geekhack

geekhack Community => Keyboards => Topic started by: alwaystheshift on Mon, 27 July 2020, 14:03:49

Title: Key press registered by just resting finger on rubber dome
Post by: alwaystheshift on Mon, 27 July 2020, 14:03:49

Hi, does anyone know what could be the reason for a keyboard register a key press by just resting the finger on the rubber dome?

Normally the keys require the rubber dome to be pressed to the bottom, but with this particular key I have to leave the key without the keycap since it seems the keycap touching the rubber dome causes the key to register the key press indefinitely.

Any help is appreciated, thanks.

Title: Re: Key press registered by just resting finger on rubber dome
Post by: -Jerry- on Mon, 27 July 2020, 15:31:26

The only thought off the top of my head (with no particular expertise) is that there is something conductive under the dome making it effectively on a hair-trigger. What particular keyboard is it you have? That might help get an idea of the layout :)

Title: Re: Key press registered by just resting finger on rubber dome
Post by: rxc92 on Mon, 27 July 2020, 16:57:51

Could you take a picture of it? Perhaps it’s damaged so even slight pressure can trigger it.

Title: Re: Key press registered by just resting finger on rubber dome
Post by: alwaystheshift on Tue, 28 July 2020, 09:33:04

Thanks for the replies.

The keyboard is a Thinkpad Wired USB Keyboard.

I noticed that the rubber dome was damaged, half of it was unglued, so I glued it back and I tried to clean it but the dirt stuff doesn't seem easy to remove. I opened the keyboard and is also not accessible from behind. After all that the key worked well for awhile but the issue came back after a few hours using it.

Here is a picture of the key: https://i.imgur.com/YFC4UwZ.jpg (looks much more dirtier in the photo)

I guess I'll have to find a way to clean it better.

Title: Re: Key press registered by just resting finger on rubber dome
Post by: Maledicted on Wed, 29 July 2020, 13:29:30

Quote from: alwaystheshift on Tue, 28 July 2020, 09:33:04

Thanks for the replies.

The keyboard is a Thinkpad Wired USB Keyboard.

I noticed that the rubber dome was damaged, half of it was unglued, so I glued it back and I tried to clean it but the dirt stuff doesn't seem easy to remove. I opened the keyboard and is also not accessible from behind. After all that the key worked well for awhile but the issue came back after a few hours using it.

Here is a picture of the key: https://i.imgur.com/YFC4UwZ.jpg (looks much more dirtier in the photo)

I guess I'll have to find a way to clean it better.

91% isopropyl alcohol. If there's anything gummed up inside that isopropyl doesn't remove easily, use goo gone (sparingly, since it in this application it could seep between the layers of the membrane) ... and remove all of that with isopropyl and leave it to dry a day or two, maybe resting on alternating sides every few hours so that excess liquid can spread out and evaporate more quickly. My guess is that the dome itself is shot again. It is hit or miss trying to repair damaged rubber domes, especially with scissor switches since there's basically no room at all for excess adhesive. Do you particularly like the feel of that keyboard?

Yours doesn't even look all that dirty compared to what I see every day. What did you attempt to clean it with previously?