Follow these safety, servicing and ESD precautions to prevent damage and to protect against potential hazards such as
electrical shock.
1-1-1. Warnings
1.
For continued safety, do not attempt to modify the circuit board.
2.
Disconnect the AC power and DC power jack before servicing.
1-1-2. Servicing the LCD Monitor
1.
When servicing the LCD Monitor, Disconnect the AC line cord from the AC outlet.
2.
It is essential that service technicians have an accurate voltage meter available at all times. Check the calibration of
this meter periodically.
1-1-3. Fire and Shock Hazard
Before returning the monitor to the user, perform the following safety checks:
1.
Inspect each lead dress to make certain that the leads are not pinched or that hardware is not lodged between the
chassis and other metal parts in the monitor.
2.
Inspect all protective devices such as nonmetallic control knobs, insulating materials, cabinet backs, adjustment and
compartment covers or shields, isolation resistorcapacitor networks, mechanical insulators, etc.
3.
Leakage Current Hot Check (Figure 1-1):
WARNING : Do not use an isolation transformer during this test.
Use a leakage current tester or a metering system that complies with American National Standards Institute (ANSI
C101.1, Leakage Current for Appliances), and Underwriters Laboratories (UL Publication UL1410, 59.7).
(READING SHOULD)
NOT BE ABOVE 0.5mA
DEVICE
UNDER
TEST
TEST ALL
EXPOSED METAL
SURFACES
2-WIRE CORD
*ALSO TEST WITH
PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED)
4.
With the unit completely reassembled, plug the AC line cord directly into a 120V AC outlet. With the unit’s AC switch
LEAKAGE
CURRENT
TESTER
EARTH
GROUND
Figure 1-1. Leakage Current Test Circuit
rst in the ON position and then OFF, measure the current between a known earth ground (metal water pipe, conduit,
etc.) and all exposed metal parts, including: metal cabinets, screwheads and control shafts.
The current measured should not exceed 0.5 milliamp.
Reverse the power-plug prongs in the AC outlet and repeat the test.
1-1-4. Product Safety Notices
Some electrical and mechanical parts have special safetyrelated characteristics which are often not evident from visual
inspection. The protection they give may not be obtained by replacing them with components rated for higher voltage,
wattage, etc. Parts that have special safety characteristics are identied by on schematics and parts lists. A substitute
replacement that does not have the same safety characteristics as the recommended replacement part might create
shock, re and/or other hazards. Product safety is under review continuously and new instructions are issued whenever
appropriate.
1-1
Page 5
1-2
1. Precautions
1-2. Servicing Precautions
WARNING: An electrolytic capacitor installed with the wrong polarity might explode.
Caution: Before servicing units covered by this service manual, read and follow the Safety Precautions section of
this manual.
Note: If unforeseen circumstances create conict between the following servicing precautions and any of the
safety precautions, always follow the safety precautions.
1-2-1 General Servicing Precautions
1.
Always unplug the unit’s AC power cord from the AC power source and disconnect the DC Power Jack before
attempting to:
(a) remove or reinstall any component or assembly, (b) disconnect PCB plugs or connectors, (c) connect a test
component in parallel with an electrolytic capacitor.
2.
Some components are raised above the printed circuit board for safety. An insulation tube or tape is sometimes
used. The internal wiring is sometimes clamped to prevent contact with thermally hot components. Reinstall all such
elements to their original position.
3.
After servicing, always check that the screws, components and wiring have been correctly reinstalled. Make sure that
the area around the serviced part has not been damaged.
4.
Check the insulation between the blades of the AC plug and accessible conductive parts (examples: metal panels,
input terminals and earphone jacks).
5.
Insulation Checking Procedure: Disconnect the power cord from the AC source and turn the power switch ON.
Connect an insulation resistance meter (500 V) to theblades of the AC plug.
The insulation resistance between each blade of the AC plug and accessible conductive parts (see above) should be
greater than 1 megohm.
6.
Always connect a test instrument’s ground lead to the instrument chassis ground before connecting the positive lead;
always remove the instrument’s ground lead last.
1-3. Static Electricity Precautions
Some semiconductor (solid state) devices can be easily damaged by static electricity. Such components are commonly
called Electrostatically Sensitive Devices (ESD). Examples of typical ESD are integrated circuits and some eld-effect
transistors. The following techniques will reduce the incidence of component damage caused by static electricity.
1.
Immediately before handling any semiconductor components or assemblies, drain the electrostatic charge from your
body by touching a known earth ground. Alternatively, wear a discharging wrist-strap device. To avoid a shock hazard,
be sure to remove the wrist strap before applying power to the monitor.
2.
After removing an ESD-equipped assembly, place it on a conductive surface such as aluminum foil to prevent
accumulation of an electrostatic charge.
3.
Do not use freon-propelled chemicals. These can generate electrical charges sufcient to damage ESDs.
4.
Use only a grounded-tip soldering iron to solder or desolder ESDs.
5.
Use only an anti-static solder removal device. Some solder removal devices not classied as “anti-static” can generate
electrical charges sufcient to damage ESDs.
6.
Do not remove a replacement ESD from its protective package until you are ready to install it. Most replacement ESDs
are packaged with leads that are electrically shorted together by conductive foam, aluminum foil or other conductive
materials.
7.
Immediately before removing the protective material from the leads of a replacement ESD, touch the protective
material to the chassis or circuit assembly into which the device will be installed.
Caution: Be sure no power is applied to the chassis or circuit and observe all other safety precautions.
8.
Minimize body motions when handling unpackaged replacement ESDs. Motions such as brushing clothes together,
or lifting your foot from a carpeted oor can generate enough static electricity to damage an ESD.
Page 6
1-3
1. Precautions
1-4. Installation Precautions
For safety reasons, more than two people are required for carrying the product.
1.
Keep the power cord away from any heat emitting devices, as a melted covering may cause re or electric shock.
2.
Do not place the product in areas with poor ventilation such as a bookshelf or closet. The increased internal
3.
temperature may cause re.
Make sure to turn the power off and unplug the power cord from the outlet before repositioning the product. Also check
4.
the antenna cable or the external connectors if they are fully unplugged. Damage to the cord may cause re or electric
shock.
Keep the antenna far away from any high-voltage cables and install it rmly. Contact with the highvoltage cable or the
5.
antenna falling over may cause re or electric shock.
When installing the product, leave enough space (10cm) between the product and the wall for ventilation purposes.
6.
A rise in temperature within the product may cause re.
Page 7
1. Precautions
Memo
1-4
Page 8
2. Product specications
2-1. Feature & Specications
Model2494HS / 2494HSI / 2494HM
Support PC / DVI / HDMI
�
DC DC 50000:1 Applied
�
Adopted two 3W speakers.
�
USB (1 up, 2 down) optional
�
HDCP Applied for HDMI/DVI-D Fixed Aspect Ratio Support
�
Supports xed horizontal and vertical ratios
�
Supported camera effects: Black/Sepia/Green/Blue
�
Supports the Off-timer function
�
ItemDescription
Model2494HS / 2494HSI2494HM
2. Product specications
Feature
Specications
LCD PanelTFT-LCD panel, RGB vertical stripe,
normally black transmissive,
23.6-Inch viewable, 0.2715(H)x0.2715(V)
mm pixel pitch
This section describes the disassembly and reassembly sequences for this monitor.
WARNING: As this monitor has parts that are sensitive to static electricity, be careful when handling them.
3-1. Disassembly (2494HS / 2494HSI)
Cautions: 1. Turn the monitor off before beginning the disassembly process.
2. Disassemble the monitor carefully as directed in the following procedures.
3. When disassembling the monitor, do not use any metal tools except for the provided jig.
PartDescriptionPicture DescriptionScrews
1. Place a soft cloth on the table and
place the monitor on it so the front
part is facing downwards. Hold and
pull the stand downwards to remove it
from the monitor set.
Stand
Rear cover
2. Remove the four (4) screws on the
bottom, as shown in the gure on the
right.
3. Hold the projected part of the rear
cover with one hand, hold the front
cover with the other hand, and
then lift and remove the rear cover
upwards.
Caution : If you remove the rear
cover by holding and lifting
the red circle part marked
with ‘NO’ upwards (to the
left of the gure on the
right), a crack may occur
on the Function-PCB
connector. Make sure to
hold and lift the red circle
part marked with ‘YES’
upwards (to the right of
the gure on the right), to
remove the rear cover.
YESNO
If handled
incorrectly,
a crack may
occur on the
Function-PCB
connector.
3-1
Page 13
3-2
3. Disassembly and Reassemble
PartDescriptionPicture DescriptionScrews
4. Remove the shield lamp using a at
SHIELD-
LAMP
screwdriver or the provided jig.
Caution : Be careful because the
shield lamp is sharp.
Removing
the cables
ASSY
CHASSIS
5. Remove the lamp wire, function wire,
speaker connector, and LVDS cable
connected to the chassis.
6. Remove the four (4) hex screws on
the bottom of the shield, as shown in
the gure on the right.
7. Remove the eight (8) screws
designated in the gure on the right,
lift the boards upwards and remove
the cable shown in the gure on the
right.
BOARD,
IP-Board
MAIN
8. Remove the main board and IP-board
from the shield cover.
Page 14
3-3
3. Disassembly and Reassemble
3-2. Disassembly (2494HS)
Cautions: 1. Turn the monitor off before beginning the disassembly process.
2. Disassemble the monitor carefully as directed in the following procedures.
3. When disassembling the monitor, do not use any metal tools except for the provided jig.
PartDescriptionPicture DescriptionScrews
1. Place a soft cloth on the table and
place the monitor on it so the front
part is facing downwards.
Remove the four (4) screws
designated in the gure on the right
and remove the stand.
Caution : When removing the screws,
make sure to hold the stand
body with one hand so that
the stand does not fall over.
Stand
Rear Cover
2. Remove the four (4) screws on the
bottom, as shown in the gure on the
right.
3. Hold the projected part of the rear
cover with one hand, hold the front
cover with the other hand, and
then lift and remove the rear cover
upwards.
Caution : If you remove the rear
cover by holding and lifting
the red circle part marked
with ‘NO’ upwards (to the
left of the gure on the
right), a crack may occur
on the Function-PCB
connector. Make sure to
hold and lift the red circle
part marked with ‘YES’
upwards (to the right of the
right gure) to remove the
rear cover.
YESNO
If handled
incorrectly,
a crack may
occur on the
Function-PCB
connector.
Page 15
3. Disassembly and Reassemble
PartDescriptionPicture DescriptionScrews
4. Remove the shield lamp using a at
SHIELD-
LAMP
screwdriver or the provided jig.
Caution : Be careful because the
shield lamp is sharp.
Removing
the cables
ASSY
CHASSIS
MAIN
BOARD,
IP-Board
5. Remove the lamp wire, function wire,
speaker connector, and LVDS cable
connected to the chassis.
6. Remove the four (4) hex screws on
the bottom of the shield, as shown in
the right gure.
7. Remove the eight (8) screws
designated in the right gure, lift the
boards upward and remove the cable
shown in the gure on the right.
8. Remove the main board and IP-board
from the shield cover.
※Reassembly procedures are in the reverse order of disassembly procedures.
3-4
Page 16
4. Troubleshooting
4-1. Troubleshooting
1.
Before troubleshooting, setup the PC ‘s display as below.
• Resolution: 1920 x 1080
• H-frequency: 75 kHz
• V-frequency: 60 Hz
2.
If no picture appears, make sure the power cord is correctly connected.
3.
Check the following circuits.
• No raster appears: Function PBA. Main PBA. IP-Board
• 5V develop but no screen : Main PBA
• 13V, 5V does not develop: IP-Board, Main PBA
4. Troubleshooting
4-1
Page 17
4-2
4. Troubleshooting
4-2. When the Power Does Not Turn On
The LED on the front panel of the monitor does not work when the power is connected and the
Symptom
Major checkpoints
-
Power button is pressed.
Check if the Power switch on the rear panel of the monitor has been turned on.
-
Check the SMPS fuse and the IP-Board output power.
-
Check the connection between the IP-Board and the Main Board inside the monitor.
-
Check the power part of the Main Board and check if a similar symptom appears at another
-
output terminal.
CN600
IC203
Main Board Front
Diagnostics
Check the connection status of the
Function assy.
Can DC 5V be measured on pins 6, 7
of the CN600 connector when pins 3, 4,
and 5 are 0V?
Yes
Can DC 3.3V be measured on pin 3 of
the IC203 when pin 1 is DC 5V?
Yes
Check and replace the main board
related to the scaler.
CautionMake sure to disconnect the power before working on the IP board.
No
No
Replace the IP board.
Check the circuits related to
the IC203.
Page 18
4-3
4. Troubleshooting
4-2-1. Circuit Diagram and Waveform for Power Failures
Page 19
4-4
4. Troubleshooting
4-3. When a blank screen is displayed (Analog)
The LED power is on but no picture is displayed on the screen when the D-SUB cable is
Symptom
Major checkpoints
-
connected
Even though the LED power turns on, the screen is blank when connecting the VGA cable.
-
Check the D-sub cable connections.
-
Check whether the LVDS cable is connected correctly to the panel.
-
Check whether the lamp connector of the panel is connected correctly to the IP board.
-
CN400
IC202
X200
Diagnostics
Check the signal cables and
their connections.
Yes
Check if X200 is oscillating normally.
①
Yes
②
③
④
Check if R, G and B inputs are
measured at R106, R110 and R121.
Yes
Check if Hsync and Vsync are
measured at R115 and R116.
Yes
Check if Hsync and Vsync are measured
at pins 32 and 33 of IC202.
R106
R110
R121
Main Board Front
No
No
No
No
R115
R116
Check and replace related
circuits if necessary.
Check the input part.
Check the input part.
Check the circuit around
IC202.
Yes
Do output signals appear at pins 8 to 30
⑤
Is DC 5V measured at pins 1, 2, and 3
⑥
CautionMake sure to disconnect the power before working on the IP board.
of CN400?
Yes
of the CN400?
Yes
Replace the LCD panel.
No
No
Check the input part.
Check the +5V_Panel signal
and the BL_EN signal.
Page 20
4-5
4. Troubleshooting
4-3-1. Circuit diagrams and waveforms (analog) when a blank screen is
displayed on the monitor
②
③
④
Page 21
4-6
4. Troubleshooting
①③
④
Page 22
4-7
4. Troubleshooting
4-4. When a Blank Screen Is Displayed (DVI)
SymptomThe LED power is on but no picture is displayed on the screen when the DVI cable is connected.-
Check if the LED power turns on but no screen is displayed when connecting the DVI cable
-
Check if the DVI cable has been connected.
Major checkpoints
-
Check if the LVDS cable has been properly connected to the LCD panel.
-
Check if the Inverter board has been connected properly to the lamp connector of the LCD panel.
-
IC202
X200
R142~R151
CN400
Main Board Front
Diagnostics
①
②
③
CautionMake sure to disconnect the power before working on the IP board.
Check the signal cables and
their connections.
Yes
Check if X200 is oscillating normally.
Yes
Check if R, G and B signals are
measured at R142~R145, R148~R151.
Yes
Check if the output signal appears at
pins 8 to 30 of CN400.
Yes
Replace the LCD panel.
No
No
No
Check and replace related
circuits if necessary.
Check the input part.
Check the circuit around
IC202.
Page 23
4-8
4. Troubleshooting
4-4-1. Circuit diagrams and waveforms (DVI) when a blank screen is displayed
on the monitor
①
②
Page 24
4-9
4. Troubleshooting
①
②
③
Page 25
4-10
4. Troubleshooting
4-5. Error Examples and Actions
Error AppearanceSymptoms and ActionsRemarks
Symptom: DVI signals are not recognized.
Cause: This error occurs because the PC cannot
recognize the mode information since the
DVI DDC is not input to the monitor.
Action: Input the DVI DDC.
*On how to input DDC, refer to the
training manual.
Page 26
4-11
4. Troubleshooting
4-6. Adjustment
4-6-1. Service Adjustment Conditions
1.
Precautions before a Service Adjustment.
1) Check whether the devices for the service adjustment are operating normally.
2) Secure a space that is sufciently wide for disassembling the monitor.
3) Prepare a soft mat on which the monitor will be disassembled.
2.
Entering Service Mode.
Entering:
Exiting:Power OFFPower ON
Auto Color Adjustment
3.
Use a 16 gray-scale or gray-black-mixed pattern for the video input.
1) For the OSD Language, select the language at the top..
2) Press and hold the OSD “(Enter/Source)” for 5 seconds.
MenuBrightness 0Contrast 0
Hold down the Enter button for ve (5) seconds.
4-6-2. Firmware Download
You have to complete the post-operation using a MICOM Jig (RS232 Jig) after replacing the Main Board.
You can update the Micom using a MICOM Jig (RS232 Jig).
Requirements
The following devices are required for adjusting the monitor
-
A Computer with Windows 95, 98, 2000, XP or NT.
-
MTI-2059 DDC Manager Jig
-
RS232 Jig
-
Entering the Micom Code
You have to complete the operation using the DDC Manager after replacing the Main Board.
-
Connect devices as shown below.
-
You can update the Micom using the DDC Manager.
-
Connect to the Parallel Board
DDC Manager
RS232 JIG
CN101
Connect to the Main Board (CN101)
Page 27
4-12
4. Troubleshooting
Entering the Micom Code
1. Run “winDDC” and select “MSTAR”, “TSUMxxx”, “DSUB15(Analog)”, “PMC25LV020” step by step.
2. Click “Load File” and select the latest code in the format of “*.hex”.
Page 28
4-13
4. Troubleshooting
3. Click “Program”
Entering the EDID
You can update the EDID/DDC (Analog / DVI / HDMI) using the DDC Manager Jig.
-
Connect the devices as shown below
-
MTI-2059
DDC Manager
Signal Connector
Connect to the
Monitor (D-SUB/
-
DVI/HDMI)
Page 29
4-14
4. Troubleshooting
Entering the EDID
1. Install the Winddc.exe program onto the PC.
2. Click the Winddc icon.
3. Select Open.
4. Select Port #1
5. Open a DDC le.
*File Name
“SM2494HMA.ddc” → Analog DDC
“SM2494HMD.ddc” → Digital DDC
“SM2494HMH.ddc” → HDMI DDC
6. Click Next (OK).
③
④
⑤
⑤
Page 30
4-15
4. Troubleshooting
7. Enter the Monitor S/N and press Enter.
Enter for Analog, Digital and HDMI.
Page 31
4-16
4. Troubleshooting
4-6-3. Service Function Spec.
1. 1. Set the Brightness and Contrast to 0.
2. Press and hold the Enter and Source keys.
3. The SVC Function OSD appears.
*To exit from the SVC Function OSD, you have to turn the power off.
Panel Information
Software Version
MICOM Checksum
The SVC Function OSD consists of a 103 (Horizontal) x 82 (Vertical) Grid.
The SVC Function OSD consists of Panel Information, the Software Version and the Micom Checksum.
Navigating Menus
1. Press the (▼) key to move up and press the (▲) key to change the value of a selected.
Page 32
4-17
4. Troubleshooting
Replacing the Panel
When replacing the panel: After replacing the panel, select the Panel Ch. No. item and press and hold the MENU key
for 5 seconds.
The Panel Ch. No. increases by 1 and the Panel On Time is reset to 0.
At the same time, the Panel Cycle is also reset to 0.
Other Functions
1. Auto Auto : On / Off
2. PixelShift : On / Off
3. Country : English / Korean / Chinese / Japanese