Jump to content
Sign in to follow this  
hueyjones70

800XL not responding to keyboard input

Recommended Posts

I have an 800XL that does not respond to keyboard inputs for ESC, and the 1-6 keys.  I thought I had a bad mylar but I tried two different mylars and a mechanical keyboard.  When I used the mylars and the keyboard on a different computer, everything worked as it should.  Where do I start my search for the problem?

Share this post


Link to post
Share on other sites

Swap the keyboard mux chips (the two little 4000-series ICs) and see if the non-functional keys change.

Share this post


Link to post
Share on other sites

Check the connector that the ribbon cable plugs into.  Maybe some debris, dirt,  gunk or oxidation or something only on that contact point for that trace preventing a connection there?   

 

Just trying to think of the simple stuff first to rule out.

Share this post


Link to post
Share on other sites

Does the red LED turn on when you turn on the computer?

 

Is it one of the mechanical keyswitch type keyboards? If so the keys may need considerable excercise (hundreds of repeated pressing of each key) to start registering again after years of disuse.

 

I agree swapping/replacing the 4051's is the first target though.

 

XL keyboard types for reference if you can match up which yours is:

 

Share this post


Link to post
Share on other sites
1 hour ago, Nezgar said:

Does the red LED turn on when you turn on the computer?

 

Is it one of the mechanical keyswitch type keyboards? If so the keys may need considerable excercise (hundreds of repeated pressing of each key) to start registering again after years of disuse.

 

I agree swapping/replacing the 4051's is the first target though.

 

XL keyboard types for reference if you can match up which yours is:

 

I tried one mechanical and two mylar and got the same result. I will try cleaning the contacts and check the ICs. I forgot to mention that before the unresponsiveness started, when I turned it acted as if a key had been pressed and had gotten stuck. That led to the disassembly of the computer and checking other keyboards. The stuck key effect didn't happen again.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...