Thomson LCD TV 40FT2253 Backlight Failure Solved

Question

Hello, I have a Thomson television model 40FT2253, which is a 40" LCD screen, but for some time now I can no longer use it due to a backlight issue.  When I turn on the screen, the image appears for about 2 seconds and then disappears. In reality, it doesn't disappear; the backlight turns off by itself. In fact, when I bring a lamp close to the screen, I can see the image. But of course, without backlighting, the image is barely discernible with a lamp.  I have already tried updating the TV's firmware, but it hasn't changed my problem. I think the issue comes from an internal component. I believe the backlight lamps are functioning since they light up, even if only for a short time. Furthermore, if I turn the screen off and on again, I can see the image, but it does not last long. So for me, the lighting tubes are working.  I have also opened the device, and at first glance, nothing seems damaged on the circuits.  Thank you in advance for your help.

jeannets · Accepted Answer

Good evening,  Here’s what the specifications say about this television released in 2011:  Backlighting:Fluorescent tubesType: CCFL"Cold Cathode" which provides a specific light spectrum.  So, there are two possibilities..  1° the tubes have their hour count and like the fluorescent lights in the house, the end has become all black, the Fluorescence is worn out, it lights up for two seconds and then collapses without producing light... it can be changed if you feel capable, find the components... it’s included in the panel... it takes up the entire dining room table... A technician won’t do it... Or you can change the panel..  2° The converters that power the tubes produce the required voltage, around 800 volts... they have a failure (possibly caused by the short circuit of the fluorescent tubes) this can also be changed, it’s in the TV... there are several.  To successfully carry out this kind of diagnosis, you need a system to test the proper functioning of the fluorescent tubes... or not... independently of the TV converters...  Also, you need to be able to test the converters with equivalents of the fluorescent tubes...  You cannot test one and conclude that it’s the other... because it’s not this one.  So there’s a view of the landscape.... which seems a bit bleak to me.

luffi55 · Answer

Almost a year later, I finally managed to repair this screen. First of all, thanks to Jeannets for their help, which was very useful to me (and I'm sorry for not keeping you updated as promised). I had planned to wait until I had the money to get the screen repaired, but I eventually called a repairman who made it clear that no one would want to fix it (as Jeannets told me). He even suggested I throw it away, so since I had nothing to lose by completely opening the panel, I went ahead with one last attempt just in case. After searching, I thought the tubes were dead, especially one that wouldn't turn on at all. Without a tube tester, I couldn't know if it was really dead. But as I leaned over the power circuit for the tubes (which is right next to the tubes), I noticed that a transformer was unsoldered due to I don't know what (there was a burn mark next to it). Maybe a poor-quality solder that finally gave way. Of course, it was the transformer that managed the tube that wasn't lighting up at all. I made a solder joint as best I could (the fiberglass on the board was burned, so it couldn't ensure contact anymore). This solder connects the transformer to the contact point of the tube (by comparing it with the other tubes, I quickly saw how it was set up). As a result, the backlighting is back (I think that the non-functioning tube was causing the backlight to cut off after 3 seconds). So, as Jeannets said, if you have the same problem, either it's one or more tubes that are not working and need to be replaced, or it's a transformer. There's also an option you can easily find online, it could be a dead transformer from the power board, which is very noticeable if they are swollen on top. (There are videos on the internet that explain this last point very well). In conclusion, I don't know if my repair will last for a while, we'll see, but for now it seems to be working.

ARDECHOIS9 · Answer

Hello, my LG TV model 47LN5400 purchased in 2014, when starting up with the remote, the screen lights up correctly and then immediately turns off, the small red light on the switch that indicates whether the unit is powered on or off is blinking. I disassembled the TV and looked for any overheated parts or dry solder joints, but it's not easy to see with the naked eye. If you have any ideas, I'm open to suggestions, thank you in advance for any response.

Thomson LCD TV 40FT2253 Backlight Failure

3 réponses

Access issue to my "contact me" profile

Windows spotlight is not working.

Total av has charged my bank account.

Personalized e-ticket purchased on viagogo?

Cheats for gta san andreas on xbox 360

Samsung j5 unable to answer

My nikon coolpix s3000 won't turn on anymore.

Bug with the "backspace" key

Do you know maillotsofficiels.fr?

Wii balance board issues