My tv (Samsung UN46FH6030) starts turning off and on repeatedly after about 2 min and won't stop unless I unplug it.

SOURCE: Samsung LCD TV doesn't power on, just blinks 5 times

After about 5 years the Samsung LCD televisions backlight fails which prevents the TV from coming on and the powerlight just flickers the backlight can be changed but it is often alot easier and cheaper to buy a new Television

SOURCE: My 42 inch LG plasma turns on and off repeatedly

Theres a short between the start-up processor signal on the interface board and power supply. It keeps sending the same start-byte over and over again to the power board. This could also be a DC high voltage shutdown on the power board its self. Now the tv is in protection mode to prevent further damage. Get it serviced at your local repair center. If its under warranty take it back.

SOURCE: Which Replacement Power Board for LNT4665F Samsung LCD TV?

Howdy,
It would be a lot cheaper if you just replace the two caps that have gone bad. Just get a cheap solder pencil from the store and about an inch of solder and you are in business.
The Power Supply Board is the center Board (towards left) after you remove the back off the TV. Remove Board from TV with the 6-7 screws. Replace capacitors CM852 & CM853; 2200ufd 25volts.

Thaks for using FIXYA, BIG IRISH.

SOURCE: Samsung LN46A550 LCD power on/off

Apparently this is a known problem with flat panel TVs made a few years ago due to bad capacitors in the power supply. This same problem appeared in computer mother boards at about the same time so that the capacitors went open or shorted causing problems.There is videos on You Tube that addresses this problem see: http://www.youtube.com/watch?v=ZccykxrtX9g as a starting point and look around for other repairs

Wale Sarumi KomputerSolution

• 6993 Answers
• Posted on Jan 05, 2012

SOURCE: Samsung LCD TV not switching on, but just clicks away.

Hello,

The issue you describe is consistent with a power supply board issue. This is the board where the AC goes to. This problem may have occurred as a result of irregular power supply, or excess power supply or power surge.

The TV is receiving current but cannot circulate or transfer the current to other necessary part of the TV because of the defective power supply board. You might be lucky it's just a blow fuse. Also a defective transformer can cause your TV not to power on.

All these can be checked on the power supply board.

But more often bad capacitors causes problem on the power supply board. I do not think the power board needs replacement, rather those defective capacitors is causing this issue. Open unit up and take a look at the power supply board.You will probably see one or more electrolytic filter capacitors that are bulged up in the top-not perfectly flat like the others.

The value of these capacitors will be different, most likely they will be somewhere around-820 to 2200uF/25 V( or /10V sometimes)

You can replace them with same values but I would recommend the voltage rating to be higher(like 35V for an original 25V) for reliability purposes.

What happens is,these bulged top capacitors will cause a low and unfiltered DC voltage=main board will malfunction(the relay will keep clicking until the caps are holding enough charge to bring the voltage up over a threshold point).

You can buy these capacitors at any Fry's or Radioshack store or you can order them online at vendors like "mcmelectronics.com"(look for electrolytic capacitors). After replacing these capacitor(capacitors) most likely the normal operation will be restored. Or you can by a refurbished complete power board to save you some stress.

Note: There may be also some other causes for this symptom ,like a defective T con board ,or main board,but the bulged top capacitors are the most common cause for this issue.

If you don't know about TV repairers, take the TV to the nearest repairman to fix the fault for you. Also, note that TV stores a lot of current, so wait a while before opening the TV back cover.

I hope this helps.

Regards.