ViewSonic VSXXXXX User Manual
Service Manual
ViewSonic VG2427wm
Model No. VSXXXXX
23.6” Color TFT LCD Display
(VG2427wm_SM Rev. 1a Mar. 2009)
ViewSonic 381 Brea Canyon Road, Walnut, California 91789 USA - (800) 888-8583
Copyright
Copyright © 2008 by ViewSonic Corporation. All rights reserved. No part of this publication
may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any
language or computer language, in any form or by any means, electronic, mechanical, magnetic,
optical, chemical, manual or otherwise, without the prior written permission of ViewSonic
Corporation.
Disclaimer
ViewSonic makes no representations or warranties, either expressed or implied, with respect to
the contents hereof and specifically disclaims any warranty of merchantability or fitness for any
particular purpose. Further, ViewSonic reserves the right to revise this publication and to make
changes from time to time in the contents hereof without obligation of ViewSonic to notify any
person of such revision or changes.
Trademarks
Optiquest is a registered trademark of ViewSonic Corporation.
ViewSonic is a registered trademark of ViewSonic Corporation.
All other trademarks used within this document are the property of their respective owners.
Product disposal at end of product life
The lamp in this product contains mercury. Please dispose of in accordance with local, state or
federal laws.
Revision History
Revision SM Editing Date Description of Changes TPV Model Editor
TDRMNDDKWBVSPC
1a 03/27/2009 Initial Release
TDRMNDDYWBVSPC
TDRMNDDCWBVSPC
TDRMNDDBWBVSPC
Eric
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TABLE OF CONTENTS
1. Precautions and Safety Notices ......................................................................................... 4
2. Specification ....................................................................................................................... 7
3. Front Panel Function Control Description ....................................................................... 8
4. Circuit Description............................................................................................................. 13
5. Adjusting Procedure .......................................................................................................... 24
6. Trouble Shooting Flow Chart ............................................................................................ 32
7. Block Diagrams ................................................................................................................ 33
8. Schematic Diagrams ........................................................................................................ 35
9. PCB Layout Diagrams ...................................................................................................... 44
10. Exploded Diagram and Spare Parts List ........................................................................ 50
11. Recommended Spare Parts List .................................................................................... 53
12. Different Parts List........................................................................................................... 66
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1. Precautions and Safety Notices
1. Precautions and Safety Notices
1.1 Safety Precautions
This monitor is manufactured and tested on a ground principle that a user’s safety comes first. However, improper
use or installation may cause damage to the monitor as well as the user. Carefully go over the following WARNINGS
before installing and keep this guide handy.
WARNINGS
．This monitor should be operated only at the correct power sources indicated on the label on the rear end of the
monitor. If you’re unsure of the power supply in your residence, consult you local dealer or power company.
．Use only the special power adapter that comes with this monitor for power input.
．Do not try to repair the monitor your self as it contains no user-serviceable parts. This monitor should only be
repaired by a qualified technician.
．Do not remove the monitor cabinet. There is high-voltage parts inside that may cause electric shock to human
bodies, even when the power cord is unplugged.
．Stop using the monitor if the cabinet is damaged. Have it checked by a service technician.
．Put your monitor only in a clean, dry environment. If it gets wet, unplug the power cable immediately and consult
your service technician.
．Always unplug the monitor before cleaning it .Clean the cabinet with a clean, dry cloth. Apply non-ammonia based
cleaner onto the cloth, not directly onto the glass screen.
．Keep the monitor away from magnetic objects, motors, TV sets, and transformer.
．Do not place heavy objects on the monitor or power cord.
1.2 Product Safety Notice
Many electrical and mechanical parts in this chassis have special safety visual inspections and the protection
afforded by them cannot necessarily be obtained by using replacement components rated for higher voltages,
wattage, etc. Before replacing any of these components read the parts list in this manual carefully. The use of
substitute replacement parts which do not have the same safety characteristics as specified in the parts list may
create shock, fire, or other hazards.
1.3 Service Notes
1. When replacing parts or circuit boards, clamp the lead wires around terminals before soldering.
2. When replacing a high wattage resistor (more than 1W of metal oxide film resistor) in circuit board, keep the
resistor about 5mm away from circuit board.
3. Keep wires away from high voltage, high temperature components and sharp edges.
4. Keep wires in their original position so as to reduce interference.
5. Usage of this product please refer to also user’s manual.
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1.4 Handing and Placing Methods
Correct Methods: Incorrect Methods:
Only touch the metal frame of the LCD panel or the
front cover of the monitor. Do not touch the surface of
the polarizer.
Surface of the LCD panel is pressed by fingers and that
may cause “Mura.”
Take out the monitor
Taking out the monitor by grasping the LCD panel. That
may cause “Mura.”
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Place the monitor on a clean and soft foam pad.
Place the monitor on the lap, the panel surface must
be upwards.
Placing the monitor on foreign objects. That could
scratch the surface of the panel or cause “Mura.”
The panel is placed facedown on the lap. That may
cause “Mura.”
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2. Specification
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3. Front Panel Function Control Description
Use the buttons on the front control panel to display and adjust the OSD controls which display on the screen. The
OSD controls are explained at the top of the next page and are defined in “Main Menu Controls”.
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Do the following to adjust the display setting:
1. To display the Main Menu, press button [1].
NOTE: All OSD menus and adjustment screens disappear automatically after about 15 seconds. This is adjustable
through the OSD timeout setting in the setup menu.
2. To select a control to adjust, press
3. After the desired control is selected, press button [2]. A control screen like the one shown below appears.
4. To adjust the control, press the up or down buttons.
5. To save the adjustments and exit the menu, press button [1] twice.
The following tips may help you optimize your display:
• Adjust the computer's graphics card so that it outputs a 1920 x 1080 @ 60Hz video signal to the LCD display.
(Look for instructions on “changing the refresh rate” in the graphics card's user guide.)
• If necessary, make small adjustments using H. POSITION and V. POSITION until the screen image is completely
visible. (The black border around the edge of the screen should barely touch the illuminated “active area” of the LCD
or to scroll up or down in the Main Menu.
The line at the bottom of the screen
shows the current functions of buttons 1
and 2: Exit or select the Brightness
control.
display.)
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Main Menu Controls
Adjust the menu items shown below by using the up and down buttons.
Control Explanation
Auto Image Adjust automatically sizes, centers, and fine tunes the video signal to eliminate
waviness and distortion. Press the [2] button to obtain a sharper image.
NOTE: Auto Image Adjust works with most common video cards. If this function does not work on
your LCD display, then lower the video refresh rate to 60 Hz and set the resolution to its pre-set
value.
Contrast adjusts the difference between the image background (black level) and the foreground
(white level).
Brightness adjusts background black level of the screen image.
Audio Adjust
Volume increases the volume, decreases the volume, and mutes the audio.
Mute temporarily silences audio output.
Color Adjust provides several color adjustment modes, including preset color temperatures and
a User Color mode which allows independent adjustment of red (R), green (G), and blue (B). The
factory setting for this product is 6500K (6500 Kelvin).
sRGB-This is quickly becoming the industry standard for color management, with support being
included in many of the latest applications. Enabling this setting allows the LCD display to more
accurately display colors the way they were originally intended. Enabling the sRGB setting will
cause the Contrast and Brightness adjustments to be disabled.
9300K-Adds blue to the screen image for cooler white (used in most office settings with
fluorescent lighting).
7500K-Adds blue to the screen image for cooler white (used in most office settings with
fluorescent lighting).
6500K-Adds red to the screen image for warmer white and richer red.
5000K-Adds red to the screen image for warmer white and richer red.
User Color Individual adjustments for red (R), green (G), and blue (B).
1. To select color (R, G or B) press button [2].
2. To adjust selected color, press
Important: If you select RECALL from the Main Menu when the product is set to a Preset Timing
Mode, colors return to the 6500K factory preset.
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and .
Information displays the timing mode (video signal input) coming from the graphics card in the
computer, the LCD model number, the serial number, and the ViewSonic® website URL. See your
graphics card’s user guide for instructions on changing the resolution and refresh rate (vertical
frequency).
NOTE: VESA 1920 x 1080 @ 60Hz (recommended) means that the resolution is 1920 x 1080 and
the refresh rate is 60 Hertz.
Manual Image Adjust displays the Manual Image Adjust menu.
H./V. Position (Horizontal/Vertical Position) moves the screen image left or right and up or
down.
H. Size (Horizontal Size) adjusts the width of the screen image.
Fine Tune sharpens the focus by aligning text and/or graphics with pixel boundaries.
NOTE: Try Auto Image Adjust first.
Sharpness adjusts the clarity and focus of the screen image.
Dynamic Contrast allows the user to turn the contrast ratio enhancement on or off.
Aspect ratio Selects the image size for 4:3 and full screen.
ECO Mode provides the lower power consumption by reducing the brightness.
Standard: The default brightness setting.
Optimize: Decreases the brightness by 25 %.
Conserve: Decreases the brightness by 50 %.
Setup Menu displays the menu shown below:
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Language Select allows the user to choose the language used in the menus and control screens.
Resolution Notice advises the optimal resolution to use.
OSD Position allows the user to move the OSD menus and control screens.
OSD Timeout sets the length of time the OSD screen is displayed. For example, with a “15
second” setting, if a control is not pushed within 15 seconds, the display screen disappears.
OSD Background allows the user to turn the OSD background On or Off.
Memory Recall returns the adjustments back to factory settings if the display is operating in a
factory Preset Timing Mode listed in the Specifications of this manual.
Exception: This control does not affect changes made with the User Color control, Language
Select or Power Lock setting.
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4. Circuit Description
4.1 Main Board
U401 NT68667UFG/C
The NT68667 is a highly integrated flat panel display controller that interfaces analog, digital, and video inputs. It
combines a triple ADC, a DVI compliant TMDS receiver, a digital YUV receiver, a high quality zoom and shrink
engine , a multi-color on screen display (OSD) controller , an advanced color engine , and many other functions in a
single chip. It provides the user with a simple, flexible and cost-effective solution for various flat panel display
products.
The NT68667 operates at frequencies up to 188MHz/190Mhz, suitable for LCD monitor up to
1680x1050/1920x1080 resolution. The NT68667 also has a built-in noise reduction function to provide more stable
video quality, spread spectrum to provide low EMI solution, sRGB for video color space convert and post pattern for
manufacture test.
The display provided single/double pixel clock LVDS interface.
In addition, NT68667 includes an integrated 8-Bit Microcontroller (MCU). It contains an 8-bit 8031 micro-controller,
1,280-bytes internal data memory, four 7-bit resolution A/D Converter, 10-channel 8-bit resolution PWM DAC,
two16-bit timer/counters, and a UART. Except those, it has two-channel hardware DDC solution, and VESA 2Bi/2B+
master/slave I2C bus interface.
Block Diagram
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Pin Assignment
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15
16
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U701 AP1117D33L and U704 AP1117E18LA: DC power convert, convert to 3.3v and 1.8v.
AP1117 is a low dropout positive adjustable or fixed-mode regulator with 1A output current capability. The product is
specifically designed to provide well-regulated supply for low voltage IC applications such as high-speed bus
termination and low current 3.3V logic supply. AP1117 is also well suited for other applications such as VGA cards.
AP1117 is guaranteed to have lower than 1.4V dropout at full load current making it ideal to provide well-regulated
outputs of 1.25 to 5.0 with 6.4V to 18V input supply.
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Pin Descriptions
Name I/O Pin # Function
Adj (GND) I 1
Vout O 2
Vin I 3
A resistor divider from this pin to the Vout pin and ground sets the output voltage.
(Ground only for Fixed-Mode)
The output of the regulator. A minimum of 10uF capacitor (0.15 ESR 20)
must be connected from this pin to ground to insure stability.
The input pin of regulator. Typically a large storage capacitor (0.15 ESR
20) is connected from this pin to ground to insure that the input voltage does
not sag below the minimum dropout voltage during the load transient response.
This pin must always be 1.3V higher than Vout in order for the device to regulate
properly.
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4.2 Power Board
IC901 LD7576
The LD7576X series bring high performance, combines with highly integrated functions, protections and
EMI-improve solution. It’s an ideal solution for those cost-sensitive system, reducing component count and overall
system cost.
The LD7576X series features near-lossless high voltage startup circuit, green-mode power-saving operation,
leading-edge blanking of the current sensing and internal slope compensation. They also consist with more
protections of OLP (Over Load Protection), OVP (Over Voltage Protection) and OTP (Over Temperature Protection)
to prevent the circuit damage under abnormal conditions.
The LD7576X series are available in DIP-8 and SOP-8 package.
Typical Application
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Block Diagram
Pin Name Function
This pin is to program the frequency of the low frequency timer. By connecting a capacitor to
1 CT
2 COMP
3 CS Current sense pin, connect to sense the MOSFET current
4 GND Ground
5 OUT Gate drive output to drive the external MOSFET
6 VCC Supply voltage pin
7 NC Unconnected Pin
8 HV
ground to set the OLP delay time. And this pin can be used for latch mode protection. By pulling
this pin lower than 0.8 V, the controller will be entered latch mode until the AC power-on recycling.
Voltage feedback pin (same as the COMP pin in UC384X), By connecting a photo-coupler to
close the control loop and achieve the regulation. A high quality ceramic capacitor (X7R) is
required for general applications (102pF at least).
Connect this pin to positive terminal of bulk capacitor to provide the startup current for the
controller. When Vcc voltage trips the UVLO(on), this HV loop will be off to save the power loss on
the startup circuit.
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