Troubleshooting LCD Backlight Failure Samsung LNT-4066

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Troubleshooting LCD Backlight Failure in a Samsung LN-T4066

[@kredlitz]

Good sir, thank you very much for this video. My LNT-4661 had this exact problem, and I performed your steps identically, and have a working TV again (with the ever so slight dark band). I had purchased an $1800 plasma (decided to buy high end), but can now return it and put my LCD back up, you saved me a lot of money today. Fixed for $75, the cost of a multimeter, soldering iron, and some miscellaneous items.

[@davidb5255]

Excellent video, thanks. This was exactly the fault on my LE40C650, picture and sound came on initially then picture went blank. Managed to work out which backlight tube was causing the overload protection to shutdown the inverters. Slight complication on my TV in that the inverters drive a pair of tubes as one dual output device. Managed to lift the leads on one of the secondary outputs and insert some insulating plastic film and then bypass its primary side so I did not have to remove the entire inverter. Saved me loads on a new TV, missing backlight barely noticeable.

[@destruxxx]

Great video and great to have somebody on KZbin that knows what they're doing.

[@michelelucas9302]

MANY MANY THANKS !!!! This tip fixed the TV I was working on Thanks for creating!!!!

[@aaronbelga3148]

thank you for enlighten and you help me a lot to repair my mom tv and save more money to buy a new tv,thanks a lot

[@180indian]

Followed this to diagnose and repair a Sony Brava KDL 40S4100. It worked just fine. Thanks for the great video and clear instructions. Another TV diverted from the garbage.

[@biksus666]

Finally, one good video. Thank you so much!

[@grantfullen9559]

I love these videos. GREAT JOB sharing with us.

[@jillsissel72]

Hi and thank you for this informative video. I was able to fix the backlight problem on the Samsung 4061F in part to this instructive video! Much appreciated!

[@kenoconnell3976]

Thank You...Excellent video, very helpful.

[@bkj242]

This is awesome great job of and very informative. Please keep up the great work!!! AWESOME GUY!!

[@cptstubing]

Nicely done video, thanks for sharing!

[@triggeral]

Thankyou, for the advice and posting and sharing your knowledge .. wasn't sure....

[@technodaz]

Just found your channel , thanks a lot ! I wish tho I found this a year ago when I had a set that was doing this (im no expert like yourself) ended up ripping all the bulbs out and replacing them with 600 leds on strips and adding a 12v 2a psu and while it worked , this would have been a lot quicker as it was doing exactly the same thing but I could not for the life of me figure out how to bypass a bulb like that !

[@jimkoukoutsidis7879]

Very helpful.Thanks!!!

[@sansanchezjr71]

thank you for sharing your experience with us!, great explanation, excellent

[@arlinjv]

Thank you! Thank you! Thank you! This was exactly the problem with my TV. (Well the caps had also gone bad... )

[@davecc0000]

Steve, Would be educational to see how to "ring" a transformer like you mention here. Thanks for including us in your "classroom"! Cheers!

[@TheBibleChannel07]

THANK YOU. YOU ARE ONE OF THE BEST

[@norcal715]

Yes I have done that in some sets, this customer just wanted a quick fix and didnt want to spend any money on this set. It was given to them.

[@Psycho0188]

Awesome details and thanks for that little bypass. I am stuck on one TV right now and was wondering if you knew if this is even an error code or what. I have a Samsung UN60J6200AF and it doesn't turn on AT ALL. I get 6 flashes on the red power LED. The blue light on the LED board remains solid. I also have a solid red led on the mainboard. At first I suspected the power board, but the fuse and capacitors are fine on that. I could not get the LED panel to light up, even disconnecting the mainboard and powering on the system. Before I go any further I just wanted to know if you had any insight on these sets or if you could point me in the right direction.

[@schmittync15]

Great video. I;m also looking how to determine which type of jumper to use.

[@mattcantrell5640]

Excellent video! Thanks! I've been trying to diagnose an older 46" samsung LCD that has backlighting coming on on one side only. Do you think this same issue may be causing it? Or would it likely shut the whole set off, like you mention? I have picture and sound, just very dim on left side (backlighting not coming on). thanks!

[@eman59461]

Very nice video it will help my save many TVs.

[@norcal715]

I am sorry but I dont know where you can get new fluorescent tubes also. I would suggest the you find a scrap set with the same size panel and try and replace those tubes. I have had great success with that.

[@Suringuy]

I love your video, Thanks so much for your kindness.

[@dsmall7777]

I have an LG 50-GA6400-UG Same scenario; picture goes out but the sound works well. I can see the picture in the background with a flash light . The inverter board was replaced twice and both times failed within a week. Could it be something else that is blowing these boards or did I get bad used boards?

[@davidbrown8303]

LOL wow this was recorded 8 years ago. This tv was probably modern when you made this video.

[@djbobbyd3985]

First, I would like to say all your videos are great. You are one one the smartest technicians I have come across on youtube, thanks for all your hard work. I have a dynex dx-46L150A11 and roughly 6 months ago I replaced the backlight inverter board, cuz after 40-60 secs of powering it on I would loose video but not audio. It worked great for the last 6 months and now I'm having another issue. If I power the set on I get the "please wait" message then it goes black but audio works. I did the famous flashlight test and I can see the video playing. So my question is does this sound like the backlight inverter board again? I did a physical check of all the boards and there is no sign of anything burnt out. It just has me puzzled, cuz last time, before I changed the backlight inverter board the video would last 40-60 secs before going black and now it goes black right after the "Please wait" message. Can you tell me what you think? Thanks in advance

[@bcnae99]

Did you make that stand? If so, Can you share how you made it? That would be VERY nice to have and would make things a lot easier!

[@13liborio]

Where do you have the multimeter ground lead connected to? Your testing with the positive lead on the test points but I don't see your ground lead connection.

[@SlowMotion7575]

Fantastic! I have a 4661F, very similar TV, with same issue. I followed your approach, with my rudimentary meter, planning on taking the same approach with a cheap solution w/ a jumper. However, as I was testing, on the 2nd/3rd transformer, the TV started working again. What could I have done that would have 'kick started' this? Some sort of short, or something loose that was re-adjusted?

[@asogwamark]

very much useful, thanks a lot!

[@triggeral]

Hello, You said the Florescet tube was bad. How did you test that??? Also when you were testing the transforms,Where did you have your negitive lead?? Thank you again for shareing you knowledge... I've got one that has backlighting problems that I'm trying to fix.... messge me back please, when you get a minute..

[@dmitrivinguert8314]

Hi again, just would like to say if you keep cracked panels you could use a spare working CCFL from them to replace bad ones and then there would not be any darker line on the screen. Takes more time but looks nice.There is many SONY mostly 40inch LCD TVs that I have fixed that way. Regards

[@mikeharvey6898]

Samsung LN 5285F. I wanted to try and test my inverter boards using a voltmeter but you never showed where to ground the voltmeter probe just where to test. I have since ordered and received 3 of 4 inverter boards from you ( LL,RL, and RU ). The LU you didn't have in stock. I replaced the 3 boards but made no difference. The original problem was that the tv would boot up, picture would start then drop out. Audio but no video. Not sure where to go from here.

[@GoldCoastCB]

Good video, but please note this - I followed this video on my LA40A450 and found a high result on #5 from the top. I pulled the transformer off #5 and tried the loop trick. It didn't work on my model. I was going to give in and by a new inverter board but through I'd visually check the CCFL tubes for contact. This video doesn't suggest that step! Yeap, #5 CCFL tube had dropped out of the holder, thus why the high reading and no picture. I re-soldered the transformer back on and all is good.

[@chrisizzard1976]

Hi i have a samsung le40a556p1f when I turn the tv on it works fine for 2 seconds then the back light goes off i have replaced the inverter board but still no change. Any ideas would be appreciated

[@depressoespresso]

hi norcal, my 40" samsung has sound and picture, but no backlight. there are no popped/bulging caps on the power supply. after watching this video, i attempted to go through and test the transformers. in the video you have a single test point coming from the two feedback pins. on mine, there is a test point coming off of each one of the 4 pins. so, i put the positive pen on one of the 2 inside testpoints, and the negative pen on the other one of the 2 inside testpoints.(continued)

[@mortlock59]

Hi, My Proscan 42LA45H has sound but no picture or backlights. I am trying to test the CMO inverter boards 4H.V2308.021 & 031/D2, but the test points look very different to those shown in this video, so I would appreciate some help on testing these boards, thanks a bunch.

[@mohasimo4310]

Thanks you for this video

[@ArcadeMachine15]

how am i supposed to remove my inverter? it looks like yours but is feels like its on to something when i unscrewed it and tried pulling it out, I'm guessing that is the backlight bulbs? So I'm sorta stuck here because I don't want to force it so am i supposed to slide it off the black plastic part?

[@laouaraziz9536]

Thanks so much for your tome

[@norcal715]

Based on the ringing test of the transformer and the feedback voltage thats all it could be. The negative lead for all of the voltage measurements was on chassis ground.

[@brunoabellana4010]

thanks bro....

[@norcal715]

is the dark side a sharp cutoff or is it gradual? If it is gradual then it is most likely the panel, sharp difference between sides could be the tcon.

[@tedbeckham92]

Excellent Video. I did wonder why the tube was not replaced. Is it because it is not possible or incredibly difficult to replace?

[@Watcher3223]

_"I did wonder why the tube was not replaced. Is it because it is not possible or incredibly difficult to replace?"_ It is a fairly difficult job to replace the faulty tube because you have to dismantle the panel assembly, which itself is a bit of a tricky and risky job. If you're not careful, you can easily damage or destroy the LCD panel.

[@norcal715]

Common chassis ground, any metal part like the back of the panel or even the ground on the in/out jacks.

[@norcal715]

I agree most likely main board. Red LED should blink while set is starting but then go out after that.

[@errmaliabdulhamid2062]

I m really sorry I couldn't understand the transformer part what did u do how its work, where did u put the other pin of your voltmeter pleas clearify norcal715

[@walker55able]

Thank you I am guessing I have a similar issue with a Sony Bravia LCD Kdl 32v40300 is the process the same ?my inverter board id different.Thanks

[@taumiringaorangi1241]

hi I have a veon 50inch model:VN50D3LED. my back lights have gone .if done flashlight test image and sound are their but very dark do use have the part for this or what is the most cost effective way to fix thanks

[@miguelangelquinonestorres6784]

Good morning, I'm in need of advice, my tv has white dots all over, any idea what is wrong? Sound and picture Ok but it looks like stars at night, please advise or if you have a video on 5his repair can you refer it to me, thanks a lot.

[@norcal715]

usually the backlight tubes run from right to left so if one were out it would affect a horizontal band. Dim on one side could a lcd panel failure. Look closely and see if you see shadows when there is moving video. I have had many LCD failures with dim picture on one side.

[@frankmolino5458]

Hi Does this testing procedure hold true for LED tv's as well ? Thanks for the video , wish your shop was close by me :-) The two guys Samsung referred me to carried guns lol....Wanted $150 to drive out to look at the set and the second came out for $100 , didn't open the set up and said it was the Main board and wasn't worth fixing (2 1/2 years old) but offered to buy it from me . A $1300 tv not worth repairing ???

[@p1bump]

I don't have the little silver dots to test this tube resistance as you did. By the way, I have a samsung ln-s4051d. This circuit board on mine is a HI40024WI-B and the slave side -H

[@jbrown5551]

excellent video ,,, very smart guy

[@billm.2091]

Samsung LCD # LN40c630k1fxza, tv works fine for 2-3 weeks, then black screen w/ sound. I did the flashlight test you posted and TV is on , but back light is out. I can unplug TV and turn it on a week later and it is fine. I want to purchase correct part, but not sure as it works intermittently. Please assist with your thoughts, thank you.

[@diyelectronics5375]

You can measuring by ring tester if transformers is good or bad for the simple moves

[@poisonoverdose1]

Great video. I have a Samsung 46" LCD model LN-S45920. The back light is on, as well as the sound...but no picture. Just a warm, glowing black screen. Do you have any idea what might be wrong? Perhaps the T-con card? Thanks for your support. Dan Tietjen

[@Surdo13]

I have a Samsung LNT4669FX/XAA with a dark screen on half of the screen with a little blurring in the dark side of screen! I was given an opinion that it might be the T-con board! What do you think my problem is? Thanx!!!

[@MYNICEEV]

How many LED strips do you think I should use on a 42" to stop the risk of shadowing. I can power the LED's through a plug and socket arrangement with an external supply. So numbers is not an issue for the internal power supply of the TV.

[@MrAkipeed]

I have panasonic viera 32 inch lcd tv bearing mode no Th-l32c8dx.the other day while removing from wall mounting ,it slipped from hand and the lcd panel hit the knee and after plug in the panel showed broken glass image in bottom,an area of 6 sq cm.then when i start cable the same image with vertical lines start appearing with the program sound coming good .pls advise its disposal asap.thanks

[@norcal715]

look around the inverter transformers for little blue capacitors, look at the color very carefully and see if if any of them are discolored. I have had a few leaky capacitors and they discolor when they get hot. A good shop should not charge more than $125-$150 on a 32 inch for this repair.

[@ocayaro]

Great video.

[@RyanDunbar1]

What is the real fix/solution for this kind of problem ? Why is this one bulb drawing so mush current ? Can one replace the bulb?

[@mega1971tron]

I was thinking the same thing. Why bypass the bulb and give it back like that? just replace the bulb that is drawing too much

[@norcal715]

If you were trying it time after time the weak tube may have heated up enough to fire. Try it again when its ice cold and see if it gos out again.

[@sanpervideo]

Please let me know that camera was recorded on video. make and model of the camera ....

[@AquarelleArtist]

Yes! Video quality is excellent. I'd like to know too.

[@SlowMotion7575]

Thanks. I put it back together, and have been using it without an issue for a week or so now. Comes on without issue after being off all day/night etc. I'm certainly not looking over at this gift horse.

[@williamrace5082]

Hi- great videos!!! I have a RCA model RLC3708A 37" that is doing the shutdown after powering up the backlight inverter.. the inverter transformers have 5 leads one end & two on the other...The ac voltage at the test points goes to 26 volts before the system shuts off..Can you give me a clue on what to do next. ps. all the backlights turn on momentarily and the red-off , light does not flash..Thanks...

[@philliphreak2081]

I am curious about a flickering light issue. The tv works fine, expect for the blinking. Whatever is on, including all inputs, just blinks. I have read an easy fix for similar models that just has you cutting a jumper (jp852/jp854). Does this fix work on the LNT 4066 models? If so, which jumper would I be cutting? Thanks!

[@Striving2BHuman]

Backlights on these go side to side. If you are missing the right half of the image then you have a different problem. Beware of fixit information posted online. You could do damage to yourself or to the set if you are not an experienced technician.

[@titusdaniel]

Is the negative lead attached to the frame of the TV?

[@crushsmith7534]

great video. I love your videos, you show some hackery to just make it work. Why not replace the tube? Another thing I wanted to ask you have you tried using other parts from other makes of tv's just to get them running. The reason I ask I have 1 spectra 32 inch and a samsung 39 inch they both use au t-cons the spectra has a bad screen and the samsung has a bad main and t-con with not being able to find a replacement main for the samsung. Out of pure desperation I hooked the main and t-con out of the spectra to the samsung to my surprise tv started right up the spectra is led so for the back light I think I will use the led out of the spectra in the samsung right now I have 2 plugs one powering the backlight-power supply in the samsung and one driving the screen-main-t-con. Even if I could find a main I am not sure the tv would be worth repairing the cost of them are so low at this point.

[@crushsmith7534]

just up date it worked lol used the screen t-con and backlight from the samsung main spectra been watching it since

[@anno32]

can i use this troubleshout method on other inverters too? or only for this inverter?

[@MRJREGGAE1]

Hi, Norcal. I have a 32" Toshiba tv mdl #32av500u. It turns on, the screen lights up but there is no picture and no sound. Can you assist me please? Thanks.

[@adamroberts4277]

Hi. Hope you can give me some advice. Got a Sharp LC-40SH340K. It stays in standby, with blinking SB LED every 1 second. Check power supply outputs, and they are correct. Also tried an additional power supply that is know to be working. No Luck. Checked power going to inverter and it is correct. not sure what i can test. There is no error line that is sent back to the power supply. However the power supply relay dosent click either. The Panel is - Samsung LTA400HM07, TCON is LJ96-05827A inverter is SSI400_12A01. Power supply is the crappy - Vestel 17PW82-2 V1 090511 (one bought just to test) Any other ideas what to check ? As I cant get any function from it then Im at a loss. is there a way to trigger the BL on/off line to test the inverter and leds. I believe the TCON is mounted along the top edge of the panel, so not easily accessible !! Could it be the AV board ? Look forward to your reply. Seems a shame to bin it. Cheers, Adam

[@frankmolino5458]

Would this test of backlight work on my Samsung UN55ES6150 Smart TV ?

[@mdedonislam1748]

Dear I have a panasonic tv model TH -50ph30w. Power light 13 times blinking. Where is the problem? Thanks

[@norcal715]

Look for FM801 and FM802 on the power supply board, they are small red round fuses. Check them and see if one is blown, if one is bad check the transistors(fets) on the heatsinks nearest the inverter transformer. Chances are they are shorted. better just replace the whole power supply board

[@fargo1996]

Great video thanks. My problem is a little different. TV is a Samsung LCD LNS4041DX/XAA. When I press the power button, the TV chimes on/off but red LED flashes 4 times and I get no picture OR sound, just black screen. No backlights coming on either and the caps on Power supply board are fine. Which board should I replace? I have some technical knowledge so please help!

[@jorgemontalvo30]

hi I have a Samsung tv LN-T4066 and the audio do nor work properly sometimes , can you advise me what to do? do I need a new main board? also can you explain to get the main menu to reset my tv settings ?

[@chuongle3828]

where do you connect the other lead of the meter? Only the red lead is shown in the video.

[@norcal715]

May have some smaller bad caps on main board as well

[@JoshTeslow]

I have an LN52C530 and my entire backlight has just gone dim (or possibly out), but the TV doesn't shut itself off like the one in this video. That leads me to believes it's not one of the transformers or a tube... correct me if I'm wrong. Any idea what it might be?

[@golf2002corsa]

hi there m8. i have a samsung le40n87bd lcd tv the fault is i have jumpey lines on the left hand side on the screen after 30mins or so it goes of or if i hit the tv. what board is it needs fixing or replaced. i do not know how to upload a picture so you can see what i mean. thanks

[@MYNICEEV]

I was thinking of 1cm (10mm) gap between strips. I am going to buy them on a roll. I have found high bright white ones. Would they be ok. Many thanks for taking the time and trouble to help me. It is much appreciated.

[@kevinhancock4064]

H8 I have another inverter to install later tonight as itvwas cheap (working and tested ) if that isjtthe issue is it likely the back lights themselves?

[@norcal715]

The backlights are quite reliable in comparison the the transformers failing (arcing). The typical life of the fluorescent tubes are 30000 to 60000 hours. good luck

[@golf2002corsa]

hi thanks for reply. i can not see the video of the sanyo how can i get that up. im newish on here. thanks

[@grotoy123]

Hi there, I have a Samsung LA40R71B and my tv has the same problem as shown in the video. But on seeing the inverter board, my connections are different and the 1st and 4th pins of the transformer seem to be shorted and the 2nd and 3rd pins (which are feedback in the tv shown in video) are shorted and go to the diode via a resister. Please help me out to find the defective tube. Thanks

[@davidchan6624]

I have a Sony kdl 40s3000 that has a dim picture even though I have maximize the settings. Is this a backlight issue or something else? Thanks

[@dannypetraglia4723]

I have an asus PB278Q 27 inch monitor with a totally with screen display and no video reproduction? Cables are connected nice and tight. Any help?

[@vigideme]

Hi Norcal75, greats videos, thanks for share. I'd like to ask you, where do you get transformer for inverters circuits, I'm looking for a transformer from a Inverter card of Samsung LN52A550 TV, card 01450A, LL, t's the T113 tag on PCB and the number on the transformer is 2034C B 8091, could you please help me to get this trasnformer?,i'm not sure about this transfomer is god or not, it's the transformer how give current to the other tranformer, it's the first T and is not connected to any CCFL.

[@clestrabeck9741]

my TV turns on and it talks but the picture want show. it's an digital lifestyle LCD Tv, WT 323model LT32323 FA 28-32072011054, part number FA,2B-32072, from what I have read,l might need a inverter board. how do I order one and how does one look.

[@ThePHILALLENSHOW]

Amen!

[@rodneyramjit7851]

Hi I got a 42inch Sanyo TV model no.42840 the issue with it is the green led keep blinking no picture or sound help please thanks

[@melvinkimble45]

Where do you put negative lead when checking ac.voltage on transformers

[@jasonw1900]

Samsung un40f5500afxza works fine except for a dim 6" or so horizontal dim band on lower section of screen, just was given tv and want to save it if possible

[@MamaCzy54]

Also want to point out, this tv was free as it was getting thrown out by a family member. I know it's an approx $500 TV, so it could be worth fixing. The smoke thing makes me nervous about having it in my home though. It was a very little bit of smoke and it was white, but still ABNORMAL! What is your expert opinion on what the issue is? I just don't want to get screwed at some tv repair place.

[@michaelligato4506]

I have a sharp LC TV model number LC 50 ub30u serial number 505 BO2 15853 the TV has power it goes on but there's no light I also have sound could you please show me a video on how to fix it