Key chatter ((((bouncing)) with membrane keyboard

[mudmanc4]

Ubuntu 20.04

Gnome 3.36.8

 

I've been using a Matias FK302 since release, roughly ten years now, nearly flawless outside of the occasional bounce.

 

Naturally as time goes on this got worse to the point i knew a cleaning / replacement was necessary. So I started the process with keycap soup:

 

Then began opening the switches, they are simplified APLS SKBM clones with Matias tweaks. I've successfully cleaned these switches in the past so I knew what to expect, none the less I "successfully" bent a contact in the first switch opened after a quick clean, I was  in a hurry, didn't bother to lube the slider even.

 

 

The mount is metal, and is a bit rusty after ~ten years use and abuse, this along with the bent contact, are terms for a complete disassemble, new key switches soldered and paint. So I shelved the keyboard until after the holiday shipping tripe is completed, where I can be assured the switches will arrive un bastardised. < is that a word? 

 

So I went with a Lenovo 54Y9400 I had sitting around. A good membrane (rubber dome) keyboard widely used in data entry.

 

First few days no issues. Now the real issue is rearing it's ugly head. But what is it?

 

As I understand, rollover is  programmed on board, as in keyboard. Yet when a keyswitch contacts bounce past the point of the programming, you clean / replace the switches. Simple, unless the logic board  is borked.

 

I've been fixing the double characters prior to this sentence, here is an example:

 

TL;DR example on membrane KB:

 

1234567890))((.>??MMnNvcxxzASD  you get the idea.

 

This is on the Lenovo 544Y9400 membrane keyboard.

 

[Searching] links me to mechanical switches why what and how toos, nothing about when a membrane KB does this, I've looking in  /dev for ukbd to no avail, done a short bit of searching for the keyboard controller in Ubuntu, google is helping by assuming I'm working with a MIDI device. And eliminating all other interests several pages in.

 

Thoughts, ideas?/  << nice bounce eh?/

 

 

 

 

 

[mudmanc4]

Third keyboard now bouncing, yes the latest I'm typing on is a membrane, I can fiind nothing on the net about this issue.

 

I suppose the issue could be with all three KBs however unlikely.

[mudmanc4]

kbdrate -r 32 -d 250 

 

Improved the issue by a factor of 99.9%

 

https://linux.die.net/man/8/kbdrate