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Equipment Repairs => LCD TV forum => Topic started by: call me al on January 01, 2019,08:09:02

Title: samsung ue40f8000sz
Post by: call me al on January 01, 2019,08:09:02

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

Title: Re: samsung ue40f8000sz
Post by: Turnip on January 01, 2019,13:05:51

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.

Title: Re: samsung ue40f8000sz
Post by: t1412 on January 01, 2019,14:02:26

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

Title: Re: samsung ue40f8000sz
Post by: downunder on January 01, 2019,18:08:07

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

Title: Re: samsung ue40f8000sz
Post by: call me al on January 03, 2019,06:37:59

Hi Bruce The psu is BN44-00635A

Title: Re: samsung ue40f8000sz
Post by: downunder on January 03, 2019,14:35:45

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

Title: Re: samsung ue40f8000sz
Post by: call me al on January 03, 2019,16:13:05

thanks for all the info will take apart tomorrow and will report back :c017:

Title: Re: samsung ue40f8000sz
Post by: call me al on January 06, 2019,12:45:51

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  :03:

Title: Re: samsung ue40f8000sz
Post by: michael first on January 06, 2019,15:20:07

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.

Title: Re: samsung ue40f8000sz
Post by: downunder on January 07, 2019,03:45:33

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

Title: Re: samsung ue40f8000sz
Post by: michael first on January 07, 2019,04:17:42

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 

Title: Re: samsung ue40f8000sz
Post by: call me al on January 15, 2019,08:44:13

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

Title: Re: samsung ue40f8000sz
Post by: Turnip on January 16, 2019,12:10:35

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.

Title: Re: samsung ue40f8000sz
Post by: Electroman2000 on May 07, 2020,09:46:15

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

Title: Re: samsung ue40f8000sz
Post by: call me al on May 08, 2020,15:43:07

Sorry never got it solved :c023: