AOC LM923 Service Manual
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AOC LM923 Service Manual

AOC LM923 Service Manual

19'' lcd monitor
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AOC LM923

SERVICE MANUAL

19" LCD MONITOR
LM923
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 RELIABILITY FOR CHANGES,
ERRORS OR OMISSIONS.
Page 1 of 55

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Summary of Contents for AOC LM923

  • Page 1: Service Manual

    AOC LM923 SERVICE MANUAL 19” LCD MONITOR LM923 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 RELIABILITY FOR CHANGES, ERRORS OR OMISSIONS.

  • Page 2: Table Of Contents

    AOC LM923 Table of Content Revision List…………………………………………………………………………………………………………. 1. Monitor Specifications………………………………………………………………………………………….. 2. LCD Monitor Description……………………………………………………………………………………….. 3. Operating Instructions………………………………………………………………………………………….. 3.1 General Instructions…………………………………………………………………………………………... 3.2 Control Buttons………………………………………………………………………………………………... 3.3 Adjusting the Picture………………………………………………………………………………………….. 4. Input/Output Specification……………………………………………………………………………………... 4.1 Input Signal Connector……………………………………………………………………………………….. 4.2 Factory Preset Display Modes……………………………………………………………………………….. 4.3 Power Supply Requirements…………………………………………………………………………………...

  • Page 3: Revision List

    AOC LM923 REVISION LIST Revision Date Revision History TPV Model Nov-28-05 First Version Release T980KAXHLFMRA Page 3 of 55...

  • Page 4: Monitor Specifications

    AOC LM923 1.MONITOR SPECIFICATIONS ITEMS SPECIFICATIONS Driving system TFT LCD Size 48.0cm(19.0") Type M190EN02 LCD Panel Pixel pitch 0.294mm( H )x 0.294mm( V ) Viewable angle 170˚ (H) 170˚ (V) Response time (type) 25 ms for AU panel Sync. Type...

  • Page 5: Lcd Monitor Description

    AOC LM923 2. LCD MONITOR DESCRIPTION The LCD MONITOR will contain a main board, a power board, a keypad board and an audio board which house the flat panel control logic, brightness control logic and DDC. The power board will provide AC to DC Inverter voltage to drive the backlight of panel and the main board chips each voltage.

  • Page 6: Operating Instructions

    AOC LM923 3. OPERATING INSTRUCTIONS 3.1 GENERAL INSTRUCTIONS Press the power button to turn the monitor on or off. The other control buttons are located at front panel of the monitor. By changing these settings, the picture can be adjusted to your personal preferences.

  • Page 7: Adjusting The Picture

    AOC LM923 3.3 ADJUSTING THE PICTURE Adjustment steps: 1. Press the MENU-button to activate the OSD window. 2. Press < or > to select the desired function. 3. Press the MENU-button to select the function that you want to adjust.
  • Page 8 AOC LM923 User / Blue Blue Gain from Digital-register. Auto Adjust the H/V Position, Auto Config Focus and Clock of picture. (Analog-Only Do not execute Auto Config, Model) return to main menu. Adjust the horizontal position of H. Position the OSD.

  • Page 9: Input/Output Specification

    AOC LM923 4. INPUT/OUTPUT SPECIFICATION 4.1 INPUT SIGNAL CONNECTOR PIN NO. DESCRIPTION PIN NO. DESCRIPTION Red Video Green Video Detect Cable Blue Video Ground DDC-Serial Data Ground H-Sync Red Ground V-Sync Green Ground DDC-Serial Clock Blue Ground VGA connector layout...

  • Page 10: Factory Preset Display Modes

    AOC LM923 4.2 FACTORY PRESET DISPLAY MODES： HORIZONTAL VERTICAL STANDARD RESOLUTION FREQUENCY FREQUENCY Dos-mode 720 x 400 31.47kHz 70.0Hz 640 × 480 31.47kHz 60.0Hz 640 × 480 37.50kHz 75.0Hz 800 × 600 37.879kHz 60.0Hz SVGA 800 × 600 46.875kHz 75.0Hz 1024 ×...

  • Page 11: Panel Specification

    AOC LM923 4.4 PANEL SPECIFICATION 4.4.1 Display Characteristics 4.4.2 Optical Characteristics Page 11 of 55...

  • Page 12: Parameter Guide Line For Ccfl Inverter

    AOC LM923 4.4.3 Parameter guide line for CCFL Inverter   Page 12 of 55...

  • Page 13: Block Diagram

    AOC LM923 5. BLOCK DIAGRAM 5.1 MONITOR EXPLODED VIEW bezel 34G1275AKG-3B main frame 15G6093 AU rear cover 34G1276-GM-4B shield 85G6081-5 Key pad 33G4713 AS L hinge ass’y 37G 490 1 clamp 33G4695 -1-C stand 34G1273-GM-B base 34G1277-GM-B Page 13 of 55...

  • Page 14: Software Flow Chart

    AOC LM923 5.2 SOFTWARE FLOW CHART Page 14 of 55...
  • Page 15 AOC LM923 1) MCU initialize. 2) Is the EPROM blank? 3) Program the EPROM by default values. 4) Get the PWM value of brightness from EPROM. 5) Is the power key pressed? 6) Clear all global flags. 7) Are the AUTO and SELECT keys pressed? 8) Enter factory mode.

  • Page 16: Electrical Block Diagram

    AOC LM923 5.3 ELECTRICAL BLOCK DIAGRAM 5.3.1 Main Board LCD Interface (CN503) Scalar IC MST8111B W78E65 (Include ADC, OSD) (U601) (U401) EPR_SDA EPR_SCL H sync V sync EEPROM Key Board AT24C16N Control (U602) Crystal D-Sub 14.318MHZ Connector (X401) (CN301) DB15_SDA,...

  • Page 17: Inverter/Power Board

    AOC LM923 5.3.2 Inverter/Power Board AC input Bridge Rectifier Transformer Rectifier diode EMI filter and Filter Start Circuit: R906、 R907 CN902 Feedback Over Voltage Circuit Control IC Protect ON/OFF OSC and MOSFET DC Convert Output Circuit Circuit Lamp Over ON/OFF...

  • Page 18: Schematic

    VAA3 VAA4 VCC5V onBACKLITE 5.PANEL INTERFACE onPanel_5V/3.3V VCPU VCC12V VCC3.3 VCC2.5 AdjBACKLITE AdjBACKLITE VAA1 VLCD VAA2 VAA3 VAA4 VCC5V Title 4.SCALER VLCD MST 8011/8111 FOR AOC Size Document Number 2.POWER Date: Wednesday, November 10, 2004 Sheet Page 18 of 55...
  • Page 19 1/16W R207 4.7K 　 1/16W 100K 　 1/16W Q204 onPanel_5V/3.3V PMBS3904 4.7K 　 1/16W C207 C208 R211 Title 100uF/16V MST 8011/8111 FOR AOC 0.1uF 　 1/16W Size Document Number POWER Date: Wednesday, November 10, 2004 Sheet Page 19 of 55...
  • Page 20 CLK+ clk- CLK- JACK D306 D307 D308 D309 D310 D311 D312 D313 BAV99 BAV99 BAV99 BAV99 BAV99 BAV99 BAV99 BAV99 VCC5V Title MST 8011/8111 FOR AOC Size Document Number INPUT Date: Wednesday, November 10, 2004 Sheet Page 20 of 55...
  • Page 21 C403 22pF 600 OHM BUS TYPE/NC C404 0.1uF C427 BYPASS R401 10uF/16V AVSS_LPLL C428 0.1uF R402 R401 Direct Bus 4.7K Title MST 8011/8111 FOR AOC 3-WIRE 4.7K Size Document Number SCALER Date: Wednesday, November 10, 2004 Sheet Page 21 of 55...
  • Page 22 LVBCKM LVB2P LVB2M CONN R502 LVB1P LVB1M 0 1/16W 　 LVB0P VLCD LVB0M VLCD C509 C510 C511 47uF/16V 0.1uF 0.1uF Title MST 8011/8111 FOR AOC Size Document Number PANEL INTERFACE Date: Wednesday, November 10, 2004 Sheet Page 22 of 55...
  • Page 23 POWER R624 　 1/16W Mute_key C606 C608 C610 OUT-L+ OUT-R+ C616 C609 OUT-R- OUT-L- C607 0.001uF 0.001uF 0.001uF 1uF/25V 0.001uF 0.001uF CONN Title MST 8011/8111 FOR AOC Size Document Number Date: Wednesday, November 10, 2004 Sheet Page 23 of 55...

  • Page 24: Audio Board

    CN101 PIN 5 GND, PIN6 715L1279-A CIRCUIT /SHUTDOWN,PIN7 C137-C138 100P FOR EMI 1104 Title 2003/12/03 VOLUME,PIN8 MUTE TI_TDA3003D2/TDA3002D2 3W/9W AUDIO 2003/07/18　э CN104 パ3 PIN 倒　7 PIN Size Document Number AOC 19"LCD MONITOR FOR NMV Date: Thursday, December 04, 2003 Sheet Page 24 of 55...

  • Page 25: Power Board

    AOC LM923 6.3 POWER BOARD 715G1142-4-AUE Page 25 of 55...
  • Page 26 AOC LM923 Page 26 of 55...
  • Page 27 AOC LM923 Page 27 of 55...

  • Page 28: Pcb Layout

    AOC LM923 7. PCB Layout 7.1 MAIN BOARD 715L1237-1 Page 28 of 55...

  • Page 29: Audio Board

    AOC LM923 7.2 AUDIO BOARD 715L1279- A Page 29 of 55...

  • Page 30: Power Board

    AOC LM923 7.3 POWER BOARD 715G1142-4AUE 7.4 KEY BOARD 715L1205-1-C3 Page 30 of 55...

  • Page 31: Maintainability

    AOC LM923 8. MAINTAINABILITY 8.1 EQUIPMENTS AND TOOLS REQUIREMENT Voltmeter. Oscilloscope. Pattern Generator. DDC Tool with an IBM Compatible Computer. Alignment Tool. LCD Color Analyzer. Service Manual. User Manual. Page 31 of 55...

  • Page 32: Trouble Shooting

    AOC LM923 8.2 TROUBLE SHOOTING 8.2.1 Main Board No power No power Press power key and look if the picture is normal Please reinsert and make sure the AC of 100-240 is normal Reinsert or check the Adapter/Inverter section Measure U201 PIN2=2.5V U202 PIN2=3.3V...
  • Page 33 AOC LM923 No picture (LED orange) No picture The button if X601 oscillate Replace X601 under control waveform is normal Check reset circuit of Check Correspondent component U601 is normal Measure U201 PIN2=2.5V U202 PIN2=3.3V Replace U601 Replace U201, U202...
  • Page 34 AOC LM923 White screen White screen Measure Q204 base X601 oscillate waveform is normal is low level? Replace X601 Check Q204 is broken or Check reset circuit of CN503 solder? U601 is normal Check Correspondent Check Correspondent component. component. Replace PANEL...

  • Page 35: Power/Inverter Board

    AOC LM923 8.2.2 Power/Inverter Board No power Check CN902 pin2, 4 = 12V Check AC line volt 110V or 220V Check AC input Check the voltage of C905(+) Check bridge rectified circuit and F901 circut Check start voltage for the pin3 of IC901...
  • Page 36 AOC LM923 2.) W / LED, No Backlight Check CN902 pin2, 4 = 12V Check adapter or Main Board Check ON/OFF signal Check Main Board Check U201 pin9=12V Change Q201 or Q202 Check U201 PIN1 have the output of sawtooth wave at short time Change U201 Check D201 (-)/ D202 (-) have the output of square wave at short time.

  • Page 37: Keypad Board

    AOC LM923 8.2.3 Keypad Board OSD is unstable or not working Is Key Pad Board connecting normally? Connect Key Pad Board Replace Button Switch Is Button Switch normally? Replace Key Pad Board Is Key Pad Board normally? Check Main Board...

  • Page 38: White-Balance, Luminance Adjustment

    6500 color temp. parameter is x = 313±20, y = 329 ±20, Y = 180 cd/m 3. Into factory mode of AOC LM923 Turn on power, press the MENU button, pull out the power cord, and then plug the power cord. Then the factory OSD will be at the left top of the panel.

  • Page 39: Edid Content

    AOC LM923 10. EDID CONTENT 112: Page 39 of 55...

  • Page 40: Bom List

    AOC LM923 11. BOM LIST T980KAXHLFMRA Location Part No. for TPV Description Quantity Unit Q1G 330 10120 SCREW FOR FP/RC AUPC980A8 AUDIO BOARD FOR T980K* CBPC980KAXAC CONVERSION BOARD FOR T9 KEPC980KA9 KEY BOARD FOR T980K* PWPC1942AUE3 POWER BOARD 15G6093 AU...
  • Page 41 AOC LM923 M1G 330 4128 SCREW M3X4 M1G 330 6 47 SCREW M1G 330 6128 SCREW M1G1140 6128 SCREW 4X6 M1G1730 6128 SCREW M3x6 Q1G 330 10120 SCREW FOR FP/RC Q1G 340 10 47 SCREW Q1G 340 12 47 SCREW 705L980KF34045 19"...
  • Page 42 AOC LM923 CN104 33G8024 7B H HEADER FEMALE 7P MTGU101 90G6071 1 HEAT SINK 715L1279 A C101 65G0603221 32 CHIP 220PF 50V NPO C102 65G0603104 12 CER2 0603 X7R 16V 100N C103 65G0603104 12 CER2 0603 X7R 16V 100N C105...
  • Page 43 AOC LM923 C151 65G0603104 12 CER2 0603 X7R 16V 100N C152 65G0603104 12 CER2 0603 X7R 16V 100N L105 71G 56Z601 CHIP BEAD 600 OHM 0805 L107 71G 56Z601 CHIP BEAD 600 OHM 0805 L108 71G 56Z601 CHIP BEAD 600 OHM 0805...
  • Page 44 AOC LM923 X601 93G 22 55 J 20MHz/20PF/49US 40G 457624 1B LABEL-CPU 715L1237 1 PCB BOARD C201 65G0603104 32 CHIP 0.1UF 50V X7R C203 65G0603104 32 CHIP 0.1UF 50V X7R C205 65G0603104 32 CHIP 0.1UF 50V X7R C206 65G0805105 22...
  • Page 45 AOC LM923 C420 65G0603104 32 CHIP 0.1UF 50V X7R C421 65G0603104 32 CHIP 0.1UF 50V X7R C423 65G0603104 32 CHIP 0.1UF 50V X7R C425 65G0603104 32 CHIP 0.1UF 50V X7R C426 65G0603104 32 CHIP 0.1UF 50V X7R C428 65G0603104 32 CHIP 0.1UF 50V X7R...
  • Page 46 AOC LM923 FB303 61L0603000 RST SM 0603 JUMP MAX 0R FB304 71G 56G151 A TB160808G151 FB401 71G 56Z601 CHIP BEAD 600 OHM 0805 FB402 71G 56Z601 CHIP BEAD 600 OHM 0805 FB403 71G 56Z601 CHIP BEAD 600 OHM 0805 FB404...
  • Page 47 AOC LM923 R311 61L0603102 RST SM 0603 RC0603 1K P R312 61L0603101 RST SM 0603 RC0603 100R R313 61L0603222 RST SM 0603 RC0603 2K2 R314 61L0603103 RST SM 0603 RC0603 10K R315 61L0603101 RST SM 0603 RC0603 100R R316 61L0603101...
  • Page 48 AOC LM923 R625 61L0603103 RST SM 0603 RC0603 10K R626 61L0603103 RST SM 0603 RC0603 10K R627 61L0603103 RST SM 0603 RC0603 10K R634 61L0603101 RST SM 0603 RC0603 100R R635 61L0603101 RST SM 0603 RC0603 100R R636 61L0603101 RST SM 0603 RC0603 100R...
  • Page 49 AOC LM923 C107 65G0603104 32 CHIP 0.1UF 50V X7R C108 65G0603104 32 CHIP 0.1UF 50V X7R C109 65G0603560 31 CHIP 56PF 50V NPO C110 65G0603560 31 CHIP 56PF 50V NPO C111 65G0603560 31 CHIP 56PF 50V NPO C112 65G0603560 31...
  • Page 50 AOC LM923 C914 67G215L102 3R LOW E.S.R 1000UF +/-20% C915 67G215L102 3R LOW E.S.R 1000UF +/-20% C916 67G215S471 3K EC 470UF 16V C921 65G306M4722BP 4700PF +-20% 400VAC C950 65G306M3322BP 3300PF 20% CN201 33G8021 2D AC CONN.2P R/A 87210-0236 CN202 33G8021 2D AC CONN.2P R/A 87210-0236...
  • Page 51 AOC LM923 C114 65G0603104 32 CHIP 0.1UF 50V X7R C115 65G0603104 32 CHIP 0.1UF 50V X7R C202 65G0805104 22 0.1UF +-10% 25V X7R 080 C203 65G0805105 27 CHIP 1UF Y5V 0805 C209 65G0805105 27 CHIP 1UF Y5V 0805 C210 65G0805105 27...
  • Page 52 AOC LM923 Q203 57G 763 3 AO4411 SO-8 Q204 57G 763 3 AO4411 SO-8 Q205 57G 417 4 PMBS3904/PHILIPS-SMT(04 Q206 57G 417 4 PMBS3904/PHILIPS-SMT(04 Q207 57G 417 6 PMBS3906/PHILIPS-SMT(06 Q208 57G 417 6 PMBS3906/PHILIPS-SMT(06 Q902 57G 417 4 PMBS3904/PHILIPS-SMT(04 Q903...
  • Page 53 AOC LM923 R918 61L0805472 CHIRP 4.7K OHM +-5% 1/8 R919 61L1206470 CHIP 47OHM 5% 1/4W R920 61L1206470 CHIP 47OHM 5% 1/4W R921 61L1206471 CHIPR 470 OHM+-5% 1/4W R922 61L0805102 CHIPR 1K OHM +-5% 1/8W R923 61L0805000 CHIP O OHM 1/8W...
  • Page 54 AOC LM923 PT202 6G 31502 1.5MM RIVET R111 61G 21015352T 15KOHM 1% 1/6W R112 61G 60227252T 2.7KOHM 5% 1/6W R201 61G 60220352T CFR 20K OHM+-5% 1/6W R202 61G 60210352T CFR 10KOHM +-5% 1/6W R203 61G 60210352T CFR 10KOHM +-5% 1/6W...
  • Page 55 AOC LM923 R914 61G 2J22858H 0.22OHM 2W +-5% NR901 61G 58050 WT NTC 5 OHM 5A 96G 29 8 TUBE C901 65G305M1022BP Y2 1000PF M 250VAC Y5P 95G 900 42 WIRE HARNESS 96G 29 6 SHRINK TUBE UL/CSA CN901 87G 501 19 RF...

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