AOC C787 Service Manual
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AOC C787 Service Manual

AOC C787 Service Manual

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SERVICE MANUAL



COLOR MONITOR

C787

41A50-122


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  • Page 1: Service Manual

    SERVICE MANUAL COLOR MONITOR C787 41A50-122...
  • Page 2 THESE DOCUMENTS ARE FOR REPAIR SERVICE INFORMATION ONLY. EVERY REASONABLE EFFORT HAS BEEN MADE TO ENSURE THE ACCURACY OF THIS MANUAL; WE CANNOT GUARANTEE THE ACCURACY OF THIS INFORMATION AFTER THE DATE OF PUBLICATION AND DISCLAIMS LIABILITY FOR CHANGES, ERRORS OR OMISSIONS,...

  • Page 3: Table Of Contents

    TABLE OF CONTENTS PAGE 1. SPECIFICATIONS ..................... 2. PRECAUTION AND NOTICES ................SAFETY PRECAUTIONS ................PRODUCT SAFETY NOTICE ............... SERVICE NOTES ................... HIGH VOLTAGE WARNING ............... 3. OPERATING INSTRUCTIONS ................4. ADJUSTMENT ......................ADJUSTMENT CONDITIONS AND PRECAUTIONS ....... MAIN ADJUSTMENTS ................. ADJUSTMENT METHOD ................

  • Page 4: Specifications

    1. SPECIFICATIONS FOR C787 SERIES COLOR MONITOR CRT : 43.2CM(17") 90 Deflection, 29mm Neck, 0.26mm Dot Pitch, Non-Glare Screen Viewable image Size: 40.6CM (16") diagonal Display Color: Unlimited Colors External Controls: Power On/Off, OSD key, Function knob: Contrast, Brightness, H-Size, H-Center, V-Size, V-Center, ZOOM, Pincushion, Trapezoid, Pin-Balance, Parallelogram, Rotation, Moire Reduce, Recall, Degaussing, Color Temperatur.
  • Page 5 11. Power Source: Switching Mode Power Supply AC 100 ~240V, 50/60Hz Universal Type 12. Operating Temperature: 0°C to 40°C Ambient 13. Humidity : 10% to 85% Relative, Non-Condensing 14. Weight: 16.0 Kgs(Net), 19.5Kgs(Gross) 15. Dimensions Monitor: Carton: 570(W) x 537(H) x 565(D) mm Monitor: 420(W) x 450(H) x 435(D) mm 16.

  • Page 6: Precaution And Notices

    2. PRECAUTIONS AND NOTICES SAFETY PRECAUTIONS 1. Observe all caution and safety related notes located inside the display cabinet. Operation of the display with the cover removed, may cause a serious shock hazard from the display power supply. Work on the display should not be attempted by anyone who is not thoroughly familiar with precautions necessary when working on high voltage equipment.

  • Page 7: High Voltage Warning

    HIGH VOLTAGE WARNING Operation of monitor outside of cabinet or with back removed may cause a serious shock hazard. Work on this model should only be performed by those who are thoroughly familiar with precautions necessary when working on high voltage equipment.

  • Page 8: Operating Instructions

    This monitor has power saving function following the VESA DPMS. Be sure to connect the signal cable to the PC. If your C787 Series color display requires service, it must be returned with the power cord.

  • Page 9: Adjustment

    4. ADJUSTMENT ADJUSTMENT CONDITIONS AND PRECAUTIONS Approximately 30 minutes should be allowed for warm up before proceeding. Adjustments should be undertaken only on those necessary elements since most of them have been carefully preset at the factory. 4-2 MAIN ADJUSTMENTS FUNCTION LOCATION DESIGNATION...
  • Page 10 FACTORY PRESET H: 36.51kHz V: 51.34Hz 6500 9300 CONTRAST H-MOIRE REDUCE BRIGHTNESS V-MOIRE REDUCE H-CENTER R-GAIN H-SIZE G-GAIN V-CENTER B-GAIN V-SIZE R-BIAS ZOOM G-BIAS TOP COMER R-BIAS BOTTOM COMER COLOR TEMPERATURE 9300 PINCUSHION COLOR TEMPERATURE 6500 TRAPEZOID DEGAUSS PIN-BALANCE OSD EXIT PARALLELOGRAM RETURN ROTATION...
  • Page 11 E. To switches the input signal to the other Timing Mode. Please follow step C ~ D to get the optimum picture. F. Select the " " RETURN function and press the MENU Key, then the Factor Preset window will be returned to the original OSD window.(user's operating condition) G.

  • Page 12: Circuit Description

    RELATIVE PLACEMENT OF TYPICAL COMPONENTS Purity Magnets 6-pole Convergence Magnets 4-pole Convergence Magnets Deflection Yoke 6. Convergence adjustment A. Produce a magenta crosshatch on the display. B. Adjust the focus for the best overall focus on the display. Also adjust the brightness to the desired condition. C.
  • Page 13 On Screen Display Controller The IC103 is designed for display the built-in characters or fonts onto monitor screen. The display operation is by transforming data and control information from micro controller to RAM through a serial data interface. Pin2 is used to control the internal oscillator frequency by DC voltage input from external low pass filter (R125, C114, R161) and filter (R126, C115) is used to regulate the appropriate bias current for internal oscillator the resonate at specific dot frequency.
  • Page 14 5-3 TRANSISTOR & DIODE CIRCUIT LOCATION FUNCTION AL DESCRIPTION D101 For C102 Discharge Q101 For LED Indicator Control D418 Protection Diode for Snubber Clip Diode ZD401 D431 Protection Diode for B+ Control D405, D424 Speed up for Q403 D406, D407 Supply a bias for D408 D408 Damping Diode and Modulation Diode...
  • Page 15 LOCATION FUNCTION AL DESCRIPTION D706 Rectifier for -200V Supply Q703 Picture Mute Control AMP Q705, Q709 Brightness Control CKT Q708 Vertical Dynamic Focus Control AMP D901 ~ D904 Bridge Rectifier for AC Source D909 Rectifier for Start Power Supply D910 Clip Diode for Snubber CKT D911 IC901 VCC Supply...

  • Page 16: Trouble Shooting Chart

    6.TROUBLE SHOOTING CHART 6-1 NO RASTER, CRT RELATIVE CIRCUIT PROBLEMS CHECK MAIN PCB POWER SUPPLY 60.5V, 14.5V, 80V CHECK POWER SAVING CIRCUIT, H-SYNC, V-SYNC SIGNAL CHECK THE HIGE VOLTAGE REFER ITEM S.M.P.S. OF CRT ABOUT 25.5 ~ 26.5KV CHECK FAILSAFE CKT IC401 PIN 2 RELATIVE CKT.
  • Page 17 2.ABNORMAL VIDEO LEVEL ON SCREEN CHECK THE VOLTAGE OF IC801 PIN 6, 9, 22 ABOUT 12V CHECK 12V RELATIVE CIRCUIT CHECK THE SIGNAL INPUT OF R.G.B. ABOUT 0.7Vpp CHECK SIGNAL CABLE OR INTERFACE CARD. CHECK IC801 PIN 15 CLAMP PULSE PIN 16 BLANK PULSE CHECK THE IC105 RELATIVE CIRCUIT OR IC401 PIN 16 OUTPUT...

  • Page 18: Abnormal Display

    6-2 ABNORMAL DISPLAY 1.NO SIGNAL ON SCREEN CHECK VIDEO IC801 VCC ABOUT 12V CHECK THE 12V PIN OF P802 CONNECTOR CHECK THE OUTPUT VOLTAGE OF IC801 PIN 18, 20, 23 ABOUT 3Vpp CHECK THE RELATIVE CIRCUIT OF IC801 CHECK THE B+ VOLTAGE OF VIDEO PCB ABOUT 80V CHECK THE 80V RELATIVE CIRCUIT OF SMPS ON MAIN PCB...

  • Page 19: No Blanking

    6-3 NO BLANKING CHECK THE RELATIVE CIRCUIT OF BLANKING CHECK THE RELATIVE CIRCUIT OF C433, D410, R635, R636, IC105 ON MAIN PCB CHECK IC801 PIN 16 ON VIDEO PCB, CHECK G1 RELATIVE CIRCUIT Q705, R718, C707 ON MAIN PCB 6-4 HOR./OSC/DEF/HV CIRCUIT FAULT 1.

  • Page 20: Abnormal Horizontal Deflection

    6-5 ABNORMAL HORIZONTAL DEFLECTION 1. ABNORMAL HORIZONTAL WIDTH OF VIDEO READJUST H-WIDTH FUNCTION CHECK THE RELATIVE CIRCUIT OF Q404, Q405, & Q406 CHECK FBT B+ VOLTAGE ABOUT 60.5V AT FH=31KHz CHECK THE RELATIVE CIRCUIT OF SMPS. Q911, Q912, Q914, Q915 & IC401 PIN 4, 5, 6, VR 902 CHECK THE HV OF CRT ABOUT 26KV...

  • Page 21: Abnormal Vertical Scanning

    6-6 ABNORMAL VERTICAL SCANNING 1. ABNORMAL VERTICAL SIZE READJUST V-SIZE FUNCTION VALUE CHECK THE IC601 PIN 7 ABOUT 40V CHECK ZD601, ZD602 R626 & SMPS RELATIVE CIRCUIT CHECK VERT. OSC CIRCUIT CHECK IC401 PIN 22, 23, 24 CHECK IC601 PIN 6 OUTPUT ABOUT CHECK IC401 PIN 12, 13 38Vpp RELATIVE CIRCUIT...

  • Page 22: Power Supply Trouble Shooting Chart

    6-9 POWER SUPPLY TROUBLE SHOOTING CHART BEFORE CHECK SW.REG. PLEASE REFER TO THE POWER SUPPLY BLOCK DIAGRAM POWER SUPPLY OUTPUT: (A) VARIABLE OUTPUT : 60.5V - 145V (DEPENDING EPENDING UPON H.SYNC FREQUENCY) CONSTANT OUTPUT : 6.3V, 14.5V, 24V, 80V BEAD SET ABNORMAL VARIABLE OUTPUT MAKE SURE THAT CHECK AC LINE...

  • Page 23: Mechanical Of Cabinet Front Dis-Assembly

    MECHANICAL OF CABINET FRONT DIS-ASSEMBLY...

  • Page 24: Parts Listing

    PARTS LIST OF CABINET LOCATION    C787    SPECIFICATION    (LOW RADIATION 220V)            CHAS ASS'Y        CMC785QJ2...
  • Page 25 PARTS LIST OF CHAS LOCATION C787 SPECIFICATION     CRPC785Q CRT BOARD ASS'Y     421- SCREW WASHER 203- 124- PCB SUPPORT 15A 5640- AL GND LUG 15A 5659- 500 - REAR BRACKET 581- 26 -...
  • Page 26 LOCATION C787 SPECIFICATION C951 215- 470 - 47uF +-20% 250V CF419 FERRITE BEAD CN902 33A 3074- 2P PLUG D403 11H - DIODE 1N4148 D901 55P - RECT. DIODE IN5408 D902 55P - RECT. DIODE IN5408 D903 55P - RECT. DIODE IN5408...
  • Page 27 LOCATION C787 SPECIFICATION R630 208- 109 - 1 OHM +-5% 1W R632 61A 153M- 229 - 2.2 OHM +-5% 3W R633 61A 153M- 229 - 2.2 OHM +-5% 3W R723 61A 152M- 121 - 120 OHM +-5% 2W R725 61A 175L-...
  • Page 28 LOCATION C787 SPECIFICATION C124 309- 100 - 10uF +-20% 50V C125 309- 100 - 10uF +-20% 50V C126 309- 100 - 10uF +-20% 50V C127 309- 100 - 10uF +-20% 50V C128 309- 100 - 10uF +-20% 50V C130 309-...
  • Page 29 LOCATION C787 SPECIFICATION C906 444- 681 - 680PF 10% 50V Y5P C914 305- 100 - 10Uf +-20% 50V C916 305- 101 - 100uF +-20% 25V C918 64A 176J- 332 - 0.0033uF +-5% 100V C919 64A 176J- 102 - 0.001uF +-5% 100V...
  • Page 30 LOCATION C787 SPECIFICATION FB401 TIN COATED FB903 SHIELD BEAD FB904 19 - BEAD J001 19 - BEAD J002 TIN COATED J003 TIN COATED J004 TIN COATED J005 TIN COATED J006 TIN COATED J007 TIN COATED J008 TIN COATED J009 TIN COATED...
  • Page 31 LOCATION C787 SPECIFICATION J065 TIN COATED J066 TIN COATED J067 TIN COATED J068 TIN COATED J069 TIN COATED J070 TIN COATED J072 TIN COATED J073 TIN COATED J074 TIN COATED J075 TIN COATED J076 TIN COATED J077 TIN COATED J078...
  • Page 32 LOCATION C787 SPECIFICATION J137 TIN COATED L101 339 - 3.3UH +-10% L102 172- 221 - 220 OHM +-5% 1/4W NR630 101 - NTCR 100 OHM +-15% Q101 420- TR. 2SA733P/NEC Q102 446- 2SC1213AC Q401 419- SG - TR. KSC945GC Q402 521- TR.
  • Page 33 LOCATION C787 SPECIFICATION R136 602- 103 - 10K OHM +-5% 1/6W R137 602- 103 - 10K OHM +-5% 1/6W R138 602- 103 - 10K OHM +-5% 1/6W R139 602- 103 - 10K OHM +-5% 1/6W R140 602- 103 - 10K OHM +-5% 1/6W...
  • Page 34 LOCATION C787 SPECIFICATION R449 602- 472 - 4.7K OHM +-5% 1/6W R450 602- 122 - 1.2K OHM +-5% 1/6W R451 602- 102 - 1K OHM +-5% 1/6W R460 172- 154 - 150K OHM +-5% 1/4W R461 602- 563 - 56K OHM +-5% 1/6W...
  • Page 35 LOCATION C787 SPECIFICATION R735 602- 332 - 3.3K OHM +-5% 1/6W R736 602- 752 - 7.5K OHM +-5% 1/6W R737 602- 103 - 10K OHM +-5% 1/6W R738 602- 102 - 1K OHM +-5% 1/6W R739 61A 175L- 333 -...
  • Page 36 PARTS LIST OF CRT PC BOARD LOCATION SPECIFICATION 785QJ CRPC 581- 26 - LABEL 705A 769P- R57 - Q802/Q803/Q804 ASS’Y 705A 769P- R87 - CRT SOCKET ASS’Y C810 305- 470 - 47UF 20% 100V C853 103 - 0.01uF 20% 2KV Z5U C857 65A 517K- 102 -...
  • Page 37 LOCATION SPECIFICATION QJAI C828 64A 176J- 104 - 0.1uF +-5% 100V C829 64A 176J- 104 - 0.1uF +-5% 100V C831 442- 330 - 33PF 5% 50V NPO C832 442- 330 - 33PF 5% 50V NPO C833 442- 330 - 33PF 5% 50V NPO C834 442- 330 -...
  • Page 38 LOCATION SPECIFICATION QJAI FB809 SHIELD BEAD FB810 TIN COATED FB811 TIN COATED FB812 TIN COATED FB813 TIN COATED J802 TIN COATED J803 TIN COATED J804 TIN COATED J805 TIN COATED J806 TIN COATED J808 TIN COATED J809 TIN COATED J810 TIN COATED J811 TIN COATED...
  • Page 39 LOCATION SPECIFICATION QJAI R817 602- 393 - 39K OHM +-5% 1/6W R818 602- 101 - 100 OHM +-5% 1/6W R819 602- 102 - 1K OHM +-5% 1/6W R820 602- 102 - 1K OHM +-5% 1/6W R821 602- 102 - 1K OHM +-5% 1/6W R822 602- 102 -...
  • Page 41 PARTS LIST OF CRT SOCKET ASS'Y LOCATION PARTS SPECIFICATION 11A 6010- SOCKET HOLDER 87A 3504- CRT SOCKET PARTS LIST OF Q802/Q803/Q804 ASS'Y LOCATION PARTS SPECIFICATION 361- HEAT SINK M1A 1730- 10 - SCREW Q802 509- TR. 2SC3953E Q803 509- TR. 2SC3953E Q804 509- TR.
  • Page 42 PARTS LIST OF Q901 ASS'Y LOCATION PARTS SPECIFICATION 348- HEAT SINK M1A 1730- 10 - SCREW Q901 723- TR. 2SK3299/NEC PARTS LIST OF Q425 ASS'Y LOCATION PARTS SPECIFICATION 32A 3028- MICA 360- HEAT SINK M1A 1730- SCREW Q425 728- HSB772P PARTS LIST OF D921 ASS'Y LOCATION PARTS...

  • Page 44: Block Diagram (Deflection)

    9. BLOCK DIAGRAM...

  • Page 46: Ic Block Diagrams

    10. IC BLOCK DIAGRAM...
  • Page 47 IC401 TDA4856/41...
  • Page 49 IC102 ST24W08/24C08 PRE 1 MODE/WC IC904 LM7812 SERIES INPUT PASS OUTPUT ELEMENT CURRENT GENERATOR PROTECTION STARTING REFERENCE ERROR VOLTAGE AMPLIFIER CIRCUIT THERMAL PROTECTION...
  • Page 52 11-2 CRT BOARD LAYOUT...

  • Page 53: Schematic Diagram

    SCHEMATIC DIAGRAM...

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