Samsung LNT4665FX-This TV will not turn on, and upon removing the back cover I discovered scorch marks on part CS815 on the Power Supply Board. Should I replace the entire Power Supply Board?

I'm willing to bet you have faulty capacitors in the power supply. You can either have the individual capacitors replaced(cheap fix) or replace the power supply board. This is my best guest as this model is known for this problem. If you don't feel comfortable in opening up your set, get a professional to look it over

I'd go with a power board for starters, are the other voltages ok on the power board or are they all low

sounds like there is an issue with the power supply board in the tv. if the fans are not running then you may want to check those connections. also check the power supply board for any scorch marks.

First of all stop trying to turn the tv on because you can damage a second board by repeatedly attempting to power the set up after a power supply failure. I have seen it on this model. Usually what happens to this set is the power supply filter capacitors fail. If you were to look at them you would see they are physically bulging. These capacitors are rated at 2200uf/10volts. They can be changed with a higher voltage capacitor to outlast the original components. If you choose to replace the entire power supply more than likely this will happen again in a few years. Anyone who can solder somewhat can replace these parts and repair the problem. A reasonable repair cost for this repair would be between 95-175 at a repair shop. Good luck, Russmann. You're welcome.

hmmmm its easy really..

• unscrew rear cover
• cables from power board to other components
• unscrew and remove power board
• put in new board and screw down
• re connect cables
• screw back on the rear panel
• plug in
• turn on
• watch!!
• 
  

There are some capacitors that have blown on the power supply board. Samsung is covering the cost to repair this problem on certain models. You can call 1-800-samsung to find out if your unit is covered.

Sounds like the power supply board has failed, VERY common problem. You can call 1-800-samsung for the nearest service center.

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.

The capacitors are located near the bottom right side heatsink if you check the link below. I'm sure a few of them might be bulging on top but you can replace the 2200uF/10v as well.
http://cgi.ebay.com.sg/POWER-SUPPLY-UNIT-BN44-00168B-from-SAMSUNG-LN-T4665FS_W0QQcmdZViewItemQQitemZ120424815286#ebayphotohosting

There are two easy fixes you can try. Both require you to take the back panel off. If you are not comfortable doing this, take it to a repair shop.
UNPLUG IT.
Place the TV face down on a soft/solid surface.
After you get the back panel off, there are three silver boxes. There are white and black wires leading from the off switch to the top silver box. Take the cover off that box.
Inside is a ceramic fuse. Test that fuse. If it is blown, your local electronics shop can find a replacement.
If not, disconnect the white and black wires from the PC board. Remove the 6 screws holding it in place.
Look for scorch marks under the board.
Cut a thick piece of plastic and tape id down over the scorch marks.
Re-attach the board with the six screws and re-connect the black and white wires.

Turn the power switch to the OFF position and plug in the TV.
Turn on the power switch while WATCHING the board you just removed.
If you hear a sizzle, turn off the switch and get a thicker piece of plasic.
If not, the TV should come back on.
Re-assemble the silver box and put the back on.

Hope this helps.