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Jack, Technician
Category: TV
Satisfied Customers: 11036
Experience:  35 years experience as audio,video repair and installation tech
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Samsung TV issue

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I have a a very strange problem. My TV is a Samsung LE46A558P3F.

It is to do with the backlight settings. If I go into 'menu', and change 'backlight' to anything above 5, the screen cuts out - as in, completely black.

The tv is still on and audio is still fine. I have memorised the remote sequence to turn the backlight back down to 5. Doing so doesn't make the display work again straight away - but by powering off and on, it's working again (with backlight set to 5).

If I pull up the menu and set backlight to 4,3,2,1,0 the screen gets progressively darker, as you'd expect. Going 0,1,2,3,4,5 gets lighter again, as you'd expect. But as soon as you hit 6, the screen gets brighter for just a second then goes black. The only way to get picture again is as described above - doing it 'blind', use the remote to set the backlight to 5 or less, power off and on, tv is fine again. In fact, if you set it to 'dynamic' (which sets the backlight at 10) and power cycle the tv, again you get you get the nice bright picture you'd expect for just a second before going black again.

This is all regardless of input, by the way. All inputs - DTV, Ext1&2, HDMI1&2 behave the same way - will only display anything if backlight is set to 5 or less.

I am an electronics engineer to trade and have no issues with taking my TV apart (it's way out of warranty). I would like some advice, however, if this problem is known to you and if you can advise what the most likely part is that needs to be repaired/changed - the PSU, the mainboard, or the inverter/slave?

Hello Bob , my name is Jack

Perhaps I can help you with this problem but I saw that you asked this question yesterday (sept/9) and would like to know if you still need help with it ?

Customer: replied 3 years ago.

Yes please, I haven't had an answer yet. I'm still using the tv (albeit with a dimmer screen than I'd like) but if you have seen this problem before and can point me in the right direction I can get a spare board off ebay and give it a try. The good thing about this issue I suppose, is that 90% of these type of tv's that are dead, have had their screens broken - so there's lots of people who strip them down and sell off the boards as spares.

Or maybe I have one of the PSU's that has the dodgy capacitors on it that I've read about some models of Samsung suffering, which would be an even easier fix... (I haven't had the back off it yet to see if any caps are burst)

O.k then , be right back with some info
Hello Bob
I`ll start by saying that this model has 2 inverter boards master and slave but they are mainly distribution inverters for the power/main inverter board where the control (dimmer) is done and that would be most likely where the problem would be located although a defective inverter board master or slave may affect it and it would be difficult to test those boards without replacing them .
I mean that the TV's service manuals now are mainly block diagrams , no schematics and they don`t give you voltages test points and in this case current draw measurements etc. etc.
Not to worry though I did find you a link where you can buy pretty much the whole innards of this tv for £65.00 so you cant go wrong there.
The power board alone cost that normally.
Take a look at the address below;
Just copy/paste that address in your browser`s address bar.
Hope this help and please take the time to rate my answer positively (use the smiley) if that answers your question , otherwise do not rate at all , just let me know and we`ll see what can be done.
Note that you can reach me here at any time after rating if you have questions or need help with those.
Cheers ***** *****
Jack and other TV Specialists are ready to help you
Customer: replied 3 years ago.

Hi Jack

That's a great tip, thanks. I had been looking at ebay and found psu's, mainboards and inverter master&slaves all running at about £35-ish but if these guys can do a complete set at 65 is well worth it. Seems I might get another year or three out of the tv... I also got my hands on the service/repair manual for it from a Russian site for €4.95 Smile

Thanks again, I'll get started on looking into buying those spares from the site you mentioned.



Much welcome Bob and let me know if you need help.
Thanks again