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Comment by reeddavid | Hacker News Reader

Not a company, but sharing a personal project: I got a free broken 55" TV and turned it into a big daylight panel. I got a great explanation of why this works well (fresnel lens) from the DIY Perks channel on YouTube: Turning Smashed TVs into Realistic Artificial Daylight (https://www.youtube.com/watch?v=8JrqH2oOTK4).

The main board had failed so the screen was black and the backlight cycled on and off. After disconnecting the main board, the backlight stayed on. I am using the existing LED lights, but may replace them with the excellent color quality LEDs recommended by DIY Perks.

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Just FYI, repairing flat panel TVs by replacing the boards is fairly easy. Sometimes it's even an upgrade if you find a newer revision of the same board.

The boards tend to be used in multiple models of TV, so they're easier to find than you might think.

Though it's not exactly cheap. Some of the boards are often over one or two hundred dollars

Yeah, though most are between 100-200. If you can find a list of what model numbers and revisions will work for your TV, you can watch Ebay for a used one.

I was given one with a black stripe down the screen. I opened it up and wiggled a ribbon cable... and the line disappeared. Used it for a few years afterwards and gave it away still working

I'm curious - was that TV edge-lit? I've been on the search for a suitable TV for this project for a while now. Most of the cheap/broken TVs you can find are backlit with fluorescent tubes. I disassembled one and discovered it did not have the lens. And from searching for TVs, it looks like most large screens (beyond about 30") directly backlight with LEDs rather than using LEDs around the sides. Was wondering if the direct-lit LED TVs still had the lens.

Yes, it is edge-lit. And since the original power supply still works, I was able to use the existing LEDs. I'm not a huge fan of the spectrum/quality of the light though, so I may replace the existing edge lights with pleasing LED strip lights.

Be careful white (which are actually blue) LEDs may be damaging to your retinas.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5313540/

CONCLUSION

The study results indicate that LED blue-light exposure poses a great risk of retinal injury in awake, task-oriented rod-dominant animals. The wavelength-dependent effect should be considered carefully when switching to LED lighting applications.

Does this work with old cellphones? I’ve got a lot more cellphones lying around than TVs/monitors.

What's the energy draw on this compared to, say, an LED lightbulb?

From the recommendations I've read, replacing the backlight with your own LED strip is easier than trying to get the backlight of the original TV working properly again (if it's not already); and sometimes even worth replacing if it works as getting just the backlight to turn on can be annoying (not exactly a standard, some take "strange" voltages or are hard to figure out, no specs).

Side note: use 'nice' LED strip lights if you go this route. I did a similar project with a small 19" monitor, for the lensz etc, and grabbed cheapo home Depot LED strip -- it worked about as expected: not daylight/bright enough. I'd reel off specs but the LED strip had none on the box. :-)

Next, larger lens waiting at my brother's house will get a better treatment.

As an aside, it's a really neat project to do, my kids thought it was super cool to help with. Large one will go in stairwell.

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