DEC Keyboards with sticky keys

william degnan billdegnan at
Thu Nov 16 09:59:50 CST 2017

On Thu, Nov 16, 2017 at 10:48 AM, Douglas Taylor via cctech <
cctech at> wrote:

> I have a couple of LK401 keyboards and they generate a 'keyboard error -
> 4' error on power up test when attached to a VT420.  The problem seems to
> be one or more keys that are 'stuck on'.
> When the keyboard is turned upside down and shaken I can get the self test
> to pass.
> Is it possible to open the keyboards and repair this type of problem?
> I also have LK411 keyboards that have a PS/2 type of connector, is there
> an adapter to let me use these keyboards instead of the LK401s?  Are the
> signals the same, only the connectors being different?
> Doug
Try this?

If this is like your keyboard, you can use a product called Keypad-fix

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