Two dead LK201 keyboards

[Peter Coghlan]

Paul Koning wrote:
> 
> Gentlepeople,
> 
> I'm doing some work with my Pro 380 over the holidays, but have run into a
> snag because both my LK201 keyboards are dead.  They fail poweron self test
> -- LEDs stay on and no response to any keypresses.
> 
> The odd thing is that the circuit board itself seems ok; I had a spare board
> that tests fine by itself, so I installed it as a replacement control board
> on one of those keyboards and now it fails.  So that suggests there's
> something wrong with the key array that breaks selftest.  
> 
> I don't understand that because the documentation says a stuck key would
> produce a selftest pass along with an indication reporting stuck key.  And
> while I know LK201 keyboards don't like spilled liquids, one of those
> keyboards definitely hasn't been abused that way and I don't see signs the
> other one has, either.  So having both fail the same way is puzzling.
> 
> Any ideas?
>

I wonder what happens if several keys are stuck/shorted?

It might also be good to check if the microprocessor (8051?) is running.

(I've got at least two or three LK201 keyboards that are all acting
erratically :-(  I'm not sure I have any good ones left.)

> 
> I'm considering building a PC keyboard LK201 emulation, should be a fairly
> simple bit of Arduino code. 
>

Supplies of good non-USB PC keyboards are probably beginning to get harder
to find now too...

Regards,
Peter Coghlan.