Although TVs are complex in their circuitry there are a lot of problems that owners can diagnose and repair themselves. Sometimes the repairs are worth attempting if the parts are cheap and methods are easy.
One of the most common problems is when you turn on your TV and there is sound but no video. There is no video at all meaning that the startup logo does not appear and no images appear at all. When the TV does complete its startup you will hear the audio of whatever channel it is tuned to. Changing the channels should work but no video will appear.
When this problem happens it is most likely your TV’s Backlight system.
Unfortunately when your backlights go out you have to disassemble the entire TV including the screen, cards and everything to get to these backlights which are in the deepest and first installed area of your TV. It is not a repair for the faint of heart but it is possible if you have some basic repair skills and determination.
Testing The LCD Panel For Video Output.
If your Backlights are not working then you won’t see the picture but the picture will still be working on the display. Take a bright flashlight and hold it near the screen. Look for any images on the screen.
If you see images then it is almost certain that your Backlights have gone out.
If you don’t see images then it could be your video driver card which is not difficult to replace.
LED Backlights are on strips. There can be anywhere from 4 to 12 strips. It will depend on the manufacturer and the model of the TV. Some TVs have left and right side light strips but most have strips that go from the left to the right side of the TV. They are wired so that if a single LED burns out the rest should continue to work but at some point if more than a few burn out then they all stop working.
Unfortunately to test the individual LED Strips you will need to disassemble the entire Television. This is pretty difficult but it is possible. Once you have it open you have to send power to the LED Backlight Strips and see if they light up.
They do make LED Test Units which are just DC Power you can test each strip by touching it to the positive and negative connections. Most people that aren’t professionals will just use a 9 volt battery to test the LED Strips but I can’t advise that because it might cause damage.
Another test you can try before disassembling everything is to remove the screen driver card ribbon cable from the Screen. If you do this then you should have a white screen. This would mean the LED Backlights are ok but the driver card needs to be replaced. Don’t expect this to be the case if your screen passed the flashlight test and you saw images but it is worth trying as you are disassembling the unit.
How To Order New TV LED Backlight Strips
After you have tested the light strips and determined that one or many of the LED Lights aren’t lighting up you will need to replace the entire strip. It is highly recommended that you replace all of the strips at the same time because ones that are working today probably will fail soon.
Get your TV’s Model Number and look for replacement LED Backlight Strips online. Many of the large merchant sites should have them. Unfortunately you are likely to find that the only parts available are used.
If you can only find used LED Backlight Strips you really shouldn’t be paying much for them. I would not suggest using Used LED Backlights because they could be coming from a unit with many hours on it.
If your TV is over 5 years old and the replacement parts cost more than 30% of the cost of a new television then you should not bother attempting the repair. A professional shop with many parts tvs that they can harvest free parts from might attempt the repair. Or a shop that is willing to replace each individual bad LED light could do the repair for next to nothing and save the TV for a few more years.
It will be your decision on how much time and money you are willing to spend.
Replacing LED Backlight Strips
The actual process of replacing the strips is very easy. They are held in place with double sided tape. You can use a razor blade and then some stiff plastic card like a credit card (but don’t use an actual credit card) to help you peal the strip off the metal backing plate. They have connectors on the end so they are easy to connect to the power.
Unfortunately if you purchased used light strips you might not have the double sided tape for reattaching the lights. This is why this repair is not easy. If you have all the parts and they are new and you have the skill then it is not too difficult.
However this is much harder than just replacing a Power or Driver Card which only requires removing the back and a couple screws.
Final Note
Replacing your LED Backlight Strips is something that is possible. There are some tiny screws which you will need a jeweler’s screw driver set to remove and those small screw drivers are easy to pick up. The test for the strips can be done with a $40 DC Power tester. The Strips themselves probably will cost you $50 but could cost more.
The repair for someone who has never done it before will probably take an entire day if not two days.
You should really decide is it worth trying to save this TV. If it is a very expensive model just out of warranty then sure you should repair it. Or maybe bring it someplace to be repaired.
If you own the base model no frills TV then just buy a new one and save yourself the hassle.
Since you did test the screen you could disassemble the TV and sell the boards online and maybe recapture some of your money for the new one. It just depends if its worth the effort and you might just list them with no buyers if you have an off brand cheap model.