Samsung tv model un55d6000sfxza Has a stand by light on but it will not turn on. How do I fix it. Do I need to replace the power board or main board?

SOURCE: Samsung TV won't turn on- trying to fix it. A challenging problem

I had the same problem. I live in NJ and called the local authorized "service provide" listed on the Samsung website. What a joke. Quoted $350 just to show up, never showed up. So I opened my own TV. Took off the plastic back (10 screws) took off the large metal RF shield (12-14 screws) and noticed a blown component. The markings on the component were KL15L and it is apparently an NTC Thermistor. Obviously it got fried and not knowing if there was other damage I decided to set out to replace the entire Power PCB Board Assembly and not the component. There were two part numbers on the assembled board (BN97-00457E & BN94-00622E). After searching online I also found a suitable replacement number for these (BN96-04896A). I found two places who claimed to have the part or have it on order (shopjimmy.com and vancebaldwin.com). After placing orders with both and having neither come through, I broadened my search and found out that the LNR409D was basically the same model as my LNR408D so I looked for its Power PCB Board Assembly part number which turned out to be BN41-00521B. Google search for that part number showed the item available on ebay. I bought it a week ago (ebay 260311519904) for $144 plus $12 shipping. I removed the bad board an hour ago (6 screws about 7 connectors) installed the new one, plugged in the connectors, replaced the covers, plugged in the TV... AND IT WORKS!
Suggestion: If your TV is out of warranty then open it up (what have you got to lose) and see if the problem is obvious and maybe something you can fix (replace) yourself. The parts, spare boards, etc. are out there if you look.

SOURCE: how hard it is to replace by yourself main board Samsung LN-T4065

You need to do some more diagnosing of the problem. If you get sound and change channels take a bright flashlight and place it again the screen. Look for an image around the edge of the flashlight.
If you see an image that means the LCD controller board (TCON) is probably good.

The problem is probably one of three causes;
1) Inverter board is bad
2) CCFT (cold cathode fluorescent light) are bad.
3) Power to the inverter board is bad. You can also check the connectors.

SOURCE: On Samsung main board model bn94-01708u with no video.

Hi, I think you need to replace the video card.
Thanks! mannu_rakesh

SOURCE: first lost pic now no sound replaced main

YOUR OTHER POWER SUPPLY IS GOOD, YOU NEED TO REPLACE THE Y-BUFFER AND Y-MAIN BOARDS

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.