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.

Sony LCD Projection television KDF-55WF655 - KDF-60WF655 – Diagnostic indication – Led blinking and causes – Lamp hour reset – Power supply circuit

Diagnostic Test Indicators
When an error occurs, the POWER/STANDBY or LAMP LED will flash a set number of times to indicate the possible cause of the problem. If there is more than one error, the LED will identify the first of the problem areas. If the errors occur simultaneously, the one that corresponds to the fewest flashes is identified first.
Results for all of the following diagnostic items are displayed on screen. No error has occurred if the screen displays a “0”.

Diagnostic Item Description	Number of times STANDBY or LAMP LED lamp flashes	Probable Cause	Detected Symptoms
Lamp cover error	3 times	- Lamp cover is not fastened securely	- No picture/No sound
Fan error	4 times	- Fan1-4 Power is not supplied.(G2 board) - Fan connector is not seated securely - Fan caught wires or harnesses	- No picture/No sound
Temp error	4 times	- Internal temperature is too high - IIC-E line connector is not seated properly (WE:H3 board, WF/XS:H4 board)	- No picture/No sound
Lamp driver error	5 times	- Lamp driver defect	- No picture/No sound
Low B error	6 times	-No "DD 6V " output (G1 board)	- No picture/No sound
Audio error	7 times	- Short-circuit of Audio power supply line (KD board, G1 board) - Blowout of a fuse (F4702,F4703,F4704 on KD board) - IC failure (IC4703,IC4708,IC4710 on KD board)	- No picture/No sound
D-OVP error	8 times	- Overvoltage of +3.3V or +2.5V (A board, B board)	- No picture/No sound
ATSC-OVP error	10 times	-No "DTL MODULE 5V " output (G1 board, G2 board)	- No picture/No sound
Lamp error	LAMP-LED is ON.	- Lamp is dead	- No picture/No sound

Releasing the POWER/STANDBY LED Flash
Unplug the power cord from the outlet to temporarily stop the POWER/STANDBY lamp from flashing.
Self-Diagnosis Screen Display
For failures that are difficult to reproduce, or accompany occasional power off and/or picture mute, the Self-Diagnosis screen display is useful to specify the cause.
To Bring Up Screen Test
In standby mode, press the buttons on the Remote Commander sequentially, in rapid succession, as shown below:
1. Display  > Channel 5 > Sound Volume - > Power ON

Clearing the Result Display
To clear the result display to “0”, press the buttons on the Remote Commander sequentially when the diagnostic screen is displayed, as shown below:
1. If the screen is already displayed, proceed to step 3. If not, Power off (Set to Standby model).
2. Press Display > Channel 5 > Sound Volume - > Power ON
3. Press Channel 8 > ENTER
Clearing the Self-Diagnostic Screen
The self diagnosis screen display is cleared by turning off the set using the Remote Commander or the power switch.

Self-Diagnosis Function Operation

Blinking	Causes	Description
3	Lamp cover	The rib at the back of the lamp cover closes the SW on the T board to ground pin 3 of CN8001. It is monitored by the DE-micro (pin 94 of IC6902) and turns off the lamp when it is opened.
4	Fan	Fan rotation is detected by "FAN-PROT" and the DE-micro (pin 92 of IC6902) turns off the lamp when it is "high".
4	Temp	When the temperature sensor on the H3 board (WE models) or H4 board (WF/XS models) detects high temperature, or IIC-E line connector (CN6022:G2 board, CN44:H3board/H4board) is not seated securely, the DE-micro turns off the lamp.
5	Lamp driver	When the "LAMP-PROT" (pin 95) is low, the lamp is not turned on. If the "LAMP-HV-DET" (pin 96) is low at the same time, it is classified as no high voltage of the lamp driver.
6	Low B error	When no "DD 6V " is detected, pin 129 of TV-micro is low and it turns off the main power.
7	Audio	When DC voltage is detected at the speaker or woofer outputs, pin 128 of TV-micro is low and it turns off the main power.
8	D-OVP	When overvoltage of "+3.3V" or "+2.5V" is detected, pin 126 of TV-micro is low and it turns off the main power.
10	ATSC-OVP	When no "Digital Module 5V" is detected, pin 127 of TV-micro is low and it turns off the main power.
LAMP	Lamp	When the "LAMP-PROT" (pin 95) is low, the lamp is not turned on. If the "LAMP-HV-DET" (pin96) is high at the same time, it is classified as no lamp or a dead lamp.

Reading and Resetting Lamp and Panel time
Use the following to determine the lamp and panel time of a set.
Screen Display Method
In standby mode, press the buttons on the Remote Commander sequentially, in rapid succession, as shown below:
1. Press Display > Channel 5 > Sound Volume + > Power ON
2. To enter the DE-micro service menu, press Jump 3 times.
3. To display the Lamp time, press Channel [2] 9 times.

To reset the lamp time press Channel 3 > Mute > Enter .
WRI-EXE(Character color is Red) is momentarily displayed and LampTM is reset to “0”.

Exiting Service Mode
After completing the changes exit service mode by turning off the set using the Remote Commander or the power switch.

POWER SUPPLY CIRCUIT 

CLICK ON THE IMAGE TO ZOOM IN 

Panasonic TX-L37G10E – Service mode access – Self check mode – LVDS connection details

Self Check
Self-check is used to automatically check the bus lines and hexadecimal code of the TV set. To enter Self-Check mode, keep pressing the down (-/v) button on the TV set and press the STATUS button on the remote control. To exit Self Check, switch off the TV set at the power button.

Power LED blinking and causes

When abnormality has occurred the unit, the protection circuit operates and reset to the stand by mode. At this time, the defective block can be identified by number of blinking of the Power LED on the front panel of the unit.

LED BLINKING AND CHECK POINTS 

Blinking times	Contents	Check point
1	INVERTER_SOS	A BOARD, P UNIT
2	FAN_SOS	A BOARD
3	SOS	A BOARD
4	SUB_F_12V	A BOARD P UNIT
5	MAIN_9V	A BOARD
6	SUB_5V	A BOARD V BOARD
7	SUB_3.3V	A BOARD
8	MAIN_3.3V	A BOARD V BOARD
9	SOUND_SOS	A BOARD
10	ZWEI_SOS	A BOARD
13	Emergency SOS	A BOARD
14	AUDIO_PWM_SOS	A BOARD

Service Mode Function
MPU controls the functions switching for each IICs through IIC bus in this chassis. The following setting and adjustment can be adjusted by remote control in Service Menu
How to enter SERVICE
While pressing (-/v) button on the TV unit, press on the remote control for 3 times within 2 seconds.
Note:
To exit from Service mode, press 0 the exit button on remote control.
Key Command
# Press the 3/4 button to change the adjustment values or function.
# Press the 1/2 button to step up/down through the functions and adjustments
# Press the numerical button VOLUME (+/-) to change of each option item.
# Press the OK button after each adjustment has been made to store the required values.

LVDS CONNECTION DETAILS  

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.