Samsung curved UN65KU650DFXZA blinking backlight

[steves7839]

The TV has no sound or picture, but the backlight and standby light blink on every few seconds, then off. Even the remote blinks red twice every second.
The symptom was the same with T-Con ribbons disconnected, panel LED power disconnected, and remote interface disconnected.
I've just tried a broken-screen main board from ebay, and the symptoms are exactly the same.
Suggestions or links to a manual?

[freakaftr8]

Re: Samsung curved UN65KU650DFXZA blinking backlight

What's PS-on doing when this happens?

[Hamie]

Re: Samsung curved UN65KU650DFXZA blinking backlight

Probably a bad panel

https://www.badcaps.net/forum/showthread.php?t=67341

[steves7839]

Re: Samsung curved UN65KU650DFXZA blinking backlight

What's PS-on doing when this happens?

PS-ON comes up, DC to the main board measures correct 13V, main board has 5V and 3.3V. When mainboard is disconnected from PS, the backlight comes on. Disconnecting the panel ribbons and remote sensor had no effect on the cycling. I doubt anything on the PS would cycle on/off/on this way, what do you think?

Hamie, it's surprising that the panel could cause this. Both backlight and standby cycle on/off/on even with the ribbon cables disconnected from the panel. That said, based on the history you linked to, I'm going to return the replacement Main board. Thanks for the link!
I've read some posts elsewhere that blame an unfinished wifi firmware update for the condition. But that would have to involve the main board. My replacement main board was said to come from a "ship-wrecked" set.

With this menu-driven, "super-smart" 4K TV and reduced-button remote, how would one even do a factory reset without a picture?

[freakaftr8]

Re: Samsung curved UN65KU650DFXZA blinking backlight

OK disconnect LVDS cable reconnect everything else in power up. Does it still flicker

[Hamie]

Re: Samsung curved UN65KU650DFXZA blinking backlight

Even with the ribbons disconnect form the panel the TV will cycle. Try another mainboard but im pretty sure if that doesn't work then the panel is more than likely the cause

[freakaftr8]

Re: Samsung curved UN65KU650DFXZA blinking backlight

Right but besides the ribbons disconnected from the tcon to the panel, I would be more concerned about how the TV behaves with just the LVDS connector disconnected from the tcon .

Curious if the main board itself has the issue order something loading down from the tcon.

[steves7839]

Re: Samsung curved UN65KU650DFXZA blinking backlight

The second main board made no difference.

With LVDS ribbons disconnected at either end, it behaves the same, BL and standby LED flash on/off/repeat.
I also notice a flashing red LED on the "few-button" remote when it's used.

It's a mystery what is the mechanism causing a bad panel to do this.
So my friend-of-a-friend has an 18-month old curved paperweight.

[budwich]

Re: Samsung curved UN65KU650DFXZA blinking backlight

if there are some form of edge boards along the bottom or otherwise, you might try checking some of the smd's there in. In other types of sets, some times people have found shorted / open caps on these boards that they were able to locate and replace "on set".... if those (edge board integrity) are the source of the problem.

[freakaftr8]

Re: Samsung curved UN65KU650DFXZA blinking backlight

Disconnect black cable going from power supply to mainboard. Plug tv in. Do the backlights stay on?

There are pull up resistors that turn on the backlights with the main board disconnected from the power supply. We're going to see if your backlights are causing this problem

[steves7839]

Re: Samsung curved UN65KU650DFXZA blinking backlight

Yes. When I disconnect the Main Board-Power Board harness the backlights stay on.

[freakaftr8]

Re: Samsung curved UN65KU650DFXZA blinking backlight

OK this rules out power supply and backlights.

Plug everything back in the way it was and only leave the LVDS cable that goes from the main board to tcon disconnected.

I ask you to do this before but I didn't get a response from this. It sounds like you left the tcon connected to panel but you disconnected that the ribbons at the panel.

I want you to eliminate the tcon from the main board.

If backlights turn on and you can hear audio this eliminates the main board as a fault.

[Hamie]

Re: Samsung curved UN65KU650DFXZA blinking backlight

He has a bad panel

There is no tcon in this set it's built into the mainboard.

You cannot disconnect the panel from the mainboard or the TV cycles.

[Hamie]

Re: Samsung curved UN65KU650DFXZA blinking backlight

I hope to the op contacts the person he bought the original mainboard from to let him know his part isn't faulty

[freakaftr8]

Re: Samsung curved UN65KU650DFXZA blinking backlight

My bad. Yes I agree. Bad panel. I guess since I saw the tcon cage I didn't look close enough

[freakaftr8]

Re: Samsung curved UN65KU650DFXZA blinking backlight

Great. I have this same tv in my bedroom. Just looked at the model number. Panel has tcon on driver board. Yuck.