Toshiba Satellite L750D Keyboard Issue (some keys)

  Claustro84 15:38 09 Feb 2018

Have a Satellite L750D which was working absolutely fine until recently. I had put new thermal paste, a routine task for me, and had reinstalled Windows 10 64. There were no issues and I was able to use the laptop normally after this procedure.

However, out of nowhere, specific buttons do not work , including CTRL, A, S, C and V (and Others).

I thought a bad connection was affecting it so I removed the keyboard and put it back. The problem persisted.

I tried removing the drivers from Windows, but the problem appears to be deeper, as the same buttons also do not work in the BIOS (eg when typing a password).

I tried removing the keyboard cable again, the battery of the laptop and the CMOS battery. Held power button for 60 seconds to reset CMOS. After a reset the problem persists again.

I then decided to update to the most recent available BIOS version, as the current one was severely outdated. The update went fine, but the problem persisted.

I then thought that maybe the keyboard itself is problematic. Luckily I had another Satellite variant sitting around. I tried the keyboard from that one... and the problem persists - on the exact same keys both in BIOS and in Windows. So it can't simply be the keyboard. Trying a Linux live CD confirmed that the problem persists.

I am very confused here. I am certain that I caused no damage to the board , and I am 100% certain that the keys worked at first without problem , as I was able to perform a full installation of Windows 10 and Office, having to use the keyboard to type the product keys for each respective software. The computer was working fine, as it should have been expected to, then suddenly this problem surfaced and has left me perplexed.

I could try to find an identical replacement keyboard, but the fact that the second keyboard tried works and POSTs normal yet does not type the same specific keys is a major concern for me.

Temperatures are fine and the system otherwise has no issues.

What should my next course of action be?

  alanrwood 15:58 09 Feb 2018

Sounds like either a keyboard plug/socket/connector problem or maybe a motherboard problem. (One of the K/B strobe tracks broken. I hope not).

  john bunyan 16:03 09 Feb 2018

Just to be sure, can you borrow an external keyboard? Quite cheap to buy and useful anyway. It would narrow the issue down.

  john bunyan 16:05 09 Feb 2018

Or try the on screen keyboard

On screen keyboard

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