Kaypro II Keyboard Repair

I was recently went to a swap meet at the System Source museum in Hunt Valley Maryland and scored a Kaypro II off the "free pile". The system appeared to have suffered some water damage and even though the power LED came on, I got no other life out of it. Inspecting the system and found that the main unit looked pretty clean inside, but the keyboard on the other hand suffered considerable water damage. I also had an Kaypro system that I had acquired a long time ago but it's keyboard didn't work either, so I need to get one of them working. 

Here is a look at the inside of the keyboard before I started. 

Here is a closeup where you can really see the damage. 

I quickly realized that the only way to properly fix this was to strip it down, clean everything and re-assemble it. The first step was to remove the key switches. I used a de-soldering pump to unsolder the two contacts on each switch. To get the switch out of the frame you need to push in the tabs on either side of the switch. Some of the switches needed to be pried loose because the rust was holding them to the frame. Be sure to note where the switches with the light colored bodies are, these are slightly different then the others and need to go back in the correct locations. 

Here is the keyboard with all the switches removed.

The metal frame is held in place with two riveted standoffs in the upper left and lower right corners. My only option was to drill these out and figure out how to re-connect them later. 

To cleanup the frame I started with a wire wheel brush in a drill to get off the worst off the rust and then used some fine grit wet sand paper to finish the cleanup. It doesn't need to be perfect since you really don't see it when the keyboard is assembled. The final step was to give it a coat of black spray paint. I forgot to take a picture of that before I re-assembled it. 

The circuit board looked pretty bad, but some scrubbing with soap and water cleaned it up of nicely.

The board has a row of diodes across that top that are under the frame so would be hard to replace once re-assembled. I tested these with a multi-meter to be sure they were good before I re-assembled it. 

The most tedious part of the repair was cleaning the key switches. I initially started testing each one with a multi-meter and only taking apart the ones that didn't work, but so many did not work well that I decided to skip the initial testing and just clean all of them. To get the key switches apart simply lift the plastic clips on either side. 

Here is a look at a particularly bad key switch. I cleaned up the plastic with a Q-Tip and some alcohol. If the contacts were really dirty I used a little emery paper first then the alcohol.

In most cases I did this without removing the contacts, but in come cases they contacts were so dirty that I decided to remove them to give them a good cleaning. 

After re-assembling each switch I tested it with a multi-meter. I did occasionally find one that still didn't work so I had to re-open it and clean it some more. 

With the switches cleaned I re-soldered them in. To clean the keycaps I just soaked them in a bucket of soapy water then scrubbed with an old toothbrush. 

I did not have the tools to re-rivet the metal frame, but did have some rivets that fit into the standoff so I just glued them in place with some super glue.  

Here is a the fully re-assembled keyboard:

The inside of the case also had some rust damage. Like the other rusted parts I cleaned it up with a wire wheel and then gave it a coat of spray paint. You won't see the inside so I didn't bother to try to match the blue, I just used what I had.