I find what you did was not only easier and a time-saver, but economical and practical as far as the customer was concerned. A quick and inexpensive repair - another one working.
RoughJustice 2k18 Right and what those that don't understand how these power supplies work, will not shorten the life. If another led fails then it was already on its way out. Running the lights at 15 or under will ensure no further stress to any of the remaining leds.
Dispite what some people are saying about your repair methods, you're doing what the client requests. I'll be attempting this repair on a Samsung TV soon, (my intial diagnosis was a faulty T-con board, this video has set me on the right path). Great video
That's because those critics have no idea what they are talking about. When I hear them say things like you should have replaced the diode as now the rest are going to be stresses just proves they know nothing about how the current limited power supplies work. An led will drop its junction voltage no matter what. It is the current you are controlling not the voltage. The led strong runs at around 150 to 250 volts depending on how many LEDs are in the string. The power supply doesnt care. It is running on the current drop and it will maintain current bo matter what. The biggest killer of leds is turning up the backlight to full. Running on full will produce more heat and if there is a weak diode it will pop. Turning the backlight down to 75% max will ensure that none of them are stressed to the point of an early failure. 1 or 2 jumpers diodes will make absolutely no difference at all. I have been running one at home I fixed 2 years ago and the only way you can tell is if I put up an all white screen then you can see a slightly darker area. Some people make accurate comments but most are just repeating someone else's uneducated opinion. On this set it was fix it as customer requested or scrap the set. This one is still working fine.
12voltvids I've read through all of the comments, I did notice a lot of people saying the same thing. Your video has given me the confidence to make the repairs to my tv. Again great video and it will be my "go to" reference video to make my repairs, will save me some money. I did check the backlight setting on my LG led/lcd tv, it was on 70%, changed the setting to 60%, the tv is seven years old and still going strong.
All things considered, this is an appropriate repair for this situation(waitng time, cost,etc) and it seems that no matter how often you say it, some people just don't get it! Dave, you have a lot of patience giving the same answers over and over, that would drive me bonkers.
You're right about not using the backlight for 100% full brightness! I use my Samsung Led TV with 10 out of 20 backlight brightness. And even with that setting it is stillbright enough! I even think all of my settings are just set in the middle. After 8 years, the TV is still going strong!! Indeed a good tip everybody!! Sorry for my bad English...
Good fix. Last time I had to fix one of these Samsung TVs, I had quite a hard time. There was no datasheet for the LED backlight driver IC, and I couldn't find schematics anywhere. Turned out to be the red glue under a SMD resistor. It became somewhat conductive and was throwing off a transistor bias, causing the PWM coming from the main board not to reach the driver IC. Without that signal, the LEDs stay off.
Great video. I appreciate you taking the time to post this. A huge time saver knowing how to test the strips without tearing down the entire assembly! Thanks 12voltvids!!
Great video! I had my own TV shop from 1976-84 in Michigan, but never worked on the LED/LCD TVs before. Another problem with over driving the LEDs is permanent screen burn from stationary images. I know, because I created that problem on my 65 inch Samsung LED TV. Using the "dynamic mode" constantly caused large dark areas on the display. Thanks again for sharing this video.
LCD TVs suffer image retention, but it is not caused by the backlight level. It is pixels that stay in one state for a long time tend to stick, and this can me permanent. LED tv is still an LCD panel, just the light source is LED as opposed to fluorecent. OLED and Plasma on the other hand, and CRT for that matter will get permanent screen burn. Look at my latest lorex camera video from yesterday and I show a shot from my old CRT camera monitor all burned to crap. Even when it is off you can see the image.
One thing that slightly confused me is when testing the strips individually before tearing it all apart, you used 50V as source voltage. When removed, you used 30V. Does it really make a difference except for how bright it will get?
Another great video. I like how you challenge these other techs when they start talking crap. Most of them can not back up there statements but you certainly can. Your hard work is greatly appreciated..
Just picked up a Samsung tv with the same problem. This video has definitely helped and no doubt ill be able to fix it now. Seems like a common fault. 👍👍
Thank you! My two-year old Samsung QLED went out just out of warranty. It is going bright/dim/bright/dim. Now I know that this is the backlight going out (I'm no computer tech), and I had the brightness turned up to high. Bought a Bravia to replace it, but wondering if it is worth repairing the Samsung?
It might be around $50 to buy the replacement backlights but while replacing the backlights you might crack the lcd. My best suggestion is to throw it up on Marketplace and let someone pick it up that wants to try to repair it and no scrap it!
OUTSTANDING! One the most professional, step-by-step, yet succinct repair videos I`ve watched. I repair a tremendous amount of electronic and mechanical devices and found this one particularly helpful. Thank you kindly sir!
A cheap repair that can literally save people hundreds or possibly thousands, bridge out the dead led with a few cents worth of wire and solder, it's a shame so many people would just throw the set away. Great repair as always.
Send me a set of 3 strips for a dollar! You can't just replace a single LED. There is no gain doing that. First of all you can't easily remove those chips as they are bonded to the heat sink, and even if you do how are you going to bond the new one to the heat sink? You cant just solder one across it, as it will overheat in a few seconds and fail. Trust me on that one I tried that a few years ago. These are not the same type of LEDs used in light bulbs, and they also have the crap driven out of them. If you are going to change them then you need to order in the entire set for the panel otherwise you are no further ahead. This works, and I have 2 sets that have worked after jumping a bad LED for years. Just turn the brightness of the back lights down. 0.107 volts more across each LED is not going to hurt them. Usually why a single LED fails in the first place is not due to it being a bad LED. It is because it wasn't bonded properly to the heatsink at the factory and overheated. The rest that haven't failed are generally OK.
12voltvids your observation is high end and appreciated ,i started tv repairing my age 17and I didn’t know fully operation during that time but I know several thinks how to check all the active and passive devices.All the times i under stood observation is main things that will find all the issues.
Refreshing to see you keep the heat on for a good few seconds when soldering. Just picked up a 46in Smart Samsung and have found 2 failed leds in the same string. Now its time to visit the TV shop and see if they will give me a few strings from a S/H parts box. I can just hear them now... Sure, that's $50.00 thanks. lol.
Thanks for the educated movie. I have one question please: What would be the cause for one stripe of LEDs to work not on full power ? The picture on the top part of my Samsung tv shows but looks dimmed or darker Thanks
I have rhe same issue. Sound and pic with flashlight. I figured the led driver but how can I test the led strip with a multimeter. I dont have a way to apply the 50v like you did.
A real backlight tester works really well, and they are dirt cheap. Mine has saved me hours of fiddling. They automatically adjust the voltage, and can be used for single LEDs or entire arrays. No jumpers, bare wires or alligator clips required. Also, the most common failure after repair is another backlight going bad, even after adjusting the backlight brightness down. Replacing individual backlights is not recommended because other backlights that may appear to be working perfectly can still be damaged and fail within a month. We always recommend replacing all the backlights as a kit. If the customer insists on just replacing the one failed LED, we only offer a warranty on that LED, and not on any of the other backlights. People have brought their TVs back up to three times before finally saying they will just purchase a new TV when, if they had of done it right and replaced all the strips their TV would stay repaired.
I don't fix tvs for customers. They are all my sets and they have all been fine. I give them away after they are fixed. The only ones I have done for "customers " which are friends I have done more as a favor and charged them perhaps 50.00. That is their limit when they bring them to me, so there is no way to replace all of them. When the backlight kit sells for 100.00 by the time it gets here and labour on top would push repair to a minimum 175.00. Nobody will spend that when a new one is 200.00. I don't accept tvs from people and the ones you see are generally mine. That is why I am so fast to condemn a set that has a bad processor without attempting to replace a board.
Hi, my LED tv has the same problem. I bought led strip having same number of led diodes as original but the strip is different. Now after doing the repair when I start the TV from standby, the back light blinks for a second and then there is no light. It is repeating means the back light only flashes for a second when it starts and then goes off. please help me with this problem.
@@arsalankhan9560 This is why I simply jumped the bad led. The 3v increase presented across the entire strip will have absolutely no impact on the life of the rest despite what the "internet experts" have to say, as the vast majority have no idea what they are talking about. I educate the owners if the set and remind them that no TV should be run with the backlight above 75% as all that is going to do is shorten the life of all the LEDs in the panel.
@@arsalankhan9560 You need the exact led strip for the TV you are repairing. Has to have the same number of led and same voltage / current rating otherwise the power supply will detect a fault and shut them down. I did have a Samsung set that was flickering led that turned out to be an open 10ohm resistor on the power supply causing it. There is a video for that one o my channel. It was a 10ohm that went up to about 150 or so. A surface mount.
Could you probe the lighting string connector and check resistance or continuity rather than sending voltage down it? I don't have a bench power supply.
Could a resistor or diode be used instead of a straight jumper wire? Maybe a 3v Zener diode? To keep voltage drop across each led relatively the same to not stress the other leds? Just curious in terms of longevity
Do the math. The voltage increase is 0.107 per LED. Not going to hurt it. Now if you were to remove 5, well then you might have an issue. This increase can be offset by just turning down the level anyway, and for that matter I should go into the service menu and turn down the master limiter.
I'm attempting this same kind of repair on a TV I got for free (55 inch Samsung). @4:30 where are you holding the black lead on your multimeter? Also what else can I use to test the LEDs? I don't have a power supply...
Originally, I watched your videos to learn some basics and have been successful fixing all kinds of stuff. Now I find myself watching you fix thing I could care less about. Officially, Im addicted to this channel. Does anyone know a good support group?
I saw another video where, after changing the smd led with bad results (burning again) he decided to jump the burned led with an old fashioned led THT. What do you think?
When you connect the 50V to test the leds, do you set current limiting on your bench supplies to keep from smoking the leds? Or is there something downstream that limits the current? Great vid BTW. I have a ~2011 Samsung 55 incher and the right half of the screen is dark, so I suppose the led arrangement is different for that model. I will find out when I take it into surgery.
Thanks for sharing this vide , I have same tv with 3 led were not working, i replaced the led bulb and all the leds were working, when i put the led strip back, As soon i connected the led connectorsame led bulb blow again. Do u think someting to do with power supply? Can u kindly help me with this. Thank u.
Extremely informative video, all steps and proper procedures were documented with clear instruction, thankful to have come across this video, just picked up a 55 LED Samsung with a backlight issue, hoping to put my soldering skills to the test! Thanks!
@@dannybfmv Hey Danny! So I had ordered the individual LEDs to solder on, did a few strips and such, but it still wouldn't display properly, made me question if buying the strips would of fixed it! I eventually called it after about a days work on the TV, there were far too many burnt out to do them individually
I know this is a few years old, but just wanted to say that when I replaced the LED strips in my Samsung, I used thermal tape to attach them to the metal back in hopes of dissipating more heat to hopefully longer. Over a year and so-far, so good!
Are you able to use the LED tester to check all of the backlight LEDS from the connectors that plug into the power supply board? I took my TV apart again and took the panel outside and held up and looked through it using the sun as the light and I did not see any damage. I just do not understand why the backlights do not comeon. When I checked each tv individually they work. but, Idk how to check to see if they work as designed . I called Hitachi but they are closed today
Tv has been running for years. Have done this a few times. I don't do much work on tvs anymore. They are so cheap that people just recycle them and get a newer cheaper better model..
I have a Samsung UN65H6203AFXZA Version no. MH01 that has had a new powersupply installed, but the same problem is still there. The red standby light is on full time and you cannot turn the tv on or off, no response with the button or remote. Where would you start looking for the problem? I'm very techincal and have repaired a few led tvs in the past. I hate to throw away a 65 inch 2 year old tv if I don't have to. Thanks!
ON MY POWER SUPPLY UNDER IT IT HAS NON CONDUCTIVE PAPER THAT HAS PLASTIC RIVET HOLDING IT UNDER THE CIRCUIT BOARD IS THERE ANY SPECIAL WAY TO REMOVE THE PLASTIC RIVETS OR HAVE SEEN THEM THANK YOU
Greetings, Thanks for the Vid. I have a HiSense 55" Roku TV It shut off the other day and would not turn back on. The standby light turns on when plugged in then dims and flashes once goes black for a couple seconds this sequence repeats continuously. I replaced the power board. Same issue. I measured the power from the USB port and the USB power seems to cycle with the light sequence. as if the TV is rebooting. Any ideas ?
Ohhhhh buddy. I'ma about to make a lot of money. I have found about 7 TVs just this month. 5 worked and 2 were smart TVs with the backlight not functioning. Sold the 5 other tvs for cheap because they weren't smart TVs. 1 70" smart TV and a 40" smart tv both with back light out are about to get died and sold for 150$-250$ minimum on FB market place and/or offer up. This video helped me out a lot!!
on a un55hu7200f curved tv, will aftermarket strips work? Factory parts have seq. numbers but aftermarket part numbers all match and are all the same. on factory parts the diffusers run with line patterns east to west with of some of them clocked 45 degrees. I cannot find factory parts will the after-market work
i have the bn44-00775a board for the 60in. No backlights, replaced them still no backlights. Old ones just flashed off and on nonstop with several burned out. New ones check out fine but no backlight when i get them into the tv. I have picture and sound. Measure 12.3Vdc to main board but 380-400vdc to the led d+. Legend says it should be 326v. Any ideas what to try next?
Would it not be easier just to run a resistor across the bad led? I'm having a similar problem, just about ready to test leds, I have power at driver, changed main out but I also have no screen menu on flashlight test and no chime.
As per your video I can see the logo of samsung through flash at the time of turning it on. I have a Samsung Led Tv 40 inch which has edge lit strip inside. I have checked the power supply board which has +led,nc,nc,-led which is connected to the edge lit led . The output voltage I can see is 89.9v from the board but the led strip is not turning on. After led drop the voltage is around 68 volt. I have tried power each led through a 9v battery and every led is turning on. How should I get it repaired ? please help.
hi while you measured the output voltage from the p.s board to the LED strips, you put the positive probe to each pin. and your black probe was always connected to chassis/ ground? since each LED strip connected to DC voltage, i thought you should connect the black probe to the negative pin, and the red to the positive. while i measured my board this way, i got a strange readings. but when i put the negative on the ground, the voltages showed fine. what is the correct way? thanks
@@12voltvids Thanks But if i put my probes on + and - i dont get a correct reading. But if i put my probes on + and ground, than the voltage reading is correct. Is it should be like that, or maybe something is bad in my p.s?
I do not see the bad connections that you are talking about.. I creased and tore my reflector that was on the back of the TV and i do think you are able to see it when you get the TV back together. It was stuck down with double sided tape. This panel will not last long with this jumper in place because most likely the existing LEDs are already being over driven by too much current and the jumper will just make the current be higher for the remaining LEDs. You only made one connection from the good led bypassed over the bad LED?
could you test continuity on the + to - wires on each strip for an open? I seem to have a backlight issue and I tested continuity on each strip and I had it in one direction and not the other (ala LED characteristic) Think I still have an issue? I measured 47V on each of the 2 LED feeds. Sharp 43" LC-43LB481U. All voltages were present on the power board, images visible with flashlight. If I cut the dimmer wire will it bypass a possible dimmer issue or will loss of dimmer signal make it not light? TV was heading to the dumpster anyway so I thought I would take a stab at it. suspected the power board but it seems to test ok unless that 47V is way low
@@12voltvids I think what you are doing is ie. 15 lights1 of 3 strips, #13 is dead; therefore, you jump 12 to 13. video timestamp: diagnostic 13:54. timestamp: repair 15:18. Item terminology on my part may not be accurate but concept sb understood. Ie (LOL) the whatchamacallit that does the thing. Thanks for your time
@@petacare2512 I just jumper over the dead LED. They are all in series each is + - + - + -. The negative of one to the positive of the next. So I short the + and - together of the bad LED to that current can flow though the rest of the string. The power supply is a constant current source and will compensate for the bad LED.
@@12voltvids gotcha, thanks again. Trying to learn how to fix flat screen TV s. Save the earth. Things should last forever, like the used to. It is now a disposable world but, doesn't have to be. I guess that's marketing. Be blessed.
Whenever I got the LED TV set that the panel is cracked (For instance, the 2017 Element ELEFW195), is there a way that I can make one as a ceiling lights to light up the room?
Bluethunderboom Tv led are not good as a room light because they fire the light our in a narrow beam. So they will light the ceiling bright but no light down. Plus they need high voltage and need to by mounted on the big metal back for cooling.
The thing that I don't understand is why doesn't the MFG put in some kind of limiting circuits or cut down the current going to the back lights at maximum setting (Kind of leaving some bit of headroom)? Ex if per say one strip allows 30VDC max the maximum setting 20 or 100 US be preset at 28VDC?
They do have current limiters that should keep the current under the maximum, however because all the LED are in series, all it takes is 1 out of the 38 in this panel that goes south, and everything goes down. Now, sure you could air on the side of caution, and limit it well under the limit, and that may be great, you will never have a failure, but you are also not going to sell any units when the competition set goes brighter in the showroom. In a brightly lit showroom the eye is naturally attracted to the set with the brightest most contrast picture, and it is that showroom where someone makes that decision what to buy. From a manufactures standpoint if it makes it past the warranty they are happy. For the odd one that fails, give them a new one and cut their losses.
Ray H I thought the whole point of led backlight was to simplify and cheapen the backlight design. A CCFL tube needs a driver because florescent tubes require high voltage AC. but it might as well still have CCFL because it got a damn inverter in it. All they had to do was wire the leds in parallel then they could drive then from any of the DC rails in the PSU. No drivers needed
Can you say "MFG Conspiracy"? Secondly, I thought it was pretty dumb on Samsung or The MFG of the LCD panel to make those three strips in series to begin with instead of giving each their own B+!
I agree when they could simply put in a low voltage supply in place of a HV circuit! IMO I think these boards were originally designed for a ccfl panel which was modified by MFG to go from HV to LV. Kind of either lets use the left over or oops we f'ed up!
Mine was being fixed supposedly but when they put the new backlights it was burned again. The damage before was that half of the side of the TV has no backlights functioning. Now when they put the new ones it got burnt. Should this be between the main board and power supply? Please answer please please please sir.
just had to stop at the power to the LED testing ! Well you know if the wire source is bad you get no power to the LED ! I found that out after i replaced to bad strips and went and did them all ! But make sure you supply wire is working first after you put in new LED!
Nice and clear instructions. but I have a question. I have a samsung UE32F6800. I have 5 strips of leds. I dont have a tester to test strips but I have moved each strip around and all work. but they will not all work together. I may have strips 3 4 5 working but 1 and 2 not working. Or top 1 and 2 working and 3 4 5 not working. Ive also had 1 2 working but 3 4 5 not working. Does anyone have any sergestions. thank you.
I had another one a while back that had a resistor on the power supply board a little surface mount resistor that went up in value in was causing the backlight not to light there is a video on it on my channel. I do virtually no work on television these days because there's no money in it when you can buy new TV down at Walmart for 150 bucks nobody spends anything on fixing televisions they break they get tossed.
I guess you went where not many TV repairmen go because I think they don't think it's worth fixing them. You've just proved them wrong. You've absolutely taught us so much. Now If I can remember those voltages, I'll be fine. I like the way you isolated each backlight. Are the backlight strips that expensive? Missing one isn't so bad. You made it look so easy but I know the experience you gave yourself and us it well worth the time. The reason people throw them away is because they don't know how to fix them, they don't have the money to fix them, they've been told that they're unfixable by a lot of TV repairmen. Plus, if the repairmen have to dig that deep, they are going to charge people an arm and a leg. Just a heads up on copyright law. If you have a business, you come under the fair use law and you can use the RUclips feed for up to 30 seconds with any flack. Only if it's for your business for testing purposes now.
I stick to 8 seconds to be safe. In a shop environment this repair probably not worth it. Took a good 2 hours. At shop rates that isn't worth it. I charged them 100 and they were happy as a pig in mud. It was a free TV they got from the cable provider for signing up. Simple repair but most shops are not going to go through the trouble of disassembling the screen
@@12voltvids Yes I know but you, doing this out of your home, you can be a kind soul and I can see that. You're just a good person. That was a fascinating fix though even if it took awhile. Thanks for replying by the way.
@@larrypierce2777 I try to fix as many as possible and show how it's done. I make my money from the video advertising. So I can do these jobs that someone making a living from just could not do. If I still did this for a living I would have moved on real quick to the next and I would be living off the estimate charge like the majority of the shops still in business. I left the business in 2003 because I could see the direction it was headed and got out at the first opportunity.
Please help. I have same problem. I have 55inch Samsung UHD 4k TV. I bought new strips and still tv doesn't work. When you were testing the leds individually at the end of video with voltmeter, did you have power going into strip? Or was it your voltmeter causing the led to light up? I only have a voltmeter. No other fancy equipment. Please help. I even replaced the power board. Only thing left is main board.
Power was not on. For testing leds he used a multimeter in the diode-check mode. In that mode the meter supplies its own voltage, usually about 3V. You can get a decent multimeter at Harbor Freight for cheap.
Remember the phrase, "getting the bugs out?" Got him out at 11:01. When I worked on TVs back in the late 60's, a lot of them were still using vacuum tubes. I'll never forget one TV I opened up and 100's of cockroaches started running away. They probably liked the heat from the tubes and enjoyed eating the paper on transformers and the wire sleeves. Disgusting, I made sure to bill the customer for a can of raid. When I change my LEDS, I'm going to use a heat gun to soften the double sided tape and avoid tearing the diffuser. Might also be able to heat it again to reattach.
Thanks a lot, I was able to fix my TV, just an hour of work, no need to wait weeks for new LED strips from china and you don't even notice the lack of one diod
Thank you for the very informative video. Does flickering on one side of the screen also indicative of bad led backlights as well? My tv initially had flickering on on side but after about 20 minutes the flickering would stop. The side that was flickering would be darker. Now after the flickering stops, the picture remains very dark. I would hate to see another tv just going to the landfill but is there another test for cause of flickering that can be done?
12voltvids has done a few vids on flickering,one of them the board was loose and he tightened it that fixed it,his theory board was warming up,the board was sending signal to leds .
Hi there. Thanks for putting together this video. I have a u5002 with low backlight emits about half of what it used to be. Yes, I have running it at 20 to compensate for that. Is there a way to adjust it back up again? I thank you for your reply in advance.
Change the LEDs or buy a new TV. The problem with LEDs is they start to lose brightness the minute they are turned on. As the hours add up, they become dimmer and dimmer.Not much you can do about it. By 10,000 hours they will have lost about 50% brightness.
I have the same Samsung tv, only 2 leds on the backlite strips are working, all other leds are out. Lot of information supplied but no mention of my possibility
One more question, my TV also has a dead LED in a string of 5. Can I do the same thing as you? Will it be better if I connect 2 regular LED (in parallel) across that dead one? (2 in parallel is to lower the current passing through the regular LED to make them will not burn out, if just one the current may be too high)
Ok I was hoping I could get some help. I have a 55" Samsung TV model un55fh6030 and the backlighting went dim. When I go to adjust the backlighting it will go to the number 2 and once I turn it to 3 it goes much darker and will increase slightly when I go up on the numbers but it's still very dark at 20, level 2 is the brightest
I have samsung syncmaster 2253BW ...I hit power button and the picture appears fine for about 2-3 seconds and goes away. Turn off power and hit power again and picture is back again for 2-3 seconds again Any ideas? I'd really like to save this monitor cause its a double monitor setup and would like to keep them paired ;-)
They got rid of plasma sets for 2 reasons. 1) they were pretty reliable, and 2) the sucked back a fair bit of juice, but they shure looked good. I have several plasma sets here. A few the panels are slowly starting to fail, but the rest of them look great and they are 10 years old and older.
How many volts are LED's commonly used in TVs? (Specifically Samsung 60") I guess what I mean is what is the voltage specification for a single LED? I've spent the last 2 days watching about 50 videos on the subject. This is the best one!
How many strings of faulty LED christmas lights would you like me to send you. I have about a dozen. Long strings of 70 lights either the first 25 or the last 35 are out on most. 1 LED went open and the rest on the string went out too. If they short then the rest keep working, but if one goes open they all die. I have hundreds of dollars in broken lights. I put up so they look like crap so I can tall everyone, see how bad these are.
I did this repair a while back for a client by putting a resistor in space of the burn out led and it did not work for long the client come back saying the screen stopped working I replace the LED and put an extra LED it's been about 6 months now and client has not complained. I think that will help on fix and make it last longer.
Electronic Artis My Hitachi set I use as a digital advertising sign runs 24/7 and I jumped the bad led 3 years ago. It is also cranked up full so it can be seen from the street during the day. Still going strong. A resistor won't cut it. The reason your panel probably failed is because other leds were also stressed from operating at full brightness. If you are going to change the lights replace all the lights at once.
Not necessary. Just jump it. No resistor necessary, that would probably create a bigger issue, as the power supply will push more current to all the rest to over come the resistance. LEDs are not resistors. They have a specific voltage drop. Removing 1 in a 28 series string will increase the voltage across the remaining LEDs by 0.107 volts. Putting a resistor could increase it more because the power supply is going to crank up the voltage to compensate for the current being consumed by a resistor.
All TVs currently on the market with the exception to OLED, which stands for "Oranic LED" are LCD. Recently manufactures started using fancy names like LED and QLED to confuse the market. They are still LCD panels, it is just the back lights. Conventional LCD screens were lit with fluorescent tubes that ran in behind the panel. Newer televisions use LEDs as the light source, and these are arranged in 1 of 3 configurations. This panel has full array dimming, where the entire panel can be dimmed. Other sets use local dimming where each LED can be independently controlled. (this is a much more complex set up that is not used much because of the circuitry required to control each light.) and edge light where the lights are running across the top and bottom of the screen only, and shine into a light pipe to illuminate the panel.
I thought I was right. I have a Vizio that still shows a picture even if the backlight setting is 0. I don't see the reason for running a backlight on maximum either. The blacks should be black.
I wish mine only had one LED out. I got the TV for free and decided I'd replace the individual LEDs instead of buying new strips. Start to finish took about 3 hours. Once you get into a rhythm with a hot air gun and some solder paste its not that bad. Cost me $12 and 3 hours.
Hi 12voltvids, thanks for the great video on showing us how to fix the no black light problem. I have a led tv also with no black light problem. But it is with a curve screen. Do you have any experience and/or suggestions in how to handle the screen? I am afraid it will break when I try to take it out before checking the leds.
I have similar problem basically the same set. I have aprox 200vdc at the led portion of power supply, no backlights lit. Fed 45vdc into individual pairs gto the led strips middle strip no light bottom and top both have partial lights lit. I have replacement strips coming but I'm at a loss as fto why when I direct feed if the leds are in series why only some light? I have the set apart waiting on the strips just wondering if I got a voltage spike that impacted each strip. Stips are down to $22 shipped for replacements on ebay matching specs of original strips and part numbers.
Led fail 2 ways. They either short or go open. If an led shorts it goes out and passes current through it. If it goes open no current flows and they all go out.
Would it have been possible to replace the dead LED with a new one instead of bypassing it? I've got a TV where the backlight is working, but has very obvious bright and dark patches all over the screen, likely from being used in a digital signage capacity
Sure if you can get the same type led. There was no money in this repair. I was just getting it going. Any parts I put in were coming out of my pocket.
Nice job. Thanks for the information. I'm looking at one (Samsung UN40H5003AFXZA) that the 150 volt LED supply won't work with the LEDs plugged in. I put 50 volts on each LED section, and two started bright, then went out. The last one works and according to my meter pulls 50 mA. The other two appear not to draw any current. I'm still suspicious of the power supply although I've found no "smoking" gun 🙂. Even though the two don't appear to pull any current, the power supply still fails when the LEDs are plugged in. Hmm. I like that you actually troubleshoot things. :) Okay (8/28/22), I replaced the LEDs and the power supply works. I would strongly recommend against placing 50 volts on any LED strip. I would start at about 24 volts, and sneak up on it. At about 3.2 volts, this type of LED is pretty close to maximum brightness, so for 13 LEDs, that's 41.6 volts maximum for 12 LEDs it's even less. There is a 150 volt supply for the LEDs (it measures closer to 180). What you may have missed is that Samsung put a [switch-mode] current regulator in the LED strips' return path, and it runs at about 25 % duty cycle. I measure about 103.5 volts across the LED set when operating. This works out to about 2.72 volts per LED, which makes sense. Thanks again for the information and video. I'm not convinced this one has adjustable brightness.
These new tv's are not lasting very long just over 2 years old not good my plasma is 7 years old and still going strong. good fix though dave you saved another from the landfill.
WHAT IF ALL THE BACKLIGHTS WERE WORKING WHEN YOU TESTED THEM BEFORE REMOVING THE PANEL? WHAT WOULD HAVE BEEN THE NEXT STEP. NOW WE HAVE BACKLIGHT TESTER.
The only con to their smart t.v's is that when when watching a movie you have to set the brightness a little bit higher when their's a night time scene in the movie.
Two thumps up! I have one that the power light flashes 2 times and I see the back lights come on then off. When I disconnect the ps from the main board connector, the back lights do stay on. With the main board connected and I disconnect the main board from one of the two panel cables, the lights come on. When I connect BOTH cables to the panel the lights will not come on. I suspect the power supply is not giving out enough juice to power everything and my problem is the power supply. Appreciate your thoughts and do you repair PS boards?
@@12voltvids WOW. So you agree its the power supply board? I also tested the mosfet and the inside pins had 120vts but outside pins showed 34vts which is way off.
Divide & conquer. Instead of testing every LED, measure continuity from (roughly) the center of the series string to either end; if you get continuity, the bad LED is in the other half, else it’s in that half you just tested. Once you find the bad half, divvy it in two and repeat until you get down to the bad LED; saves time over testing every LED, especially if you have to test a lot of LEDs (or Christmas bulbs, for that matter!) Since it looks like each LED has 3 leads, are these RGB LEDs, or two white LEDs back-to-back? In which case, each strip might be a parallel set of 2 series strings, or maybe a series string of 2-3 parallel white LEDs?
William Squires More than likely 2 in each individual chip. As far as measuring half a string, my meter won't put enough voltage across a string to get a reading. In diode test mode there is enough voltage / current to dimly light each lamp. So this is the way to do it. Only takes a few seconds to Pierce the white paint on the board and make connection with the conductor and the good light will light and the bad one will not.
So basically, Samsung has scientifically researched the amount of impurities needed to induce a certain lifetime on LEDs. Then, they test and obtain an average lifespan. They wire the LED's in series knowing the lowest average LED installed in said strips is the one forcing a new purchase of a TV set. Very clever, Samsung.
Unfortunately this is not a very good fix. When shorting the led you are increasing the voltage on all the other LEDs. (slights but significant) Instead of shorting it its best to use another LED or make a small resistor such that the voltage remains equal on all the other LEDs without shorting the life of all the others. In your case, after shorting the LED the weakest LED of the strip was burnt out due to the increase in voltage.
I didn't have any spare LEDs to swap out and there was not enough money in this to go about ordering them. Yes I know I could get a set of LEDs but there was literally no money in this. I made 50 bucks to do this job, and I couldn't buy a set of LED strips for that. Since the owner of this set got it as a gift from a furniture store for buying a new bed they put zero value in it. I made 50 bucks and they got their free TV back working and you don't see the dead LED. This was more of a troubleshooting video, to show what goes wrong. You are welcome to change the LEDs if you wish, but in this case the owner would not authorize spending any more than they did.
My tv works for an hour or so and goes black with sound. I can see the picture using the flashlight test. I just replaced the power board. Any idea what could be wrong?
I find what you did was not only easier and a time-saver, but economical and practical as far as the customer was concerned.
A quick and inexpensive repair - another one working.
RoughJustice 2k18
Right and what those that don't understand how these power supplies work, will not shorten the life. If another led fails then it was already on its way out. Running the lights at 15 or under will ensure no further stress to any of the remaining leds.
Dispite what some people are saying about your repair methods, you're doing what the client requests. I'll be attempting this repair on a Samsung TV soon, (my intial diagnosis was a faulty T-con board, this video has set me on the right path). Great video
That's because those critics have no idea what they are talking about. When I hear them say things like you should have replaced the diode as now the rest are going to be stresses just proves they know nothing about how the current limited power supplies work. An led will drop its junction voltage no matter what. It is the current you are controlling not the voltage. The led strong runs at around 150 to 250 volts depending on how many LEDs are in the string. The power supply doesnt care. It is running on the current drop and it will maintain current bo matter what. The biggest killer of leds is turning up the backlight to full. Running on full will produce more heat and if there is a weak diode it will pop. Turning the backlight down to 75% max will ensure that none of them are stressed to the point of an early failure. 1 or 2 jumpers diodes will make absolutely no difference at all. I have been running one at home I fixed 2 years ago and the only way you can tell is if I put up an all white screen then you can see a slightly darker area. Some people make accurate comments but most are just repeating someone else's uneducated opinion. On this set it was fix it as customer requested or scrap the set. This one is still working fine.
12voltvids I've read through all of the comments, I did notice a lot of people saying the same thing. Your video has given me the confidence to make the repairs to my tv. Again great video and it will be my "go to" reference video to make my repairs, will save me some money. I did check the backlight setting on my LG led/lcd tv, it was on 70%, changed the setting to 60%, the tv is seven years old and still going strong.
All things considered, this is an appropriate repair for this situation(waitng time, cost,etc) and it seems that no matter how often you say it, some people just don't get it! Dave, you have a lot of patience giving the same answers over and over, that would drive me bonkers.
It is draining. Some people just don't get it, and never will.
You're right about not using the backlight for 100% full brightness! I use my Samsung Led TV with 10 out of 20 backlight brightness. And even with that setting it is stillbright enough! I even think all of my settings are just set in the middle. After 8 years, the TV is still going strong!! Indeed a good tip everybody!! Sorry for my bad English...
Good fix. Last time I had to fix one of these Samsung TVs, I had quite a hard time. There was no datasheet for the LED backlight driver IC, and I couldn't find schematics anywhere. Turned out to be the red glue under a SMD resistor. It became somewhat conductive and was throwing off a transistor bias, causing the PWM coming from the main board not to reach the driver IC. Without that signal, the LEDs stay off.
Great video. I appreciate you taking the time to post this. A huge time saver knowing how to test the strips without tearing down the entire assembly! Thanks 12voltvids!!
I fixed my UA46F5000 thanks to you!
I had a single defective LED just like you had. A simple jumper fixed it like a charm.
Great video! I had my own TV shop from 1976-84 in Michigan, but never worked on the LED/LCD TVs before. Another problem with over driving the LEDs is permanent screen burn from stationary images. I know, because I created that problem on my 65 inch Samsung LED TV. Using the "dynamic mode" constantly caused large dark areas on the display. Thanks again for sharing this video.
LCD TVs suffer image retention, but it is not caused by the backlight level. It is pixels that stay in one state for a long time tend to stick, and this can me permanent. LED tv is still an LCD panel, just the light source is LED as opposed to fluorecent. OLED and Plasma on the other hand, and CRT for that matter will get permanent screen burn. Look at my latest lorex camera video from yesterday and I show a shot from my old CRT camera monitor all burned to crap. Even when it is off you can see the image.
One thing that slightly confused me is when testing the strips individually before tearing it all apart, you used 50V as source voltage. When removed, you used 30V. Does it really make a difference except for how bright it will get?
Another great video. I like how you challenge these other techs when they start talking crap. Most of them can not back up there
statements but you certainly can. Your hard work is greatly appreciated..
How much is a strip of led lights
Just picked up a Samsung tv with the same problem. This video has definitely helped and no doubt ill be able to fix it now. Seems like a common fault. 👍👍
Thank you! My two-year old Samsung QLED went out just out of warranty. It is going bright/dim/bright/dim. Now I know that this is the backlight going out (I'm no computer tech), and I had the brightness turned up to high. Bought a Bravia to replace it, but wondering if it is worth repairing the Samsung?
It might be around $50 to buy the replacement backlights but while replacing the backlights you might crack the lcd. My best suggestion is to throw it up on Marketplace and let someone pick it up that wants to try to repair it and no scrap it!
Love this video. Thank you. Managed to fix my dads old 32" that he was going to trash. Now i have a 32 inch computer monitor.
Ha, my buddy was about to throw his 65 inch as well, I decided to give it a try and now I have a 65 inch screen monitor and I love it.
OUTSTANDING!
One the most professional, step-by-step, yet succinct repair videos I`ve watched.
I repair a tremendous amount of electronic and mechanical devices and found this one particularly helpful.
Thank you kindly sir!
A cheap repair that can literally save people hundreds or possibly thousands, bridge out the dead led with a few cents worth of wire and solder, it's a shame so many people would just throw the set away. Great repair as always.
Most end users have no clue: 'If it is dead, it is dead'
Hundreds or thousands. The part is less than 1 Dollar and he botches it. Never by pass
Send me a set of 3 strips for a dollar! You can't just replace a single LED. There is no gain doing that. First of all you can't easily remove those chips as they are bonded to the heat sink, and even if you do how are you going to bond the new one to the heat sink? You cant just solder one across it, as it will overheat in a few seconds and fail. Trust me on that one I tried that a few years ago. These are not the same type of LEDs used in light bulbs, and they also have the crap driven out of them. If you are going to change them then you need to order in the entire set for the panel otherwise you are no further ahead. This works, and I have 2 sets that have worked after jumping a bad LED for years. Just turn the brightness of the back lights down. 0.107 volts more across each LED is not going to hurt them. Usually why a single LED fails in the first place is not due to it being a bad LED. It is because it wasn't bonded properly to the heatsink at the factory and overheated. The rest that haven't failed are generally OK.
12voltvids your observation is high end and appreciated ,i started tv repairing my age 17and I didn’t know fully operation during that time but I know several thinks how to check all the active and passive devices.All the times i under stood observation is main things that will find all the issues.
jumping out the dead led's is not the way to fix this. it will just cause the rest to go out sooner.
I love to see stuff repaired instead of being thrown away.
We all learn hw this stuff works with every unit repaired.
Thank you so for your technique
LED repair and Troubleshoot Save me time and my TV work again
Refreshing to see you keep the heat on for a good few seconds when soldering. Just picked up a 46in Smart Samsung and have found 2 failed leds in the same string. Now its time to visit the TV shop and see if they will give me a few strings from a S/H parts box. I can just hear them now... Sure, that's $50.00 thanks. lol.
Thanks for the educated movie.
I have one question please:
What would be the cause for one stripe of LEDs to work not on full power ? The picture on the top part of my Samsung tv shows but looks dimmed or darker
Thanks
I have rhe same issue. Sound and pic with flashlight. I figured the led driver but how can I test the led strip with a multimeter. I dont have a way to apply the 50v like you did.
Well you can open the screen up and measure the individual LEDs.
A real backlight tester works really well, and they are dirt cheap. Mine has saved me hours of fiddling. They automatically adjust the voltage, and can be used for single LEDs or entire arrays. No jumpers, bare wires or alligator clips required.
Also, the most common failure after repair is another backlight going bad, even after adjusting the backlight brightness down. Replacing individual backlights is not recommended because other backlights that may appear to be working perfectly can still be damaged and fail within a month. We always recommend replacing all the backlights as a kit. If the customer insists on just replacing the one failed LED, we only offer a warranty on that LED, and not on any of the other backlights. People have brought their TVs back up to three times before finally saying they will just purchase a new TV when, if they had of done it right and replaced all the strips their TV would stay repaired.
I don't fix tvs for customers. They are all my sets and they have all been fine. I give them away after they are fixed. The only ones I have done for "customers " which are friends I have done more as a favor and charged them perhaps 50.00. That is their limit when they bring them to me, so there is no way to replace all of them. When the backlight kit sells for 100.00 by the time it gets here and labour on top would push repair to a minimum 175.00. Nobody will spend that when a new one is 200.00. I don't accept tvs from people and the ones you see are generally mine. That is why I am so fast to condemn a set that has a bad processor without attempting to replace a board.
When you were checking voltage at led connector @4:02 , do you keep multimeter on DC or AC?
DC.
Hi, my LED tv has the same problem. I bought led strip having same number of led diodes as original but the strip is different. Now after doing the repair when I start the TV from standby, the back light blinks for a second and then there is no light. It is repeating means the back light only flashes for a second when it starts and then goes off. please help me with this problem.
@@arsalankhan9560
This is why I simply jumped the bad led. The 3v increase presented across the entire strip will have absolutely no impact on the life of the rest despite what the "internet experts" have to say, as the vast majority have no idea what they are talking about. I educate the owners if the set and remind them that no TV should be run with the backlight above 75% as all that is going to do is shorten the life of all the LEDs in the panel.
Now what to do? Actually the original strip has half of its diodes damaged so i have to replace it.
@@arsalankhan9560
You need the exact led strip for the TV you are repairing. Has to have the same number of led and same voltage / current rating otherwise the power supply will detect a fault and shut them down. I did have a Samsung set that was flickering led that turned out to be an open 10ohm resistor on the power supply causing it. There is a video for that one o my channel. It was a 10ohm that went up to about 150 or so. A surface mount.
i see this a lot in new tvs. I agree if you turn them down to 50% or below they will last longer and possibly never fail
can I use wires from some earbuds to skip over the broken LED? And can I make a proper connection with sautering?
Could you probe the lighting string connector and check resistance or continuity rather than sending voltage down it? I don't have a bench power supply.
Could a resistor or diode be used instead of a straight jumper wire? Maybe a 3v Zener diode? To keep voltage drop across each led relatively the same to not stress the other leds? Just curious in terms of longevity
Do the math. The voltage increase is 0.107 per LED. Not going to hurt it. Now if you were to remove 5, well then you might have an issue. This increase can be offset by just turning down the level anyway, and for that matter I should go into the service menu and turn down the master limiter.
I'm attempting this same kind of repair on a TV I got for free (55 inch Samsung). @4:30 where are you holding the black lead on your multimeter? Also what else can I use to test the LEDs? I don't have a power supply...
did you ever get an answer? I have the same question. How is he making a circuit??
@@Ranchpig67 never got an answer. He had replied to another comment the day before I posted my question; so I was assuming he was active.
Originally, I watched your videos to learn some basics and have been successful fixing all kinds of stuff. Now I find myself watching you fix thing I could care less about. Officially, Im addicted to this channel. Does anyone know a good support group?
12 volts anonymous!!!
@@Washburn-rr5eh
I've even picked up a Canadian accent...eh
I saw another video where, after changing the smd led with bad results (burning again) he decided to jump the burned led with an old fashioned led THT. What do you think?
When you connect the 50V to test the leds, do you set current limiting on your bench supplies to keep from smoking the leds? Or is there something downstream that limits the current?
Great vid BTW. I have a ~2011 Samsung 55 incher and the right half of the screen is dark, so I suppose the led arrangement is different for that model. I will find out when I take it into surgery.
Thanks for sharing this vide , I have same tv with 3 led were not working, i replaced the led bulb and all the leds were working, when i put the led strip back, As soon i connected the led connectorsame led bulb blow again. Do u think someting to do with power supply? Can u kindly help me with this. Thank u.
Extremely informative video, all steps and proper procedures were documented with clear instruction, thankful to have come across this video, just picked up a 55 LED Samsung with a backlight issue, hoping to put my soldering skills to the test! Thanks!
Did you manage to fix it, I have a 55" with backlight issues too
@@dannybfmv Hey Danny! So I had ordered the individual LEDs to solder on, did a few strips and such, but it still wouldn't display properly, made me question if buying the strips would of fixed it! I eventually called it after about a days work on the TV, there were far too many burnt out to do them individually
I know this is a few years old, but just wanted to say that when I replaced the LED strips in my Samsung, I used thermal tape to attach them to the metal back in hopes of dissipating more heat to hopefully longer. Over a year and so-far, so good!
Are you able to use the LED tester to check all of the backlight LEDS from the connectors that plug into the power supply board? I took my TV apart again and took the panel outside and held up and looked through it using the sun as the light and I did not see any damage. I just do not understand why the backlights do not comeon. When I checked each tv individually they work. but, Idk how to check to see if they work as designed . I called Hitachi but they are closed today
Never thought of jumping over the LED. Seems like a good fix if its just one LED bad.
Tv has been running for years. Have done this a few times. I don't do much work on tvs anymore. They are so cheap that people just recycle them and get a newer cheaper better model..
@@12voltvids Thank you so very much. It helped me alot. I love working on things and I have watched you almost a year. Great stuff. thank you
I have a Samsung UN65H6203AFXZA Version no. MH01 that has had a new powersupply installed, but the same problem is still there. The red standby light is on full time and you cannot turn the tv on or off, no response with the button or remote. Where would you start looking for the problem? I'm very techincal and have repaired a few led tvs in the past. I hate to throw away a 65 inch 2 year old tv if I don't have to. Thanks!
ON MY POWER SUPPLY UNDER IT IT HAS NON CONDUCTIVE PAPER THAT HAS PLASTIC RIVET HOLDING IT UNDER THE CIRCUIT BOARD IS THERE ANY SPECIAL WAY TO REMOVE THE PLASTIC RIVETS OR HAVE SEEN THEM THANK YOU
There is a clip. Just depress it and it will come out. Needle nose pliers makes this task easy.
@@12voltvids THANK YOU SO MUCH
Greetings, Thanks for the Vid. I have a HiSense 55" Roku TV It shut off the other day and would not turn back on. The standby light turns on when plugged in then dims and flashes once goes black for a couple seconds this sequence repeats continuously. I replaced the power board. Same issue. I measured the power from the USB port and the USB power seems to cycle with the light sequence. as if the TV is rebooting. Any ideas ?
Thank you for this video. I was able to revive a broken TV by bypassing two burnt out LEDs.
Ohhhhh buddy. I'ma about to make a lot of money. I have found about 7 TVs just this month. 5 worked and 2 were smart TVs with the backlight not functioning. Sold the 5 other tvs for cheap because they weren't smart TVs. 1 70" smart TV and a 40" smart tv both with back light out are about to get died and sold for 150$-250$ minimum on FB market place and/or offer up. This video helped me out a lot!!
I've given up on tvs.
on a un55hu7200f curved tv, will aftermarket strips work? Factory parts have seq. numbers but aftermarket part numbers all match and are all the same. on factory parts the diffusers run with line patterns east to west with of some of them clocked 45 degrees. I cannot find factory parts will the after-market work
i have the bn44-00775a board for the 60in. No backlights, replaced them still no backlights. Old ones just flashed off and on nonstop with several burned out. New ones check out fine but no backlight when i get them into the tv. I have picture and sound. Measure 12.3Vdc to main board but 380-400vdc to the led d+. Legend says it should be 326v. Any ideas what to try next?
I have model LC50LB26IU and the Tab Boards seam to be hot glues to the base.Any ideas sir
You helped guide me in the correct direction for fixing a LED TV. Thank you for this video very nice of you to share what you are doing.
Well I do make a couple bucks a month for my effort.
Would it not be easier just to run a resistor across the bad led?
I'm having a similar problem, just about ready to test leds, I have power at driver, changed main out but I also have no screen menu on flashlight test and no chime.
No. LEDs are not resistive devices. Jumping it won't hurt it. My tv has been running with a hundred led for 2 years.
Hi, what can I do, If I do not have external 50 V power supply? Thx!
As per your video I can see the logo of samsung through flash at the time of turning it on. I have a Samsung Led Tv 40 inch which has edge lit strip inside. I have checked the power supply board which has +led,nc,nc,-led which is connected to the edge lit led . The output voltage I can see is 89.9v from the board but the led strip is not turning on. After led drop the voltage is around 68 volt. I have tried power each led through a 9v battery and every led is turning on. How should I get it repaired ? please help.
hi
while you measured the output voltage from the p.s board to the LED strips, you put the positive probe to each pin. and your black probe was always connected to chassis/ ground?
since each LED strip connected to DC voltage, i thought you should connect the black probe to the negative pin, and the red to the positive.
while i measured my board this way, i got a strange readings.
but when i put the negative on the ground, the voltages showed fine.
what is the correct way?
thanks
The 3 strips are in series so using the chassis as the ground reference makes it easy to find the open strip.
@@12voltvids Thanks
But if i put my probes on + and - i dont get a correct reading.
But if i put my probes on + and ground, than the voltage reading is correct.
Is it should be like that, or maybe something is bad in my p.s?
I do not see the bad connections that you are talking about.. I creased and tore my reflector that was on the back of the TV and i do think you are able to see it when you get the TV back together. It was stuck down with double sided tape. This panel will not last long with this jumper in place because most likely the existing LEDs are already being over driven by too much current and the jumper will just make the current be higher for the remaining LEDs. You only made one connection from the good led bypassed over the bad LED?
could you test continuity on the + to - wires on each strip for an open? I seem to have a backlight issue and I tested continuity on each strip and I had it in one direction and not the other (ala LED characteristic) Think I still have an issue? I measured 47V on each of the 2 LED feeds. Sharp 43" LC-43LB481U. All voltages were present on the power board, images visible with flashlight. If I cut the dimmer wire will it bypass a possible dimmer issue or will loss of dimmer signal make it not light? TV was heading to the dumpster anyway so I thought I would take a stab at it. suspected the power board but it seems to test ok unless that 47V is way low
You can test each led with a meter. I have done that.
Thanks for the workshop. Question when you jumped with 30 watts on damaged element, what source did you jump from? Good element jump the bad?
Are you referring to when I put in external power to light the individual strips?
@@12voltvids I think what you are doing is ie. 15 lights1 of 3 strips, #13 is dead; therefore, you jump 12 to 13. video timestamp: diagnostic 13:54. timestamp: repair 15:18. Item terminology on my part may not be accurate but concept sb understood. Ie
(LOL) the whatchamacallit that does the thing. Thanks for your time
@@petacare2512
I just jumper over the dead LED. They are all in series each is + - + - + -.
The negative of one to the positive of the next.
So I short the + and - together of the bad LED to that current can flow though the rest of the string. The power supply is a constant current source and will compensate for the bad LED.
@@12voltvids gotcha, thanks again. Trying to learn how to fix flat screen TV s. Save the earth. Things should last forever, like the used to. It is now a disposable world but, doesn't have to be. I guess that's marketing. Be blessed.
I have this problem with my tv and I need your help
What is the tester you use starting @12:22?
multimeter in diode mode
Whenever I got the LED TV set that the panel is cracked (For instance, the 2017 Element ELEFW195), is there a way that I can make one as a ceiling lights to light up the room?
Bluethunderboom
Tv led are not good as a room light because they fire the light our in a narrow beam. So they will light the ceiling bright but no light down. Plus they need high voltage and need to by mounted on the big metal back for cooling.
The thing that I don't understand is why doesn't the MFG put in some kind of limiting circuits or cut down the current going to the back lights at maximum setting (Kind of leaving some bit of headroom)? Ex if per say one strip allows 30VDC max the maximum setting 20 or 100 US be preset at 28VDC?
They do have current limiters that should keep the current under the maximum, however because all the LED are in series, all it takes is 1 out of the 38 in this panel that goes south, and everything goes down. Now, sure you could air on the side of caution, and limit it well under the limit, and that may be great, you will never have a failure, but you are also not going to sell any units when the competition set goes brighter in the showroom. In a brightly lit showroom the eye is naturally attracted to the set with the brightest most contrast picture, and it is that showroom where someone makes that decision what to buy. From a manufactures standpoint if it makes it past the warranty they are happy. For the odd one that fails, give them a new one and cut their losses.
Ray H what I can't understand is why the damn thing is using a complicated high voltage circuit to drive a simple assed LED which needs only 3v DC
Ray H I thought the whole point of led backlight was to simplify and cheapen the backlight design.
A CCFL tube needs a driver because florescent tubes require high voltage AC.
but it might as well still have CCFL because it got a damn inverter in it. All they had to do was wire the leds in parallel then they could drive then from any of the DC rails in the PSU. No drivers needed
Can you say "MFG Conspiracy"? Secondly, I thought it was pretty dumb on Samsung or The MFG of the LCD panel to make those three strips in series to begin with instead of giving each their own B+!
I agree when they could simply put in a low voltage supply in place of a HV circuit! IMO I think these boards were originally designed for a ccfl panel which was modified by MFG to go from HV to LV. Kind of either lets use the left over or oops we f'ed up!
Mine was being fixed supposedly but when they put the new backlights it was burned again. The damage before was that half of the side of the TV has no backlights functioning. Now when they put the new ones it got burnt. Should this be between the main board and power supply? Please answer please please please sir.
just had to stop at the power to the LED testing ! Well you know if the wire source is bad you get no power to the LED ! I found that out after i replaced to bad strips and went and did them all ! But make sure you supply wire is working first after you put in new LED!
Nice and clear instructions. but I have a question. I have a samsung UE32F6800. I have 5 strips of leds. I dont have a tester to test strips but I have moved each strip around and all work. but they will not all work together. I may have strips 3 4 5 working but 1 and 2 not working. Or top 1 and 2 working and 3 4 5 not working. Ive also had 1 2 working but 3 4 5 not working. Does anyone have any sergestions. thank you.
I had another one a while back that had a resistor on the power supply board a little surface mount resistor that went up in value in was causing the backlight not to light there is a video on it on my channel. I do virtually no work on television these days because there's no money in it when you can buy new TV down at Walmart for 150 bucks nobody spends anything on fixing televisions they break they get tossed.
@@12voltvids Thank you for your info. how do i find that video
@@adventcliff2040 search my Samsung videos.
I guess you went where not many TV repairmen go because I think they don't think it's worth fixing them. You've just proved them wrong. You've absolutely taught us so much. Now If I can remember those voltages, I'll be fine. I like the way you isolated each backlight. Are the backlight strips that expensive? Missing one isn't so bad. You made it look so easy but I know the experience you gave yourself and us it well worth the time. The reason people throw them away is because they don't know how to fix them, they don't have the money to fix them, they've been told that they're unfixable by a lot of TV repairmen. Plus, if the repairmen have to dig that deep, they are going to charge people an arm and a leg. Just a heads up on copyright law. If you have a business, you come under the fair use law and you can use the RUclips feed for up to 30 seconds with any flack. Only if it's for your business for testing purposes now.
I stick to 8 seconds to be safe. In a shop environment this repair probably not worth it. Took a good 2 hours. At shop rates that isn't worth it. I charged them 100 and they were happy as a pig in mud. It was a free TV they got from the cable provider for signing up.
Simple repair but most shops are not going to go through the trouble of disassembling the screen
@@12voltvids Yes I know but you, doing this out of your home, you can be a kind soul and I can see that. You're just a good person. That was a fascinating fix though even if it took awhile. Thanks for replying by the way.
@@larrypierce2777
I try to fix as many as possible and show how it's done. I make my money from the video advertising. So I can do these jobs that someone making a living from just could not do. If I still did this for a living I would have moved on real quick to the next and I would be living off the estimate charge like the majority of the shops still in business. I left the business in 2003 because I could see the direction it was headed and got out at the first opportunity.
Please help. I have same problem. I have 55inch Samsung UHD 4k TV. I bought new strips and still tv doesn't work. When you were testing the leds individually at the end of video with voltmeter, did you have power going into strip? Or was it your voltmeter causing the led to light up? I only have a voltmeter. No other fancy equipment. Please help. I even replaced the power board. Only thing left is main board.
Power was not on. For testing leds he used a multimeter in the diode-check mode. In that mode the meter supplies its own voltage, usually about 3V. You can get a decent multimeter at Harbor Freight for cheap.
I really liked your video. You are really knoweledgeable i appreciate the fact you have taken the time to share it
Remember the phrase, "getting the bugs out?" Got him out at 11:01. When I worked on TVs back in the late 60's, a lot of them were still using vacuum tubes. I'll never forget one TV I opened up and 100's of cockroaches started running away. They probably liked the heat from the tubes and enjoyed eating the paper on transformers and the wire sleeves. Disgusting, I made sure to bill the customer for a can of raid.
When I change my LEDS, I'm going to use a heat gun to soften the double sided tape and avoid tearing the diffuser. Might also be able to heat it again to reattach.
Thanks a lot, I was able to fix my TV, just an hour of work, no need to wait weeks for new LED strips from china and you don't even notice the lack of one diod
Hello...is there any way to glueing back a LED lens? I broke one off....tried a glue gun and....it appears when I start the TV
Thank you for the very informative video. Does flickering on one side of the screen also indicative of bad led backlights as well? My tv initially had flickering on on side but after about 20 minutes the flickering would stop. The side that was flickering would be darker. Now after the flickering stops, the picture remains very dark. I would hate to see another tv just going to the landfill but is there another test for cause of flickering that can be done?
abl,automatic brightness limiter ,12voltvid did a video on it,he replaced a resistor on a panasonic in the abl circuit.
12voltvids has done a few vids on flickering,one of them the board was loose and he tightened it that fixed it,his theory board was warming up,the board was sending signal to leds .
Hi there. Thanks for putting together this video. I have a u5002 with low backlight emits about half of what it used to be. Yes, I have running it at 20 to compensate for that. Is there a way to adjust it back up again? I thank you for your reply in advance.
Change the LEDs or buy a new TV. The problem with LEDs is they start to lose brightness the minute they are turned on. As the hours add up, they become dimmer and dimmer.Not much you can do about it. By 10,000 hours they will have lost about 50% brightness.
I have the same Samsung tv, only 2 leds on the backlite strips are working, all other leds are out. Lot of information supplied but no mention of my possibility
I have the same issue with my Samsung tv and we've only had It for a little over a year. Is this repair expensive?
One more question, my TV also has a dead LED in a string of 5. Can I do the same thing as you? Will it be better if I connect 2 regular LED (in parallel) across that dead one? (2 in parallel is to lower the current passing through the regular LED to make them will not burn out, if just one the current may be too high)
Just jump them over. Go into your menu and turn the backlight level down to 75%. This will extend the life of the panel
@@12voltvids Thanks for your reply.
I follow your advice and fixed it. So far it is working. I am happy.
Ok I was hoping I could get some help. I have a 55" Samsung TV model un55fh6030 and the backlighting went dim. When I go to adjust the backlighting it will go to the number 2 and once I turn it to 3 it goes much darker and will increase slightly when I go up on the numbers but it's still very dark at 20, level 2 is the brightest
It makes me think it's not the LED strips but something with a controller board
Awesome video. I didn't even think about jumping the LED. I was about to just replace all the strips and get a new board if I had to. Thanks
Thank you repaired my son's tv quick and easy by watching your video 🙂
I have samsung syncmaster 2253BW ...I hit power button and the picture appears fine for about 2-3 seconds and goes away. Turn off power and hit power again and picture is back again for 2-3 seconds again Any ideas? I'd really like to save this monitor cause its a double monitor setup and would like to keep them paired ;-)
I liked when they had Plasma screens. They lasted years. I still have a 12 year old 50 inch Plasma screen and its never had a problem
They got rid of plasma sets for 2 reasons. 1) they were pretty reliable, and 2) the sucked back a fair bit of juice, but they shure looked good. I have several plasma sets here. A few the panels are slowly starting to fail, but the rest of them look great and they are 10 years old and older.
How many volts are LED's commonly used in TVs? (Specifically Samsung 60") I guess what I mean is what is the voltage specification for a single LED? I've spent the last 2 days watching about 50 videos on the subject. This is the best one!
It depends on how many LEDs there are and how they are configured. So there is no magic number. They all differ by model.
Where can I buy these spare parts
I have replaced my all my LED strips as well as my whole power supply board, any idea what could it be ?
And I still have no picture
Did you figure out what was wrong with your tv?
Fixed it.. thanks ! What a bad design ! Today even christmas lights don't fail anymore if one single LED is faulty !
How many strings of faulty LED christmas lights would you like me to send you. I have about a dozen. Long strings of 70 lights either the first 25 or the last 35 are out on most. 1 LED went open and the rest on the string went out too. If they short then the rest keep working, but if one goes open they all die. I have hundreds of dollars in broken lights. I put up so they look like crap so I can tall everyone, see how bad these are.
I did this repair a while back for a client by putting a resistor in space of the burn out led and it did not work for long the client come back saying the screen stopped working I replace the LED and put an extra LED it's been about 6 months now and client has not complained. I think that will help on fix and make it last longer.
Electronic Artis
My Hitachi set I use as a digital advertising sign runs 24/7 and I jumped the bad led 3 years ago. It is also cranked up full so it can be seen from the street during the day. Still going strong. A resistor won't cut it. The reason your panel probably failed is because other leds were also stressed from operating at full brightness. If you are going to change the lights replace all the lights at once.
12voltvids what are your thoughts about adding an extra LED diode in the panel will it help preventing burn out.
Not necessary. Just jump it. No resistor necessary, that would probably create a bigger issue, as the power supply will push more current to all the rest to over come the resistance. LEDs are not resistors. They have a specific voltage drop. Removing 1 in a 28 series string will increase the voltage across the remaining LEDs by 0.107 volts. Putting a resistor could increase it more because the power supply is going to crank up the voltage to compensate for the current being consumed by a resistor.
I thought LED stood for "Light emitting diode"
Or is this an LCD? I am still learning new things.
All TVs currently on the market with the exception to OLED, which stands for "Oranic LED" are LCD. Recently manufactures started using fancy names like LED and QLED to confuse the market. They are still LCD panels, it is just the back lights. Conventional LCD screens were lit with fluorescent tubes that ran in behind the panel. Newer televisions use LEDs as the light source, and these are arranged in 1 of 3 configurations. This panel has full array dimming, where the entire panel can be dimmed. Other sets use local dimming where each LED can be independently controlled. (this is a much more complex set up that is not used much because of the circuitry required to control each light.) and edge light where the lights are running across the top and bottom of the screen only, and shine into a light pipe to illuminate the panel.
I thought I was right. I have a Vizio that still shows a picture even if the backlight setting is 0. I don't see the reason for running a backlight on maximum either. The blacks should be black.
I wish mine only had one LED out. I got the TV for free and decided I'd replace the individual LEDs instead of buying new strips. Start to finish took about 3 hours. Once you get into a rhythm with a hot air gun and some solder paste its not that bad. Cost me $12 and 3 hours.
Hi 12voltvids, thanks for the great video on showing us how to fix the no black light problem.
I have a led tv also with no black light problem. But it is with a curve screen. Do you have any experience and/or suggestions in how to handle the screen? I am afraid it will break when I try to take it out before checking the leds.
I Would suggest using the glass panel suction devices attached to home made bent pipes in the same arc as your curved screen, it could work!
I have similar problem basically the same set. I have aprox 200vdc at the led portion of power supply, no backlights lit. Fed 45vdc into individual pairs gto the led strips middle strip no light bottom and top both have partial lights lit. I have replacement strips coming but I'm at a loss as fto why when I direct feed if the leds are in series why only some light? I have the set apart waiting on the strips just wondering if I got a voltage spike that impacted each strip. Stips are down to $22 shipped for replacements on ebay matching specs of original strips and part numbers.
Led fail 2 ways. They either short or go open. If an led shorts it goes out and passes current through it. If it goes open no current flows and they all go out.
Is there any possible way this problem could happen and be fixed without repair like this?
Nope. All the LEDs are in series like old xmas lights. One goes open, and the rest go out.
Can you do that with smd led strip backlight?
Would it have been possible to replace the dead LED with a new one instead of bypassing it? I've got a TV where the backlight is working, but has very obvious bright and dark patches all over the screen, likely from being used in a digital signage capacity
Sure if you can get the same type led. There was no money in this repair. I was just getting it going. Any parts I put in were coming out of my pocket.
Nice job. Thanks for the information. I'm looking at one (Samsung UN40H5003AFXZA) that the 150 volt LED supply won't work with the LEDs plugged in. I put 50 volts on each LED section, and two started bright, then went out. The last one works and according to my meter pulls 50 mA. The other two appear not to draw any current. I'm still suspicious of the power supply although I've found no "smoking" gun 🙂. Even though the two don't appear to pull any current, the power supply still fails when the LEDs are plugged in. Hmm. I like that you actually troubleshoot things. :) Okay (8/28/22), I replaced the LEDs and the power supply works. I would strongly recommend against placing 50 volts on any LED strip. I would start at about 24 volts, and sneak up on it. At about 3.2 volts, this type of LED is pretty close to maximum brightness, so for 13 LEDs, that's 41.6 volts maximum for 12 LEDs it's even less. There is a 150 volt supply for the LEDs (it measures closer to 180). What you may have missed is that Samsung put a [switch-mode] current regulator in the LED strips' return path, and it runs at about 25 % duty cycle. I measure about 103.5 volts across the LED set when operating. This works out to about 2.72 volts per LED, which makes sense. Thanks again for the information and video. I'm not convinced this one has adjustable brightness.
These new tv's are not lasting very long just over 2 years old not good my plasma is 7 years old and still going strong. good fix though dave you saved another from the landfill.
on my tv not work 2 diodes of 40.. can i do the same thing like you? @12voltvids
thanks
Yes
@7:17 Aren't we glad that our power supplies can handle temporary dead shorts?
Fun stuff.
Lol...
WHAT IF ALL THE BACKLIGHTS WERE WORKING WHEN YOU TESTED THEM BEFORE REMOVING THE PANEL? WHAT WOULD HAVE BEEN THE NEXT STEP. NOW WE HAVE BACKLIGHT TESTER.
What size wire for jumper?
I always have mine set at 10. What are they visually impaired or something to set it at 20.
Virgil Williams
15 and below should be fine. I run my 4 k at 12.
The only con to their smart t.v's is that when when watching a movie you have to set the brightness a little bit higher when their's a night time scene in the movie.
Virgil Williams
They come out of the box at 20 and most people never turn them down.
Planned obsolescence.
Two thumps up! I have one that the power light flashes 2 times and I see the back lights come on then off. When I disconnect the ps from the main board connector, the back lights do stay on. With the main board connected and I disconnect the main board from one of the two panel cables, the lights come on. When I connect BOTH cables to the panel the lights will not come on. I suspect the power supply is not giving out enough juice to power everything and my problem is the power supply. Appreciate your thoughts and do you repair PS boards?
I had one that had a 10 ohm resistor go to about 200 that caused that symptom.
@@12voltvids WOW. So you agree its the power supply board? I also tested the mosfet and the inside pins had 120vts but outside pins showed 34vts which is way off.
Divide & conquer. Instead of testing every LED, measure continuity from (roughly) the center of the series string to either end; if you get continuity, the bad LED is in the other half, else it’s in that half you just tested. Once you find the bad half, divvy it in two and repeat until you get down to the bad LED; saves time over testing every LED, especially if you have to test a lot of LEDs (or Christmas bulbs, for that matter!) Since it looks like each LED has 3 leads, are these RGB LEDs, or two white LEDs back-to-back? In which case, each strip might be a parallel set of 2 series strings, or maybe a series string of 2-3 parallel white LEDs?
William Squires
More than likely 2 in each individual chip. As far as measuring half a string, my meter won't put enough voltage across a string to get a reading. In diode test mode there is enough voltage / current to dimly light each lamp. So this is the way to do it. Only takes a few seconds to Pierce the white paint on the board and make connection with the conductor and the good light will light and the bad one will not.
So basically, Samsung has scientifically researched the amount of impurities needed to induce a certain lifetime on LEDs. Then, they test and obtain an average lifespan. They wire the LED's in series knowing the lowest average LED installed in said strips is the one forcing a new purchase of a TV set. Very clever, Samsung.
Best replacement video for backlights.
I fix the broken LED light and I test them every thing was good.
After 1 hour using tv the back lights gots again dark .
What is the problem?
Unfortunately this is not a very good fix. When shorting the led you are increasing the voltage on all the other LEDs. (slights but significant) Instead of shorting it its best to use another LED or make a small resistor such that the voltage remains equal on all the other LEDs without shorting the life of all the others. In your case, after shorting the LED the weakest LED of the strip was burnt out due to the increase in voltage.
why not solder in a scrapped back light led or some generic 3v led ? even if not match exact .. close enough ??
I didn't have any spare LEDs to swap out and there was not enough money in this to go about ordering them. Yes I know I could get a set of LEDs but there was literally no money in this. I made 50 bucks to do this job, and I couldn't buy a set of LED strips for that. Since the owner of this set got it as a gift from a furniture store for buying a new bed they put zero value in it. I made 50 bucks and they got their free TV back working and you don't see the dead LED. This was more of a troubleshooting video, to show what goes wrong. You are welcome to change the LEDs if you wish, but in this case the owner would not authorize spending any more than they did.
@@12voltvids understood.. Currious if some generic 5 cent white LED would have worked ?
My tv works for an hour or so and goes black with sound. I can see the picture using the flashlight test. I just replaced the power board. Any idea what could be wrong?
Probably a dead led