Samsung LN52A750R1 turns on, backlight comes on,nothing shows on the screen then turns off. keeps doing this over and over until the tv is unplugged. I have checked the caps and they look good.

You have bad LED backlights

It sounds like you may have a couple of issues, it's normal for the backlights to come on if the main is unhooked but the flashing sounds like bad lamps. The 5 volts is standby voltage, next step is measure the PS_On pin when you turn the set on and see if you get around 3 volts there, if you don't you have a main board issue.

Just a thought. Maybe someone inadvertently turned the screen off which is possible in the video settings. You would do this on purpose for falling asleep to music from videos. AND perhaps the TV was turned off before the screen was turned back on and it's stuck in that mode. I would search for the button sequences needed for putting the TV into service mode. (google). If you can get into service mode and it's visible at least you would know the LED display is working. From there just look around to see if there's something applicable. Last resort is to factory reset in service mode. I could be all wet about this, only a suggestion. Nothing lost if it doesn't work.

Hi,

You have diagnosed the fault yourself. The main board of your TV is defective and needs to be replaced.

Good Luck.

I will replace the T-CON board first.

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I went to Sceptres website it answerd all my questions as well as walked me thru until problem was fixed.

with tv in standby press INFO / MENU / MUTE / STANDBY on remote tv will come on with service menu DO NOT CHANGE ANY SETTINGS
look at list you will see reset
ONLY USE DOWN NAVAGATION KEY until RESET is highlighted
then PRESS RIGHT NAVAGATION KEY the tv will reset
PRESS STANDBY TO EXIT
the tv will need retuneing after
hope this helps