Texas Instruments TI-99/4A Repair - The Flaky Mitsumi Keyboard

In this video I'll be restoring functionality to the keyboard in my beige model TI-99/4A computer. What you'll see is a common problem with these Mitsumi keyboards as they age. I found two new old stock keyboards to replace my damaged one, but doing a keyboard swap was not the only thing needed to restore this machine...

[@eightbit1975]

I think all of the membrane Mitsumi TI99/4A keyboards belong in one location....my firepit.

[@rickibaron4816]

You could have saved yourself both time and money by contacting a TI994a user group on the Internet. This is a common problem with the beige consoles. The black keyboard will work on the beige computer.

[@MaxsGarage]

I’m aware they are interchangeable but I wanted to keep the beige machine stock and use the same keyboard. Plus since it’s an easy fix and it was cheap enough I didn’t have a problem buying the NOS keyboards and fixing them.

[@johneygd]

I wonder how even those new old stock keyboards could not function properly,or the outside heat temperature could,ve a bad influance on the membeame by wearing it out or it could cause oxidation etc,,,
Anyway if those ti99 keyboards are prone to failures overtimes,i would,ve think a tripple times before buying a ti99,now i have just to wait and hope for the best.

[@dingusbingus7463]

I just recently got one of these, keyboard is non-functional, other than that it boots without issue. When i opened it up there was no shield for the keyboard, and something that looks like lithium paste on one of the chips

[@michaelstoliker971]

That first 9 =-pin port is a serial printer port.

[@kyledross]

The 9-pin port on the back is for the cassette player/recorder. The 9-pin port on the side is for joysticks. There is no serial port on the console... that was available as a sidecar expansion or an expansion card in the Peripheral Expansion Box.

[@winman4862]

Sweet man!

[@AllGamingStarred]

No WASD is weird as fuck