So I recently got this keyboard from Ebay after somebody posted it
here. The keyboard stems from a Pravetz 8A computer, which is from what I understand the Bulgarian counterpart of the Apple IIe. The 8A was build between '86 and '88. If you want more information about it here's what I have found:
http://www.pravetz.info/pravetz-8a.htmlWhen it arrived it was extremly dirty and the keycaps were in a disgusting condition. For those who never bought an old keyboard, the first step is usually to put the keycaps in some warm water with dental tablets. They didn't really help this time and I had scrub each keycap - in hindisght that was a good decision since the legends are engraved. The keycaps are not doubleshot and probably ABS. They have a slightly spherical profile and feel very solid.
Here's a picture of the spacebar stabilizer, it's a bit squeaky and needs some lube/grease. It's actually not as angled as it seems on this photo.
The keyboard features some cross-stem switches (not MX compatible), most of them with black housings, but with some brown and beige housings as well. The switch on the spacebar has a grey stem and feels heavier, but I couldn't feel a difference between the different housing colors, I don't think they make a difference. I don't know what exactly that is on top of the grey stem but it didn't come off. The enter key is the only key that uses two switches.
Now to the switches. As you can see the switches are secured with some screws on the PCB. I don't think there's an option to plate mount these switches.
From the outside you can already see the most important part of the switch, the reed switch. Opening a switch is not as easy as you would think, there's a part of the housing molten so that it doesn't open without scraping a bit of the molten part away. Hard to explain, but worse than glue. There's also an additional tiny copper pin that goes through a tiny hole to prevent opening it as well. If you noticed, one of the legs to fix the switch on the PCB broke off
The switch inside is quite simple, a magnet is attached to the slider and goes next to the reed switch when the key is pressed. A reed switch works with two very small metal plates that connect when a magnet is brought nearby. The slider itself only hits the bottom of the housing, it's not really clear on the photos.
And that's it! Here, have a typing video:
