Samsung UN 6030 LCD tv. Dim pix

If you have replaced the main board and power supply board and are still getting a uniform blue screen on your Samsung LED TV, it could indicate one of the following issues:

1. T-Con Board: The T-Con board, or Timing Control Board, is responsible for managing the flow of video data from the main board to the LCD panel. If the T-Con board is damaged or not functioning properly, it can result in a blue screen.
2. Backlight Inverter: The backlight inverter is responsible for powering the backlight of the TV. If the backlight inverter is not working properly, it can result in a uniform blue screen.
3. LCD Panel: The LCD panel could be damaged or have developed a problem, causing the uniform blue screen.
4. Signal Cable: The cable connecting the main board to the T-Con board or the LCD panel could be damaged, causing a lack of signal and a blue screen.

It's best to consult with a professional repair technician or the manufacturer for further diagnosis and repair. They will be able to determine the exact cause of the issue and recommend the best course of action.

Based on the symptoms you described, it sounds like there may be an issue with either the power supply board or the main board of your Samsung LCD TV. The fact that the TV keeps turning on and off repeatedly on its own, and now it won't start up at all, suggests that there may be a problem with one of these components.
When you unplug the cord connecting the power supply board to the main board, and the TV backlights stay on without turning off, it indicates that the power supply board is working properly. However, when connected to the main board, the backlight turns on and off, which suggests that the issue is with the main board.
It's possible that the main board is malfunctioning and not providing the correct signals to the power supply board, which is causing the backlight to turn on and off. Replacing the power supply board with a new one and still experiencing the same issue, confirms that the problem is not with the power supply board.
It's important to diagnose the problem correctly and not just replace parts without properly testing them, as this can lead to wasted time and money. A proper diagnosis can be made by a technician with a scanner that can read the codes and check the signals of the main board and power supply board.
It's also a good idea to check all cables, connectors, and other electronic parts of the TV, as any damaged or loose parts can cause the problem as well.
It's recommended to check the TV's warranty status and the manufacturer's instructions to ensure that the repair or replacement will not void the warranty. If the TV is out of warranty, it might be more cost-effective to consider purchasing a new TV, as repairing an older model might not be cost-effective.

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/ To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/ To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
In some models of LCD TVS; the backlight inverter and its T'Con board will be a part of the panel itself, and will be a built-in type inside the LCD panel. If so, they can't be replaced. In this case; a panel replacement is the only repair. For some other models, the backlight inverter section circuit will be a part of the main power supply regulator [SMPS]. To such sets, the power supply section circuit too should trouble shoot. Contact any service technician. The circuit will differ with models and versions.

You have to check all the voltages, that comes from its main power supply board, to its back light inverter board. These is one pin at the backlight inverter board; comes from the main board; which controls the back-light inverter to start and off. This voltage is generated at the main board, and send to the back-light inverter board, as control voltage. It will be best to contact any service technician. If you wish to get some details; check the site linked here.Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/

Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Here is a link for the manual - it might help - http://tv.manualsonline.com/manuals/mfg/lg/26lc7d_26lc7dc_32lc4d_42lc4d.html