Samsung backlight not working

Samsung backlight not working DEFAULT

How to fix Samsung TV with Good Backlight But No Picture

  • If you have backlight but no picture then you need to replace the main board on Samsung smart tv.

Sometimes on your samsung smart tv you may be having a good backlight picture setting but no picture will be displayed on your screen or screen goes blank or black on Samsung tv. In this article we will go over some basic troubleshooting steps for Samsung LED TV that has a blank screen but does have backlights in Samsung LED TV.

There are different boards like t con board, power supply board, LED driver board on samsung smart tv. However this Samsung LED TV has a power supply and main board. LED drivers can sometimes be built onto the power supply board. On this TV the t-con board can also sometimes be built on to the main board or into the TV panel, this TV has the t-con board connection here and then it runs into the panel. If you have a blank screen on your Samsung LED TV then do the below checks.

How to fix Backlight but no picture on Samsung smart tv

Check the t-con Board

First check that you need to perform is verify whether your t con board is working well and and in good condition, check all the components carefully. If the components are damaged then you should replace the board. If there’s no replacement board available you can also try replacing the individual components or purchasing a repair kit. 

When looking for damaged components or burn marks you can also look at the bottom side of the board. You would simply just need to disconnect all the cables and then remove the screws that hold the board to the panel. Be sure when disconnecting cables and removing screws that you take a picture of what the board looks like in the original state with all the cables connected and then you’ll have a reference for when you reconnect all the cables if you see any burnt or damaged components it is recommended to replace that board if you do not find any damaged or burnt components then go to second check.

Also Read: 1)How to Turn on a Samsung Smart tv Without Remote

2)Samsung Smart TV Black Screen with Sound

3)Fix Samsung tv Screen Dark on one Side

4)How to Fix Lines on samsung TV Screen

5)How to Fix Samsung Smart TV Black Screen

Check the LVDS Cable

The second thing to do is check the LVDS cable to be sure that it is seated properly and that there is no damage visible on it. If you do see visible damage to the LVDS cable you can search your TV model number on our website to try and find a replacement if the LVDS cable and the other components are working good then the next check to perform is voltage checkup. If you cannot see any defect in voltages then problem might be with the t con board, TV panel or main board. Try finding the problem is to replace the main board and the t-con board individually to see if one of these boards fixes the problem this will require you to purchase both boards and then see which one fixes the problem or purchase them individually and see which one fixes the problem.

Sours: https://www.asavvyweb.com/samsung-smart-tv/how-to-fix-samsung-tv-with-good-backlight-but-no-picture
LED strip tester

Ever had your TV showing nothing but a black screen even if the audio was working? Unfortunately, that’s a common issue with low/middle-end LCD/LED TVs these days… Even more frustrating, this issue often comes from a rather tiny and cheap component that can be easily replaced. Most common issues are:

  • Defective capacitor on the power supply board
  • Defective LED in the backlight system

In this post, we’ll take a look at the latter and at one way to fix it.

One of my relatives had this exact symptom happening all of a sudden. This problem on low-end TVs often occurs within the first couple years. As the repair costs for that kind of TV is pretty low, considering repairing it yourself might be a good idea!

Diagnosis

The first step into repair is to find the root cause of the issue. As backlight failure is a very common issue, this is the first thing to test. To do so, the easiest way is to power on your screen, put a flashlight very close to it and check if you can see the image through. The image would be very dark, like turning the brightness of the screen very very low.

Now that we now the image itself is fine, this means the main board is probably fine too, so we are going to test the backlight system itself.

That implies disassembling the TV to access the backlight which is between the LCD screen in the front and the boards in the rear. In my case, with a Samsung F5000, I had to process as follows:

Disassembly

First we have to remove the back housing to reveal the boards (from left to right: main board, T-CON, power supply) and disconnect the LCD panel from the T-CON board.

Rear panel - Boards

Turn the TV around to remove the front housing and the LCD panel. Be very careful with the panel as it is extremely fragile!

Front panel

Now that LCD panel is removed, we can remove the bezel that maintain the backlight diffuser and access the backlight itself.

  • Front panel - LCD panel removed
  • Backlight with cover

Here we can see that the backlight system is made of LEDs which is pretty simple to replace when being the cause of the failure.

Note: Older TVs have neon tubes for backlight, which is thicker and less exposed to this kind of failure. LED backlight is the most common thing these days, but do not mistake an LED TV with an OLED TV. The first one is a classic LCD panel with a LED backlight, whereas the second is an OLED panel that doesn’t need any backlight as it is integrated in each pixels (making the spare parts much more expensive by the way).

So, let’s remove that white cover which is part of the light diffuser to have a good look at the backlight.

Backlight without cover

As we can see, the backlight system is made of 5 LED strips. First thing to do is look for burnt LEDs. Most LED backlight systems have strips set in series, meaning that if one of the them fails, all the system goes dark…

Note: If you look closely, you’ll see that one looks different than the others! 3rd strip from the top, 6th LED from the left. We’ll test it soon!

Testing

Using a multimeter, we can confirm that the strips are indeed set in series, so now we have to test each strip individually. Professionals use LED testers such as this one (about 40$ on amazon) but as I didn’t had one at the time, I decided to make one, McGyver style! 🤓

One LED like those ones typically needs between 2.5-3.6v input voltage to light up. By looking up this model online, I found out that the ones used on those strips need 3.6v; so as there are 9 LEDs per strip: 3.6 x 9 = 32.4v input voltage required to light a single strip. That’s the maximum voltage we do NOT want to exceed, otherwise LEDs could be damaged during testing.

So, I took 3 9v batteries that were laying in a drawer, put them in series to make a virtual 27v battery (3 x 9v). It’s less then the optimal 32.4v required but not that much lower, it might be able to light the strip a bit so we can identify which is not working. Here is a look at the set-up:

LED strip tester

The thing with 9v batteries is that they are made to be plugged with one another! So you just need to put some cables on both ends and there you go.

Now we simply have to test each strips individually to see if they light up or not. For each that doesn’t completly, it will mean it has at least one defective LED.

  • LED strip tester
  • LED strip tester

After repeating this operation on all strips, I found only 1 defective LED, the same we thought looked burnt when we first had a look at the backlight (3rd strip from the top, 6th LED from the left). For a better understanding at what a burnt LED looks like here are 2 pictures of a burnt one and an OK one. Mind the roasted color compared to the regular one.

  • Burnt LED
  • Normal LED

Repair

Now that we have identify what seems to be the issue, we have 3 options:

  • Replace the whole strip with a new one
  • Replace the LED with a new one
  • By-pass the LED and cross our fingers that the backlight will still be homogeneous enough

For starters I’ll go with the third one, just to make sure there is no other issues with the TV, but afterwards it’s better to replace the LED with a new one, otherwise you might notice a darker spot on the image.

Usually we need a heater to remove the LED properly but I had none. So after a few try with a hairdryer, I went messy and soldered a wire below it. 🙈

Burnt LED - By pass

Once we have by-passed the LED, we can power the TV on. Careful! High voltage (200-300v) runs through the TV when plug, so be very careful how you handle it so you don’t electrify yourself!

And Voilà! all the backlight should light up again.

Backlight working without burnt LED

Now we just need to unplug the TV, replace the LED with a new one and put everything back together. Just to be sure, we should power the TV back on and check that everything is fine.

Screen fixed

Conclusion

There might be a lot of other root causes for similar symptoms, a black screen often looks like something very serious and therefore expensive to repair, but this case is the perfect example that taking some time to look for the root cause can sometime lead to a good surprise: here a 1$ fix!

And most of all, repairing is always better than throwing away! 😊

Category: DIY

Tags: diy, repairs, tv

Sours: https://www.molkobain.com/2019/02/02/how-to-fix-lcd-led-tvs-black-screen/
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Samsung LED TV Backlight Problem

We also had this problem with our Samsung 40 LED inch smart tv un40f6300. A dark band across top of screen a couple months ago, only to completely go dark (almost black) yesterday. If you turn off the lights, you could barely see an image. We bought this tv in February of 2014, so a few months after warranty. (FYI, this is our second Samsung to develop the dark band across the top shortly out of warranty). We just called Samsung customer service. After explaining our situation, we were transferred to an "executive". My husband explained we've had four samsungs and two developed problems. That we as a consumer and repeat customer would expect them to do something to honor our loyalty. After going back and forth as politely as we could (this was difficult), they offered to pay for the parts after it is diagnosed by an authorized local repairman. I have a feeling that even if they pay for parts that the labor will be exorbitant. We paid $700.00 for the TV at Best Buy (tax included).
I remember the good ole days when you bought a TV and it lasted 20 years! Samsung smart TV... Not so smart!!!
Sours: https://forums.tomsguide.com/threads/samsung-led-tv-backlight-problem.66735/
Samsung led TV backlight problem repair

Samsung 46" LED TV with sound but no backlight

root9 said:

Thank You JayCee just tryin to fix my issue. have you ever incountered this problem

Click to expand...


I have note directly experienced this, but I do have a few thoughts.

First, there are really only 4 possibilities if it is a hardware failure:
1. T-CON board telling the PS board to turn off backlighting,
2. Connector from T-CON to PS loose or connector from PS to LEDs loose,
3. Blown component on PS board,
4. Blown LED backlight assemblies.

Since you can see video if you use a flashlight to shine light onto the darkened LCD panel, the T-CON board must be functional thru at least the LCD drivers. Most likely it is fully OK, but its ability to control the backlight PS board is unknown until there is more data.

I think it would be very unusual for the board-to-board connectors to loosen and pop out because you. Have to pinch their sides to unlock them. Maybe a chance that it wasn’t inserted fully at the factory, but a very slim chance.

Since you have power going to the T-CON board, as proved by seeing reflected light video on screen, the PS board cannot have a problem from the mains connector all the way through to the DC voltages that go to the T-CON board. And, if the (flyback) PS is supplying power to the T-CON board, the outputs of the LED drivers CANNOT be shorted. If they were, nothing would work.

So, this brings us to the LED backlight arrays.

These come in different configurations that vary widely with size, date of manufacture and with the level of dimming technology. The biggest, newest and costliest TVs employ FALD (Full Array Local Dimming), which divides the array of backlights into sections like 8 x 8, etc.

The smallest, oldest TVs may have all of the LEDs in series and driven by one power supply. Or have 2 to 4 separate horizontal strips.

The 55” to 65” sets might have say 12 horizontal lanes.

OK, why does this matter?

Two rules:
A) in any given string, a SINGLE LED open cuts off the entire string, and
B) Once a single LED opens up in a string, the others can’t burn out.

So, once you know how many separate LED strips you have (which will match one-to-one with the number of PS outputs available for the backlights, you will know exactly how many LEDs are blown.

Since you are getting no light at all, then one diode in every separate strip must be bad.

This happens because an LED failing is somewhat contagious, in the following manner.

Let’s say that you have 4 strings of LEDs. If one LED within one string opens, then the remaining 3 strings get 4/3 the current they were design for. That over current will accelerate failure in more LEDs because they get hotter. When the next LED goes, now you have 2X the rated current. Another failure happens even more quickly, and you are done to one string running at 4X the rated current, and that won’t last but seconds.

This is painful because you may have a hundred or more LEDs but only a small fraction of them could be dead.

If this turns out to be the case, there are numerous self-help videos on youtu.be that will guide you through removing the back panel, checking the PS voltages and the integrity of connections and then encourage you to remove the inner panel to get access to the LED backlights.

The last step is where you can ruin your TV completely. Look at at least a half dozen videos on Samsung TVs showing how people can do that carefully before even considering doing it yourself.

If you get that far, the local ‘repair’ shop would have charged you to replace ALL of the LEDs, plus labor, plus profit, or just sold you a new TV after telling you it wouldn’t be worth repairing yours.

In reality, you can replace all of the actually dead LEDs for well under US$100.

Don’t try this at home until you’ve watched how to avoid destroying your TV.

One last point. It may NOT be a hardware failure, but some eagerly-eco-compliant mode that your TV got stuck in. Try doing a full factory reset before you remove the back panel and dig in.

I have no idea if this is helpful, but it may worth only what you paid for it.

Or, it could help a lot.

Cheers!

 

Sours: https://www.avforums.com/threads/samsung-46-led-tv-with-sound-but-no-backlight.2225681/

Working samsung backlight not

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Samsung led TV backlight problem repair

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