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General => General Technical Chat => Topic started by: coppercone2 on January 03, 2019, 03:35:37 pm

Title: lenovo laptop keyboard failure mode o-o
Post by: coppercone2 on January 03, 2019, 03:35:37 pm
so the keyboard on my new lenovo is acting up. if i press the shift key hard, it seems to make the display malfunction with what looks like a old noisy analog signal with lines and the speakers make a horrid buzzing noise.  :palm:

it also latches up in this state. horrific.
Title: Re: lenovo laptop keyboard failure mode o-o
Post by: tom66 on January 03, 2019, 03:46:54 pm
My guess is you have bad solder on one of the processors on the motherboard and pressing the keyboard is flexing the PCB causing this issue.
Title: Re: lenovo laptop keyboard failure mode o-o
Post by: coppercone2 on January 03, 2019, 03:49:26 pm
how come both shift keys stop working in linux but they work to put the bios password in/
Title: Re: lenovo laptop keyboard failure mode o-o
Post by: German_EE on January 03, 2019, 07:03:30 pm
When you first turn your laptop on the keyboard interfacing is controlled by the BIOS and it's almost but not quite at hardware level. Once you boot linux the keyboard driver overrides the BIOS and enables things like softkeys for AV control.

Finally, I agree with tom66. You have a loose BGA solder ball somewhere on your laptop PCB and pressing the shift key is enough to generate the problem. Take the machine back, that's what warranties are for.
Title: Re: lenovo laptop keyboard failure mode o-o
Post by: TimNJ on January 03, 2019, 09:36:02 pm
Quote from: tom66 on January 03, 2019, 03:46:54 pm
My guess is you have bad solder on one of the processors on the motherboard and pressing the keyboard is flexing the PCB causing this issue.

Could be. Once upon a time, I tightened my CPU heatsink too much and it caused my computer to either BSOD or not start at all. It wouldn't recognize the RAM. Loosened the heatsink, and it worked.Apparently a common problem, according to Google.