KIM-1 keyboard repair

The KIM-1 keyboard is a special one. Made especiallyfor the KIM-1, as you can see in the SST switch. It shows its age in the design, and looks quite familiar to the keyboards hand-held calculators of the 70ties.

In those days replacement keyboards could be bought. I have repaired several KIM-1s with it. The older revisions were worse than what appeared on later revisions.

Original KIM-1 version, SST switch on the right.

KIM-1 Rev D, SST switch on the left.

The keyboard is connected to the mainboard with two screws, as you can see on the next image, and the solder connections on the front of the motherboard to the top of the keyboard.
You also see seven holes with access to screws on the bottom of the keyboard. Those keys hold the top of the keyboard connected to the bottom part. Unscrew those seven to get inside the keyboard. Leave the two screws not in a hole alone!

Over time the keyboard may develop problems like stick keys and non-responsive keys. Due to wear or dirty contacts.

A post in the vcfed.org forum may be helpful to fix some of these problems.

User Mindwalker posted this:

I (mindwalker) remember cleaning the keyboard at one point and I found this picture from my archives.
It seems the key membrane connects to the PCB over four contacts right on the bottom row, you probably have a bad contact there. Cleaning and (carefully) tightening the screws may cure it! Just be careful with the membrane.

Or you could replace the keyboard with other keypads:

An article in KIM User Notes 10/11 has this advice for the first Revisions key (No Revision, Rev A, Rev B):