Old calculator LCD repair  - Page 1
Forum section: electronics / repair

author: joeqsmith
author_rank: Super Contributor
timestamp: September 01, 2017, 03:57:11 pm
content: I have an old Sharp calculator that the LCD started to turn black along the edges and is now to the point where it is no longer useable. The rest of the calculator is still in good condition. Are there places that refurbish LCDs? I would guess it started to leak around 20 years ago. It's been very slowly getting worse. It has some sentimental value for me or I would pitch it.

author: macboy
author_rank: Super Contributor
timestamp: September 01, 2017, 05:50:06 pm
content: If the whole display is affected (as opposed to big black blotches on a white background), it may be the polarizer films. There is usually one transparent film on top and one on the bottom, either integrated with the reflector or not. They are usually adhered to the glass, but with some care and a razor blade, you should be able to separate them. You might source polarizing film from a cellphone/laptop repair shop.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 01, 2017, 08:13:08 pm
content: The polarizer film on this calculator is separate from the glass. The one Fluke 97 I bought had a polarizer that was bad to the point where you could hardly see the display. I bought some new film and went over it without even removing the old film. Works great.This is a problem where the seal seems to have failed between the glass layers. If you have ever cracked an LCD and you see the black blobs, this is what I have but to the point where about half the viewing area is now affected.

author: Old Don
author_rank: Regular Contributor
timestamp: September 01, 2017, 08:18:01 pm
content: Cost to repair the existing LCD will be way beyond value of the calculator. Try to find a parts unit and remove the LCD.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 01, 2017, 08:35:30 pm
content: The value of the calculator is strictly sentimental. I have no idea if there are places that would refurbish one or the cost, which is why I asked. I have seen a couple of them come up but all with the same problem. Age kills them all.

author: Kryoclasm
author_rank: Regular Contributor
timestamp: September 01, 2017, 11:31:44 pm
content: It would be better to search for a identical lcd or calculator and scrap it for the parts you need.I have never heard of lcd refurbishment, it is a sealed system.Good luck.

author: wraper
author_rank: Unknown
timestamp: September 01, 2017, 11:36:22 pm
content: This LCD is completely irrepairable

author: Armadillo
author_rank: Super Contributor
timestamp: September 02, 2017, 01:46:10 am
content: Before your pitch it, you could use your HV static generator to resuscitate it and make a youtube out of it.

author: rsjsouza
author_rank: Super Contributor
timestamp: September 02, 2017, 01:59:00 am
content: Joe, just curious: which calculator is this?Unfortunately I don't have much advice to help; I have a number of LCD gadgets (all with sentimental value) that are completely black. Others are fine, but the connections are a problem - a maze of flex PCBs that have varying degrees of brokeness.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 02, 2017, 02:25:54 am
content: It's an EL-5100. There are a few newer ones on ebay and it's possible these LCDs would work on it.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 02, 2017, 03:29:20 am
content: Looking at the side where the black started from, there appears to have been some contamination. Its dry. Under the microscope, I see no signs of a crack. I suspect the early seals failed. Then again, it took many years to once it started to fail.The adhesive used to hold the LCD into the frame and hold the glass together is not something that breaks down easily with the small heat gun.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 02, 2017, 02:38:37 pm
content: After 35 years of service, into the recycle bins it goes.I bought the TRS80 maybe a year later and the LCD is still holding up fine.

author: SeanB
author_rank: Super Contributor
timestamp: September 02, 2017, 03:57:13 pm
content: Think I have one of those around Joe, will look for it if you want it.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 04, 2017, 02:12:42 pm
content: Quote from: SeanB on September 02, 2017, 03:57:13 pmThank you very much for the offer. I have already scrapped it out. That was the second pocket calculator I had owned. Lots of memories.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 04, 2017, 02:16:32 pm
content: When I could not separate the glass, one thing I had thought about trying was to submerse the display in fluid and draw down a vacuum. Thinking when it returns to atmosphere, it would draw in the new fluid then resealing the edge.