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Digital Equipment 21BM18, Service Manual

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Digital Equipment 21BM18 Service Manual Download Page 1

 

 

   

   

 

FILE NO. SM-CTV-O-

154

 

 

 

 

COLOR TELEVISION 

 

 

SERVICE MANUAL 

 

 

MODEL NO. 21

BM18

 

CHASSIS NO. EX-1A1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Please read this manual carefully before service 

 

Summary of Contents for 21BM18

Page 1: ...FILE NO SM CTV O 154 COLOR TELEVISION SERVICE MANUAL MODEL NO 21BM18 CHASSIS NO EX 1A1 Please read this manual carefully before service...

Page 2: ...ADJUSTMENTS 5 CIRCUIT ADJUSTMENTS 8 STRUCTURE AND CHASSIS FUNCTION DESCRIPTION 14 STRUCTURE BLOCK DIAGRAM 14 BLOCK DIAGRAM FOR SUPPLY VOLTAGE SYSTEM 15 CHASSIS DESCRIPTION 16 SERVICE DATA 17 TECHNICAL...

Page 3: ...111 167MHz Z8 Z35 223 447MHz Programs preset 236 0 235 Antenna input 75 unbalanced Picture tube Approx Effective screen dimensions 406 305mm Audio output THD 7 3W 3W Power source 110 240V 50 60Hz Weig...

Page 4: ...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 adjustment SAFETY PRECAUTION WARNING REFER...

Page 5: ...ined by using replacements rated at higher voltages or wattage etc Components which have these special safety characteristics in this manual and its supplements are identified by the international haz...

Page 6: ...l safety related characteristics MAINTENANCE 1 Install the TV set on a stable and level surface Do not place the set near or over a radiator or heat register or where it is exposed to direct sunlight...

Page 7: ...set 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 brightnes...

Page 8: ...enter of the screen 2 1 4 Turn both tabs at the same time keeping the angle constant to superimpose red and blue horizontal on the center of the screen 2 1 5 Adjust two tabs of the 6 pole magnet to su...

Page 9: ...n better convergence in circumference 2 2 5 Fix the deflection yoke position and put the third wedge in either upper space Fasten the deflection yoke assembly on the picture tube 2 2 6 Detach the temp...

Page 10: ...e 2 1 Make sure that the supply voltage is within the range of the rated value 2 2 Connect a digital voltmeter to the B voltage output terminal of the TV set Power on the TV and set the brightness and...

Page 11: ...service personnel should not tell user how to enter the SERVICE mode to avoid improper data settings 6 1 1 Set the volume to 0 Then press and hold the MUTE button on the remote control and press the...

Page 12: ...gun cutoff voltage GRN 20 Green gun cutoff voltage WPR 1F Red gun drive voltage WPG 1F Green gun drive voltage WPB 1F Blue gun drive voltage YDFP Y DFN 07 PAL brightness delay time NTSC brightness de...

Page 13: ...and the buttons to adjust The data sheet may differ dependent on different models The data sheet may differ dependent on different CRTs for the same model 6 3 Option set With remote control system so...

Page 14: ...6 OP_ON BLACK 0 OP2 7 OP_FSL 0 0 OP_ENGLISH English 1 1 OP_FARSI Farsi or Czech 1 2 OP_ARABIC Arabic or Slovakian 1 3 OP_RUSSIAN Russian 1 4 OP_FRENCH French 1 5 OP_GERMAN German 1 6 OP_ITALY Italian...

Page 15: ...hen power on set to 0 typically 0 1 OP_PSNS 0 2 OP_BSCREEN 1 3 OP_SECAM SECAM color system option 1 Yes 1 4 OP_DFL 1 5 OP_SIF External SIF amplifier 1 Yes 0 No 1 6 OP_EXT_SIF0 1 OP6 7 OP_EXT_SIF1 Soun...

Page 16: ...4C08 Audio Prec essor TDA7449 H Drive V OUT TDA8356J Audio Amp lifier TDA7057AQ H OUT FBT T402 Power Supply Circuit STR F6654 or STR G5653 3 3V 5V 1 15V 115V CRT Audio Video Input Output Band 1 2 Vt A...

Page 17: ...1 8V 5V 2 To A100 VD891 115V To N600 VD881 15V H VD871 15 S 5V 1 To H Out EEPROM R C Input 3 3V To N100 Keyboard Switch Transformer T804 Power Regulation and Control Circuit STR G5653 F6654 Bridge Rec...

Page 18: ...dvanced functions with fewer external components which provide much convenience for manufacturing and technical service 2 The EX 1A1chassis series mainly use the following ICs and assemblies Table 1 K...

Page 19: ...they are mounted in S DIP envelope with 64 pins The features are given in the following feature list The differences between the various ICs are given in the table on page 4 2 Features TV signal proc...

Page 20: ...processor Teletext decoder with embedded Controller TDA935X 6X 8X PS N2 series Controller 80C51 controller core standard instruction set and timing 1 s machine cycle 16 128Kx8 bit late programmed ROM...

Page 21: ...ng and italics Soft colours using CLUT with 4096 colour palette Globally selectable scan lines per row 9 10 13 16 and character matrix 12x10 12x13 12x16 VxH Fringing Shadow selectable from N S E W dir...

Page 22: ...SERVICE MANUAL 20 3 Block Diagram Fig 6 Block Diagram for TDA935 6 8 PS N2 with Mono Intercarrier Sound Demodulator...

Page 23: ...SERVICE MANUAL 21 Fig 7 Block Diagram for TDA935 6 8 PS N2 with QSS IF Sound Channel...

Page 24: ...L EWD 1 20 Automatic Volume Levelling East West drive output VDRB 21 vertical drive B output VDRA 22 vertical drive A output IFIN1 23 IF input 1 IFIN2 24 IF input 2 IREF 25 reference current input VSC...

Page 25: ...demodulator QSS IF amplifier and East West output or not and on some software control bits The valid combinations are given in table 2 2 The vertical guard function can be controlled via pin 49 or pin...

Page 26: ...SERVICE MANUAL 24 Fig 8 Pin Configuration SDIP 64...

Page 27: ...nected to an independent input output Y0 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 swit...

Page 28: ...tate the more positive voltage L LOW state the less positive voltage X STATE is immaterial Fig 21 Schematic Diagram One Switch Fig 11 Ratings Limiting values in accordance with the Absolute Maximum Sy...

Page 29: ...tected on all pins 2 General Description The TDA7057AQ is a stereo BTL output amplifier with DC volume control The device is designed for use in TVs and monitiors but is also suitable for battery fed...

Page 30: ...mode 2 General Description The TDA8356 is a power circuit for use in 90 and 110 colour deflection systems for field frequencies of 50 to 120 Hz The circuit provides a DC driven vertical deflection ou...

Page 31: ...l In 1 0dbsteps for balancefacility independent mute function All function are programmable via Serial bus 2 descripion The tda7449 is a volume tone bass and treble Balance left right processor for qu...

Page 32: ...SERVICE MANUAL 30 4 Pin Connection Fig 16 5 Electrical Characteristics...

Page 33: ...VS 9V RL 10K RG 600 all controls flat G 0dB unless otherwise specified NOTE1 1 The device is functionally good at Vs 5V a step down on Vs to 4V does t reset the device 2 BASS and TREBLE response The c...

Page 34: ...ation Two wire serial interface bus I2 C Bus compatible Filtered inputs for noise suppression with Schmitt trigger Clock frequency up to 400 kHz High programming flexibility Internal programming volta...

Page 35: ...units Cycle by cycle current limiting under voltage lockout with hysteresis over voltage protection and thermal shutdown protects the power supply during the normal overload and fault conditions Low c...

Page 36: ...F6654 Pin No Symbol Function Description 1 OCP FB Over current protection detection signal voltage limiting signal input 2 S MOSFET source 3 D MOSFET drain 4 VIN Supply voltage input for control circ...

Page 37: ...SERVICE MANUAL 35 3 WAVEFORMS OF KEY POINTS NI00 Pin58 NI00 Pin33 NI00 Pin34 NI00 Pin44 NI00 Pin22 NI00 Pin21 BU250 8DX B BSC60H HEAT...

Page 38: ...SERVICE MANUAL 36 Notes The waveforms are only for reference The waveforms may differ dependent on different models BCT 4 Pin4 N100 P40...

Page 39: ...3 6 12 Pincushion input negative 0 13 Pincushion input positive 0 8 9 0 8 8 Table 4 Function and Service Data of TDA8356 N401 s Pins Digital Multimeter Victor DT890D Pin No Symbol Reference Voltage V...

Page 40: ...ive Resistance K 1 CREF 4 0 28 2 21 9 2 VS 8 0 1 8 1 8 3 PGND 0 0 0 4 ROUT 3 3 9 4 9 3 5 LOUT 3 3 9 4 9 3 6 R_IN1 4 0 21 9 26 0 7 R_IN2 4 0 26 7 24 3 8 L_IN1 4 0 26 7 24 3 9 L_IN2 4 0 21 9 26 1 10 MUX...

Page 41: ...4 18 7 20 AVL EWD 1 0 01 27 6 21 2 21 VDRA 2 4 27 6 20 4 22 IFIN1 2 4 27 6 20 3 23 IFIN2 1 8 24 7 19 8 24 IREF 1 8 24 7 19 9 25 TUNERAGC 3 8 25 3 20 5 26 AUDEEM SIFIN1 1 3 8 27 7 21 5 27 DECSDEM SIFIN...

Page 42: ...5 27 6 20 8 50 BLKIN 6 0 27 9 21 3 51 RO 2 6 1 1 1 1 52 GO 2 5 1 1 1 1 53 BO 2 4 1 1 1 1 54 VDDA 3 2 11 0 11 3 55 VPE 0 0 0 56 VDDC 3 2 11 0 11 3 57 OSCGND 0 02 58 XTALIN 59 XTALOUT 60 RESET 0 0 0 61...

Page 43: ...teristics Components which have these special safety characteristics in this manual and its supplements are identified by the international hazard symbols or UL FCC FDA or VDE marking on the circuit d...

Page 44: ...C I R C U I T D I A G R A M F O R 2 1 B M 1 8...

Page 45: ...CRT RGB PCB...

Page 46: ...MAIN PCB...

Page 47: ...Connector XPK03 Wired Connector XPK03 Wired Connector XS161 Wired Connector XS161 Wired Connector XPK02 Wired Connector XPK02 XS600 XS600 XSA04 XSA04 XSA05 XSA05 XS320 XS320 XSY03 XSY03 XS500 XS500 X...

Page 48: ...Red Remote Sensor Board Assembly Black See Diagram B Side AV Board Assembly Grey Yellow Blue Diagram B Buttons Board Assembly or 21 30 36 38 37 Final Assembly Diagram 1...

Page 49: ...40 40 27 27 13 13 27 27 13 13 2 2 11 11 39 39 13 13 KDY KDY A View A View Blue Blue Yellow Yellow Red Red Green Green 8 8 A A Final Assembly Diagram 2...

Page 50: ...23 33 27 25 26 24 or or Final Assembly Diagram 3...

Page 51: ...y Black Black Wire clip A Wire clip A Six button assembly Six button assembly Wired connector KDY Wired connector KDY Wired connector XS10B Wired connector XS10B Wired connector XS10A Wired connector...

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