AOC L1940T Service Manual

HP L1940T

SERVICE MANUAL

19” LCD Monitor

L1940T Series

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.

HP L1940T

Table of Contents

Table of Contents ------------------------------------------------------------------------------------------------------------------------ 02

Revision List ------------------------------------------------------------------------------------------------------------------------------ 03

1.Monitor Specification ----------------------------------------------------------------------------------------------------------------04

2.LCD Monitor Description ------------------------------------------------------------------------------------------------------------05

3.Operation Instructions ---------------------------------------------------------------------------------------------------------------05

3.1 General Instructions ----------------------------------------------------------------------------------------------------- ----------05

3.2 Control Button ---------------------------------------------------------------------------------------------------------------------06

3.3 Adjusting The Picture --------------------------------------------------------------------------------------------------------------06

4. Input/Output Specification -------------------------------------------------------------------------------------------------------- 09

4.1 Input Signal Connector -----------------------------------------------------------------------------------------------------------09

4.2 Factory Preset Display Modes ---- ----------------------------------------------------------------------------------------------11

4.3 Power Supply Requirements ----------------------------------------------------------------------------------------------------11

5.Panel Specification ---------------------------------------------------------------------------------------------------------------------12

5.1 General Feature --------------------------------------------------------------------------------------------------------------------12

5.2 Optical Characteristics ------------------------------------------------------------------------------------------------------------13

6.Monitor Exploded View -----------------------------------------------------------------------------------------------------------------14

7.Repair Flow Chart ---------------------------------------------------------------------------------------------------------------------15

8. Trouble Shooting -------------------------------------------------------------------------------------------------------------------18

9. Block Diagram --------------------------------------------------------------------------------------------------------------------19

10. Schematic ------------------------------------------------------------------------------------------------------------------------------20

10.1Main Board ----------------------------------------------------------------------------------------------------------------------20

10.2 Inverter/Power Board -------------------------------------------------------------------------------------------------------25

10.3 Key Board ------------------------------------------------------------------------------------------------------------------29

11. PCB Layout -----------------------------------------------------------------------------------------------------------------------------31

1 1.1 Main Board --------------------------------------------------------------------------------------------------------------------------31

11.2 Inverter/Power Board -------------------------------------------------------------------------------------------------------------32

11.3 Key Board ---------------------------------------------------------------------------------------------------------------------------33

12. Maintainability -------------------------------------------------------------------------------------------------------------------------34

13. White-Balance, Luminance Adjustment ------------------------------------------------------------------------------------ 35

14. Check List after replacing LCD Main board ---------------------------------------------------------------------------------37

14.1 Check white-balance -------------------------------------------------------------------------------------------------------------37

14.2 Step s for writing DDC --------------------------------------------- ---------------------------------------------------------------37

15. EDID Content ---------------------------------- -------------------------------------------------------------------------- --------------52

16. BOM List ----------------------------------------------------------------------------------- ---------------------------------------53～64

HP L1940T

Revision List

Revision Date Revision History TPV Model

A00 Feb.-24-06 Initial release T981KMVDBHHPNP

1.Monitor Specifications

Driving system TFT Color LCD Panel M190E5-L0A Active Area 376.32(H) x 301.056(V) (19.0")

Pixel pitch 0.294( H )x 0.294mm( V )

HP L1940T

LCD Panel

Input

Display Colors Over 16 million Colors Pixel Clock 140MHz Max. Resolution 1280 x 1024 Plug & Play VESA DDC2BTM

Viewing Angles(Min / TYP) H:120/140; V:110/130 Response time (typ.) < 8 ms Brightness 200 nits Contrast 450:1 Video Analog /Digital Sync. Type H/V TTL H-Frequency 30kHz – 83kHz V-Frequency 56Hz – 76Hz

ON Mode

70W

≤

Power Consumption

Power Source 100~240VAC,47~63Hz

Environmental Considerations

Main Dimensions

Weight (N. W.)

Altitude

OFF Mode <1W Sleep Mode <2W

Operating Temp: 5°C to 35°C Storage Temp.: -20°C to 60°C Operating Humidity: 20% to 80%

Unpackaged(W*H*D) 413mm*477mm*265mm

Packaged(W*H*D) 524mm*513mm*239mm

Packaged 10.22Kg Unit max Unpackaged 8.4Kg Unit max Operating 0 to 12,000 feet Non-Operating 0 to 40,000 feet

HP L1940T

2. LCD Monitor Description

The LCD Monitor will contain main board, power board, key board and 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 chi ps each voltage.

Power Board

AC-IN

110-240V

Monitor Block Diagram

CCFT Drive.

Main Board

Keyboard

HOST Computer

Flat Panel and CCFL backlight

RS232 Connector For white balance adjustment in factory mode

Video signal, DDC

3. Operation Instructions

3.1 General Instructions

Press the power button to turn the monitor on or off. The other control buttons are located at front of the panel. By changing these settings, the picture can be adjusted to your personal performance.

The power cord should be connected .

Connect the video cable from the monitor to the computer VGA card.

- Press the power button to turn on the monitor , the power indicator will light up to Green.

3.2 Control Buttons

- Power Indicator:

Green — Power On mode. Orange — Power Saving mode. Blank —Power Off Mode.

Auto Adjust : Activates the auto adjustment feature for optimum image. Menu : Opens the ON-Screen Display(OSD) menu. Minus (–) : 1、If OSD is on, press to navigate backward through the OSD menu features and decrease

adjustment levels.

2、If OSD is off, press to enable the DVI signal input (available on select models).

HP L1940T

plus (+) : 1、If OSD is on, press to navigate forward through the OSD menu feature s and increase adjustment

levels.

2、If OSD is off, press to enable the VGA signal input. Power: Turns the monitor on or off.

3.3 Adjust the Picture Main Menu Press the “Menu” button, the Main Menu should be come on the screen of the monitor

HP L1940T

Service Mode

Press and hold the “Menu” button, Power off -> on “Power”,then into the service mode, Press “menu” button to

bring to OSD menu for confirmation as below:

Factory Mode

1、 Turn off monitor. 2、 [ Push “Auto Adjust” and “+ (plus)”and hold them at the same time ]+ [ Press power “Power” button untill

comes out “windows screen” ] =>then release all button,then press “Menu”button,wait untill the OSD menu with Characters “F” (below OSD menu) come on the Screen of the monitor as bellow:

3、 Pust “Menu” to exit OSD menu.

Factory Mode Indicator

Menu icons

HP L1940T

No. Control Icon

1 Brightness 2 Contrast 3 Auto Adjustment 4 Image Control 5 Color 6 Custom Color 7 Language

8 Management

9 OSD Control 10 Information 11 Factory Reset

12 Default Video Input

13 Horizontal Position 14 Vertical Position

15 Clock 16 Clock Phase

17 Power Saver 18 Mode Display 19 Power-On Status Display 20 Sleep Timer 21 Basic Menu 22 Advanced Menu 23 Power On Recall 24 Horizontal OSD Position 25 Vertical OSD Position 26 OSD Timeout 27 OSD Transparency 28 Exit

4. Input/Output Specification

4.1 Input Signal Connector

Analog Connector Pinout

Pin Mnemonic Signal Pin Mnemonic Signal

1 RV Red Video 9 +5 V +5 V (from PC) 2 GV Green Video 10 SG Sync Ground 3 BV Blue Video 11 NC None 4 NC None 12 SDA DDC Data 5 GND GND / Cable Detect 13 HS Horizontal Sync 6 RG Red GND 14 VS Vertical Sync 7 GG Green GND 15 SCL DDC Clock

HP L1940T

8 BG Blue GND

PIN 1

PIN 11

VGA connector layout

PIN 5

HP L1940T

DVI-D Digital Connector Pins

Pin. Mnemonic Signal Pin. Mnemonic Signal

1 TX 2 - TMDS Negative differential input, channel 2 13 TX 3 + TMDS Data 3 + 2 TX 2 + TMDS Positive differential input, channel 2 14 +5V +5V Power 3 SHLD 2 / 4 Shield for TMDS channels 2 / 4 15 GND GND / Cable Detect 4 TX 4 - TMDS Data 4 - 16 HPD Hot Plug Detect 5 TX 4 + TMDS Data 4 + 17 TX 0 - TMDS Data 0 6 DDC Clk DDC Clock 18 TX 0 + TMDS Data 0 + 7 DDC Data DD C D ata 19 SHLD 0 / 5 TMDS D ata 0 / 5 Shield 8 AVS Analog Vertical Sync 20 TX 5 - TMDS Data 5 -

9 TX 1 - TMDS Data 1 - 21 TX 5 + TMDS Data 5 + 10 TX 1 + TMDS Data 1 + 22 TX CLK SHLD TMDS Clock Shield 11 SHLD 1 / 3 TMDS Data 1 / 3 Shield 23 TX CLK + TMDS Clock + 12 TX 3 - TMDS Data 3 - 24 TX CLK - TMDS Clock -

DVI-D Digital Connector Pins

4.2 Factory Preset Display Modes

HP L1940T

Preset

Pixel

Format

1 640 x 480 31.469 - 59.940 - 25.175 VGA 2 640 x 480 37.861 - 72.809 - 31.500 VESA 3 640 x 480 37.500 - 75.000 - 31.500 VESA 4 720 x 400 31.469 - 70.087 + 28.322 VGA 5 800 x 600 37.879 6 800 x 600 48.077 + 72.188 + 50.000 VESA 7 800 x 600 46.875 + 75.000 + 49.500 VESA 8 832 x 624 49.726 ± 74.551 ± 57.284 MAC

9 1024 x 768 48.363 - 60.004 - 65.000 VESA 10 1024 x 768 56.476 - 70.069 - 75.000 VESA 11 1024 x 768 60.023 + 75.029 + 78.750 VESA 12 115 2 x 870 68.68 - 75.06 - 100.000 Mac 13 115 2 x 900 71.71 - 76.05 - 105.561 Sun 14 1280 x 1024 63.98 + 60.02 + 108.000 VESA

Horz Freq

(KHz)

Horz

Polarity

Vert Freq (Hz)

Vert

Polarity

60.317 + 40.000 VESA

Pixel Clk

Source

(MHz)

15 1280 x 1024 79.97 + 75.02 + 135.000 VESA

4.3 Power Supply Requirements

PARAMETER RANGE

AC Input Voltage 90 to 265V

AC Input Frequency 47 to 63 Hz

Inrush Current 50A MAX AT 220VAC and 30A AT 120VAC

Leakage Current 5 mA MAX at 120VAC

Power consumption

≤70W

HP L1940T

5. Panel Specification

5.1 General Feature

- Wide viewing angle.

- High contrast ratio

- Super fast response time

- High color saturation

- SXGA (1280 x 1024 pixels) resolution

- DE (Data Enable) only mode

- LVDS (Low Voltage Differential Signaling) interface

- RoHS Compliance

5.2 Optical Characteristics

Test Conditions

HP L1940T

Optical Specifications

6. Monitor Exploded View

HP L1940T

7. Repair Flow Chart

HP L1940T

8. Troubleshooting

Problem Possible Cause Solution

Screen is blank.

Image appears.blurred, indistinct, or too dark.

Image is not Centered.

Check Video Cable is displayed on screen. (Input Signal Out of Range) is displayed

Power cord is disconnected. Power switch is turned Off. Video cable is improperly connected. Screen blanking utility is active.

Brightness and contrast are too low Press the Minus button on the monitor front panel to auto-adjust the screen. If

Position may need Adjustment

Monitor video cable is disconnected.

refresh rate are set higher than what your monitor supports.

Connect the power cord. Turn on the power. Connect the video cableproperly. Depress any key on the keyboard or moveThe mouse to inactivate the screen blanking Utility.

that Does not work, press the Menu button to open the Basic OSD Menu, and adjust the brightness and contrast scales as needed. When OSD is inactive,press-(minus. button) to auto-adjust the screen image. Press the Menu button to access the Advanced OSD menu. Select Image Control/Horizontal Position or Vertical Position to adjust the horizontal or vertical position of the image. Connect the 15-pin monitor video cable to the VGA connector on the computer. Be sure that the computer power is off while: connecting the video Cable. Restart your computer and enter Windows Safe Mode by pressing the F6 Function

on screen.

key when the computer starts to boot up. Change your settings to a supported setting. Restart your computer so that the new settings take effect.

9. Block Diagram

HP L1940T

10. Schematic

10.1 Main Board

HP L1940T

+ 46 hidden pages