Samsung Syncmaster 743b Service Manual

							
4-3
4. Troubleshooting

4-2-1. Circuit diagrams when the power does not turn on
 
						

							
4-4 
4. Troubleshooting

4-3. When the screen is blank (Analog)
Symptom- LEven though the LED power turns on, the screen is blank when connecting the VGA cable.
Major checkpoints
- 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.
CN 400
X 201IC 200
R111, R114, R118
Diagnostics
Yes
Check the signal cables and 
their connections.
Yes
NoCheck the R111, R114, and 
R118 input terminals.
NoCheck the circuits related to 
IC200.
NoCheck the circuits related to 
CN400.Do output signals appear at pins 8 to 30 
of CN400?
NoIs DC 5V measured at pins 1, 2, and 3 
of the CN400?
Do the ③ Hsync and ④ Vsync 
waveforms appear at pins 32, 33 of 
IC200, respectively?
② Do the RGB inputs appear at R111, 
R114, and R118?
① Is X201 oscillating correctly?
Check and replace the panel.
NoCheck and replace the circuits 
related to X201.
Yes
Yes
Yes
Check the +5V_Panel signal 
and the BL_EN signal.
Yes
CautionMake sure to disconnect the power before working on the IP board.
 
						

							
4-5
4. Troubleshooting

4-3-1. When a blank screen is displayed (Analog)
3
4
②
①
 
						

							
4-6 
4. Troubleshooting

4-3-2. Waveforms when no screen is displayed (Analog) 
①
④
③
 
						

							
4-7
4. Troubleshooting

4-4. 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.
Symptom:  A full white screen is displayed regardless of 
the signals when turning on the monitor.
Cause:  This error occurs when only lamp power 
is supplied and the video signals are not 
input to the panel due to an LVDS cable 
connection error.
Action:  Replace the LVDS cable or connect the 
cable correctly so that the video signals can 
be supplied to the panel.
* A Full White pattern is a feature of a 
TN panel when no video signals are 
supplied.
 
						

							
4-8 
4. Troubleshooting

4-5. Adjustment
4-5-1. Service Adjustment Conditions
Precautions before a Service Adjustment 
1) Check whether the devices for the service adjustment are operating normally. 
2) Secure a space that is sufficiently wide for disassembling the monitor. 
3) Prepare a soft mat on which the monitor will be disassembled.
Entering Service Mode 
Entering:MenuBrightness 0Contrast 0Hold down the Enter button for five (5) seconds.
Exiting:Power OFFPower ON
Basic Service Items to Perform after Replacing a Board 
1) Check the PC color adjustment status. 
2) Input DDC (input both of Analog and Digital). 
3) Check whether the appropriate MCU code for the model is input. 
4) Hard power the monitor off after entering service mode and performing a reset.
DDC EDIT Data Input 
1) Use when updating the AD board code. 
2)   
Download the WinDDC program, DDC Input program, and Hex and DDC files appropriate to the model through the 
Quality Control department of Samsung Electronics. Install the jig and input the data, as shown in the figure. 
 
Monitor needing
adjustment
Parallel 
Connector
(25P Cable)Connect Monitor
(Signal Cable)
MTI-2031
DDC Manger
1.
2.
3.
4.
    
						

							
4-9
4. Troubleshooting

4-5-2. Service Function Specifications
Checking the Code Version
1. Check the MCU code version and checksum after entering SVC Mode.
2.   Entering SVC Mode
 
- Adjust the Brightness and Contrast values to 0. 
- Hold down the Enter button for five (5) seconds. 
- The SVC Function OSD is displayed. 
- To exit the SVC Function, turn the power off.
3.   
Safe Mode
 
-   
When the input signal is higher than the supported frequency of the product, safe mode gives users some time (one 
minute) to change the video card settings to the Recommended Mode settings.
Service Mode (Moving around)
1. Press the + button to move to other items.


Panel information
Micom version
Micom checksum
Select the Auto Auto option
Select the PixelShift option.
Country
Scaler Vender
 
						

							
4-10 
4. Troubleshooting

2. Press the - button to change the setting to On or Off.
When replacing the panel
After replacing the panel, move to the Panel item and hold down the Menu button for five (5) seconds. 
The Ch. No is incremented by 1 and then both the On Time and Cycle are set to 0.

This number is incremented by 1.
 
						

							
4-11
4. Troubleshooting

Inputting the DDC Data
Use the DDC Manager MTI-2050 version or later.
1) Click the Open [F5] icon. 
2) Select a port. 
3) Open a DDC file. 
4) Select a date and click the OK [Save] button. 
5) Click the Next [OK] button. 
6) Enter the serial number and then press the Enter button 
When inputting digital data after inputting analog data, repeat steps 2 \
to 5.

※
1
2
3
4
5
6
 
						

							
4-12 
4. Troubleshooting

Inputting the MCU Data
1) Check the following options. 
 - Manufacture: MSTAR 
 - Device Type:TSUM16_ROM128K_ext_flash 
 - Communication Port: DSUB15 (Analog) 
 - External Memory: PMC25LV010E 
2) Click the LoadFile button, select an MCU code file, and then click the Open [O] button.

1
2