fixing a samsung ue55f6515sb led tv (powercycles)

[a.ekholm]

Hi.
i recently started to learn Electronics and just got in hold of a samsung ledtv that reboots after 5-10s. I can see the logo and sometimes a meny Before the screen gets green and i hear the relay of the Power supply switching.
I tryed to meassure the voltage of the outgoint Cable to the main board and can see that i have standby voltage (3,5 or 5v don't rememer) and "working voltage" (12 or 14v don't remeber) But both voltages collaps (0v) when i hear the relay switch when it Power cycle.

If i disconnect the riboncable to the t-con board the Power supply stays on.
If i connect the powercable between the main board and Power supply it stays on
If i remove any other Cable it will Power cycle.
The t-con boards leds is flashing on when Picture and off when powersupply is off.

i'm tempted to Think that it's the t-con board that is wrong, but at the same time i woundering why the 3,5/5v (?) is colapsing and there fore suspects a defective Power supply.






can i do some testing on the powersupply it self to eliminate that?
Do you have som other suggestions for how i can test the differnet boards?
I shall try to upload some Pictures
Thanks /Andreas

[peteb2]

With any SMPS the first thing to check is the condition of the electrolytic caps.... long periods of being on making lots of heat and power on/off cycles soon take a toll on devices that are not extra-high-quality types.... There's tons of info out there on this subject alone and the best thing you can have as test gear is a good ESR meter. Failing that the standard shotgun approach of replacing all and every electrolytic with fresh good name-brand types can reward you with a repair...

If this set is an LED backlight model it could be there are issues with one of the actual LEDs or the management chip Tasked with controlling their brightness etc...

[a.ekholm]

With any SMPS the first thing to check is the condition of the electrolytic caps.... long periods of being on making lots of heat and power on/off cycles soon take a toll on devices that are not extra-high-quality types.... There's tons of info out there on this subject alone and the best thing you can have as test gear is a good ESR meter. Failing that the standard shotgun approach of replacing all and every electrolytic with fresh good name-brand types can reward you with a repair...

If this set is an LED backlight model it could be there are issues with one of the actual LEDs or the management chip Tasked with controlling their brightness etc...

I bought a t-con board from eBay. Unfortunately it doesn't work. On the board I can read that it's from another model. But the issue now is different. The power switching is gone! But I now have a video problem. A small portion of the screen white.

So I think I'm on the right track with  the t-con board.

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[BMack]

It's either the T-con or the panel. Put the original T-con in but don't connect the panel to the T-con. If the it power cycles again then you have a bad T-con, if it stays up it's a panel.

[a.ekholm]

Hi! I managed to get it working when bought a second t-con board. Initially I had a slow update speed on the screen, but after examining the board I found a missing component, and changed that and now it's alive!
Thanks/Andreas

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[mzacharias]

How old is the set? A couple years ago they had problems with loose or poorly plated connectors between the power supply and main board, causing the voltage to drop at the main board side as more current was drawn, causing a re-boot.