AOC L42H831 User manual

42″&47″LCDTV AOC L42H831&L47H831
1
Service
Service
Service
Horizontal Frequency
31~60kHz
TABLE OF CONTENTS
Description Page Description Page
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
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
Table Of Contents.......……..............................…........1
Important Safety Notice.......................................….…......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
Revision List.....................................................................2

42″&47″LCDTV AOC L42H831&L47H831
2
Revision List
Version Release Date Revision Instructions Customer Model TPV Model
E428MNNSW8AGNN
E428MNNSW8AENN
E428MNNSW8ACNN
L42H831
E428MNNSW8AC6N
E478MNNSW8AENN
E478MNNSW8ACNN
A00 Sep-12-2008 Initial Release
L47H831
E478MNNSW8AGNN
E42RMNNSW8AGNN
E42RMNNSW8A8NN
E42RMNNSW8AC6N
A01
E42RMNNSW8ACNN
Feb-25-2009 Add new BOM L42H831

42″&47″LCDTV AOC L42H831&L47H831
3
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.)

42″&47″LCDTV AOC L42H831&L47H831
4
1. General Specification

42″&47″LCDTV AOC L42H831&L47H831
5

42″&47″LCDTV AOC L42H831&L47H831
6
2. Operating Instructions
2.1 The Use of Remote Control

42″&47″LCDTV AOC L42H831&L47H831
7
S
ET
U
P MEN
U
V
IDE
O
MEN
U
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.
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.
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.

42″&47″LCDTV AOC L42H831&L47H831
8
AUDIO MENU
FEAT
U
RE MEN
U
If you selected PERSONAL, press or to highlight an option, then press ∧or∨to adjust the option. You can adjust:
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.
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.
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.

42″&47″LCDTV AOC L42H831&L47H831
9
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
as off / 5 min / 10 min
/ 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.
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-Position】、【Clock】and 【Phase】. All these items giving the tuning range
from 0 to 100.【Setting】item provides the default VGA setting values restoring.

42″&47″LCDTV AOC L42H831&L47H831
10
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 OUT– 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 IN – 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 IN – 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

42″&47″LCDTV AOC L42H831&L47H831
11
select “Composite Rear” if you have connected a video recorder to Composite Rear socket.)
2.4 Front Panel Control Knobs
1 VOL▲VOL +: Press to increase the sound volume level.
2 VOL▼VOL - : Press to decrease the sound volume level.
3 CH ▲CH +: Press to select the next higher Program
number.
4 CH ▼CH - : Press to select the next lower Program
number.
5 MENU Menu key: Press to open or exit the OSD menu.
6 INPUT Source key: Press to select the input source.
7
Power key: Press to turn on / off (standby) the TV
set.
(Please re-turn on TV after the Power-ON status
LED had changed to the Red color and finished
flashing.)

42″&47″LCDTV AOC L42H831&L47H831
12
3. Input/Output Specification
3.1 RGB Signal input
15 - Pin Color Display Signal Cable
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
1
6
11 15
5
10

42″&47″LCDTV AOC L42H831&L47H831
13
3.3 AV/S-Video/Component Video Inputs
3.4 Compatible Mode Table
VESA MODES
Horizontal Vertical
Mode Resolution Total
Nominal
Frequency
(KHz)
Sync
Polarity
Nominal
Freq.
(Hz)
Sync
Polarit
y
Nominal
Pixel
Clock
(MHz)
640x480@60Hz 800 x 525 31.469 N 59.940 N 25.175
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
VGA
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
SVGA
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
XGA
1024x768@75Hz 1312x800 60.023 P 75.029 P 78.750
SXGA 1280x1024@60Hz 1688x1066 63.981 P 60.020 P 108.000
FHD 1920x1080@60Hz 2080x1111 66.587 P 59.934 N 138.500
AV (Composite Video input)
Video1/2
System NTSC / PAL-M / PAL-N
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
System 1080i, 1080p, 480p, 720p, 480i
Y signal amplitude 1.0Vpp (including sync)
Cr, (R-Y) / Cb, (B-Y)
Signal amplitude ±0.35Vpp, 75 ohm
Impedance 75 ohm terminated

42″&47″LCDTV AOC L42H831&L47H831
14
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.

42″&47″LCDTV AOC L42H831&L47H831
15
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 .

42″&47″LCDTV AOC L42H831&L47H831
16
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.

42″&47″LCDTV AOC L42H831&L47H831
17
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 .

42″&47″LCDTV AOC L42H831&L47H831
18
6. Remove the screws in order to carry out the panel
7. Remove the panel from the bezel.

42″&47″LCDTV AOC L42H831&L47H831
19
5. Repair Flow Chart
1. No Power (No LED indicator)
2. Can not start (No LED indicator)
NG Re
p
air ke
y
board or remote control
OK
Check
p
ower su
pp
l
y
for main board NG Re
p
lace the failure com
p
onent
Check U403 NG Re
p
lace U403
OK
OK
Check ke
y
board or remote control
Check I
2
C communication
Can not start
OK
NG
Check power cord and board interface Plug in power cord and interface
OK
Check F901, BD901,C905 NG Replace F901,BD901, C905
OK
Check voltage of IC902
Check D907,C921,C923,IC905,IC906
NG Check Q901, IC902
OK
Check T901
OK
Replace T901
NG
NG
Replace D907,C921,C923,IC905,IC906

42″&47″LCDTV AOC L42H831&L47H831
20
3. No display (LED indicator Green )
Check 12V
power supply
Check Panel NG Replace Panel
Check back light is OK
OK
Check LVDS cable
and connector
OK
Check U403 NG Replace U403
OK
Check U401 NG Replace U401
NG NG
OK
Check BL-ON/OFF signal
Check PS
signal
OK
OK Check power
board
NG
NG
NG
Check Q705、Q704 Replace Q705、Q704