Sharp TV Backlight repair?

[Hpd]

Hi I have a sharp TV (LC-49CFG6021k) with a problem.

The tv starts and shows the 'Sharp' logo clearly but then the screen goes black. The sound works and if you shine a torch at the screen in a dark room you can see that the tv operates as it should.

Im just wondering if this is a backlight issue? even though the sharp logo does appear at the start?

Or something else?

Thanks!

 

[HERTS P&D]

Hello, Hpd, I'm also Hpd.

Sorry I can't help with your issue but Chris will be along later to help you out.

Andy

 

[Lucid]

You could be at the point where an individual LED is starting to go bad but hasn't fully gone yet. Restarting the TV clears the error, but then within seconds the LED trips out and takes the rest of the backlighting with it. Restarting again repeats the process.

There aren't that many components in a modern LCD TV. You have a power supply, the main board and the T-Con board. The fact that the set powers up (good PSU board) and the panel has a picture when you light it with a torch (good main board and T-Con board) doesn't leave much else left. You have picture but no lighting once in fail mode rather than backlight and no picture, so that would suggest that the panel is still okay too. I would take a punt on looking at the backlights.

If you have the right gear then there are YouTube videos showing how you can test the individual backlight strips to isolate which one has the faulty LED. There could be more than one. Once you know for sure then you can go ahead and replace all the backlights. You would do the whole lot rather than just one or two strips in order to maintain even illumination and consistent colour across the panel.

That Sharp set appears to be a 1080p smart TV. TESCO have it listed on their support pages, but I'm not sure if it was available to buy elsewhere too. Sharp used to be produced by UMC in Eastern Europe. They had the licence for the brand.

 

[Hpd]

Thanks for the info thats super helpful. I have had a look at what you've described on YouTube and I think i'll have a go at finding the culprit. I don't have a specific LED tester like most of the videos, would a multimeter be able to test the LED strips?

Also had a quick search and I can find a used set of LED strips on eBay for £50

 

[RandomGrinch]

All as above!
This seems to be a decent video of the operation! :

Having swapped out the LED's on an LG set, I like how he tapes the filters/diffusers together, before removing them.
There is nothing worse than putting the last screw back in, powering up and finding the screen is full of bright spots, as the many layers of diffusers were put back in the wrong order!

...and again, if one set of LED's is failing, it is likely others will follow - replace the lot!

 

[Lucid]

Thanks for the info thats super helpful. I have had a look at what you've described on YouTube and I think i'll have a go at finding the culprit. I don't have a specific LED tester like most of the videos, would a multimeter be able to test the LED strips?

Also had a quick search and I can find a used set of LED strips on eBay for £50

I wouldn't buy a used set of strips. Backlight failure is one of the most common faults. You've no idea how close to failure any of those used LEDs might be, so spending £50 on someone else's used LEDs and then going through the hassle of fitting them when second-hand TVs of that size won't cost much more seems like a lot to spend for a gamble solution. I'd either go with new LEDs or replace the set and sell the major parts. You have a fully working LCD panel, the PSU, a main board (they don't fail that often) and a T-Con board plus a remote.

To test the LEDs you need to drive each strip with the correct voltage. A multimeter won't help.

Check out your local Facebook selling groups or put a message on your profile to see if there's someone local who does repairs. I know a good guy in Perranporth, but that's a three and a half hour drive one way so not really feasible for you even if you have a car.

 

[RandomGrinch]

. I don't have a specific LED tester like most of the videos, would a multimeter be able to test the LED strips?

A CR2032 battery over the LED contacts (watch polarity!) is enough to test an LED. The output current from the battery is low enough that no damage will occur

 

[Hpd]

thanks I have tested every LED with the CR2032 battery idea and also with continuity test using a multimeter. All of them light up the same and seem fine! Any advice from here? Thanks!

 

[Lucid]

I've messaged a couple of friends with broader experience. Awaiting replies.

 

[Hpd]

I've messaged a couple of friends with broader experience. Awaiting replies.

Thanks for the help. I re-assembled the tv and noticed that the wires were quite loose in the plug that goes from the PSU to the backlight LEDs.

I seated them so they were firm and the tv now works. Not sure if that’s relevant or if the disassembly/assembly fixed it some other way.

thabks for all of the help I appreciate it

 

[HERTS P&D]

Hpd, are you telling me it was a loose connection?

Happy you got it sorted.


Andy from Herts P & D.

 

[Hpd]

Hpd, are you telling me it was a loose connection?

Happy you got it sorted.


Andy from Herts P & D.

Yeah I guess so! All working so I’m glad I attempted it at all. Thanks again