My Samsung UN75F6300 LED TV has a clicking power supply with a measured output dropping in and out from 0-5VDC. No picture. I have replaced the three boards; power supply, main and Tcon boards. I have a power supply repair kit available, but tried a power board swap out first. No visible indication of blown capacitors. The original power supply was a BN44-00621C (L75S1_DHS) and I replaced it with a BN44-00621A (L75X1Q_DHS), best fit available. Different version levels and board numbers but form, fit, and components match. TV responds with the same fault when either is board installed. Disconnecting the power supply output illuminates the back light. Any suggestions from here?
SAMSUNG BN44-00621A L75X1Q_DHS POWER SUPPLY / LED BOARD https://www.abctay.com/wholesale-samsung-bn4400621a-l75x1qdhs-power-supply-led-board-p-260.html
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I have the same TV and same symptoms. Haven't tried replacing any of the three boards.
In my case I've carefully inspected the main board and the power supply board, front and back, looking for any kind of anomaly (burning, heat marks, bulging caps, etc) and cannot find anything. Both boards and all cables look 100% brand new and without blemish.
I fully disassembled the tv (including removed glass panel) and hooked up an led tester to the backlights and each row lights up fine. The tester reports a voltage of 66.5V (+/- .1v) after the lights stabilize for about 5 seconds.
I also checked the fuse on the power supply board, it shows zero ohms across it.
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