Please help me understand what's wrong with my Unicomp

[stratokaster]

I have a Unicomp Spacesaver M keyboard that is acting strange.

Sometimes there are troubles with the following keys: `, 1, q, a, z. One moment they are perfectly fine, the next moment they are not registering and sometimes they are randomly repeating (so I press Z only once and get a bunch of Zs instead). Sometimes they work okay by themselves, but don't register if pressed together with the left Shift. But if I twist the keyboard, those strange signs will go away for a while.

I have read somewhere that such a behaviour is a sign of missing rivets. I opened the keyboard and all the rivets are perfectly fine.

So what's my course of action in these circumstances?

[Muirium]

If it's new: a refund / replacement.

If not: oh boy. It'll be a lot of work to pinpoint what is the underlying problem.

[stratokaster]

Unfortunately, not new...

[ohaimark]

Sell the keycaps and buy a new used one for $40.

[stratokaster]

Well, I guess it's an easy thing to do if you're in the US, but I'm located in Ukraine and Unicomp boards are kind of rare here.

I like this Spacesaver M because it's an older model which has 1.25U bottom row modifiers.

I guess I will have to open up the assembly and see if the membrane is damaged. Obviously I'll have to screw mod it afterwards It should be either the membrane or the controller.

[XMIT]

This is a membrane issue.

Have a look at the Model M membrane, which hasn't changed in layout in 30 years. This is the best photo I could find quickly:



The keys you mention - `, 1, q, a, z - are all on one "column". Did you spill anything into the keyboard?

A full bolt mod is your best option here but yes it is very labor intensive. When you have everything open gently clean the sensing sides of the membrane and both sides of the mylar sheet between the membranes with isopropyl alcohol and a lint free cloth. Also use a pencil eraser to clean the edge connectors on the membranes where they meet the controller.

There is a tiny chance that there is a cracked solder joint or something on the controller but I doubt it. If the bolt mod doesn't make things go away - and you don't have another controller to try - look for cracked solder joints.

Good luck!

[stratokaster]

The keys you mention - `, 1, q, a, z - are all on one "column". Did you spill anything into the keyboard?

A full bolt mod is your best option here but yes it is very labor intensive. When you have everything open gently clean the sensing sides of the membrane and both sides of the mylar sheet between the membranes with isopropyl alcohol and a lint free cloth. Also use a pencil eraser to clean the edge connectors on the membranes where they meet the controller.

Thank you!

I haven't spilled anything into the keyboard. In fact, when it arrived to me, the ` and 1 keys were already occasionally repeating. It just became worse over time.