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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
UN65KS8000F - won’t stay powered on



New User

Sep 1, 2019, 4:04 PM

Post #1 of 1 (1940 views)
UN65KS8000F - won’t stay powered on Can't Post

TV power cycles (bootloops) constantly.

I have verified that all LEDs work.

With main board not connected to power supply board, LED backlight comes on and stays on.

With main board connected to power supply, status LED at IR receiver comes on. Push power button on remote, status LED goes off, backlight comes on, Samsung LED on lower trim comes on, backlight goes off, Samsung LED goes off, status LED turns on for about a second and then the cycle starts over.

Disconnecting the ribbon cables to LCD panel makes no difference, WiFi adaptor or speaker make no difference. Leaving all connected except the upper 20 pin cable from main to power supply boards and power cycle does not occur. While the power cycling is occurring, the voltage reads around 12.9 (board shows 13 volt... guessing nominal) but drops to 9.6-9.8 volts as cycle starts.

I have purchased a “know good” main board from eBay and same results.

From what I’m reading around the web, this may be a bad LCD panel. For shits-n-giggles, I swapped the main board from a UN55KS8000 into the TV and the backlight works, the screen starts bright at the lower right corner and the the brightness spreads outward until the whole screen is bright then starts over after several seconds.

Thoughts? Guessing not main board as same result OR the two 65” main boards are suffering same issue. Could be bad LCD panel. Could be a bad capacitor in the main board. There is a little electronic “screeching” (lack of better description) noise from the power supply. Could the fluctuating voltage and noise indicate a bad capacitor? Could a drop from 12.9 to 9.6-9.8 cause the cycle?


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