 OY 00 SP 00 7 00 00 OY 00 00 9 QN LO LO LO CN 00 CON 00 CN 00 CN SP SP CON LO SPI SP COO e e OY 00 OO ba 15 5 0 O O fr fr O fi O O bs HHHHAHSSUVUHHRVUADOCCVCCA RH HAHA ORDA LO LO 7 Sf LO OY eA CN OO sf sr XO 00 LO QOO CN TOR SF LO QOO en 00 sf LO XO 00 1 n lt sr 00 n 00 L0 QO m CN 0 sr LO sr L0 lt 00 XO OY O a 00 ad rim OO OO st LO LO D 00 OO OO LO LO LO LO LO LO LO XO SP SP SP SP SP LO 00 00 00 Oy Oy XO XO XO XO XO
48. tabilize 5 for stereo decoder 7101 The heather voltage is reduced by R3235 38 and 5235 Diagram to obtain 6 3Veff at the CRT 7 4 SOUND AMPLIFIER Diagram C Sound amplifier is a Bridge Tied Load BTL amplifier including short circuit protection mute and stand by mode IC used can be TDA8941P for 14 and 17 models TDA8943SF for 20 and 21 models or TDA8944J for stereo models Behaviour is the same for 3 models TDA8944J is a double amplifier that means 2 supplies 2 inputs and 2 outputs Supply Vcc SVR Main supply Vcc is taken from 11V of Power Supply C2540 diagram D The IC creates internally a half supply present in SVR pin and decoupled by 10uF capacitor C2182 Sound input IN Amplifiers have differential inputs IN IN Audio input is connected to IN decoupled by 220nF capacitor C2181 84 and IN is decoupled to ground by other 220nF capacitor C2179 93 To avoid oscillations there is a 1n5 C2183 95 capacitor connected between both inputs Mode input MODE This input is commanded by mute signal proceeding from the pin 6 of 7015 diagram and has three modes depending of the voltage level Standby mode Vmode Vcc Consumption is very low used during stand by In this case Vmute 0V T7657 and T7659 are cut MODE signal is high Mute mode 2 5V lt Vmode lt Vcc No sound output used when the set is switched on off there is no signal channel search change of program etc In t
49. tage by controlling T on and so the frequency and the duty cycle Output control is done by the following way If line output is higher current input of the differential amplifier 1 7533 is higher amplifier has a reference voltage of 2 5V Current in 7533 and also in the optocoupler 17515 is higher Voltage in pin 4 is lower T on is internally reduced and output is reduced Output voltage of supply can be adjusted by R3518 7 5 4 Secondary side Line supply Line supply present at capacitor C2530 should be adjusted to the correct value depending on the TRC by means of P3534 Sound supply 11V This supply is used for sound output amplifier and to feed 3V3 stabilizer uC supply 3V3 5V3 is regulated by T7575 D6570 and T7571 7 5 3 Stand by When the set is put in standby line driver pin33 of IC7015 diagram A stops and deflection supply is not loaded Only a reduced load to supply the uC 3 3 is necessary To reduce more the power consumption during standby T7572 is cut by STBY signal 1 of 7015 diagram A then current in 1 7533 is increased by means of 06531 and output voltages are reduced As a consequence of this the supply switch to burst mode operation During working time C2514 is charged till 12V then supply stops and C2514 is discharged till 11V 7 6 The CTU Stereo chassis is based in the TDA9875A chip This is a single chip Digital Sound Processor fo
50. tructions for repair should be caried out The power supply and deflection circuitry on the chassis the CRT panel and the neck of the CRT should be cleaned FIG 9 21 the EHT should be avoided To prevent damage to the picture tube the method indicated in Fig 9 has to be applied to discharge the picture tube Make use of an EHT probe and a universal meter is OV after approx 305 2 ESD All IC s and many other semi conductors are sensitive to electrostatic discharges ESD Careless handing during repair can reduce life drastically When repairing make sure that you are connected with the same potential as the mass of the set via wrist wrap with resistance Keep components and tools on the same potential 3 Proceed with care when testing the EHT section and the picture tube 4 Never replace any modules or any other parts while the set is switched on 5 Use plastic instead of metal alignment tools This will prevent any short circuits and the danger of a circuit becoming unstable 6 Upon a repair of a transistor or an IC assembly e g a transistor or IC with heatsink and spring remounting should be carried out in the following order 1 Mount transistor or IC on heatsink with spring 2 Resolder the joints Notes 1 After replacing the microcomputer first solder the shielding before testing the set This is needed as the shielding is used for earth connection If this is not done the set can switc
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