AOC l42h831 schematic

42″&47″ LCD TV AOC L42H831&L47H831

Service

Service

Service

31~60 kHz

TABLE OF CONTENTS

Description Page Description Page

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

Important Safety Notice.......................................……......2

Revision List…………………………………………………3

1. General Specification..............................………........4

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

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

2.2. To Use The Menu…...…………………….……….......7

2.3. How To Connect…….…………………….……….....10

2.4. Front Panel Control Knobs……………….……….....11

3. Input/Output Specification…………....................…....12

4. Mechanical Instructions…………………….................14

5. Repair Flow Chart ……………………….…….…….....19

6. PCB Layout ………………..………………....….......24

SAFETY NOTICE

ANY PERSON ATTEMPTING TO SERVICE THIS CHASSIS MUST FAMILIARIZE HIMSELF WITH THE CHASSIS

6.1.Main Board…………..……………...……….......24

6.2.Power Board……………..………….……….......27

6.3.Key Board………………………..……….......29

6.4.IR Board………………………..……….......29

7. Adjustment………………………………...................30

8. Block Diagram.……...........................................31

9. Schematic……………...…………..………………...32

9.1 Main Board…………………………………...….......32

9.2.Power Board…………….…………...………….......42

9.3.Key Board……………….……….………….......46

10. Exploded View………………………………….…...47

11. BOM List……………….…………………………….49

12. Different Parts List…………………………….100

Horizontal Frequency

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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42″&47″ LCD TV AOC L42H831&L47H831

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 might 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 radiations 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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42″&47″ LCD TV AOC L42H831&L47H831

Revision List

Version Release Date Revision Instructions Customer Model TPV Model

E428MNNSW8AGNN

A00 Sep-12-2008 Initial Release L42H831

A01 Sep-12-2008 Initial Release L47H831

E428MNNSW8AENN
E428MNNSW8ACNN

E428MNNSW8AC6N

E478MNNSW8AENN

E478MNNSW8ACNN

E478MNNSW8AGNN

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42″&47″ LCD TV AOC L42H831&L47H831

1. General Specification

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42″&47″ LCD TV AOC L42H831&L47H831

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42″&47″ LCD TV AOC L42H831&L47H831

2. Operating Instructions

2.1 The Use of Remote Control

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42″&47″ LCD TV AOC L42H831&L47H831

SETU

V

2.2 To Use the Menus

1. Press the MENU button to display the main menu

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

3. Use the cursor left/right to enter a submenu.

4. Press the ENTER button to enable/disable the function.

5. Press the MENU or EXIT button to exit the menu.

Press the MENU button to enter the main OSD (On Screen Display). Adjust the items including Setup menu, Video

menu, Audio menu and Feature menu. However, some function items in the menus may only be enabled in the

particular source modes

The Setup menu in TV mode shows as below. In others source modes, the Setup menu only shows Menu

Language and Aspect Ratio items.

P MENU

1. PROGRAM NO: Show the TV channel label menu for user modifying channel labels specifically.

2. AIR/ CABLE: Select TV source signal from the Air (antenna) or Cable (CATV).

3. AUTO SEARCH: Automatically scan all NTSC TV channels and then store in the channel table. In

channel scan process, the OSD can display the number of channels which had been found.

4. SKIP: you can select the ship ON/OFF,so that the program no channel can be delete or added.

IDEO MENU

The Video menu in most source modes shows as below. It provides several video adjustment items for user fine

tuning the video display. Only in VGA source modes, the Video menu simply provides Contrast, Brightness, Back

light and Settings (Preset) items.

If you selected PERSONAL, press or to highlight an option, then press ∧or∨ to adjust the option. You can adjust:

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42″&47″ LCD TV AOC L42H831&L47H831

1. CONTRAST: Video contrast adjustment, the tuning range is 0 ~ 100.

2. BRIGHTNESS: Video brightness adjustment, the tuning range is 0 ~ 100.

3.SATURATION: COLOR saturation adjust, the tuning range is 0 ~ 100

4. TINT: Video tint adjustment, the tuning range is R50 ~ G50.

5. SHARPNESS: Video sharpness adjustment, the tuning range is 0~10

6. BACKLIGHT: Backlight strength adjustment, the tuning range is 0 ~ 10.

7. EDGE ENHANCE: Press < or > to select HIGH, OFF, or LOW.

8.NOISE REDUCTION: Press < or > to select HIGH .OFF, LOW or MID.

9.COLOR TEMPERATURE: Press < or > to select COOL, STANDARD, or WARM.

AUDIO MENU

The Audio menu in TV mode shows as below. It provides audio adjustment for user to modify the audio setting.

Audio language setting is only available with ATSC TV source, the option is disable under other source modes.

Press ∧or ∨to highlight AUDIO, then press > The AUDIO menu opens.

Press ∧or ∨ to highlight PRESET, then press < or > to select an audio mode. You can select:

• VOICE

• MUSIC

• THEATER

• PERSONAL

If you selected PERSONAL, press∧ or∨ to highlight an option, then press ∧ or ∨to adjust the option. You can

adjust:

• BALANCE—Adjust the balance between the right and left audio channels.

• BASS—Adjust the low sounds.

•TREBLE—Adjust the high sounds.

FEATURE MENU

The Feature menu in AV/S-video mode shows as below. It provides certain optional control functions such as image

size, sleep timer, blue screen on/off, transparent, closed caption, color system. This menu gives users the most

flexibilities to satisfy their generally demands. According to the various requirements in different source modes,

certain features should be hidden (disable) on the menu. The details footnotes will be described clearly below.

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42″&47″ LCD TV AOC L42H831&L47H831

1. LANGUAGE: you can select the ENGLISH SPANISH Portuguese French

2. IMAGE SIZE : you can select WIDE, ZOOM, CINEMA, NORMAL

3. SLEEP TIMER: Enable or disable the TV standby timer. User can set the TV standby timer

/ 15 min/ 30 min / 45 min / 60 min/ 90 min / 120 min / 180min/ 240min. Timer starts to count down after cursor

leaving the sub-menu. (At the moment, the item shows 『** min Left』and the cursor highlights on the Feature

icon.)

4. BLUE SCREEN: you can select blue screen ON/OFF

5. TRANSPARENT: you can select from 0 to 7

6. CLOSED CAPTION：Press or to highlight CLOSED CAPTION, then press or to select the closed captioning

mode. You can select CC1.CC2, CC3, CC4, TT1, TT2, TT3 or TT4.

7. COLOR SYSTEM: this function you select color system.default is auto you can choose NTSC, PAL M, PAL N.

8. RESET: you can use it reset all setting to default.

as off / 5 min / 10 min

VGA SETTING MENU

VGA Set: This option only shows and is available in VGA mode, which provides several items for the VGA display

fine tuning, such as : 【H-Position】、【V-P osition 】、【Clock】and 【Phase】. All these items giving the tuning range

from 0 to 100.【Setting】item provides the default VGA setting values restoring.

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42″&47″ LCD TV AOC L42H831&L47H831

2.3 How to Connect

1. HDMI – Connect the primary source for digital video such as a DVD multimedia player or set top box

through this all digital connector. The white color band on the rear of the TV indicates this connection.

2. VGA AUDIO– Connect the audio for a computer to this jack.

3. HEADPHONE – Connect headphone to this jack.

4. COMPONENT (YPb/CbPr/Cr with Audio L/R) – Connect the primary source for component video

devices such as a DVD Player or set top box here. From left to right, use red for Pr, blue for Pb, green

for Y, red for right audio (R) and white for left audio (L) inputs.

5. AV OU T – Connect a VCR for recording to these jacks

6. S-VIDEO1 – Connect an S-Video device to this jack.

7. RGB PC – Connect the video and audio cables from a computer here.

8. AV1 I N – Connect the primary source for composite video devices, such as a VCR or video game.

9. Use the white and red connectors to connect the external audio from the same source. The signal

being carried by the S-Video cable and connector, if connected, will take priority over the Video RCA

connector (yellow connector).

10. S-VIDEO2 – Connect an S-Video device to this jack.

11. Use the white and red connectors to connect the external audio from the same source. The signal

being carried by the S-Video cable and connector, if connected, will take priority over the Video RCA

connector (yellow connector)

12. AV2 I N – Connect the primary source for composite video devices, such as a VCR or video game.

Once your equipment is connected, use the following procedure to view the input signal:

Press the source button on the remote controller to select the relevant source to view. (ex: Press VIDEO button to

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42″&47″ LCD TV AOC L42H831&L47H831

select “Composite Rear” if you have connected a video recorder to Composite Rear socket.)

2.4 Front Panel Control Knobs

1 VOL▲

2 VOL▼

3 CH ▲

4 CH ▼

5 MENU

6 INPUT

VOL +: Press to increase the sound volume level.

VOL - : Press to decrease the sound volume level.

CH +: Press to select the next higher Program
number.

CH - : Press to select the next lower Program
number.

Menu key: Press to open or exit the OSD menu.

Source key: Press to select the input source.

Power key: Press to turn on / off (standby) the TV
set.

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(Please re-turn on TV after the Power-ON status
LED had changed to the Red color and finished
flashing.)

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42″&47″ LCD TV AOC L42H831&L47H831

3. Input/Output Specification

3.1 RGB Signal input

15 - Pin Color Display Signal Cable

1

6

11 15

5

10

Pin No. Description Pin No. Description

1 Red Video 9 No Pin

2 Green Video 10 Sync Ground

3 Blue Video 11 SDA(Remote Control)

4 SCL(Remote Control) 12 Serial Data for DDC

5 Ground 13 H-Sync.

6 Red Ground 14 V-Sync.

7 Green Ground 15 Serial Clock for DDC

8 Blue Ground

3.2 HDMI Digital connector pin assignments

Pin No. Description Pin No. Description

1 TMDS Data2+ 2 TMDS Data2 Shield

3 TMDS Data2- 4 TMDS Data1+

5 TMDS Data1 Shield 6 TMDS Data1-

7 TMDS Data0+ 8 TMDS Data0 Shield

9 TMDS Data0- 10 TMDS Clock+

11 TMDS Clock Shield 12 TMDS Clock-

13 CEC 14 NC

15 SCL 16 SDA

17 DDC/CEC Ground 18 +5V Power

19 Hot Plug Detect

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42″&47″ LCD TV AOC L42H831&L47H831

3.3 AV/S-Video/Component Video Inputs

AV (Composite Video input)

Video1/2

Amplitude 1.0 V (p-p), negative sync.

Impedance 75 ohm terminated

S-Video (Y / C input)

S-Video1/2

System NTSC / PAL-M / PAL-N

Y signal amplitude 1.0Vpp (including sync)

C signal amplitude 0.286Vpp

Impedance 75 ohm terminated

Component (Y, Pb/Cb, Pr/Cr input)

Video1

Y signal amplitude 1.0Vpp (including sync)

Impedance 75 ohm terminated

3.4 Compatible Mode Table

System NTSC / PAL-M / PAL-N

System 1080i, 1080p, 480p, 720p, 480i

Cr, (R-Y) / Cb, (B-Y)

Signal amplitude

VESA MODES

±0.35Vpp, 75 ohm

Horizontal Vertical

Nominal

Mode Resolution Total

640x480@60Hz 800 x 525 31.469 N 59.940 N 25.175

VGA

SVGA

XGA

SXGA 1280x1024@60Hz 1688x1066 63.981 P 60.020 P 108.000

FHD 1920x1080@60Hz 2080x1111 66.587 P 59.934 N 138.500

640x480@72Hz 832 x 520 37.861 N 72.809 N 31.500

640x480@75Hz 840 x 500 37.5 N 75 N 31.500

720x400@70Hz 900 x 449 31.469 N 70.087 P 28.322

800x600@56Hz 1024 x 625 35.156 P 56.25 P 36.000

800x600@60Hz 1056 x 628 37.879 P 60.317 P 40.000

800x600@72Hz 1040 x 666 48.077 P 72.188 P 50.000

800x600@75Hz 1056 x 625 46.875 P 75 P 49.5

1024x768@60Hz 1344x806 48.363 N 60.004 N 65.000

1024x768@70Hz 1328x806 56.476 N 70.069 N 75.000

1024x768@75Hz 1312x800 60.023 P 75.029 P 78.750

Frequency

(KHz)

Sync

Polarity

Nominal

Freq.

(Hz)

Sync

Polarit

y

Nominal

Pixel

Clock

(MHz)

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42″&47″ LCD TV AOC L42H831&L47H831

4. Mechanical Instructions

L42H831

1. Remove the 4 screws to remove the base.

2. Remove 13 screws to remove the rear cover.

3. Remove the main board, power board and speakers.

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42″&47″ LCD TV AOC L42H831&L47H831

4. Remove the screws to remove the BKT-VESA and PCB Bracket.

5. Release the key board and IR board.

6. Remove the screws to remove the panel BKT .

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42″&47″ LCD TV AOC L42H831&L47H831

7. Remove the screws in order to carry out the panel

8. Remove the panel from the bezel.

L47H831

1. Remove the 4 screws to remove the base.

2. Remove the screws to remove the rear cover.

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42″&47″ LCD TV AOC L42H831&L47H831

3. Remove the main board, power board , speakers and bkt-stand.

4. Remove the screws to remove the BKT-VESA and BKT-PCB-holder.

5. Remove the screws to remove the panel BKT .

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42″&47″ LCD TV AOC L42H831&L47H831

6. Remove the screws in order to carry out the panel

7. Remove the panel from the bezel.

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42″&47″ LCD TV AOC L42H831&L47H831

5. Repair Flow Chart

1. No Power (No LED indicator)

Check power cord and board interface

OK

Check F901, BD901,C905

OK

Check voltage of IC902

OK

Check T901

OK

Check D907,C921,C923,IC905,IC906

NG

2. Can not start (No LED indicator)

NG

NG

Replace T901

NG

NG

Replace F901,BD901, C905

Check Q901, IC902

Plug in power cord and interface

Replace D907,C921,C923,IC905,IC906

Can not start

OK

Check key board or remote control

OK

Check power supply for main board

OK

Check U403

OK

Check I2C communication

NG

NG

Replace U403

Repair key board or remote control

NG

Replace the failure component

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42″&47″ LCD TV AOC L42H831&L47H831

3. No display (LED indicator Green )

Check back light is OK

OK

Check LVDS cable

and connector

OK

Check U403

OK

Check U401

NG

NG

NG

OK

Check Panel

Replace U403

Replace U401

Check 12V

power supply

OK

Check BL-ON/OFF signal

NG

Replace Panel

NG

NG

Check Q705、Q704

Check PS

signal

NG

NG

OK

Replace Q705、Q704

Check power

board

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42″&47″ LCD TV AOC L42H831&L47H831

4. Abnormal display

Check the source

OK

NG

Reset source

Check signal filter circuit

OK

OK

Check U401

OK

Check panel

NG

TV signal Check TV system setup

AV/SV signal

PC signal

HDMI signal Check U507 Replace U507

NG

NG

Replace the filter or inductance

OK

Check TU701

Check the circuit from
connector to U401

Check the circuit from
connector to U401

Replace U401

Replace panel

NG

Replace TU701

NG

NG

NG

Replace the failure
component

Replace the failure
component

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42″&47″ LCD TV AOC L42H831&L47H831

p

5. No sound

Check the source

OK

Reset source

Check signal filter circuit

Check Earphone jack

OK

Check U603

Check U606

NG

NG

SIF signal Check TV system setu

AV/SV/COMP
ONENT/PC
signal

HDMI signal

NG

NG

Replace the filter or inductance

Replace the Earphone jack

NG

NG

Replace U603

Replace U606

OK

Check TU701

Check U603

Check U507

NG

NG

Replace TU701

Replace the failure
component

NG

Replace U507

OK

Check speaker

NG

Replace speaker

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42″&47″ LCD TV AOC L42H831&L47H831

6. Key Board

OSD is unstable or not working

Is Key Pad Board connecting normally?

Y

Is Button Switch normally?

Y

Is Key Pad Board Normally?

Y

Check Main Board

N

Connect Key Pad Board

N

N

Replace Button Switch

Replace Key Pad Board

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42″&47″ LCD TV AOC L42H831&L47H831

6. PCB Layout

6.1 Main Board

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42″&47″ LCD TV AOC L42H831&L47H831

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42″&47″ LCD TV AOC L42H831&L47H831

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42″&47″ LCD TV AOC L42H831&L47H831

6.2 Power Board

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42″&47″ LCD TV AOC L42H831&L47H831

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42″&47″ LCD TV AOC L42H831&L47H831

6.3 Key Board

6.4 IR Board

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42″&47″ LCD TV AOC L42H831&L47H831

7. Adjustment

Approximately 2 hours should be allowed for warm up before proceeding white balance adjustment.

Before started adjust white balance, please set the Ca210 Channel to 05 Channel and set it’s mode to xyLv mode.

Color Temp. Cold Normal Warm

PC/HDMI/AV

/YpbPr

How to setting the Ca210 channel, you can reference to Ca210 user guide or simple use the “Memory CH” up or

down to set the channel to 05 channel, and use the “Mode” key to set the mode to xyLv.

Following is the procedure to do white-balance adjust

Factory mode:

. Turn on the TV, press MENU key with remote control, then press number key 1 Ⅰ Æ 9 Æ 9 Æ 9. It will

achieve the factory mode. Select the item of White Balance and press right key to enter it.

. Select “source” like PC/AV/YPbPr/HDMI, then select “color temⅡ p” to adjust the corresponding R/G/B

values.

Note:

1. set the input signal format of PC as 1024x768 @60 Hz, AV as NTSC system, YPbPr as 576i, HDMI as 1080i

2. before adjusting all color temp, make PC and YPbPr auto color first.

x 285 295 313

y 293 305 329

LV Panel max luminance

3. the model usually needn’t to be adjusted W/B, only to make auto color.

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