Norcent LT2790BK User manual

27’’ LCD TV Norcent LT2790BK
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Service
Service
Service
显示桌面.scf
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.
7.1 Main Board……...……………………....….......25
7.2 Power Board………………………….....….......27
7.3. Key Board….…......………….................…….........29
7.4 IR Board...……………...…..................................29
8. Block Diagram..……..............….......................30
8.1 Main Board......……….………...............................30
8.2 Power Board…...……...….…..........................31
9. Schematic Diagram...………….………..………….......32
9.1 Main Board……...…..……..………......................32
9.2 Power Board...……………….……………………...49
9.3 Audio Board………..……………..………………..50
9.4 Side Board …………………………………………..51
9.5 IR Board………….………………………………..52
10. Exploded View……...................................................53
11.BOM List………………………….....……….……….....54
Table Of Contents.......…….…..............................…........1
Revision List.…….….....................................……......2
Important Safety Notice.……..................……......3
1. Monitor Specification..…............................………........4
2. Operating Instructions……...……………….……….......5
2.1 The Use Of Remote Control..………….…..................5
2.2 Front Panel Control Knobs..............….......…...........6
2.3 OSD Operating…………….…............……...............7
2.4 How To Connect...………........................…............14
3. Input/Output Specification............……………............16
3.1 Input Signal Connector............………….................16
3.2 Factory Preset Display Modes........………...............17
4. Mechanical Instructions..………....……......................18
5. Repair Flow Chart…….……………………..................21
6. White Balance, Luminance Adjustment………….....23
7.PCB Layout……..…………………....….…….....25
CAUTION: USE A SEPARATE ISOLATION TRANSFOMER FOR THIS UNIT WHEN SERVICING

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Revision List
Version Release Date Revision History TPV Model
A00 Jan- 8-2007 Initial release E276MZNKWNNRNP

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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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1. General Specifications

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2. Operations Instructions
2.1 The Use of Remote Control
“POWER”
Press to power ON/OFF
(standby) TV.
(Note:1.TV is never completely
power off unless physically
unplugged.
2.Press to turn on TV after the
Power on status LED had
changed to the Green color
and stopped flashing. )
“VIDEO”
Press repeatedly to choose
S-Video/
Composite source mode
(Video 1 ~ 4).
“COMP”
Press repeatedly to choose
Component
source mode (Video 5 ~ 6).
“PC”
Press repeatedly to choose
VGA or HDMI source mode
(Video 7 ~ 8).
“TV”
Press to choose ATSC/NTSC
TV source mode.“0 ~ 9 /-
number” Press to enter TV
channel number to select
channel (Press ‘-’ to indicate
choosing the sub-channel).
“SLEEP”
Press to set a time period
(OFF/ 30min/ 60min/ 90min)
after which the TV should
switch itself to standby mode.
“FREEZE”
Press to freeze the displayed
picture
“VOL- / VOL+”
Press + or - to adjust the
volume.
“MENU”
Press to open or exit menu.
“ ”,“ ”,“＜”,“＞”,“OK”
Press to adjust the various
function items on the menu.
“V-CHIP”
Press to lock / unlock Parental
Control temporarily. (After
setting the restricted table of
MPAA or TV Rating.)
“DISPLAY”
Press to show the information
about the input source、TV
channel、display resolution and
current time.
“MUTE”
Press to set TV sound mute
ON/OFF
“PREV CH”
Press to display the previous
TV.
“MTS/SAP”
Press to activate the NTSC TV
sounds, such as: Stereo, SAP
or Mono tone.
“WIDE”
Press to choose the display
aspect as: Normal, Wide,
Zoom or Cinema mode.
“SOURCE”
Press repeatedly to choose the
various input sources (Video 1
~ 8). Press + or - to browse
through the TV channels.
“Exit”
Press to exit menu or OSD.
“VIDEO ADJ”
Press to choose the Brightness
or Contrast adjustment.
“AUDIO ADJ”
Press to switch the ATSC
multi-channel TV sounds.
“CC”
Press repeatedly to change the
closed caption type as
CC ON /CC ON WHEN
MUTE/CC OFF.
“EPG”
Press to show the information
the same as “DISPLAY” key.
“FAV”
Press to display the favorite TV
channel.
(After setting the favorite TV
channel on main menu).

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2.2 Front Panel Control Knobs

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2.3 OSD Operations

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2.4 How to Connect

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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
Pin Signal Assignment Pin Signal Assignment
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 Horizontal Sync.
6 Red Video Ground 14 Vertical Sync.
7 Green Video Ground 15 Serial Clock for DDC
8 Blue Video Ground
HDMI Digital connector pin assignments
Pin Signal Assignment Pin Signal Assignment
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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Apply power to the display by turning the power switch to the "ON" position and allow about ten seconds for Panel
warm-up. The Power-On indicator lights "GREEN" when the display is on.
With proper signals feed to the display, a pattern or data should appear on the screen, adjust the brightness and
contrast to the most pleasing display, or press auto-adjust to get the best picture-quality.
This TV (with PC function) has power saving function following the VESA DPMS. Be sure to connect the signal
cable to the PC.
If your TV requires service, it must be returned with the power cord.
3.2 Factory Preset Display Modes:
Analog RGB input signal timing
VESA MODES
Horizontal Vertical
Mode Resolution Total
Nominal
Frequency
(KHz)
Sync
Polarity
Nominal
Freq.
(Hz)
Sync
Polari
ty
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
VGA
640x480@75Hz 840 x 500 37.5 N 75 N 31.500
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 48.097 P 72.188 P 40.000
SVGA
800x600@75Hz 1056 x 625 460875 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
WXGA 1360x768@60Hz 1792x795 47.712 P 60.015 P 85.5
HDMI input signal timing
VESA MODES
Horizontal Vertical
Mode Resolution Total
Nominal
Frequency
(KHz)
Sync
Polarity
Nominal
Freq.
(Hz)
Sync
Polari
ty
Nominal
Pixel
Clock
(MHz)
720P 1280×720P 45.00 60 74.25
1080i 1920X1080i 33.75 60 74.25
480P 720X480P 31.54 60 27.00
480i 720X480i 15.75 60 13.51

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4. Mechanical Instructions
Step Figure Description
Preparation
and
remove
the base
Remove the
screws
remarked in
red.
Remove
back cover
Remove the
screws
remarked in
red.

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Remove the
shield
Remove the
screws
remarked in
red
Remove the
boards
Remove
connector an
the screws
remarked in
red
Remove the
bezel

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Remove the
screws
remarked in
red