Years ago I started testing TV LED Backlights with 9 volt batteries. There are even videos of me doing that on Youtube. Well I fianlly broke down and bought a LED tester. The reason was that I had just received a second identical TV to one where I had replaced all of the LED strips and this time I did not want to buy any, but to reuse the good ones from the last TV instead. But I was in for a big surprise. Only two LEDs were bad in the last TV so I was sure I was all set to fix the new one. However in the new TV there were at least 20 bad LED's. Even with 8 good LED strips out of 10, I was still not able to fix all the lED's!! The best I could do was to leave 2 bad LED's. On top of that, as I reasembled the TV two lenses fell off of the strips, so it has to be taken back apart and repaired again!
The short story is that this tester works great. I did have one strip that tested bad in the TV but tested good once it was removed for some reason.
Here is some of my LED strips that I have collected over the years that needed testing.
Here is how to test the LED strips. Basically you go + to + on each strip. Note that the strips are not always labeled correctly! The - terminals are usually just shorts. Trial and error is the quickest way to find the correct polarity. You can use a jumper to short out one end of the LED strip if you want to go positive to negative at one end of the strip. Once you replace the bad strips then test everything to make sure it works together before reasembling the TV. Sometimes the LED strip connectors have issues.
This are some really burnt out LED's
The results are not that good! A number of the lenses fell off and had to be glued back on. It turns out that the lens has to be centered on the money or else you get uneven lighting. You can slso easily see where a LED is not working. I guess I should have purchased new LED strips.....
I studied the "Lens Crooked" issue and what happens is that one of the three bumps slips off and the lens ends up higher on one side that the other, or off center. This is quite common when you reglue the lens. I do not know why so many of the lenses fell off the strips in this TV. I suspect maybe it was dropped or something. Also, I was reusing LED strips that had been removed form another TV, that process is known to loosen or even pop off the lenses.
I took it back apart and reglued three LED Lenses back in place. Then, while putting it back together, I heard another lens fall off. Then I took it apart again and found not one, but three lenses had fallen off. None of the loose lenses had been glued on before. So I glued them and put it back together again. The bad LED is on an "A" strip and I only have "B" strips that are spare. Overall it looks much better but still is not perfect. The only real solution is to replace all the LED strips with new ones....
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