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.
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...
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.
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.
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.
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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.
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...
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...
AOC LM923 5.2 SOFTWARE FLOW CHART Page 14 of 55...
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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.
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...
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...
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...
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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...
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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...
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...
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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.
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...
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.
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...
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