Atari 800XL Keyboard Question

[gandalf1369]

I am in the process of trying to "rehabilitate" an 800XL that has been sitting boxed-up in my basement for more than 15 years.  I set it up and connected it to my Commodore 1702 monitor and it boots up to basic with no problem (except for the really lousy video!) BUT the "/" character appears on the screen continuously.   It is as if I was pressing the "/" and not letting go.

 

I will be installing an UAV video upgrade this weekend to hopefully fix the video, but I was wondering if anyone has any ideas about the keyboard problem.  Any possible easy fixes??  If it helps the keyboard has a Stackpole label on its bottom.

 

Appreciate any suggestions - thanks . . .

[xrbrevin]

welcomes!

im thinking debris under the keycap or a spillage in the contact PCB/membrane area. look for a physical cause and move onto electronic if necessary.

keyboard issues commonly entail damaged traces or wires but this results in lack of function, not a constant press like yours has.

its possible a short has occurred as in order for a keypress to register, 2x of the 24 keyboard wires have to make contact. a quick check of the schematic shows that / is pins 7 and 15 so its unlikely a short would occur in the ribbon connector or socket.

 

 

[Sugarland]

Try pressing / many times to try to free it up. Otherwise you may need to disassemble the keyboard and take a look at the mylar on the stackpole.

 

Basements are often not good place to store computers because of humidity. If the basement is unfinished with no air circulation that's not good. That may have caused the keyboard issue.

Edited January 24, 2020 by Sugarland

[MagicMarc-er]

Welcome!  This site:  http://www.best-electronics-ca.com/ will be your new best friend for parts and, since you might need a new keyboard mylar, this is where you'll find them.  

[gandalf1369]

Thanks everyone for the replies and suggestions.  I did look for debris under the "/" but found nothing.  The key appears to move very freely down and up so it isn't stuck.  After I get the UAV installed I'll take another look . . .  

[hueyjones70]

Sometimes the mylar gets a slight indentation that makes the key contact points to be permanently touching each other. If you haven't fixed the problem yet, I have found that you can get some of those stick-on paper rings that are used as reinforcers for pages in a notebook and place it over the appropriate key contact on the mylar. This creates a space between the and that takes care of the problem.