Text preview for : x223wd_110.pdf part of Acer X223WD LCD Monitor
Back to : x223wd_110.pdf | Home
Acer X223WD
Service Guide
1
Service Guide Version and Revision
Version Release Date Revision History TPV model
A00 Aug.-20-2007 Initial Release TC7SMADB2WAFHC
2
Copyright
Copyright Š 2003 by Acer Incorporated. 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 Acer Incorporated.
Disclaimer
The information in this guide is subject to change without notice. Acer Incorporated makes no representations or
warranties, either expressed or implied, with respect to the contents hereof and specifically disclaims any warranties
of merchantability or fitness for any particular purpose. Any Acer Incorporated software described in this manual is
sold or licensed "as is". Should the programs prove defective following their purchase, the buyer (and not Acer
Incorporated, its distributor, or its dealer) assumes the entire cost of all necessary servicing, repair, and any
incidental or consequential damages resulting from any defect in the software.
Intel is a registered trademark of Intel Corporation.
Pentium and Pentium II/III are trademarks of Intel Corporation.
Other brand and product names are trademarks and/or registered trademarks of their respective holders.
Trademarks
Acer is a registered trademark of Acer Incorporated.
All other trademarks are property of their respective owners.
Conventions
The following conventions are used in this manual:
Screen messages Denotes actual messages that appear on screen.
Note Gives bits and pieces of additional information related to the current topic.
Warning Alerts you to any damage that might result from doing or not doing specific actions.
Caution Gives precautionary measures to avoid possible hardware or software problems.
Important Remind you to do specific actions relevant to the accomplishment of procedures.
3
Preface
Before using this information and the product it supports, please read the following general information.
1. This Service Guide provides you with all technical information relating to the BASIC CONFIGURATION decided
for Acer's "global" product offering. To better fit local market requirements and enhance product competitiveness,
your regional office may have decided to extend the functionality of a machine (e.g. add-on card, modem, or extra
memory capability). These LOCALIZED FEATURES will NOT be covered in this generic service guide. In such
cases, please contact your regional offices or the responsible personnel/channel to provide you with further
technical details.
2. Please note WHEN ORDERING FRU PARTS, that you should check the most up-to-date information available on
your regional web or channel. If, for whatever reason, a part number change is made, it will not be noted in the
printed Service Guide. For ACER-AUTHORIZED SERVICE PROVIDERS, your Acer office may have a
DIFFERENT part number code to those given in the FRU list of this printed Service Guide. You MUST use the list
provided by your regional Acer office to order FRU parts for repair and service of customer machines.
Warning: (For FCC Certified Models)
Note: 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:
1. Reorient or relocate the receiving antenna.
2. Increase the separation between the equipment and receiver.
3. Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
4. Consult the dealer or an experienced radio/TV technician for help.
Notice:
1. The changes or modifications not expressly approved by the party responsible for compliance could void the
user's authority to operate the equipment.
2. Shielded interface cables and AC power cord, if any, must be used in order to comply with the emission limits.
3. The manufacturer is not responsible for any radio or TV interference caused by unauthorized modification to this
equipment. It is the responsibility of the user to correct such interference.
As ENERGY STARŽ Partner our company has determined that this product meets the ENERGY STARŽ
guidelines for energy efficiency.
Warning:
To prevent fire or shock hazard, do not expose the monitor to rain or moisture. Dangerous high voltages are present
inside the monitor. Do not open the cabinet. Refer servicing to qualified personnel only.
4
Precautions
Do not use the monitor near water, e.g. near a bathtub, washbowl, kitchen sink, laundry tub, swimming pool or in
a wet basement.
Do not place the monitor on an unstable trolley, stand, or table. If the monitor falls, it can injure a person and
cause serious damage to the appliance. Use only a trolley or stand recommended by the manufacturer or sold
with the monitor. If you mount the monitor on a wall or shelf, uses a mounting kit approved by the manufacturer
and follow the kit instructions.
Slots and openings in the back and bottom of the cabinet are provided for ventilation. To ensure reliable
operation of the monitor and to protect it from overheating, be sure these openings are not blocked or covered.
Do not place the monitor on a bed, sofa, rug, or similar surface. Do not place the monitor near or over a radiator
or heat register. Do not place the monitor in a bookcase or cabinet unless proper ventilation is provided.
The monitor should be operated only from the type of power source indicated on the label. If you are not sure of
the type of power supplied to your home, consult your dealer or local power company.
The monitor is equipped with a three-pronged grounded plug, a plug with a third (grounding) pin. This plug will fit
only into a grounded power outlet as a safety feature. If your outlet does not accommodate the three-wire plug,
have an electrician install the correct outlet, or use an adapter to ground the appliance safely. Do not defeat the
safety purpose of the grounded plug.
Unplug the unit during a lightning storm or when it will not be used for long periods of time. This will protect the
monitor from damage due to power surges.
Do not overload power strips and extension cords. Overloading can result in fire or electric shock.
Never push any object into the slot on the monitor cabinet. It could short circuit parts causing a fire or electric
shock. Never spill liquids on the monitor.
Do not attempt to service the monitor yourself; opening or removing covers can expose you to dangerous
voltages and other hazards. Please refer all servicing to qualified service personnel
To ensure satisfactory operation, use the monitor only with UL listed computers which have appropriate
configured receptacles marked between 100 - 240V AC, Min. 5A.
The wall socket shall be installed near the equipment and shall be easily accessible.
Special Notes On LCD Monitors
The following symptoms are normal with LCD monitor and do not indicate a problem.
Notes
Due to the nature of the fluorescent light, the screen may flicker during initial use. Turn off the Power Switch and
then turn it on again to make sure the flicker disappears.
You may find slightly uneven brightness on the screen depending on the desktop pattern you use.
The LCD screen has effective pixels of 99.99% or more. It may include blemishes of 0.01% or less such as a
missing pixel or a pixel lit all of the time.
Due to the nature of the LCD screen, an afterimage of the previous screen may remain after switching the image,
when the same image is displayed for hours. In this case, the screen is recovered slowly by changing the image
or turning off the Power Switch for hours.
5
Table Of Contents
Chapter 1 Monitor Features ................................................ 7
Introduction ............................................. 7
Electrical Requirements ............................................. 8
LCD Monitor General Specification ............................................. 9
LCD Panel Specification ............................................. 10
Support Timing ............................................. 12
Monitor Block Diagram ............................................. 13
Main Board Diagram ............................................. 14
Software Flow chart ............................................. 15
Main Board Layout ............................................. 17
Installation ............................................. 18
Attaching/Removing the base ............................................. 19
Chapter 2 Operating Instructions ............................................. 20
External Controls ............................................. 20
Front Panel Controls ............................................. 21
eColor Management (OSD) ............................................. 22
How to Adjust a Setting ............................................. 23
LOGO ............................................. 28
Chapter 3 Machine Disassembly ............................................. 29
Chapter 4 Troubleshooting ............................................. 35
Chapter 5 Connector Information ............................................. 39
Chapter 6 FRU (Field Replacement Unit) List ............................................. 41
Exploded Diagram ............................................. 42
Chapter 7 Schematic Diagram ............................................. 45
6
Monitor Features Chapter 1
Introduction
Scope
This specification defines the requirements for the 17" MICROPROCESSOR based Multi-mode supported high
resolution color LCD monitor. This monitor can be directly connected to general 15-pin D-sub VGA connector, also
supports VESA DPMS power management and plug & play function. There is a build-in stereo audio amplifier with
OSD control to drive a pair of speakers.
Description
The LCD monitor is designed with the latest LCD technology to provide a performance oriented product with no
radiation. This will alleviate the growing health concerns. It is also a space saving design, allowing more desktop
space, and comparing to the traditional CRT monitor, it consumes less power and gets less weight in addition MTBF
target is 50k hours or more.
Chart of X223WD
Panel LTM220M1-L01
Signal Interface D-Sub 15-pin / DVI 24-Pin
Sync Type Separate / Compatible
Color Temp User Adjust Support
DDC DDC2B
Speaker No
Headphone Jack No
Microphone Jack No
USB Hub Not support
Tilt / Swivel Yes / No
7
Electrical Requirements
Standard Test Conditions
All tests shall be performed under the following conditions, unless otherwise specified.
Ambient light : Dark room
Viewing distance : 30-50 cm for LCD performance
Warm up time
All specifications :
30 minutes
Measuring equipment : Photo detector PR650 w/2°
Measurement field
Control temperature 6500° K
User brightness control : Set to Factory preset value (cut off raster)
User contrast control : Set to factory preset value, which allows that the brightest two of
32 linear distributed gray-scales (0700mv) can be
distinguished.
User red/white balance,
Green/white balance and
Blue/white balance control : In the center (unless otherwise specified)
AC Supply voltage :
230Vą 5, 50ą3Hz
Ambient temperature :
20+5
Display mode : 1680x1050 60Hz, all white
Measurement systems
The units of measure stated in this document are listed below:
1 gamma = 1 nano tesla
1 tesla = 10,000 gauss
cm = in x 2.54
Lb = kg x 2.2
Degrees F = [°C x 1.8] + 32
Degrees C = [°F - 32]/1.8
u' = 4x/(-2x + 12y + 3)
v' = 9y/(-2x + 12y + 3)
x = (27u'/4)/[(9u'/2) - 12v' + 9]
y = (3v')/[(9u'/2) - 12v' + 9]
nits = cd/(m2) = Ft-L x 3.426
lux = foot-candle x 10.76
8
LCD Monitor General Specification
Driving system TFT Color LCD
Active Display Area 433.44(H) × 270.90mm(V)
LCD Panel Pixel pitch 0.258 (per one triad) x 0.258
Contrast Ratio 1000 : 1
Response time 5ms
Separate Sync. H/V TTL
Input H-Frequency 30kHz 83kHz
V-Frequency 56-76Hz
Viewing angle (H) 90+/-20and (V) 90+/-10
Warm up time >30 Min
Max. Dot Clock 165MHz
Display mode 1680 × 1050 @60Hz
ON Mode < 65W
EPA ENERGY STARŽ
OFF Mode < 1W
Set to factory preset value, which allows that the brightest two of 32 linear distributed
Contrast control
gray-scales (0 700mv) can be distinguished.
Power Source 90~264VAC,47~63Hz
Operating Temp: 0° to 40°C
Environmental Storage Temp: -30° to 60°C
Considerations Operating Humidity: 0% to 90%
Storage Humidity: 0% to 90%
Main Dimension(monitor) 518(W)×400 (H)×177(D) mm
Leakage current < 0.75mA at 254Vac, 50Hz.
Peak surge current < 100 A peak at 230 VAC and cold starting&25 & DC Output at Full-load
9
LCD Panel Specification
General Specifications
Absolute Maximum Ratings
10
Optical Specifications
11
Support Timing
12
Monitor Block Diagram
The LCD MONITOR will contain a main board, a power board, and keypad board which house the flat panel control
logic, brightness control logic and DDC.
The power board will provide AC to DC Inverter voltage to drive the backlight of panel and the main board chips
each voltage.
CCFL Drive. Flat Panel and
CCFL backlight
Inverter Board Main Board
(include adapter)
Keyboard Input : Input :
D-SUB Signal DVI Signal
AC-IN
90V-264V
13
Main Board Diagram
Crystal LCD Interface
(X201) (CN301)
14.318MHz
FLASH ROOM
PM25LV010A
(U402)
Scalar IC TSUMU58BWHL-LF
(Include MCU ,ADC, OSD)
EEPROM (U202)
M24C04-W
MN6TP
(U204) H sync
V sync
RGB
Key Board D-Sub DVI
Control Connector Connector
CN201 (CN101) (CN103)
D-Sub DDC DVI DDC
M24C02-WMN6TP M24C02-WMN6TP
(U101) (U102)
14
Software Flow Chart
1
Y
2 3
N
N
4
N
5
Y
6
N
7 8
Y Y
9
N
10 11
Y
N N
12 13
Y Y
N
14 15 16
Y
17
N
18 19
Y
15
Remark:
1) MCU initializes.
2) Is the EEPROM blank?
3) Program the EEPROM by default values.
4) Get the PWM value of brightness from EEPROM.
5) Is the power key pressed?
6) Clear all global flags.
7) Are the AUTO and SELECT keys pressed?
8) Enter factory mode.
9) Save the power key status into EEPROM.
Turn on the LED and set it to green color.
Scalar initializes.
10) In standby mode?
11) Update the lifetime of back light.
12) Check the analog port, are there any signals coming?
13) Does the scalar send out an interrupt request?
14) Wake up the scalar.
15) Are there any signals coming from analog port?
16) Display "No connection Check Signal Cable" message. And go into standby mode after the
message disappears.
17) Program the scalar to be able to show the coming mode.
18) Process the OSD display.
19) Read the keyboard. Is the power key pressed?
16
Main Board Layout
Symbol Description Symbol Description
U202 056G 562172 X201 093G 22 53
U702 056G 563 31 CN301 033G801930F H
U204 056G1133 32 CN401 033G3802 9
U101 056G1133 34 CN201 033G3802 6
U402 056G1133713 FB205 061G0805000
CN101 088G 35315F H FB204 071G 56V301 B
17
Installation
18
Attaching/Removing the Base
19
Operating Instructions Chapter 2
Press the power button to turn the monitor on or off. The other control buttons are located at front panel of the
monitor. By changing these settings, the picture can be adjusted to your personal preferences.
ˇ The power cord should be connected.
ˇ Connect the video cable from the monitor to the video card.
ˇ Press the power button to turn on the monitor position. The power indicator will light up.
External Controls
Item Description Item Description
1. Power Switch 4. Auto Adjust botton/Exit
2. Power LED 5.
3. Empowering / Exit 6. MENU/ENTER
20
Front Panel Control
21
eColor Management (OSD)
22
How to Adjust a Setting
23
Adjusting the picture
24
25
26
OSD Message
a. Outline
b. The Description For OSD Message
Item Description
Auto Config When Analog signal input, if User Press Hot-Key "Auto", will show this message, and the
Please Wait monitor do the auto config function.
Input Not When the Hsync Frequency, Vsync Frequency or Resolution is out of the monitor
Supported support range, will show this message. This message will be flying.
Cable Not Analog-Only Model: When the video cable is not connected, will show this message.
Connected This message will be flying.
Analog-Only Model: When the video cable is connected, but there is no active signal
No Signal
input, will show this message, then enter power saving.
27
Logo
When the monitor is power on, the LOGO will be showed in the center, and disappear slowly.
How To Optimize The DOS-Mode
Plug And Play
Plug & Play DDC2B Feature
This monitor is equipped with VESA DDC2B capabilities according to the VESA DDC STANDARD. It allows the
monitor to inform the host system of its identity and, depending on the level of DDC used, communicate additional
information about its display capabilities.
The DDC2B is a bi-directional data channel based on the I˛C protocol. The host can request EDID information over
the DDC2B channel.
This monitor will appear to be non-functional if there is no video input signal. In order for this monitor to
operate properly, there must be a video input signal.
This monitor meets the Green monitor standards as set by the Video Electronics Standards Association (VESA)
and/or the United States Environmental Protection Agency (EPA) and The Swedish Confederation Employees
(NUTEK). This feature is designed to conserve electrical energy by reducing power consumption when there is no
video-input signal present. When there is no video input signals this monitor, following a time-out period, will
automatically switch to an OFF mode. This reduces the monitor's internal power supply consumption. After the video
input signal is restored, full power is restored and the display is automatically redrawn. The appearance is similar to
a "Screen Saver" feature except the display is completely off. Pressing a key on the keyboard, or clicking the mouse
restores the display.
Using The Right Power Cord
The accessory power cord for the Northern American region is the wallet plug with NEMA 5-15 style and is UL listed
and CSA labeled. The voltage rating for the power cord shall be 125 volts AC.
Supplied with units intended for connection to power outlet of personal computer: Please use a cord set consisting of
a minimum No. 18 AWG, type SJT or SVT three conductors flexible cord. One end terminates with a grounding type
attachment plug, rated 10A, 250V, and CEE-22 male configuration. The other end terminates with a molded-on type
connector body, rated 10A, 250V, having standard CEE-22 female configuration.
Please note that power supply cord needs to use VDE 0602, 0625, 0821 approval power cord in European counties.
28
Machine Disassembly Chapter 3
This chapter contains step-by-step procedures on how to disassemble the monitor for
maintenance.
Disassembly Procedure
1. Remove the cover hinge as the following indicator. (Fig 1)
Fig 1
2. Remove the screws as following indicate to release base stand . (Fig 2)
Fig 2
29
3. Remove the back cover and regard the hook. (Fig 3-4)
Fig 3
Fig 4
30
4. Remove the keyboard. (Fig 5)
Fig 5
5. Remove the bezel. (Fig 6)
Fig 6
31
6. Remove the screws to remove the panel. (Fig 7-9)
Fig 7
Fig 8
Fig 9
32
7. Remove the screw as following indicate to remove the main board, audio board and power board. (Fig
10-12)
Fig 10
Fig 11
33
Fig 12
34
Troubleshooting Chapter 4
This chapter provides troubleshooting information for the X223WD:
1. No Power
No power
Press power key and look if the
picture is normal
NG
Please reinsert and make sure the
AC of 100-240 is normal
OK NG Reinsert or check the
power section
Measure U701 Pin2=3.3V, U702 Pin
2=1.8V
NG
OK Measure CN401 Pin3=5V?
OK
Check if X201 oscillate
waveforms are normal Replace U701,U702
NG
Replace X201 OK
Replace U202
35
2. No Picture
No picture
Measure U701 Pin2=3.3V, U702
Pin 2=1.8V
OK NG
Replace U701,U702
Check if X201oscillate waveforms are
normal
NG
OK Replace X201
Check if the sync signal from
computer is output and video cable
is connected normally
NG Input the sync signal of computer, or
OK change the cable
Replace U202
36
3. Panel Power Circuit
Check the PPWR panel power relative circuit Q301, Q302
Check CN301 PIN1 should have
In normal operation, when LED =green, Q301B =5 V,
response from 0V to 5V When we NG
If PPWR no-response when the power switch
switch the power switch from on to off
Turn on and turn off, replace the U202
OK
Replace panel
4. Keypad Board
OSD is unstable or not working
NG
Is Keypad board connecting normally? Connect Keypad Board
OK
NG
Is Button Switch normally? Replace Button Switch
OK
NG
Is Keypad board normally? Replace Keypad Board
OK
Check main board
37
5. No Backlight
Check C802 (+) =12V
NG
OK Change F801
Check ON/OFF signal
NG
OK Check Interface board
Check IC801 pin12=12V?
NG
Change Q805.Q808 or Q810
OK
Check the pin9&10 of IC801 have PWM wave
NG
Change Q801/Q804/Q811/Q812
OK
OK
Replace IC801
Check the resonant wave of
pin3 & pin7 for T802,T801
NG
OK Check Q802/Q803
Check the output of T801,T802
NG Change T801,T802
OK
Check connecter & lamp
38
Connector Information Chapter 5
The following figure shows the connector locations on the monitor:
39
40
FRU (Field Replaceable Unit) List Chapter 6
This chapter gives you the FRU (Field Replaceable Unit) listing in global configurations of X223WD.Refer to this
chapter whenever ordering for parts to repair or for RMA (Return Merchandise Authorization).
NOTE: Please note WHEN ORDERING FRU PARTS, that you should check the most up-to-date information
available on your regional web or channel (http://aicsl.acer.com.tw/spl/). For whatever reasons a part number
change is made, it will not be noted in the printed Service Guide. For ACER AUTHORIZED SERVICE
PROVIDERS, your Acer office may have a DIFFERENT part number code from those given in the FRU list of
this printed Service Guide. You MUST use the local FRU list provided by your regional Acer office to order
FRU parts for repair and service of customer machines.
NOTE: To scrap or to return the defective parts, you should follow the local government ordinance or regulations on
how to dispose it properly, or follow the rules set by your regional Acer office on how to return it.
41
Exploded Diagram (Model: X223WD)
42
Part List
Above picture show the description of the following component.
Item Picture Description
1 Base
2 shield
4 Panel
43
5 Power Board
6 Main Board
44
Schematic Diagram Chapter 7
Main Board
R101 0R05 1/10W 5%
R102 1K 1/16W
DSUB_H 2
R103 1K 1/16W FB102
DSUB_V 2
VGA_B+ 1 2 R104 100R 1/16W C101
DSUB_B+ 2
ZD101 ZD102 R105 R106 C102 C103 BEAD 0.047uF
2K 1/16W
RLZ5.6B 2K 1/16W 22pF 22pF R107 C104
RLZ5.6B 5pF/50V
75R 1/16W
VGA_B- R108 100R 1/16W C105
DSUB_B- 2
CN101 0.047uF
16
R110 10 R109 470R 1/16W C106
DSUB_SOG 2
DDC1_SCL 15 5 VGA_PLUG FB103 1000pF
2 DDC1_SCL
9 DSUB_5V DSUB_5V
100R 1/16W 14 4 VGA_G+ 1 2 R111 100R 1/16W C107
DSUB_G+ 2
8 VGA_B- BEAD
R113 13 3 VGA_B+ ZD103 ZD104 0.047uF
7 VGA_G- R112 C108
DDC1_SDA 12 2 VGA_G+ 5pF/50V
2 DDC1_SDA
6 VGA_R- RLZ5.6B RLZ5.6B 75R 1/16W
100R 1/16W 11 1 VGA_R+ R114 C109
VGA_G-
DSUB_G- 2
ZD105 ZD106 17 DB15
100R 1/16W 0.047uF
RLZ5.6B RLZ5.6B
VGA_R+
VGA_G+
3 VGA_B+
FB101
R115 C110
VGA_R+ 1 2
DSUB_R+ 2
3
3
D102 D103 D104 CMVCC BEAD
BAV99 BAV99 BAV99 100R 1/16W 0.047uF
R116 C111
5pF/50V
75R 1/16W CMVCC DSUB_5V
C118 C112 R117 C113
VGA_R-
2
1
2
1
2
1
0.1uF/16V DSUB_R- 2
2
1
0.1uF/16V
100R 1/16W 0.047uF
D105
BAV70
DVI_5V
CN103
3
8 R118
VSY NC 15 DVI_HPD 10K 1/16W C114
SY NC GND 6 R119 100R 1/16W DDC2_SCL Q101 R120 0.1uF/16V
DDC SCL DDC2_SCL 2 U101
7 R122 100R 1/16W DDC2_SDA 4K7 1/16W R121
DDC SDA DDC2_SDA 2
14 R123 10K 1/16W NC 4K7 1/16W 8 1
+5V 16 HOT_PLUG R124 7 VCC A0 2
HPD HPD_CTRL 2 DDC1_SCL 6 WP A1 3
11 C115 D106 D107 D108 DDC1_SDA 5 SCL A2 4
1/3shield 3 R125 NC SDA VSS
2/4shield 2 DDC_WP
19 0.1uF/16V RLZ5.6B RLZ5.6B RLZ5.6B NC
0/5shield 22 M24C02-WMN6TP
clk shield
18 R126 10R 1/16W RX0P CMVCC DVI_5V
DAT0+ RX0P 2
17 R127 10R 1/16W RX0N
DAT0- RX0N 2
10 R128 10R 1/16W RX1P
DAT1+ RX1P 2
2
1
9 R129 10R 1/16W RX1N
DAT1- RX1N 2
2 R130 10R 1/16W RX2P
DAT2+
DAT2-
1 R131 10R 1/16W RX2N
RX2P
RX2N
2
2
93G 64 42 P D101
13 BAV70
DAT3+ 12 VCC3.3
DAT3- 5
DAT4+ 4
3
DAT4- 21 R132
DAT5+ 20 10K 1/16W C116
DAT5- 23 R133 10R 1/16W RXCP R137 R134 0.1uF/16V
clk+ RXCP 2 U102
24 R136 10R 1/16W RXCN 4K7 1/16W
GND
GND
clk- RXCN 2
10K 1/16W R135 8 1
4K7 1/16W 7 VCC A0 2
JACK DDC2_SCL 6 WP A1 3
SCL A2
26
25
D109 CMVCC DVI_HPD R138 0 1/16W DDC2_SDA 5 4
SD