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Mitsumi TI-99/4A keyboard (to pillage)Mitsumi
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Cherry MX compatible key switchesAkko
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x 47 | |
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Diode 1N4148 TH (Optional) |
x 1 | |
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15-pin 0.1Samtec
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x 1 |
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OnShapeOnShape
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EasyEDA |
KEYBOARD/4A-99
New version 1.1: Now re-use the original alpha-lock switch as well.
Many Texas Instruments TI-99/4A have been cursed by cheap Mitsumi mylar keyboards which are prone to failure with age. Even the NOS replacement keyboards are often in bad shape.
This project aims to provide a drop-in replacement for the Mitsumi keyboard using modern Cherry MX compatible switches, with adapters for the original TI-99/4A keycaps.
This project is intended as an upgrade for an existing Mitsumi mylar "keyboard". As such, you will require one of these (probably non-functioning) "keyboards" to begin. We will be re-using all of the original keycaps, the metal PCB support strips and screws, and (optionally) the space bar support brackets and 15-pin ribbon connector.
Don't feel bad for it. That brown abomination should have been relegated to landfill years ago. It's one of the lucky ones!
There are a number of 3D printed parts, including keycap adapters.
Further documentation can be found on GitHub
KEYBOARD/4A-99
*PCBWay community is a sharing platform. We are not responsible for any design issues and parameter issues (board thickness, surface finish, etc.) you choose.
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