Help Identify a backlight thing. - Page 1
Forum section: electronics / beginners

author: dark_hawk
author_rank: Regular Contributor
timestamp: June 04, 2023, 01:36:22 am
content: Hi,This white thing is used to backlight the LCD of an AC remote control. Overtime it gets dim. Voltage at the terminal is 49v. Used to be 57 before some hot air and some flattening.What is it, and where can I find a replacement?Thanks

author: Jwillis
author_rank: Super Contributor
timestamp: June 04, 2023, 01:59:50 am
content: 49V for a remote seems really high. Are you sure its not 4.9V ? Anyway its a black light plate . Essentially its a piece of acrylic called a LGP or light guide plate with a reflective coating or sheet on the bottom side and a diffuser on the top. A Single LED or a LED array is on the one side. LCD lays over top. They are sold by dimension Width X Height .

author: dark_hawk
author_rank: Regular Contributor
timestamp: June 04, 2023, 02:06:34 am
content: I'm sure it's 49v. And I can't see any leds in it. Plus it's about 1 mm in thickness. I don't think it's a back light plate.There are two discrete transistors? marked Q2 and Q3 on the motherboard, an inductor and a capacitor on the back which might be a boost circuit.

author: edpalmer42
author_rank: Super Contributor
timestamp: June 04, 2023, 02:23:20 am
content: The magic phrase for this part is 'electroluminescent panel'. Apply a relatively high voltage at a frequency that's typically in the KHz range and it glows. If you're lucky, you might find an exact replacement panel. If not, some vendors claim that you can cut the panels to size, but I'd only suggest that as a last resort. A few years ago I replaced a panel on one of my old pieces of equipment. It turned out that the unit used the same display as some popular music synthesizer / piano units. It was a drop-in replacement.Check the usual sale and auction sites.

author: dark_hawk
author_rank: Regular Contributor
timestamp: June 04, 2023, 02:42:00 am
content: Magic phrase indeed. Thank you.Can't find it though.I wonder why they would use such a panel in an AC remote. Softer light on the eyes on dark environments perhaps.Might as well get a new remote, it will cost less than searching for the panel or try to convert it to a normal backlit plate.

author: james_s
author_rank: Super Contributor
timestamp: June 04, 2023, 03:55:50 am
content: That's an electroluminescent panel, sometimes called EL. 49V sounds a bit low, typically they are run around 100-150V at around 200Hz. I've seen them in remotes a handful of times, they're much thinner than LEDs and produce a nice soft even glow. There are special ICs for driving them that consist of a boost converter and full bridge. Usually when they get dim it's because the panel itself is worn out. They can be cut to size so long as you're careful not to cut off the terminals.

author: james_s
author_rank: Super Contributor
timestamp: June 04, 2023, 03:57:21 am
content: Quote from: edpalmer42 on June 04, 2023, 02:23:20 amI've cut them many times, it works fine. I normally seal the cut edges with clear packing tape but I don't know how necessary this is.

author: Jwillis
author_rank: Super Contributor
timestamp: June 04, 2023, 12:18:09 pm
content: Oh WOW! that's so cool . Learn something new everyday. Apparently there are Cuttable kits available from Technolight .https://www.technolight.com/wp-content/uploads/2019/06/EL-LIGHT-SPEC-SHEET-FINAL.pdfI look forward to playing around with one of those.