EL backlight replacement - Page 1
Forum section: electronics / repair

author: MikeK
author_rank: Super Contributor
timestamp: July 08, 2022, 08:20:31 pm
content: The backlight in my Keithley 175A is bad. There's 100VAC across the terminals, but no light. Will one of these panels take the same voltage? And can it be cut to size?https://www.ebay.com/itm/393103760354

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: July 09, 2022, 11:49:56 am
content: Any of these EL panels I have seen have been custom parts designed for aspecific display, size and voltage.It may be possible to make or modify one or modify the drive circuit for adifferent one after research into the construction and design, something Ihave not done.Jeff

author: MikeK
author_rank: Super Contributor
timestamp: July 09, 2022, 01:40:15 pm
content: The voltage isn't an issue, I realized, as I can change the capacitor in the on-board inverter to set a different drive voltage. What I've found for cutting, though, is that the panels likely have a bus bar around the perimeter. So cutting the panel likely affects the brightness if it'll even light at all. I'll have to pursue an LED solution.

author: edpalmer42
author_rank: Super Contributor
timestamp: July 09, 2022, 06:43:01 pm
content: I wanted to replace an old backlight a few months ago. I realized that there weren't a lot of backlit displays back then and the same units were widely used. The backlight I wanted to replace looked identical to the one in your picture, right down to the position of the terminals. The replacement was advertised as a replacement for many music synthesizers. It was a perfect drop-in replacement. All I did was match the size and the placement of the terminals. YMMV.Ed

author: james_s
author_rank: Super Contributor
timestamp: July 09, 2022, 06:56:07 pm
content: I've cut EL panels several times without issues. I had to do this when I replaced the backlight in my Pro-2004 scanner about 10 years ago and it's still going strong. I sealed it with packing tape although I don't know whether that was strictly necessary. Give it a try, there's a very good chance it will just work.

author: MikeK
author_rank: Super Contributor
timestamp: July 09, 2022, 07:40:06 pm
content: Quote from: edpalmer42 on July 09, 2022, 06:43:01 pmWhere did you get it?

author: MikeK
author_rank: Super Contributor
timestamp: July 09, 2022, 07:41:29 pm
content: Quote from: james_s on July 09, 2022, 06:56:07 pmI think there are two types? I've seen sheets selling as "cuttable" EL tape/sheet. Where did you get yours?

author: edpalmer42
author_rank: Super Contributor
timestamp: July 09, 2022, 08:41:01 pm
content: Quote from: MikeK on July 09, 2022, 07:40:06 pmhttps://www.ebay.ca/itm/233203448712. I bought the white one.I looked up a few of the listed synths so I could see what their displays looked like. My display is 2x40. Everything looked good so I took a chance. I could have bought a cheaper panel and cut it to size but this looked like it would be a drop-in replacement. It was. Once I unsoldered the terminals, I was able to slide the backlight out without disassembling the LCD. Slipped the new one in and soldered the terminals. Done.Of course, check the size before you buy.

author: james_s
author_rank: Super Contributor
timestamp: July 09, 2022, 08:50:46 pm
content: Quote from: MikeK on July 09, 2022, 07:41:29 pmSome random ebay seller. It was not advertised as cuttable, it only had one set of terminals, I just cut it anyway.

author: MikeK
author_rank: Super Contributor
timestamp: July 09, 2022, 10:17:21 pm
content: Thanks guys.