The brightness of my TV started playing up last week. Top half of the screen was as normal, but in the bottom half the brightness gradually dropped off going further down the screen until the picture was almost too dark to see at the bottom.
The TV must be at least ten years old, inherited from my mother when she died, so it didn't cost me anything and it owes me nothing.
OK, time for a new TV.
After much researching various screen sizes and connections at the back for my rather elderly other stuff like DVD player, sound system and PVR, I made my choice and ordered a new one. A bit more expensive than I originally intended, but as my late wife would say 'it's only money'!
Since ordering the replacement, the old TV has behaved perfectly!
The behavior of CCFL backlights and inverters, has some relatively known behaviors.
When a CCFL backlight goes black, sometimes you can turn down the brightness setting on the device, and the light will come back on. The device will then work for roughly another three weeks, before the CCFL tube will go black for the last time.
The "perfect behavior" you see now, won't last.
CCFL tubes have no filaments. They're basically gas tubes with electrodes. At around 20,000 hours, the electrodes have kinda sputtered off onto the glass of the CCFL tube. The light from the CCFL tube turns "brown" as it ages. If the entire display looks brown to you, that's the backlight tubes sputtered on the inside, with metals.
You may think the old set has deceived you, but it should not be too long before the old set has a more permanent lack of function, on one of the CCFL outputs.
Small panels can be lit with as few as one CCFL tube. The largest panels made with CCFL, could use 16 CCFL tubes. These are driven with separate inverters (there is not generally one inverter driving the whole lot of them). The power can be roughly 3W per tube, so a 16 tube set, you can feel
48W of output on your face while standing next to it.
Modern LCD panels use LED backlights, and they can be edge lit. There is a plastic sheet that distributes light from an edge element full of LEDs. And that's the replacement for the older CCFL way of lighting up an LCD panel.
Of course, more expensive TVs today, use OLEDs, quantum dots, nano LEDs and other junk. Where it might no longer be the concept of "backlighting" as with LCD panels. Those are more of a direct emission solution. But the LCD panels might have slightly less issues with pattern burn-in.
CCFL tubes as a lighting solution, last as short a time as one year for the worst of them (could be inverter failure), and up to 20 years for a good design (CCFL turns brown).
Will a LED backlight last that long ? It won't turn brown (there is no sputtering of metals inside a LED). But it will get dim as it ages.
Many thanks for that, some of which I almost understood. The TV giving the problem is a Samsung LED model, UE42F5000AKXXU. As you predicted, the fault has returned, so money spent on a new TV isn't wasted. OOI, it's a "PANASONIC TX-42MZ800B 42" Smart 4K Ultra HD HDR OLED TV with Google Assistant".
The one I got was slightly smaller than the one it replaced, but an awful lot of those on offer were bigger, and some were a lot bigger. Only a few were smaller!
Not really. You can buy larger TVs, but that doesn't mean that you cannot get smaller ones.
What we found when we swapped from widescreen CRT to wide/flat screen was that the set had to be placed further back from the viewer - an effect which was more pronounced when the TV was located in a corner at an angle. Space behind the screen was saved in spadefuls, but the same screen size would now look smaller to the viewer, hence the upgrade from (say) 30" across the diagonal to 40" or larger.
Albeit a few years back I had the problem persuading my mother to go for a 40+ inch flat screen. She didn't want anything that large in the space. It wasn't a problem with viewing distance or pixel size etc. - it was that flat screen would be physically larger that the widescreen 21 inch crt TV she already had. While the visible screen may have been 21 inch the rest of the tube was hidden with a 2+ inch surround. The manual controls were at the bottom of the cabinet adding another 1 inch to the height. The forward facing speakers were each side of the screen adding another 4 inches to the width. In the end I cut out a piece of cardboard to the size of a 42 inch flat panel TV and placed that in front of the old TV. The cardboard was smaller than the existing TV. A CRT TV had a large front to back dimension and as a result had to be slotted into the corner of the room. In my mother's case the corner wasn't the idea place for the TV and with the purchase of a flat panel TV the room was slightly re-arranged and removal of the large, and heavy, crt a lot of useful space was gained.
In my own case my first flat panel TV was 40 inch with quite a wide surround. My current TV is 5 inch with a very thin surround. I didn't lose any usable space when I swapped between 40 and 55 inches.
Smaller TVs are indeed available - for those who want them. However the steady increase says there is a ready market for larger and larger TVs, whilst room sizes stay the same or are shrinking.
No problems what so ever and with the comment that it was much clearer than the old CRT TV. This was in the early stages of sight loss. The other problem was that she really hadn't had any experience of flat panel TVs and she was thinking along the lines that a 21 inch CRT was bulky enough for the room and a 40+ inch would take up twice the space. In reality the 42 inch flat screen was much smaller.
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