Dark Oval Shaped Patch On A Calculator Screen Repaired
I found my Calculator developed dark oval shaped patch on the screen.
It disturbing to read the digits on screen. Earlier also I repaired damaged screen Multimeters with same oval patch symptom. A dark oval shaped patch on a calculator screen is typically caused by damage to the reflective foil behind the LCD screen often from age, weather effect, physical impact or pressure.
Very easy task if you have material ready, this is 5 minutes’ job. Just you need damaged smartphones display screen & scissor or sharp blade & material usually used on the workbench that’s it. I always salvage some parts of device which I feel useful, I have few damaged Smartphones screens with me.
Opened the Calculator back cover & I found reflector white sheet damaged.
Peeled of the sheet using sharp knife It was glued together with gum, in fact sheet is damaged because of degradation of glue.
After removing reflective sheet, I removed the glue using IPA & knife & again cleaned the residue first using thinner then IPA & wiped the screen with clean cotton cloth.
Before applying reflector sheet checked calculator for working without reflector sheet.
Now took out some mobile screens from my salvage part collection.
Remove all the sheets used in mobile & try one by one in which combination of sheets you get digit clarity on the calculator screen. after confirming the combination, I choose mirror reflective finish sheet with white back sheet. I cut the both reflective sheet to size of the screen.
I held the shredded sheet behind the screen and looked at it. I can see clear digits.
Now I put the replacement sheet on the screen & applied same pressure pad on it.
I have not applied any glue or tap here because on fitting back cover pressure pad can do the job put.
Assembled everything back & result is.
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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Note: You can check his previous repair articles on Wired Earphone Repaired
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Leave a Reply
Parasuraman S
November 22, 2025 at 3:26 pm
You really are an expert in such odd jobs, which others seldom venture to do! Many thanks for sharing.
Yogesh Panchal
November 23, 2025 at 10:22 pm
Sir,
Reading your articles always inspires me to do challenging odd jobs.
A D Rana
November 22, 2025 at 3:48 pm
Nice to repair Calculator Screen Darkness.
Can U tell the details what care should be taken to remove glue. Is there any chances of Damage the LCD Screen Permanently?
ANTHONY PATERSON
November 22, 2025 at 8:13 pm
Interesting repair article on a subject I was unaware. We'll done.
Yogesh Panchal
November 24, 2025 at 2:53 pm
Thank you! ANTHONY PATERSON
Yogesh Panchal
November 23, 2025 at 10:27 pm
A D Rana,
You need to take care of the flex cable connected to the screen, once it gets damaged nothing can be done without the necessary tools and materials.
Albert van Bemmelen
November 22, 2025 at 4:31 pm
Good to know that reflector sheets from old phone screens can be used as replacement. Thanks for sharing this Yogesh.
Yogesh Panchal
November 23, 2025 at 11:18 pm
Albert,
Most of old mobile screens parts are used by mobile repairer like Led Strip with LCD,Reflectors & polarizers in water damage Phone.it is time consuming job hence it is not done in main city area but still it is done in rural area where arranging parts is challenge.
Andy Shiekh
November 22, 2025 at 11:51 pm
Very useful fix
Yogesh Panchal
November 23, 2025 at 11:19 pm
Thank You! Andy Sheikh
Fred
November 23, 2025 at 2:51 am
That’s really good information you’ve shared. I’ve go a radio shack MM that has that same issue. I’m going to try some chrome vinyl wrap that I have, and give it a try.
Yogesh Panchal
November 23, 2025 at 11:22 pm
Try it Fred, you will experiencing something new.
Fred
November 26, 2025 at 12:06 am
I did! I pit the sticky side down as it were. The frame that holds the display comes apart, I removed the display, and cleaned like it was done in the article. I measured the display with digital dial calipers, opened light burn made a rectangle the measured size, and sent it to the laser. The bundle chrome wrap isn’t as bright as a phone reflector but it’s better than what it was. I’m going to order some elector material, and give it a second try.
Yogesh Panchal
November 26, 2025 at 4:14 pm
It was nice to hear, Fred
Try reflectors from any LCD device like non working Mobile phone screen /
PC monitor/LCD TV,Bike Digital speedometer etc....sometime white shiny/Matt sheet also works.Keep on trying till get the result.