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The TV had sound but no picture, though a picture was just discernable if a torch (flashlight) is shone at it. The manufacturing date was mid 2019 ie only 4 years old.
All the 22 LED's (in two strips which cost £16 on ebay) were replaced rather just replacing the failed LED because one of the strips had been assembled incorrectly probably causing hot running and a shorter life.
It's recommended to take pictures as you go along with the repair to aid with reassembly.
TV now works
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Unplug TV and lay face down preferably on a table with a blanket to protect the fragile glass screen
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All TV's are slightly different but you want to undo all the screws. At the edge there are 12 screws for this model, two smaller screws in the middle by the scart connector and the four fine-threaded screws holding on the stand if present (if wall-mounted still undo the four screws where the stand would be.
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Now the back can be lifted off as in the image. Remove mains cable (blue arrow) by pressing down the lever on the connector. Remove stand bracket (red arrow, 4 screws). Remove the long black speaker carrier module (green arrows) by removing 4 screws and unclipping 2 cables to the green printed circuit board and 1 to the infrared sensor
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Undo the ribbon cable from the small circuit board, now exposed after removing the stand bracket. To do this lift the small bar with a thumb nail or similar and the ribbon cable can be easily removed.
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Then detach this small circuit board from the metal chassis by removing two white plastic clips. These clips are sprung loaded into a hole so use a blunt knife or similar to squeeze the clips' shank and pull it out. Partially remove any tape securing the outer frame.
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Turn the TV face up and remove the outer plastic frame from the unit by levering off lots of attached plastic clips with a blunt knife or similar. Best to start at a corner otherwise the frame has a horrible habit of re-clipping itself back on.
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You can hold the TV edge-on if it helps, but when the outer frame is free the fragile glass panel (with attached small circuit board) is free to fall out, so be ready to catch it and put it safely to one side. If the TV is on its back, you can lift out the glass panel by hand. For larger TV's, you can use a suction pad to pull up the glass panel.
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Next, remove the inner plastic frame, also held on by lots of integral plastic clips, just like the outer frame.Then remove and safely store the two or three flexible sheets, noting the orientation and order of the sheets. (Good idea to keep them together).
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Then remove the flexible white reflector sheet to fully expose the 2 LED strips with glued on lenses for each LED, as in the image.
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Remove 3 screws from the green circuit board (red arrow), and slide it off the glued-on LED strips so that they are electrically isolated and ready for testing.
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To check which LED(s) has failed, it's best to use a multimeter on diode setting, which gives just enough volts to light up the LED without dazzling. Either side of each LED are two exposed 2mm diameter test points. Put the positive lead by the red arrow and the negative by the blue arrow and the LED should glow slightly if OK
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If you put the leads on the wrong way round, the LED will not light up. Note next to each LED is the diode symbol which shows the direction of current ie positive to negative, so you know which way round the leads should go.
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Note: the diodes at the ends have only one adjacent test point, so the other multimeter lead goes onto the test points by the connector (either +ive or -ive to make current flow in the right direction).
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Test each LED and you should find one or more does not light up. You may also find that the failed one(s) is a slightly different colour, but it is not always the case. If they all light up, then either the power supply is faulty or there is a dirty connection between the LED strips and the connector (clean them eg with a pencil rubber (eraser).
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An LED normally fails 'open circuit', which is why the whole string goes out for just one failure. If the LED fails 'closed circuit' There is a dull spot on the TV and the other LED's take too much current reducing their life until another fails. The working voltage across each LED should be about 3v.
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The early LED failure in this TV may have been due to the fact that one of the LED strips was not in the right place. There are guide pips (yellow arrows) showing where it should be positioned. Note the strip is on one of the pips so it can't sit flat on the metal chassis which also acts as a heat sink i.e. the adjacent LED's would run hot.
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the second image shows a gap between strip and the metal surface, hindering cooling. In my case it was one of the three LED's with compromised cooling that failed.
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If you don't have a multimeter (or LED tester), there some YouTube videos showing how to use a battery eg use a 9v battery and test three LED's at a time (3x3v=9v)
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You can replace the failed LED if you have very good soldering skills, but most people will replace all the strips (these two strips cost £16 on ebay). This ensures a longer life because if one LED has failed, the next failure won't be far behind.
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Be careful removing the old strips because they are normally well glued on. I wear gloves because it's easy to snag a finger on a sharp edge. Start at one end with a blunt knife or similar to cut the glue then twist or lever the knife a little to ease the strip away from the metal chassis. They should come off in one piece.
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Fix back the connector board with the three screws. Partially peel back the adhesive covering from the new strip at the connector end and connect it up to the board. Keeping the strip between the guide pips, gradually pull off the adhesive cover so the strip sticks in place. If happy with positioning, you can press it more firmly in place.
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Reassemble the rest of the TV, and it should all be working OK as in image.
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To reassemble your device, follow these instructions in reverse order.
To reassemble your device, follow these instructions in reverse order.
