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Old 02-08-2021, 11:03 PM   #1
events.b
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Join Date: Oct 2010
City & State: Florida
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist Tech
Posts: 23
Question Sceptre X505BV - Logo appears for 1 sec then backlight shuts off, LEDs tested good

Hello, this TV currently has me stumped. As the title states, when I power on the unit, the backlight comes on for 1 second then shuts off. The TV is still on, and I can see the video if I shine a flashlight on the screen.

Using the LED backlight tester I was able to confirm all LEDs are illuminating and seem to be working correctly when independently powered by this tester, so that leads me to believe there is something wrong with the power supply board.

Perhaps the great minds here can help me figure it out, as I don't see any thing obviously wrong with it. The backlight circuit seems to be controlled by an op-amp (U14). The part number for this op-amp is 10358. The hot side of the board is controlled by a FAN7930C PFC controller. I have not found any shorts on either side so far and the capacitors look to be ok.

The backlight circuit is located on the top left of the board (top view) or top right of the board (bottom view).

Thank you for your time.
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