AOC LT2025W Schematic

20” LCD TV Color Monitor

Norcent LT2025W

Service

Service

Service

TABLE OF CONTENTS

Description

Page

Description

Page

Table Of Contents.......…….…..............................…........1

Revision List.…….….....................................……......2

Important Safety Notice.……..................……......3

1.Monitor Specification..…............................………........4

2.Operating Instructions……...……………….……….......6

2.1 The Use Of Remote Control..…………..................6

2.2 Front Panel Control Knobs.....................…...........6

2.3 OSD Operating…………….…............……...............8

2.4 How To Connect...………........................…............13

3.Input/Output Specification............……………............17 3.1 Input Signal Connector............………….................17 3.2 Factory Preset Display Modes........………...............17

4.Mechanical Instructions..………....……......................18

5.Repair Flow Chart…….……………………..................21

6.PCB Layout………...……….……………....….…….....27 6.1 Main Board……...……………..……………....….......27

6.2Power Board………………………….....….......29

6.3Key Board….…..........................…….........30

6.4Tuner Board...………...…...................................30 7. Block Diagram..……..……................….......................31

7.1Main Board...............……..……...............................31

7.2Power Board…...……..….…...….…..........................32 8. Schematic Diagram…….….….………………….......33

8.1Main Board……...…..……….………......................33

8.2Power Board...……………….……………………...46

8.3Key Board……………..…………..………………...47

8.4Tuner Board.....…..........……………........................48

8.5IR Board...…….........…………...............................52

8.6Earphone Board...…….........………................……...53 9. Exploded View…….........………..............…................54 10. BOM List…………………… …….....……….…..........55

SAFETY NOTICE

ANY PERSON ATTEMPTING TO SERVICE THIS CHASSIS MUST FAMILIARIZE HIMSELF WITH THE CHASSIS AND BE AWARE OF THE NECESSARY SAFETY PRECAUTIONS TO BE USED WHEN SERVICING ELECTRONIC EQUIPMENT CONTAINING HIGH VOLTAGES.

CAUTION: USE A SEPARATE ISOLATION TRANSFOMER FOR THIS UNIT WHEN SERVICING

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20” LCD TV Color Monitor				Norcent LT2025W
			Revision List
	Version	Release Date	Revision History	TPV Model
	A00	Sep-22-2006	Initial Release	E206MHNKD4NCNCP
	A01	Nov-07-2006	Add TPV Model in item 10	E206AHNKD4NONCP

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20” LCD TV Color Monitor

Norcent LT2025W

Important Safety Notice

Proper service and repair is important to the safe, reliable operation of all AOC Company Equipment. The service procedures recommended by AOC and described in this service manual are effective methods of performing service operations. Some of these service operations require the use of tools specially designed for the purpose. The special tools should be used when and as recommended.

It is important to note that this manual contains various CAUTIONS and NOTICES which should be carefully read in order to minimize the risk of personal injury to service personnel. The possibility exists that improper service methods may damage the equipment. It is also important to understand that these CAUTIONS and NOTICES ARE NOT EXHAUSTIVE. AOC could not possibly know, evaluate and advise the service trade of all conceivable ways in which service might be done or of the possible hazardous consequences of each way. Consequently, AOC has not undertaken any such broad evaluation. Accordingly, a servicer who uses a service procedure or tool which is not recommended by AOC must first satisfy himself thoroughly that neither his safety nor the safe operation of the equipment will be jeopardized by the service method selected.

Hereafter throughout this manual, AOC Company will be referred to as AOC.

WARNING

Use of substitute replacement parts, which do not have the same, specified safety characteristics may create shock, fire, or other hazards.

Under no circumstances should the original design be modified or altered without written permission from AOC. AOC assumes no liability, express or implied, arising out of any unauthorized modification of design.

Servicer assumes all liability.

FOR PRODUCTS CONTAINING LASER:

DANGER-Invisible laser radiation when open AVOID DIRECT EXPOSURE TO BEAM.

CAUTION-Use of controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure.

CAUTION -The use of optical instruments with this product will increase eye hazard.

TO ENSURE THE CONTINUED RELIABILITY OF THIS PRODUCT, USE ONLY ORIGINAL MANUFACTURER'S REPLACEMENT PARTS, WHICH ARE LISTED WITH THEIR PART NUMBERS IN THE PARTS LIST SECTION OF THIS SERVICE MANUAL.

Take care during handling the LCD module with backlight unit

-Must mount the module using mounting holes arranged in four corners.

-Do not press on the panel, edge of the frame strongly or electric shock as this will result in damage to the screen. -Do not scratch or press on the panel with any sharp objects, such as pencil or pen as this may result in damage to the panel.

-Protect the module from the ESD as it may damage the electronic circuit (C-MOS). -Make certain that treatment person’s body is grounded through wristband.

-Do not leave the module in high temperature and in areas of high humidity for a long time.

-Avoid contact with water as it may a short circuit within the module.

-If the surface of panel becomes dirty, please wipe it off with a soft material. (Cleaning with a dirty or rough cloth may damage the panel.)

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20” LCD TV Color Monitor					Norcent LT2025W
1. General Specifications
		Item			Spec
		Screen Size	20” TFT-LCD Panel
		Aspect Ratio	16 : 9
		Resolution	1360 x768	(WXGA)
		Display Area (opening) H x V	443.61(H) x 249.41(V) mm
		Pixel Pitch	0.325 x 0.325 mm
	LCD Panel
		Display Colors	16.2M
		Contrast Ratio	500:1
		Brightness	450 cd/
		Viewing angle	(160° H/ 140° V )
		Response Time	8ms
		Lamp Life	50000 hrs
		Input support definition	Could support to 1360*768
	PC function		This product could only support to 60Hz, ‘Input out of range’ will
			be displayed when the input vertical frequency out of 60Hz
		Audio input	Mini jack 3.5ø stereo
		TV Standard	NTSC M
	TV
		Sound System	BTSC
	Function
		Color systems	NTSC
		Video AV	RCA x 1		Audio L/R x 1
	Video Input	S-VIDEO	S-Video x 1
		YPbPr	YPbPr x 1		Audio L/R x 1
		YPbPr support modes	480i, 480p, 720p, 1080i

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20” LCD TV Color Monitor			Norcent LT2025W
	Audio output	Audio output: L / R	Speaker (built-in): Two 3 watt speakers
			Headphone Mini-jack for stereo (3.5ø)
	OSD Language	English, French, German, Spanish, Portuguese and Traditional Chinese.
	Base Stand	Yes
	Wall Mount Standard	VESA 100 x 100 mm
		Power	AC100V-240V, 50/60Hz
	Power	Power Consumption	< 90W
		Standby Power	< 1.1W
	Panel Tilt	Forwards/Backwards/	fixed
		Rotation
		Operating Temperature	+ 5 °C ~ + 35 °C
	Environment
		Storage Temperature	- 10 °C ~ + 60 °C
		Operating Humidity	10% ~ 85%
	Dimension	W x H x D (with stand)	546mm X445mmX185mm
	Net weight	7.5 Kg (Without accessory)
		Remote control, Batteries (AAAx2), Power cord, VGA Cable, Audio Line Cable, User
	Accessory
		Manual

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20” LCD TV Color Monitor

Norcent LT2025W

2. Operations Instructions

2.1 The Use of Remote Control

Open the back battery cover of the remote control and install two AAA size batteries and then close the battery cover on to the remote control.

POWER

Power on/Off.

0~9/100 Digit buttons

To select a TV channel.

CH

Press¿ or À to adjust channel.

VOL

Press + or - to adjust the volume.

PC

To change to PC input mode.

SLEEP

To set sleep timer.

PIP

Not Supported.

MENU

Press repeatedly to display or exit

OSD menu.

V-CHIP

Press this button to setup parental control (active after child lock OSD manual is set to ON).

POP

Not Supported.

MUTE

Temporarily interrupt the sound or restore it.

DISPLAY

Press this button to display Channel.

MTS /SAP

Press this key to activate Multichannel Television Sound, Stereo, SAP or Mono sound.

PRE-CH

To display the previously selected TV channel.

TV/VIDEO

Select your input source: press repeatedly to select source.

CAPTION

Press this button to select Closed Caption mode (off, CC1~4, TXT 1~4).

SWAP

Not Supported.

SIZE

Press this button to adjust the picture size, Auto , FullScreen, WideScreen or 4:3

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	20” LCD TV Color Monitor		Norcent LT2025W
	2.2 Front Panel Control Knobs

Power Key : Press to turn on or off the TV.

MENU Key : Press to show the OSD menu and exit OSD menu at the TV.

CH Down / Up Key : Select the intended function by pressing these two keys, or switch the channels in the TV mode.

Vol + /- Key : Press to confirm your function selection and adjustment volume.

Source Key : Press to select your input source.

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20” LCD TV Color Monitor	Norcent LT2025W
2.3 OSD Operations

1.Press the MENU button to display each menu.

2.Use the cursor up/down buttons to select a menu item.

3.Use the cursor left/right buttons to enter a submenu or enable/disable the function.

4.Press the MENU button to exit the menu.

Press the MENU button to enter the main OSD (On Screen Display). Adjust the items including Picture Setup, Sound setup, Child Lock Setup, Function Setup and TV setup. When the input source is PC or Component mode, only the Sound Setup, Picture Setup and Function Setup can be selected; shown in the figure below:

When the input source is AV or S-Video mode, the Sound Setup, Picture Setup, Child Lock Setup and Function Setup can be selected; shown in the figure below:

When the input source is TV mode, the Sound Setup, Picture Setup, Child Lock Setup, Function Setup and TV Setup can be selected; shown in the figure below:

Sound Setup (Same as in PC, TV, AV, S-Video and Component modes)

1.The range of adjusting volume, bass and treble is from 0~100.

2.Select “ON” or “OFF” in Audio selection to control the sound output.

3.The range of adjusting Balance is -50~+50; when adjusting from 0 to -50, the sound from the right track fades until silence; when adjusting from 0 to +50, the sound from the left track fades until silence.

4.AVL: you can set it “ON” or “OFF”.

The function is to adjust the input sound automatically. You may enable this function when you notice that the sound in the two tracks are very different, in order to prevent the bad sound effect resulting from large sound variation.

5.Select "ON" or "OFF" for Loudness: a default setting is preset, you may adjust when necessary. The following menu will appear when selecting continuously:

6.Preset: Designed for different types of sound output, wherein, the Voice, music and theater modes are preset; you can set Bass, Treble and Equalizer in sound output mode according to your preference.

7.Equalizer: You can select and adjust 100, 300, 1K, 3K and 8K respectively (the figures represent the sound frequency range).

8.Reset to default: Reset the sound setting to the factory default value.

Picture Setting

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20” LCD TV Color Monitor

Norcent LT2025W

When the input source is in PC mode, you can select Brightness, Contrast, Position, Video noise, Sharpness, Auto Adjust, Info, Color Temp., Red, Green, Blue and Reset to default; shown in the figure below:

1.Brightness and Contrast: The range can be adjusted from 0~100.

2.Position: There are two options, Horizontal and Vertical, which can be adjusted from -50 to +50.

3.Video noise: There are two options, Phase and Clock, which can be adjusted from -50 to +50.

4.Sharpness: Select from options of Auto Softest, Soft, Normal, Sharp and Sharpest. You may adjust the above options according to your preference.

5.Auto Adjust: Automatically adjust PC input to the optimal screeen size.

6.Info: Prompt the current size for PC input definition (only the definition that can be shown by this device).

7.	Color Temp.: There are four options of Color temperature provided for users - Warm, Normal, Cool and User.
	You can select the three Color temperatures of Warm, Normal, and Cool, or manually adjust red, green or blue
	in the User setting (you can only adjust red, green and blue in the User setting).
8.	Reset to default: It is used to reset the picture settings to the factory default mode.

When the input source is in TV/AV/S-Video mode, you can select Brightness, Contrast, Color, Sharpness, Tint, Dyn. skin tone, Color Temp., Zoom and Reset to default respectively; shown in the figure below:

When the input source is in Component mode, you can select Brightness, Contrast, Video noice, Color, Sharpness, Tint, Color Temp, Zoom and Reset to default respectively; shown in the figure below:

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20” LCD TV Color Monitor

Norcent LT2025W

1.Brightness and Contrast: The range can be adjusted from 0~100; use Brightness and Contrast options to adjust the brightness and contrast of picture.

2.Video noise: There are two options, Phase and Clock, which can be adjusted from -50 to +50.

3.Color: The range can be adjusted from 0~100; use this option to adjust the Color saturation of picture.

4.Sharpness: Select from options of Auto, Softest, Soft, Normal, Sharp and Sharpest. You can adjust the sharpness of picture using any option above.

5.Tint: The range can be adjusted from -50~+50; use this option to adjust the Color tone of picture.

6. Color Temp.: There are three options of Color temperature provided for users - warm, normal and cool.

7.Zoom: There are various functions provided for zoom in/zoom out.

8.Reset: It is used to reset the picture settings to the factory default mode.

Function Setup

When the input source is in TV, AV or S-Video mode, you can select Source OSD, Language, Child lock, Timers, CC Mode and Reset to default; shown in the figure below:

1.Current Source OSD setting: When OSD is set to ON, the left upper corner of the display will show the input source or the TV channel number; when OSD is set to OFF, the input source or the TV channel number will disappear.

2.OSD language setting: There are six language options provided - English, French, German, Spanish, Portuguese and Traditional Chinese.

3.Child Lock Setup;

(1). You can enter the V-Chip level setting only when the Child Lock is ON, and the V-Chip will be enabled; you can not enter V-Chip level setting when the Child Lock Setup is OFF, and the V-Chip is disabled.

(2). Lock code: V-Chip password can be set up when the code is locked. Enter the 4-digit password which you choose! The factory default password is 0000.

4.Sleep Timer: Set the sleeping timer and the alert function which indicates the time left.

5.Closed Caption (CC) setting: Select CC1~CC4, TXT1~TXT4 or OFF.

6.Reset: It is used to reset the OSD settings.

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20” LCD TV Color Monitor

Norcent LT2025W

When the input source is in PC or Component mode, you can select Source OSD, Language, Sleep Timer and Reset to default; shown in the figure below:

Source OSD, Language, Sleep timer and Reset to default options are operated similarly as the above instructions!

Child Lock

When the input source is in TV, AV or S-Video mode, V-Chip level can be set. You can enter the Child Lock setting only when the Child Lock is ON. When you enter the Child Lock setting, a message on the display will prompt you to enter password:

You can enter the Child Lock setting to set up the V-Chip level when you enter the correct password:

1.Age: it may be set to Child, Youth, Young adult, Adult, Custom or OFF; when you select Custom, it can be set according to you preference.

2.MPAA Rating: Select the movie ratings from low to high (alert) - G, PG, PG-13, R, NC-17, X and off.

3.PG Rating: Shown in the figure below:

The empty box refers to unlocked; the solid box refers to locked.

TV Setting

The following menu appears only in the TV mode.

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20” LCD TV Color Monitor

Norcent LT2025W

1.Channel nr: Shows the current channel number.

2.Tuning mode: Select the mode of TV signal - Cable\HRC Cable\IRC Cable\ Broadcast.

3.System standard: NTSC-M , Auto

4.Auto search: Select "Auto Search" to search all signaled channel; when the searching is complete, it stays at the first channel with signal and all channels that have been located are stored. If you would like to stop "Auto Search" during the process, simply by pressing the MENU button.

5.Fine tune: NTSC-M is seldom used.

6.AFC can be set to ON or OFF. When it is set to ON, the TV will search the TV signal automatically; when there is any offset in the signal, it will automatically adjust the channel to the correct positon.

7.Skip can be set to ON or OFF. When it is set to ON, a channel can be skipped when pressing the CH button on the remote control or on the front panel.

8.Reset to default: Reset to the factory default value.

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20” LCD TV Color Monitor	Norcent LT2025W
2.4 How To Connect

1.Connect the antenna cable to the RF IN port of your VCR.

2.Connect another RF cable from the output RF of your VCR to the Antenna input of your TV. Better quality when playing from your VCR can be obtained if you also connect the Video, Audio LEFT AND RIGHT (only for stereo equipment) cables to the VIDEO, AUDIO L and R inputs AV.

If you are using only mono equipment, connect only the VIDEO and the AUDIO L (Mono) ports.

If your VCR has an S-VHS video jack:

For improved picture quality, connect an S-Video cable to the S-VIDEO input on the TV instead of connecting the VCR to the VIDEO port of AV.

S-Video does not provide audio, audio cables must still be connected to provide sound. (S-Video and AV share the same audio input port)

Watching VCR

1.If you use connection , select the TV channel 3 or 4.

2.If you use connection , select VIDEO or S-VIDEO, (see P7 TV/ VIDEO)

3.Insert videotape in the VCR and press the PLAY button.

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20” LCD TV Color Monitor

Norcent LT2025W

1.Composite Video: Connect your camera, camcorder, videogame set… to Audio port (Audio L for mono) and

Video port .

2.S-Video Connection

S-VHS quality with an S-VHS camcorder is obtained by connecting the S-VHS cable to the S-VIDEO input and AUDIO input .

How to use

1.Select VIDEO or S-VIDEO input source (see P7 TV/ VIDEO)

2.Turn on the external AV equipment.

1.Connect the three separate component video cables to the DVD player’s.

Y, Pb and Pr ports and to the Y, Pb and Pr ports on the TV.

2.Connect the audio cables to the DVD player’s AUDIO L and R ports and to the L and R AUDIO INPUT ports on the TV.

How to use

1.Select COMPONENT, (see P7 TV/ VIDEO)

2.Turn on the DVD set.

Connect DTV set top box RF output to TV Antenna input (TV channel set to CH3 or CH4). If your DTV set top box has component (Y, Pb, Pr) video ports, use them for better picture.

How to connect component video:

1. Connect the three separate component video cables to the DTV set-top box Y, Pb and Pr ports and to the Y, Pb and Pr ports on the TV.

2.Connect the audio cables to the DTV set-top box AUDIO L and R ports and to the L and R AUDIO AV ports on the TV.

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20” LCD TV Color Monitor

Norcent LT2025W

How to use

1.Select COMPONENT

2.Turn on the DTV set-top box set.

Warning: In case you notice scrolling images, wrong colors or no color, no picture or even combinations of these, on your screen, check if the connections are done in the right way. Check if the cable colors match with the Input connector colors.

1.The earphone jack is located at the rear corner of the TV.

2.

The

MUTE key on the remote control works on both internal speaker and the earphone.

3.Use volume key to adjust the volume.

Note: When a TV channel or external AV source is blocked because of a rating set via the Parental control menu, also the headphone is muted.

Care of the screen

Do not rub or strike the screen with anything hard as this may scratch, mar, or damage the screen permanently. Unplug the power cord before cleaning the screen. Dust the TV by wiping the screen and the cabinet with a soft, clean cloth. If the screen requires additional cleaning, use a clean, damp cloth. Do not use liquid cleaners or aerosol cleaners.

Mobile telephone warning

To avoid disturbances in picture and sound, malfunctioning of your TV or even damage to the TV, keep away your mobile telephone from the TV.

End of life directives

We are paying a lot of attention to produce environmentally friendly in green focal areas. Your new receiver contains materials, which can be recycled and reused.

At the end of its life specialized companies can dismantle the discarded receiver to concentrate the reusable materials and to minimize the amount of materials to be disposed of.

Please ensure you dispose of your old receiver according to local regulations.

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20” LCD TV Color Monitor

Norcent LT2025W

REGULATORY NOTICES

Federal Communications Commission Notice

This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

˙Reorient or relocate the receiving antenna.

˙Increase the separation between the equipment and the TV.

˙Connect the equipment into wall power outlet on a circuit different from that to which the receiver is connected. ˙Consult the dealer or an experienced radio or television technician for help.

Modifications –

The FCC requires the user to be notified that any changes or modifications made to this device that are not expressly approved by Norcent Technology Inc. may void the user’s authority to operate the equipment.

Cables –

Connections to this device must be made with shielded cables with metallic RF/EMI connector hoods to maintain compliance with FCC Rules and Regulations.

Canadian notice –

This Class B digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.

Avis Canadian –

Cat apparel numerous de la classed B respected toutes les exigencies du règlement sur le materiel brouilleur du Canada.

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20” LCD TV Color Monitor

Norcent LT2025W

3. Input/Output Specification

3.1 Input Signal connector

This procedure gives you instructions for installing and using the LCD TV display.

Lay the display on the desired operation and plug the power cord into a convenient AC outlet. Three-wire power cord must be shielded and is provided as a safety precaution as it connects the chassis and cabinet to the electrical conduct ground. If the AC outlet in your location does not have provisions for the grounded type plug, the installer should attach the proper adapter to ensure a safe ground potential.

Connect the 15-pin D-SUB color display shielded signal cable to your signal system device and lock both screws on the connector to ensure firm grounding. The connector information is as follow:

15 - Pin Color Display Signal Cable

1

5

6

10

11

15

Pin

Signal Assignment

Pin

Signal Assignment

1

Red Video

9

No Pin!

2

Green Video

10

Sync. Ground

3

Blue Video

11

Not Used

4

Not Used

12

Serial Data for DDC

5

GROUND

13

Horizontal Sync.

6

Red Video Ground

14

Vertical Sync.

7

Green Video Ground

15

Serial Clock for DDC

8

Blue Video Ground

3.2 Factory Preset Display Modes

Analog RGB input signal timing

VESA MODES

Horizontal

Vertical

Nominal

Nominal

Nominal

Sync

Sync

Pixel

Mode

Resolution

Total

Frequency

Freq.

Polarity

Polarity

Clock

+/- 0.5kHz

+/- 1 Hz

(MHz)

VGA

640x480@60Hz

800 x 525

31.469

N

59.940

N

25.175

SVGA

800x600@56Hz

1024 x 625

35.156

N/P

56.250

N/P

36.000

800x600@60Hz

1056 x 628

37.879

P

60.317

P

40.000

XGA

1024x768@60Hz

1344x806

48.363

N

60.004

N

65.000

1280x768@60Hz

1664x798

47.396

P

59.995

N

68.250

WXGA

1360x768@60Hz

1792x795

47.712

P

60.015

P

85.500

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	20” LCD TV Color Monitor		Norcent LT2025W
	4. Mechanical Instructions
	Step	Figure	Description

	Preparation	Remove the
	and
		screws
	remove
		remarked in red
	the base

	Remove	Remove the
		screws
	back cover
		remarked in red

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20” LCD TV Color Monitor

Norcent LT2025W

Remove shield

Remove the boards

Remove the screws remarked in red

Remove connectors and the screws remarked in red

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20” LCD TV Color Monitor

Norcent LT2025W

Remove	Remove screws
main frame	remarked in red

The end

N/A

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20” LCD TV Color Monitor

Norcent LT2025W

5. Repair Flow Chart

5.1. No Display (LED indicator green)

No display

				NG
	Check the source						Reset source
	OK
				NG
	Check LVDS cable						Replace LVDS cable
	OK
					NG
	Check 12V power supply							Return to “3”

OK

Check main board power supply

OK

NG

Check U406 Replace U406

OK

				NG
Check I2C communication						Repair I2C communication relative circuit
	OK
			NG
	Check panel				Replace panel

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20” LCD TV Color Monitor			Norcent LT2025W
5.2. Can’t start (LED indicator yellow)
	Can’t start

NG

Check keyboard

Repair the keyboard

OK

NG

Check 5V_SB

Check every chip power supply

OK

NG

Check I2C communication

Replace I2C communication component

OK

NG

Check oscillistor

Replace oscillistor

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20” LCD TV Color Monitor

Norcent LT2025W

5.3. No Power (No LED indicator)

NG

Check power cord and board interface

Plug in power cord and interface

OK

NG

Check F901, BD901, D910

Replace F901 or BD901 or D910

OK

Check the load

NG

Check IC 960

Replace IC 960

NG

Check IC930, Q930

Replace IC930 or Q930

OK

OK

NG

Check Q961, Q962

Replace Q961 or Q962

NG

Check Q931, ZD930

Replace Q931 or ZD930

OK

NG

OK

OK

Check Q960

Replace Q960

NG

Check PC950, TL950 (FB)

Replace PC950 or TL950

OK

NG

OK

Check F960

Replace F960

NG

Check T901

Replace T901

OK

Check the load

NG

Check D970, D980

Replace D970 or D980

OK

NG

Check F970 (12V), F980 (24V)

Replace F970 or F980

Check the load

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20” LCD TV Color Monitor		Norcent LT2025W
5.4. Abnormal Display
	Abnormal display

NG

Check the source

Reset source

OK

NG

Check signal filter circuit

Replace the filter or inductance

OK

NG

NG

OK

AV, S-video signal

component PC signal

Check input signal

RF signal

Check TV system setup

OK

OK

OK

NG

Check LVDS cable

Replace LVDS cable

Check TU100

Repair each relative circuit

OK

NG

OK

Check panel

Replace panel

Replace TU100

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20” LCD TV Color Monitor

Norcent LT2025W

5.5. No Sound

No sound

NG

Check the source

Reset source

OK

NG

Check signal filter circuit

Replace the filter or inductance

OK

NG

Check Earphone jack

Replace the Earphone jack

NG

OK

SIF signal

Check TV system setup

OK

NG

Check TU100

Replace TU100

OK

NG

OK

AV, component, S-video, PC signal

Check relative circuit

NG

Check Amplifier TPA3002D2 U606

Replace U606

OK

NG

Check speakers

Replace speakers

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20’’ LCD TV Color Monitor	Norcent LT2025W
5.6 Key Board
OSD is unstable or not working

	Is Key Pad Board connecting normally?	N
			Connect Key Pad Board

	Y
	Is Button Switch normally?	N
			Replace Button Switch

	Y
			N
	Is Key Pad Board Normally?			Replace Key Pad Board
	Y
	Check Main Board

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20’’ LCD TV Color Monitor

Norcent LT2025W

6. PCB Layout

6.1 Main Board

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20’’ LCD TV Color Monitor

Norcent LT2025W

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20’’ LCD TV Color Monitor		Norcent LT2025W
6.2 Power Board

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20’’ LCD TV Color Monitor	Norcent LT2025W
6.3 key Board

6.4 Tuner Board

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