Toshiba Satellite Pro 420CDT Keyboard problems

[e1z0]

Hello for everyone!

I have some problems with Toshiba Satellite Pro 420CDT maybe someone has similar problems or can point me to the right direction. I don't touched this model for a while and it just laid down in the drawer. However recently i grabbed and turned it on, noticed that the keyboard does not work as expected, some buttons does not work at all some just presses themselves (after first click). Tried to replace the keyboard (own 2 of them) the same problem, ordered one on ebay, it arrived and i checked it as well, the same problem persists and the same buttons does not work. Tried to boot from install media (do not use installed os), the same problem, the battery is removed, cmos battery is alive, tried to remove it either, the same problem. I have uploaded the video with this problem. It's really nice model, I mainly used it with DOS, it would be nice to see it working again.

Thanks in advance!

 

[TH2002]

It would probably be a good idea to check out the keyboard connector on the motherboard and the surrounding area to see if there is any visible corrosion.

Unrelated to the keyboard problem, but I also took note of a high-pitched whining noise in your video - usually, that indicates the LCD inverter board is failing. That will either need to be recapped or replaced.

 

[3lectr1c]

There's a CMOS battery in these that leaks. If you haven't removed it, do so. It may have caused board damage that could explain the issues. A laptop I have that had damage from this battery also has a high pitched noise, related to drive access. Likely caused by the damage.

 

[modem7]

Seconding the investigation of possible damage caused by a leaking battery. I have a couple of the later model, the 430CDT. The cable from the keyboard plugs into a connector on the system board, right next to where the CMOS/RTC and backup batteries are. On my second 430CDT, leaking batteries have damaged that connector beyond repair.

 

[e1z0]

Hi, there are no leak from the batteries. Now i have disconnected the internal keyboard and connected external one via PS/2 after turning it on, looks like some key is pressed (the same was with internal keyboard) and sound starts beeping...

 

[TH2002]

Given how the computer locks up and refuses to POST in the second video, I think what you're probably dealing with is a bigger problem wherein the keyboard is merely a symptom.

Toshiba laptops from this era will similarly get stuck on a blinking cursor if the primary boot device/HDD is faulty, although I can't recall if there are similar beeps in that situation. I know the keyboard being disconnected in itself shouldn't be causing those beeps though.

Also, the high pitched noise only starts when the backlight fires up. That part is definitely an inverter board related problem; if you have any plans to get this up and running it would be best to get that addressed ASAP. Only a matter of time before the caps on the inverter board blow themselves up and leave you with yet another component to replace - that happened with my 420CDT.