IBM XT keyboard acting up- phantom typing?

[qnaal]

I've used it for a couple of days, but it will occasionally act up, and type a bunch of random****.

It seems shock related- even though sometimes it would not respond badly at all to being banged around a bit, I noticed a few times that the 'phantom typing' would occur in response to the keyboard being shaken or tapped.

So, it will act up for a bit, and a few minutes later it will start working again as normal.
I have detected no patterns to this behavior.

I fear I may have damaged the controller board?
A mess of alligator clips- I may or may not have shorted the +5v to data at some point, or maybe a few other places ...

or could this just be a case of dirty contacts, interacting somehow with how it decodes the capacitive matrix? if that's how that works?
I noticed at one point that, while the rest of the board seemed to be operating normally, the numpad period key was not responding- unless I held it down or repeatedly hit it, in which case it fired sporadically.
I could run further tests on this, but right now it's all unplugged and off my desk.

also, I did a pretty ****ty job of soldering the pins onto the teensy, and might have somehow heat-damaged something on there? and also the whole thing is connected in a mess of breadboard, jumper wires, and alligator clips... but I don't think it's any of that since response to shock seemed to be isolated to the board itself.


any thoughts?

[CPTBadAss]

If you think you did a bad job soldering, I'd check that first. Use a multimeter to check continuity. That seems to be a cause for double-typing.

[qnaal]

If you think you did a bad job soldering, I'd check that first. Use a multimeter to check continuity. That seems to be a cause for double-typing.

The only thing I soldered here was the pins onto the teensy, and the connections all look good- it's more the melted plastic that worried me.
If the alligator clips could be holding a bad connection on the other hand...


And this seems a far cry from doubletyping- eg I could plug in the usb from the teensy, and as soon as it finished loading, be greeted by a barrage of <tab>s and 'z's.

[CPTBadAss]

I've had that issue in the past with two keyboards: my Pure and my 700R. I think the cause was that something was shorted somewhere when the PCB touched the case. Maybe you an check for a short with a multimeter?

[qnaal]

could perhaps be, I did take it apart a bit...

something I'm working on just blew up on me though, so I can't do any tests right now

[qnaal]

Having taken the thing apart, I notice that wiggling the connector, where the cord plugs into the controllerboard, causes output.

I tried to type a sample here, but it closed the browser window.