Commodore-Keyboard-Tester

This is a tester for Commodore matrix keyboards for the following compurters:

• C64
• VIC-20
• PET/CBM
• C16
• C128
• C128D
• SX-64

It can measure the resistance of every single key, which requires a multimeter and two 4mm lab cables.

Case (3D printed)

The 3D printed case offers a better protection of the bottom side and looks a bit nicer, than the stand off solution. It works with all released versions (100mm x 70mm PCB).

Recommended screws are 4 each of C2.9 x 6.5 (self cutting, DIN 7981). The drill diameter is 2.5mm.

In case it is desired to use 2mm lab jacks, a 3mm deeper case (Rev. 2) has been released.

Rev. 2

Rev. 2 is mainly a nicer looking silkscreen, than Rev. 1. Technically, this version is not any upgrade.

Info about rejuvenation keyboard rubber

As I said in the documentation, one reason for bad keys is the oil that is sweating from the conductive rubbers over the decades. This can be removed by soaking the rubbers in a mild caustic solution for at least 24hours.

Jeff Birt did some great research on this topic, which cou can find here:

Hey Birt! (Youtube): Resistance is futile Rejuvenating vintage computer keyboard key contacts

Instead of ammonia, I am using a lye (NaOH) solution and I wrote somethng about it on my website:

Rejuvenating The Conductive Rubber In a (Commodore) Keyboard

After treating the keyboard rubbers, it might make sense to measure their resistance before installing them in the keyboard again. I found Jeff Birt's ficture quite nice for doing so.

https://github.com/Jeff-Birt/C64_C128_Amiga_Mitsumi_Key_Tester