Lenovo Legion Y540 Keyboard Issue

2 years ago by better_than_nothin to c/diy

Problem

The laptop's keyboard works properly when the computer on first boots up, but if the computer enters any kind of low power state (i.e. goes to sleep, restarts, or shuts down) while still having a charged battery/power source plugged in then the keyboard stops working (even in the BIOS), except the backlight works and the brightness/accessory keys work. This problem persists in both windows and linux distros. On NixOS, the booting sequence messages a couple ACPI BIOS errors before starting and occasionally the kernel sends usb errors (error -71) which then crashes the desktop environment. When using 'showkey', some keys send very weird key presses.

What I've Tried

multiple Operating Systems
updating the BIOS, then flashing it back
unplugging the keyboard from the motherboard, then replugging it

Lodespawn 2 points 2 years ago

Are there any "switch off USB to conserve power" settings in the BIOS?

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better_than_nothin 1 point 2 years ago

No, however there are a couple other settings that are concerning:

Always On USB [Enabled] : The USB ports can charge external device during low power states.
Charge in Battery Mode [Enabled]: Enable or disable chargin external device when system is in hibernate or power-off state and in batter mode.
Fool Proof Fn Ctrl [Enabled]
DPTF [Enabled]
Slow Slew Rate for IA Domain [Enabled]

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better_than_nothin 1 point 2 years ago

For the record, disabling Always on USB hasn't worked.

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Lodespawn 2 points 2 years ago

Yeah the others don't seem like they would be the solution. Have you tried a USB keyboard? Not as a permanent solution, but more to see if other keyboards do it too.

Is the laptop still in warranty? If so, take it back, if not then maybe see if you can source a replacement keyboard. Might be annoying to replace depending on the chassis but probably easier than replacing the whole mainboard.

How does the cable connecting the keyboard to mainboard look? Have you tried reseating it? Is it running through any pinch points?

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better_than_nothin 1 point 2 years ago

Yep, this is a very very common problem.

I do use an external keyboard for this computer but on linux, the usb errors cause kernel panic, and I'm sure I could find a way to disable that input but I have no idea.

The laptop is no longer under warranty, but this doesn't seem to be a hardware issue as the keyboard works perfectly on first start up. I have tried reseating the keyboard to the main board, but I haven't removed the mainboard itself, and I can't tell if there's any pinch points since the cable runs all the way behind the board, but the end looks clean.

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