samsung ue40f8000sz

[call me al]

Hi folks Happy new year to all Have a Samsung UE40F8000 It comes on with smart logo then clicks off and continues doing that
 I disconnected power supply and when reconnected it came on but after 5 mins fault came back ,checked for bad joints but all looks ok.Any help appreciated

[Turnip]

Hi Al,

Suspect you have a backlight issue. Been there so suggest you replace all the strips as Sammy Leds die like dominoes. Replace two today and you get four more tomorrow, then eight the next day and so on - Chris.

[t1412]

disconnect the mainboard turn the tv on see if backlight come on if ok backlight ok psu ok  mainboard is the
fault

[downunder]

Don't suppose it uses BN44-00622 power supply?                     Bruce

[call me al]

Hi Bruce The psu is BN44-00635A

[downunder]

That's too bad, Al. The BN44-00622 has a known issue but I've not seen it on other PSUs.

If yours still plays up with the main disconnected then it's either the PSU or duff LEDs as Chris suggests.

To be sure you'd have to remove the display panel and diffuser sheets and see if any LEDs are going out.

You can run the set without the screen and the LEDs will work normally - if they're OK.                                 Bruce

[call me al]

thanks for all the info will take apart tomorrow and will report back

[call me al]

Took screen apart its edge lit leds looks ok so  put it back together.The fault is on the power board its clicking even when powered on its own.Have not found where the problem is Still head scratching 

[michael first]

Hi a happy New Year to all,try to remove  QQ856(2N700K,smd MOSFET) which puts to GND the line PS_ON_S as a protection.

[downunder]

That's an interesting tip, Michael. I once spent ages trying to locate such a device, seeing as the PSU is held up with the Main disconnected.

Bruce

[michael first]

Hi Bruce,it works in certain cases when the power supply it's OK,only the protection stage it's faulty.hope it works for Al 

[call me al]

HI Michael thanks for info removed qq856 psu comes on now but only leds at top and bottom come on,after hours of checking still havent got it sorted but thanks again to all

[Turnip]

Hi Al,

Wonder if you checked all the strings on the strip ? Had a Pana with 6 strings of ten. In my case I took the strip off the heatsink, checked every one OK - Reassembled, where the set cut to error code every few days.

Advised by 'Bruce' - Bought a new strip from China (as half the price) - Problem solved.

Unsure if edge lit Sammy's are similar, as haven't yet met your model - Chris.

[Electroman2000]

Hi All, was this issue solved? I have the same set with the exact same issue.... I took out the power supply and powered it without any connection or Backlight. The power supply keeps switchingbon and off... I would appreciate any help. Thanks

[call me al]

Sorry never got it solved