Tech Troubleshooting – LED LCD TCON and panel Troubleshooting

Model: LCD, LED

Symptom: There are vertical lines in the top right part of the screen.

Solution: The LVDS cable can cause this symptom if it is not seated correctly. Check the position of the LVDS cable and the contacts. If it is seated correctly and you still see vertical lines, replace the LVDS cable.

Model: LCD, LED
Symptom: There are two RED vertical bars and RED smears around objects.

Solution: The LVDS cable can cause this if it is not seated correctly. Check the position of the LVDS cable and the contacts. If it is seated correctly and you still see red bars and smears, replace the LVDS cable.

Model: LCD,LED
Symptom: There are horizontal black and white bars across the screen in RF ONLY

Solution: As you can see, the OSD is not affected. That tells you that the panel is OK. Replace the main board.

Model: UN55C8000XFXZA
Symptom: The right side of the screen is darker than the left.

Solution: Bring up the Test Picture. If the symptom affects the Test Picture, replace the panel.

Model: LCD, LED
Symptom: There are vertical lines in the picture.

Solution: The LVDS cable can cause this symptom if it is not seated correctly. Check the position of the LVDS cable and the contacts. If it is seated correctly and you still see vertical lines, replace the LVDS cable.

Model: PN42C430A1DXZA
Symptom: The picture has blemishes.

Solution: If the symptom affects the Test Picture, replace the panel.

Model: LNT5271
Symptom: The right side of the screen has horizontal lines.

Solution: In the example above, the line distortion is affecting the menu. Bring up the OSD menu. If the symptom affects the menu, replace the T-Con board.

Model: UN46D6500VFXZA
Symptom: Ghosting image (Double Image)

Solution: Replace the T-Con and LVDS.

Model: LN55C650
Symptom: Colored Vertical lines

Solution: Bring up the “Picture Test”. If the lines appear in the Picture Test, the cause is a bad panel. If the lines do not appear, disconnect all signal sources and check again. If the lines are still in the Picture Test, change the main board. If the lines are gone, then a signal 
source is causing the problem.

Samsung TV Panel troubleshooting – Vertical lines – dark spots – Horizontal lines

Model: UN32B6000VFXZA
Symptom: Circles on the screen

Solution: Bring up the OSD or internal test patterns. If you still see circles, replace the panel

Model: LN46B550K1FXZA
Symptom: Vertical lines on screen

Solution: Bring up the OSD or internal test patterns. If you still see the lines, replace the panel.

Model: UN46B6000VFXZA
Symptom: There’s a small triangle on the upper right hand corner.

Solution: Bring up the internal test patterns. If you still see the triangle, replace the panel.

Model: UN55B6000VFXZA
Symptom: Distorted and pink smear across top

Solution: Bring up the internal test patterns. If you still see the pink smear, replace the panel.

Model: PN50B450B1DXZA
Symptom: Vertical line on screen

Solution: Bring up the internal test patterns. If you still see the line, replace the panel.

Model: LN52B630N1FXZA
Symptom: The LED above the power button flashes constantly and then flashes at a rapid rate when a command is sent using the remote control.

Solution: Check the LVDS cable.

Model: PN50B450B1DXZA
Symptom: Vertical bar

Solution: Make sure it shows up in the front of the OSD and/or internal test patterns. If YES, replace panel.

Model: UN55B8500XFXZA
Symptom: Dark area in center of the screen.

Solution: Make sure it shows up in the front of the OSD and/or internal test patterns. If YES, replace panel.

Model: LN40B530P7FXZA
Symptom: Vertical and horizontal lines.

Solution: Make sure it shows up in the front of the OSD and/or internal test patterns. If YES, replace panel.

Samsung Full HD LED TV – Samsung UA40B6000VR – How to enter to service mode – Self diagnostic mode

Entering Factory Mode
To enter ‘Service Mode’ Press the remote -control keys in this sequence :
- If you do not have Factory remote - control

POWER OFF > INFO > MENU > MUTE > POWER ON
How to Access Service Mode Using the Customer Remote
Turn the power off and set to stand-by mode
Press the remote buttons in this order; POWER OFF-MUTE-1-8-2-POWER ON to turn the set on.
The set turns on and enters service mode. This may take approximately 20 seconds.
Press the Power button to exit and store data in memory.
- If you fail to enter service mode, repeat steps.
Buttons operations within Service Mode

Menu	Full Menu Display/Move to Parent Menu
Direction Keys UP/ DOWN	Item Selection by Moving the Cursor
Direction Keys LEFT/ RIGHT	Data Increase / Decrease for the Selected Item
Source	Cycles through the active input source that are connected to the unit

White Balance – Calibration

Method of Color Calibration (AV)
1) Apply the NTSC Lattice (N0. 3) pattern signal to the AV IN 1 port
2) Press the Source key to switch to “AV1” mode
3) Enter Service mode
4) Select the “ADC” menu
5) Select the “AV Calibration” menu.
6) In “AV Calibration Off” status, press the “Right Arrow” key to perform Calibration.
7) When Calibration is complete, it returns to the high-level menu.
8) You can see the change of the “AV Calibration” status from Failure to Success.
Method of Color Calibration (Component)
1) Apply the 720p Lattice (N0. 6) pattern signal to the Component IN 1 port
2) Press the Source key to switch to “Component1” mode
3) Enter Service mode
4) Select the “ADC” menu
5) Select the “Comp Calibration” menu.
6) In “Comp Calibration Off” status, press the “Right Arrow” key to perform Calibration.
7) When Calibration is complete, it returns to the high-level menu.
8) You can see the change of the “Comp Calibration” status from Failure to Success.
Method of Color Calibration (PC)
1) Apply the VESA XGA Lattice (N0. 21) pattern signal to the PC IN port
2) Press the Source key to switch to “PC” mode
3) Enter Service mode
4) Select the “ADC” menu
5) Select the “PC Calibration” menu.
6) In “PC Calibration Off” status, press the “Right Arrow” key to perform Calibration.
7) When Calibration is complete, it returns to the high-level menu.
8) You can see the change of the “PC Calibration” status from Failure to Success.
Method of Color Calibration (HDMI)
1) Apply the 720p Lattice (N0. 6) pattern signal to the HDMI1/DVI IN port
2) Press the Source key to switch to “HDMI1” mode
3) Enter Service mode
4) Select the “ADC” menu
5) Select the “HDMI Calibration” menu.
6) In “HDMI Calibration Off” status, press the “ Right Arrow ” key to perform Calibration.
7) When Calibration is complete, it returns to the high-level menu.
8) You can see the change of the “HDMI Calibration” status from Failure to Success.

Upgrading the Firmware

1.Insert a USB drive containing the firmware upgrade into the USB Pro port on the side of the TV.
2.If pop up is showed, press the exit or or press the No button. (If you press Yes button, display is changed to Wiselink Pro Menu )
3.Press the MENU button to display the menu.
4.Press the UP or DOWN button to select “Setup”, then press the ENTER button.
5.Press the UP or DOWN button to select “SW Upgrade”, then
press the ENTER button.
Press the ENTER button.
The message “Scanning for USB... It may take up to 30 seconds.” is displayed.
6.The message “Upgrade version ------ to version ------?
The system will be reset after upgrade.” is displayed.
Press the LEFT or RIGHT to select the “OK”, then press the ENTER button.
Self Diagnostic
This is simple test function that judge whether is TV SET’s problem or not.
There are two self-test. Picture and Sound.
Press “Menu > Support > Self Diagnosis”
The message “Picture Test / Sound Test” is displayed

2. Picture Test
1) The message “Does the problem still exist with this test pattern?” is displayed.
2) Press “Yes”. This is a TV SET problem.
3) Press “No”.
This is not a TV SET problem.
The message “If the self diagnosis picture is OK, picture distortion may caused by your external device.
Check connection.

3. Sound Test
1) The message “Does the problem still exist with this sound test?” is displayed.
2) Press “Yes”. This is a TV SET problem.
3) Press “No”.
This is not a TV SET problem.
The message “If the self diagnosis picture is OK, picture distortion may caused by your external device.
Check connection.

Samsung Plasma Television – How to troubleshooting Y sustain board – Y buffer board

Y Board Configuration

“Y” PCB configurations will vary depending on screen size. The replaceable buffer PCB style will be separate.Y Main and one piece upper and lower buffer PCB. The non replaceable buffer styles will require the Y Main to be replaced in the event the buffer circuit fails.

Y Board Circuit

This Y Main board maintains the sustain voltage waveform, the initialize waveform and generates the Y rising/falling ramp waveforms. The wave shape that is output to the respective Y electrodes varies depending on luminance levels and whether that pixel is actually selected. Y board failures usually cause the entire panel to be dark. Y board failures can sometimes be verified by visual inspection of the IC and FETs.The Y board operates similarly to the X board with some variations. The Y board output signal is opposite in polarity to the X Board signal. The Y Board signal is specific for each pixel. Pixels that are off do not receive a signal. Pixel brightness is controlled by varying the number of sustain pulses. Because the Y board signal is more detailed than the X board signal is output to a pair of multiplexing boards. The upper and lower Y buffers divide the screen in half vertically. The Y Buffer Boards apply the address waveform to the Y terminals of the panel. The Y Board signal varies depending on the input video. Each Y electrode gets a unique signal; this means that the Y signal is applied through an upper and lower buffer board.

The Y Main is responsible for the Address pulse to determine which sub pixel will be used.

The Y main is responsible for lighting the selected sub pixel to a specific illumination by using the sustain pulses.

Y Board Sustain Pulse

Only the X and Y boards are responsible for the sustain pulses. As the number of pulses increase to the individule sub-pixels, the brightness and color saturation increases as well

The Y Main is responsible to initialize or erase the charge from the sub pixel and prime it for use again.

Y Board Troubleshooting

The Y board is responsible for the address, sustain and initialize functions. Y board failures can cause the entire panel to be off. This is because the Y electrodes are not being addressed properly. Y board failures can sometimes be verified by visual inspection of the IC and FETs. Additionally inspect the green fusible resistors looking for a brown or burned component. Y board failures are much more common than X board failures. A shorted component on the Y board may load down the Vs, Vset and Vscan voltages. If the Vset is low or missing the panel will not initialize creating image retention. If the Vscan voltage is low the pixels cannot be selected creating a black screen. And finally if the Vs voltage is missing or low the panel cannot be sustained creating a dark picture. If the Vs, Vset or Vscan voltages are low or missing verify the Y board is not loading down the line. Measure the resistance of Vs, Vscan and Vset connections reference to circuit ground. A dead short or low resistance on any of these connections is an indication of a shorted component. Another symptom is a picture defect running horizontally across the screen. This is because the Y electrodes run across the screen. A bar or picture defective that is localized to the top or bottom of the screen.

To troubleshoot the Y board verify the positive Vs voltage, the negative Vs voltage and the Vsc voltage. The voltage should match the value printed on the panel.
If any of the voltages are low or missing, unplug the Y board to see if the Y board is loading down the power supply.

Another test procedure is to unplug the unit and measure the resistance of Vsc, +Vs and –Vs SMPS inputs referenced to ground, Low or zero resistance indicates a shorted FET.
As with the X board, the fast switching and high current requirements can cause the FET’s to explode or crack, visual inspection can often show this type of damage

Y Board Failure Examples

Notice how each error contains a horizontal line

These examples show Y board errors, because the Y electrodes run horizontally, errors can often be seen across the screen.
Another Y board error can be an entirely black screen.

The Y Buffer Board time shares the Y drive signal to all the Y electrodes. Y buffer failures can cause horizontal line errors or in some cases the entire panel to stay dark.

UPPER AND LOWER Y BUFFER BOARD ERROR 

On older style Plasma TV’s the upper and lower buffer can be replaced separately. With the introduction of a one piece buffer both upper and lower are replaced as an assembly. In the case of the Y Main with built in buffer circuits, the entire Y Main is replaced.

Y Buffer Connection Errors

If the connection from the Y buffer board to the panel is not installed properly the panel might show thin parallel lines. This is NOT a panel or a board error .

The connection between the buffer and the panel can cause these types of problems. The connections can be cleaned and reseated but make sure the power is removed before attempting.

Samsung plasma TV – Logic board troubleshooting tips

Logic Board Troubleshooting

A defective logic board will often display the video signal but with the wrong color or a smeared picture. If you can recognize the video pattern but there are errors in color , smearing or jittering, suspect that the Logic board is defective.

The logic board creates the timing pulses to create the X, Y and Address waveforms. Additionally the logic board is involved in controlling the power on operation. Logic board defects will usually cause the screen to show a full image but with some type of error. The error can be inverted video, jitter or improper color or luminance. If the logic board is defective all of the pixels will be illuminated but the video will be incorrect. The error may be sectionalized or across the entire panel. Another common error is related to a loss connection on the LVDS cable. It is possible to isolate the Logic board from the Main board by accessing the test pattern on the logic board.

Isolating the Logic Board

1. Access the service menu by pressing Mute + 1 + 8 + 2 + Power with the power
off.
2. Access the PDP option sub menu item.
3. Access the Pattern select submenu item.
4. Scroll through the different patterns. These test patterns are generated on the
Logic Board. If these patterns are displayed properly, the problem is before the logic board. This can be problem with the Logic-Main Board LVDS interconnect cable or a problem with the Main board. If the patterns are not displayed properly, the problem is probably caused by a defective Logic Board. Additionally a dead set may also be caused by the Logic board not sending out the relay on command. This can also be a set that cycles on or off quickly at startup.

To troubleshoot video problems or to make sure every board after the main board is working properly, the internal test patterns can be accessed in the logic board then move to the main board test patterns. Even the customer menu's can be used as a test pattern.

Logic Board Forced Operation

Step 1- With the Main PCB removed, short pins 1 & 5 on the 24P ribbon cable to the SMPS to turn the panel on. This will turn on the secondary voltages of the SMPS. Shorting the POWER ON connection to ground is the same as the power on from the power switch.
Step 2 - Carefully short pins 5 & 6 of the 6 terminal test point on the Logic PCB together. When the panel is powered on, the PDP will automatically “play” the internal test patterns stored on the Logic board that would normally be accessed only through the service menu. This will force the logic board into a loop where the internal test patterns will be displayed in sequence.
Step 3 - After the proper pins are shorted, apply power to the AC input to the panel. The TV will power up by itself and if all is well with the logic, X, Y buffers and address boards, the panel will “play” the test pattern loop. If everything looks normal the possible problem is the main board which is the only thing left not in the circuit.

The patterns that will be displayed from the logic PCB are located after the LVDS cable. If the patterns look normal, the SMPS, logic, X, Y, buffers and panel are all working properly. Use this method in cases where the video is so distorted that the menus can not be seen to access the test patterns using the service mode.

Logic Board Failure Examples

Logic PCB failures The test patterns located on the Logic board are being displayed along with the incoming video.

If the relay cycles repeatedly or will not close, verify the Standby +5VDC supply is not being pulled down by a defective Logic Board

Samsung plasma TV – Plasma TV Power supply Troubleshooting tips – Plasma television repair and service

SMPS

The SMPS power supply will vary slightly depending on the screen size. Both however will function identically.

Power supply removal requires the tech to remove either 6 or 8 screws be removed depending on the model and size of screen. After replacement of the SMPS make sure the voltages are adjusted according to the label posted on the panel.

The power supply provides switched and unswitched voltages for operation. The unswitched voltages are present as long as the unit is plugged into the wall. The +5VDC supply operates the main CPU on the digital board. The +33VDC supply is used by the tuner.
The other voltages are used by the panel drive circuits creating the Va,Vs,Vset and Ve voltages.
The Power Factor Control (PFC) circuit is used to save energy. Taking advantage of the capacitive effect of the pixel elements allows the power supply to operate at a reduced duty cycle. Using a large inductor and the capacitive effect of the panel allows energy to be stored and accessed as needed.
A separate transformer supplies the +5VDC Stand-By B+ to the Digital board. This voltage powers the Microprocessor (IC201) and enables the Key Matrix and the Remote IR Sensor. This turns on the relay activating the rest of the Power Supply PCB. If this supply is missing or low the unit will not turn on. If this signal is not present check the supply voltage for the micro.

Power Supply Troubleshooting

If the Ve voltage is low or missing disconnect the power supply cable from the X board. If the Ve voltage rises the X board is probably shorted. If the voltage stays low the SMPS board needs to be replaced. If the Vs voltage is low or missing it can be caused by a defective X or Y board. Check both boards for short circuits before replacing the SMPS board. If the Vs voltage is too high an effect called diffusion may occur. Diffusion is when the initialize voltage is too high. Excessive voltage causes unwanted pixel firing creating intermittent sub-pixel flashes. Power on-off cycling can be caused by a shorted component on the Logic board loading down the standby 5V.

Power Supply Failure Examples

One possible symptom is defects in the video such as herringbone noise

# Other symptoms would be similar to X or Y board failures as the SMPS board provides the power to these boards
# Before replacing an X or Y board be sure the Vs, Vsc and VE voltages are being provided by the SMPS board.

If the Ve voltage is low or missing disconnect the power supply cable from the X board. If the Ve voltage rises the X board is probably shorted. If the voltage stays low the SMPS board needs to be replaced. If the Vs voltage is low or missing it can be caused by a defective X or Y board. Check both boards for short circuits before replacing the SMPS board. If the Vs voltage is too high an effect called diffusion may occur. Diffusion is when the initialize voltage is too high. Excessive voltage causes unwanted pixel firing creating intermittent sub-pixel flashes. Power on-off cycling can be caused by a shorted component on the Logic board loading down the standby 5V

Power Supply Adjustments

Each plasma panel has a unique voltage setting required to display a picture properly and maintain long life. Incorrect adjustment of the power supply can create picture errors. Whenever a power supply board is replaced the new board must be adjusted to match the panel values shown on the sticker.
If a power supply board is replaced it is imperative that the new power supply be adjusted to match the existing panel settings. Incorrect adjustment can cause the picture to be too dark or too bright. Extreme misadjustment can greatly reduce panel life.

Locations of the test points and adjustments on a typical SMPS power supply. These adjustments must be performed when the SMPS or the panel is replaced.

Protection Circuits

Over Voltage Protection
The Power Supply PCB has an Over Voltage Protection circuit as well as a regulator circuit. It is designed so that when an Over Voltage condition occurs in any part of the power supply it does not affect another output stage. The following table shows the Over Voltage specifications. The unit must be unplugged to reset this error.

Intermittent shutdown may be caused by an over-voltage condition.

Item	Over Voltage Point
D3.3VDC	4.7VDC
D6VDC	8.2VDC
VA (typically 75VDC)	94VDC

Over Current Protection
If a short circuit occurs on either the VS, VA, 12V, 6V or 3.3V lines, the SMPS stops operating, but should not fail. When the short circuit is removed from the source line, the Power Supply will operate normally again.

Power Supply Diffusion

The diffusion problem can be seen using the sweeping test pattern located in the customer menu under the burn protection selection. Diffusion is caused by a power supply that is not properly matched to the panel.

Over diffusion is the most common symptom, this is where the SMPS is providing to much Vs voltage for the panel.

SMPS adjustments to eliminate the diffusion problem.

Allow the unit to warm up 15 to 20 minutes to stabilize the SMPS Operation
# Access the Customer Setup Menu, then Screen burn protection, then Signal Pattern
# Adjust the Vs voltage while monitoring the screen. Adjust the Vs voltage up or down, if the diffusion error is not diminished as the voltage change approaches 10 volts the panel needs to be replaced
# Do not adjust the Vs voltage more than 15VDC from the value printed on the panel label.

Tech troubleshooting – TCON board – Backlight Dimming through TCON board – Deference between TCON and 3D TCON board - Purpose of LED in TCON board

T-CONs Deliver P-DIM (Dimming Signals) to the Inverter
P-DIM (Called PWM-DIM which stands for Pulse Width Modulation Dimming) is a signal from the Main board that is generated by monitoring the Video content’s average brightness level. It is then sent to theBacklight driver IC to control the brightness of the backlights accordingly. The maximum brightness level isestablished by the customer through the Customer’s Menu in the Video selection under Backlights. Thissetting has a bar graph that can be set from 100% down to 0%.
The P-DIM signal will follow the percentile setting proportionately. The range of P-DIM is 3.3V to 0V. Sowhen the bar graph is set for 100% the P-DIM line will be 3.3V and the backlight brightness will be maximum.
Most often the P-DIM line is routed directly from the Main board to the Power Supply, it is routed through thePower Supply directly to the Inverter and then to the Backlight driver IC.
(If the Power Supply has an on-board Inverter, the Driver IC is on the Power Supply itself). However,on some sets, the P-DIM line is routed to the T-CON board.The T-CON then generates a control signal that is then routed to the Inverter and then to the Driver IC.

Here is the T-CON from a 42SL80. The connector in the bottom left goes to the Inverter and carries the P-DIM Control Signals. The P-DIM signal from the Main board is brought in on pin 8 of the left LVDS and is then routed to the large MCM IC. Then it is output through the 8 pin IC on the bottom left to the connector.

Troubleshooting the P-DIM Line when Routed Through the T-CON

When troubleshooting this type of P-DIM routing, you will still use the same procedure. Enter the Customer’s Menu and go to Video, then select Backlights. Place a DC voltage meter on the output from the T-CON CN3or the input to the Inverter CN2. You can check either of the two pins. While adjusting the Backlights from 100% down to 0% the P-DIM lines will vary accordingly from 2.4V at 100% down to 0.67V at 0%.

Pin	Label	Run	Diode Test
1	n/c	n/c	n/c
2	SCAN 1	0.67V>2.4V	Open
3	SCAN 2	0.67V>2.4V	Open
4	Gnd	Gnd	Gnd

Function of the Blue LED on Some T-CON Boards

On some of the LCD T-CONs there is a bright Blue LED that turns on for a brief moment during turn on and then it shuts off. These are only used in set with Florescent Bulbs as the Backlights. As in the example below (from 42LG60), it shows the Blue LED is on the lower right hand side.
The purpose of LD1 is to help excite the Selenium gas in one of the backlight bulbs. This helps the bulb to light when there’s little room light by pre-exciting the gas. With little room light, the gas in the florescent Bulbs tends to lie dormant, (Little movement). This LED help to get the Electrons moving just before the point of firing (turning on).  There is a small hole under LD1. This is how the light goes through the board to get to the Bulbs. (There is a hole in the back metal cover of the panel as well).

Differences between a T-CON and a 3D FRC T-CON

The typical T-CON’s basic responsibilities are to drive the TFT panel and to generate panel voltages.The video input through the LVDS cables is already formatted for usage by the T-CON board.

Typical T-CON

The 3D FRC T-CON basic responsible to; generate panel voltages. When not in 3D it generates the Tru-Motion, Motion Estimated Motion Compensated (MEMC) frames. When in 3D it unpacks 3D frame content. It generates 3D sync which is used by the 3D Shutter glasses. It formats the video for usage by the panel driver circuit and it drives the panel. The video input through the LVDS cables is 24 bit LVDS video.

3D FRC T-CON

Since the 3D FRC T-CON does so much more work than a standard T-CON, it has an additional 12V input via a two wire connector. The voltage is from the same source as a typical TCON board. It comes from the  power supply and switched on/off by the Main board.