AOC P/N : 41A50-144 service manual Keyboard Block check

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KEYBOARD BLOCK check

Check U302 MCU pin 43,42,41,40,39 at High state(5V)? without press any key

OK

Press power key and check U302 pin 43 = low (0V) ?

OK

Check U302 pin 38 (LED green) will have transition from hi to low or low to hi when we press the power key??

NG, MCU no response

Check U302 pin 20= 20MHz ? and pin 44 (VDD)=5V ? and pin 10 (reset)=0V ? at normal condition

NG

NG

OK

NG

Mechanical was stuck, Check !

Replace Tact-switch SW105 at keyboard if still no work replace U302 MCU at main-board and check MCU relative reset circuit, and crystal

If still no Led green indicator, check Q102, R106 & LED at keyboard !! cold solder or bad

If one of this item was NG, check the relative circuit

OK

Without press key and change mode, Check U302 pin 16,17(sda,scl)= hi 5V ? or keep transition ?

OK, no keep transition

Replace U302 MCU

Keep transition, that means eeprom no response

NG

Check U300 eeprom 24LC04 relative circuit, check U300 pin 7 = low?

NG		OK

Check JP202 is		Check U300 pin 8
connect ?		(vdd)= 5V, and check
		R300,R301 cold solder
		R300,R301 cold solder

Replace eeprom

18

Image 19

Contents

Spectrum Series SEP Table of Contents General specifications Specifications for LCD MonitorLCD-PANEL AC-IN Adapter Monitor Block DiagramInterface Connectors LCD Monitor DescriptionStorage Precautions Precautions and NoticesAssembly Precaution Operating PrecautionsPIN no Description RED Operating InstructionsAdjustment Conditions and Precautions AdjustmentAdjustment Method Adjust 6500 color-temperature Front Panel Control Knobs CHI-MEI Panel M170E1 CIRCUIT-DESCRIPTIONOSD-INDEX Explanation Input not SupportMODULE-TPYE Component SIMPLE-INTRODUCTION about LM700 chipsetPanel Clear factory mode flag Power-On Subrotine ChartSoftware Flow Chart SET factory mode flag II. Main Subrotine Loop No Screen Appear Interface-Board Trouble-Shooting chartU200-DATA Output PANEL-POWER CircuitMainboard Check Oscillator Block as above Keyboard Block check POWER-BLOCK check END Panel Luminance WAS Down There is an interferences in DOS ModeCorporation Inverter -MODULE Spec &Trouble Shooting ChartFunction Load Circuit M P O C O R P O R a T I O N Trouble Shooting of CHI-MEI Inverter DIVTL0037-D42 Part List Part Part Number QTY Description Supplier Remark Name Trouble Shooting Hight Voltage Protection Enbale Abnormality Transformer Abnormality Check U101 PIN4NO Freq ~70KHZ Part number 80AL17-1-CH Black, 80AL17-2-CH WhitePage Reference Part Quantity Cat.NO IV. Adapter BOM List Part no AL15-2-LIPCB PCB for CH-1205 Revd PCS For Front Heatsink No Voice Output AUDIO-MODULE Trouble shooting chartII. Sound Distortion Audio BOMGMZAN1 Name Description Pin DescriptionAnalog-to-Digital Converter PIN #Host Interface HIF / External On-Screen Display Clock Recovery / Time Base Conversion TFT TFT Panel InterfacePIN # Name Description 2pxl/clk 1pxl/clkTest Pins Typical Stand-alone Configuration System-level Block DiagramZoom Operating ModesNative Slow DclkDestination Stand Alone DownscalingSource Stand Alone Functional Description Clock Recovery CircuitOverall Architecture Clock Recovery Circuit Minimum Typical Maximum Clock Recovery CharacteristicsSampling Phase Adjustment Source Timing GeneratorPin Connection for RGB Input with Composite Sync ADC CharacteristicsAnalog-to-Digital Converter 2.3.1 Pin Connection Pin Connection for RGB Input with Hsync/VsyncSource Timing Measurement Sync. Signal SupportDisplay Mode Support Input Timing MeasurementData Path IRQ ControllerIRQ-Generation Conditions IRQ Event Remark RGB Offset TFT Panel Interface Timing SpecificationScaling Filter Gamma TablePCLKB*4 Pclk *1Horizontal size in TFT Vsync width and display position in TFTHsync width in TFT One pixel per clock mode in TFT Power ManagerState 3 Panel Fully Active State 0 Power OffState 1 Power On State 2 Panel Drive EnabledValue 4 bits Drive Strength in mA Panel Interface Drive StrengthHost Interface Panel Interface Pad Drive StrengthSerial Communication Protocol Timing Diagram of the gmZAN1 Serial CommunicationMulti-Function Bus MFB GmZAN1 Serial Channel Specification Parameter Min Typ MaxOn-Screen Display Control On-Chip OSD Controller OSD Color MapTclk Input Tclk SpecificationPvdd Electrical CharacteristicsDC Electrical Characteristic Parameter Min Typ Max Absolute Ratings Parameter Min Typ MaxMechanical of Cabinet Front DIS-ASSEMBLY T780KMGHBAA0A Specification Parts List of CabinetParts List of Cabinet continue Location CBPC780GM Specification Parts List of Conversion BoardLocation AI780GM Specification Location AI780GM SMD EC 22UF 16V 85C Csize KEPC780EK Parts List of KEY PC BoardParts List of Audio Board Parts List of DC-POWER BoardAdapter Module Power System and Consumption CurrentInverter Module PCB Layout TOP-LEVEL Flow Schematic DiagramII. GMZAN1 Block Lvds Block MCU Block Power Block KBL405G Adapter Schematic CH-1205C1,C2,C4 --- 1uF/50V