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Changhong Electric 21BM91, Service Manual, Page: 54 / 58

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Changhong Electric 21BM91 Service Manual Download Page 54

This circuit diagram is only for reference, specifications are subject to change without reference.

1.   Any components identified by       have special safety-related characteristics. Use replacement

Which have the same characteristics as original parts.

2.         Cold ground              Hot ground

Circuit Diagram 

Summary of Contents for 21BM91

Page 1: ...FILE NO SM CTV O 155 COLOR TELEVISION SERVICE MANUAL MODELNO CHASSIS NO CN 18EA Please read this manual carefully before service 21BM91 V2...

Page 2: ...MENTS 5 SET UP ADJUSTMENTS 5 CIRCUIT ADJUSTMENTS 8 STRUCTURE AND CHASSIS FUNCTION DESCRIPTION 24 STRUCTURE BLOCK DIAGRAM 24 BLOCK DIAGRAM FOR SUPPLY VOLTAGE SYSTEM 25 CHASSIS DESCRIPTION 26 SERVICE DA...

Page 3: ...43 NTSC3 58 NTSC4 43 SECAM 50 60Hz Channels preset 236 0 235 Antenna input 75 unbalanced Picture tube Effective screen dimensions Approx 406 305mm Audio output THD 7 Power source 220V 50Hz Weight App...

Page 4: ...ICE below 4 Service and adjustment of the TV may result in changes in the nominal EHT voltage of the CRT anode So ensure that the maximum EHT voltage does not exceed the rated value after service and...

Page 5: ...se characteristics are often passed unnoticed by a visual inspection and the X ray radiation protection afforded by them cannot necessarily be obtained by using replacements rated at higher voltages o...

Page 6: ...ts identified by the VDE marking have special safety related characteristics MAINTENANCE 1 Place the TV set on a stable stand or base that is of adequate size and strength to prevent it from being acc...

Page 7: ...t 1 3 Operate the TV for at least 15 minutes 1 4 Degauss the TV set using a specific degaussing coil 1 5 Set the brightness and contrast to maximum 1 6 Counter clockwise rotate the R B low brightness...

Page 8: ...Adjust two tabs of the 6 pole magnet to superimpose red blue line and green line 2 1 6 Remember red and blue movement Repeat steps 2 1 3 2 1 5 until optimal convergence is obtained 2 2 Circumference...

Page 9: ...en the lamp screw holding the deflection yoke assembly Fig 2 4 pole Magnet Movement 6 pole Magnet Movement Center Convergence by Convergence Magnets Incline the Yoke Up or Down Incline the Yoke Right...

Page 10: ...at the above steps until the TV is degaussed completely 2 Confirmation and Adjustment for Voltage Caution B voltage has close relation to high voltage To prevent X ray radiation set B voltage to the r...

Page 11: ...rcised when working on the TV with the back removed 4 1 After removing the back cover look for the FBT on the main PCB There should be a FCB on the FBT 4 2 Power on the TV and preheat it for 15 min 4...

Page 12: ...n service personnel adjust the whole set data during servicing As the control data have dramatic effects on functions and performance of the TV service personnel should not tell user how to enter the...

Page 13: ...Lock horizontal AFC is off 0 Yes Recommended 1 No Bit6 Mono system 1 Yes 0 No Bit5 Single language 1 Yes 0 No Bit4 TA1343 woofer or MDB output mode options 0 Mono output 1 Overlapped to main channel...

Page 14: ...ion 0 No 1 Yes BIT 1 Instant on 1 Yes 0 No BIT 0 AV Switch 4053 option 0 No 1 Yes BIT 7 Audio processing IC SOUND menu 0 No 1 Yes BIT 6 Woofer option in SOUND menu 0 No 1 Yes BIT 5 TA1343 option 0 No...

Page 15: ...1 Turn on logo display Logo write in function required 1 Yes 0 No Bit 0 No use OSD Horizontal position of OSD RCUT R cut off GCUT G cut off BCUT B cut off GDRV G drive BDRV B drive CNTX Contrast Max...

Page 16: ...ertical amplitude in 16 9 mode PAL HIT69S Vertical amplitude in 16 9 mode NTSC V01 Volume output data at 1 V25 Volume output data at 25 V50 Volume output data at 50 V100 Volume output data at 100 Bit...

Page 17: ...0 OSD 20 SVD 30 SBY 05 TREC 40 OPT 60 ASSH 07 SRY 09 BALC 40 RCUT 40 SHPX 3F BRTS 00 BAS1 64 GCUT 20 SHPN 20 RAGC 20 BAS2 20 BCUT 20 TXCX 3F HAFC 09 BAS3 50 GDRV 40 RGCN 1F V01 15 TRE1 64 BDRV 40 ABL...

Page 18: ...01 R L Video Am plifier V901 V903 Vertical Out LA78040 N602 Line Drive V404 T401 2INI IC TMPA8801PSBNG N201 AV Switch HEF4053BP N 3 50 Remote Sensor HS0038 EEPROM AT24C16 D702 Circui for Buttons On Th...

Page 19: ...Contr ol V230 V231 Sound Powe r Amplifier N301 Video Amplifier V901 V903 Second S ound Trap V204 V207 Hz Bridge Rectifier VD801 VD804 C803 C806 Filter L803 C807 9V 2 5V 2 17V 5V 1 118V 33V 27V 190V I...

Page 20: ...output power amplifying TA1343N for audio processor TDA8944J for audio power amplifying Thick film IC STR G5653 for power circuit adjustment and control The following features are available in the ch...

Page 21: ...TMPA8801CSCNG CPCNG CMCNG TMPA8801PSCNG PAN NTSC SECAM 64K 48K 32K SDIP64 TMPA8807CSBNG CPBNG CMBNG TMPA8807PSBNG PAN NTSC SECAM 64K 48K 32K Yes SDIP64 TMPA8808CSBNG CPBNG CMBNG TMPA8807PSBNG NTSC 64K...

Page 22: ...IP package The MCU contains 8 bit CPU ROM RAM I O ports timer counters A D converters an on screen display controller remote control interfaces IIC bus interfaces and the Closed Fig 7 Caption decoder...

Page 23: ...ative demodulation PIF Multi frequency SIF demodulator without external Tank coil Video Integrated chroma traps Black stretch Y gamma Chroma Integrated chroma BPFs PAL NTSC SECAM demodulation CCD Deco...

Page 24: ...SERVICE MANUAL 3 Block Diagram for TMPA8801 Fig 8 22...

Page 25: ...SERVICE MANUAL 4 Block Diagram for TMPA8807 Fig 9 23...

Page 26: ...from FBP for OSD 11 VD S to M Vertical timing pulse from sync Separator for OSD 12 CLK M to S 8 MHz clock 13 AVDD M to S Reference voltage for C Video interface 14 ADC S to M A D converter monitoring...

Page 27: ...Function 1 P61 LED1 ADC 8 bit KWU5 AIN5 LED1 I O input input output Key on wake up input A D converter analog input High current sink open drain output 2 P60 ADC 8 bit KWU4 AIN4 I O input input Key on...

Page 28: ...STOP I O input input External interrupt input STOP mode release signal input 62 P31 Int4 TC3 INT4 TC3 I O input input External interrupt input Timer Counter input 63 P30 Int3 RXIN INT3 RXIN I O input...

Page 29: ...clipped about 3 3 V by regulator circuit Supply TV DVCC voltage from HVCC 17 voltage via 27 TV IN V1 in For TMPA8801 Input terminal for Video signal Input level 1 Vp p 26 fsc out For TMPA8807 Output...

Page 30: ...inal for RF AGC control level 44 YC VCC 5 V VCC terminal for Y C circuit Supply 5 V 45 Monitor out Output terminal for CVBS or Y signal selected by BUS video SW 46 Black Det Terminal to be connected w...

Page 31: ...SERVICE MANUAL 7 Microcontrollers Descriptions MROM version TMPA8801 8807CMBNG CPBNG CRBNG CSBNG Fig 10 8 Refer to Table 18 and Table 19 about Data of the IC s Pins 29...

Page 32: ...3SF comes in a 9 lead single in line SIL medium power package The TDA8943SF is printed circuit board PCB compatible with all other types in the TDA894x family One PCB footprint accommodates both the m...

Page 33: ...e loudspeaker terminal VCC 2 supply voltage OUT 3 positive loudspeaker terminal IN 4 positive input IN 5 negative input SVR 6 half supply voltage decoupling ripple rejection MODE 7 mode selection inpu...

Page 34: ...944J comes in a 17 pin DIL bent SIL DBS power package The TDA8944J is printed circuit board PCB compatible with all other types in the TDA894x family One PCB footprint accommodates both the mono and t...

Page 35: ...Pin Description OUT1 1 negative loudspeaker terminal 1 GND1 2 ground channel 1 VCC1 3 supply voltage channel 1 OUT1 4 positive loudspeaker terminal 1 n c 5 not connected IN1 6 positive input 1 n c 7...

Page 36: ...input 2 n c 13 not connected OUT2 14 negative loudspeaker terminal 2 GND2 15 ground channel 2 VCC2 16 supply voltage channel 2 OUT2 17 positive loudspeaker terminal 2 TDA8944J Stereo power amplifier M...

Page 37: ...istort the signal in large signal condition for woofer channel is also incorporated 1 Features Sound processing circuit 2ch inputs Lch Rch 3ch outputs Lch Rch Wch Input matrix switch Volume control Ba...

Page 38: ...filter Filter for noise rejection of the bias Connect a capacitor 4 7 F between this terminal and GND 10 15 Bass LPF R Bass LPF L LPFs for bass control circuits Connect capacitors 0 027 F between each...

Page 39: ...ontrol Connect a capacitor 0 01 F between this terminal and GND 22 Woofer LPF Smoothing filter for bass boost level control Connect a capacitor 3 3 F between this terminal and GND This filter is also...

Page 40: ...output current of 1 8AP P while LA78041 has supply voltage of 30V and output current of 2 2AP P LA78040 LA78041 Vertical Deflection Output Circuit 1 Features Low power dissipation due to built in pump...

Page 41: ...Extended Temperature Devices Available 8 lead PDIP 8 lead JEDEC SOIC 8 lead MAP and 8 lead TSSOP Package 2 wire Serial EEPROM AT24C01A 1K 128 x 8 AT24C02 2K 256 x 8 AT24C04 4K 512 x 8 AT24C08 8K 1024...

Page 42: ...ber of other open drain or open collector devices DEVICE PAGE ADDRESSES A2 A1 A0 The A2 A1 and A0 pins are device address inputs that are hard wired for the AT24C01A and the AT24C02 As many as eight 1...

Page 43: ...the 1K requires a 7 bit data word address for random word addressing AT24C02 2K SERIAL EEPROM Internally organized with 32 pages of 8 bytes each the 2K requires an 8 bit data word address for random...

Page 44: ...and Y1 and the other side connected to a common input output Z With E LOW one of the two switches is selected low impedance ON state by Sn With E HIGH all switches are in the high impedance OFF state...

Page 45: ...Table 16 Inputs E Sn Channel On L L Y0n Zn L H Y1n Zn H X none Notes H HIGH state the more positive voltage L LOW state the less positive voltage X STATE is immaterial 4 Refer to Table 24 about Functi...

Page 46: ...e operation principle as STR G5600 Pin configuration function and threshold of STR G8600 are compatible with those of STR G5600 2 Block Diagram Fig 23 3 Function of Terminal Table 17 Function of Termi...

Page 47: ...24 67 K 24 71 K 0 0 24 62 K Pin No 25 26 27 28 29 30 Resistance 0 56 K 24 70 K 16 65 K 22 04 K 0 3 K 3 27 K Pin No 31 32 33 34 35 36 Resistance 3 29 K 24 27 K 2000 K 362 3 K 2000 K 0 Pin No 37 38 39 4...

Page 48: ...22 23 24 Voltage V 2 4V 2 4V 2 4V GND 0V 2 3V Pin No 25 26 27 28 29 30 Voltage V 3 4V 2 4V 4 8V 3 5V 9V 5V Pin No 31 32 33 34 35 36 Voltage V 1 8V 4 4V 2 8V 2 2V 2 5V 5V Pin No 37 38 39 40 41 42 Volta...

Page 49: ...cted 0 8 Negative input 1 7 4 9 Negative input 2 7 3 10 Mode selection input standby mute operating 0 7 8 8 9 11 Half supply voltage decoupling ripple rejection 7 6 12 Positive input 2 7 3 13 Not conn...

Page 50: ...er LPF 4 5 870 23 SCL 4 8 1464 24 SDA 4 8 1464 Table 22 Functions and Service Data of LA78040 78041 s Pins GDM8145 Multimeter Ground Resistance K Pin No Function Description Voltage of Pin V Measure w...

Page 51: ...al Multimeter Pin No Function Description Reference Voltage V Positive Resistance 20K Negative Resistance 20K 1 Signal input terminal 0 01 6 9 6 32 2 Signal input terminal 2 47 6 7 5 89 3 Signal input...

Page 52: ...Digital Multimeter Pin No Functions Description Reference Voltage V Positive Resistance 20K Negative Resistance 20K 1 Drain terminal 146 3 2 Source terminal 0 0 0 3 Ground terminal 0 0 0 4 Power supp...

Page 53: ...al Description of the special markings A The components identified by the A marking have special safety related characteristics AE The components identified by the AE marking are listed by EMC and hav...

Page 54: ...specifications are subject to change without reference 1 Any components identified by have special safety related characteristics Use replacement Which have the same characteristics as original parts...

Page 55: ...PRINTED CIRCUIT BOARD LAYOUT 1...

Page 56: ...PRINTED CIRCUIT BOARD LOYOUTS 2...

Page 57: ...ssembly Front cover assembly CRT assembly T JU8 667 003 1 1 1 1 1 1 Warning label Wire clip A Washer Fragile label Tapping screw 4X20BAHCh Notched nut M5 Tapping screw 3X12VwAHCh Rear plate 3 4 1 4 6...

Page 58: ...sembly Remote Sensor PCB Assembly Indictator PCB Assembly From Power Switch Assembly To Degaussing Coil To Deflection Yoke B wire Grey A wire Red Soldered Wired Connector XS402 CRT s Ground Wire Wired...

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