jd40 build, keys not registering

[bluehairedpete]

Hello Friendly Geek Hack folk,

I'm putting together the JD40 basic kit with clears. This is second time I've ever used a soldering iron, but it felt like it was going well. I got the whole thing wired up, and in my initial key tests, everything registers *except* three keys, right in a vertical row:
Top side:


Under side:


I'm not just using text pad to test, I've validated that the computer registers input on all keys except these three  (using xev ) . My thought is that I may have to de-solder all of the keys, then flip the board over and validate that I don't have any cold joints on the silk screen side.  I wanted to check in with you guys for advice before I went through with it though.  Any alternatives?  Maybe there is a diode or two I can dump a bunch of solder into from this side?   I don't have a spare switch to exchange with a non-registering one.. and I can't get enough leverage to pull a single one out w/o de-soldering all the switches. 

Also, since I have your attention, I've had a finicky experience with the usb plug.  It works, then it doesn't work, it hasn't worked in a while. Since i'm still in the build stage I've taken to plugging my external cable directly into the teensy.. but I've checked the continuity between the usb plug and the pcb about a thousand times  and it seems to be happy.. is it possible that is also related to a poor joint on the silk screen side?  My next attempt on that front is to start with a new set of wires and not burn off so much insulation.

[strict]

My first step would be to try to clean up the solder joints on the Teensy. If you've got a whole row not working like that, the Teensy is a very good place to start.

I would also try to clean up your wiring situation on the USB plug, maybe it's just the way the photo was taken but it looks like you might have multiple solder bridges between the 4 wires. Keep the amount of wire core that you expose to an absolute minimum, you could probably stand to reduce the amount your stripping by at least 3x or 4x. You can see the amount of exposed wire on the JD40 I built here

Good luck and keep us updated!

[bluehairedpete]

My first step would be to try to clean up the solder joints on the Teensy. If you've got a whole row not working like that, the Teensy is a very good place to start.

Huh, thanks! I wouldn't have thought of that.  I can certainly take another stab at that.

I would also try to clean up your wiring situation on the USB plug, maybe it's just the way the photo was taken but it looks like you might have multiple solder bridges between the 4 wires. Keep the amount of wire core that you expose to an absolute minimum, you could probably stand to reduce the amount your stripping by at least 3x or 4x. You can see the amount of exposed wire on the JD40 I built here

My continuity checks imply there are no solder bridges, but I imagine when I bend the plug across to get it into the teensy a short could certainly happen.  Thanks for the pic, that's helpful to see, and to visualize a goal of what my joints might look like one day  .    I'll get some fresh wire and have another go at it. 

I'll keep y'all posted, thanks for your help.

[bluehairedpete]

> My first step would be to try to clean up the solder joints on the Teensy. If you've got a whole row not working like that, the Teensy is a very good place to start.

..

> I would also try to clean up your wiring situation on the USB plug,

You, sir, have excellent instincts.  Re-soldered the teensy, brought out some new wires for the plug, and the whole thing works w/o issue.   When I get my hyper fuse keys I can take this sucker to work.


The plug:


All together now:


The board:



For any solder neophytes out there, this project is FUN. If it was easy to break by making stupid mistakes, then my board would not currently work. I learned that soldering w/o flux is a bad idea and that old usb cables are a great way to harvest wires... that will be soldered onto usb plugs. Also, to expose as little wire as possible, I used the soldering iron to burn off the insulation at the end (rather than use my poor excuse for a wire stripper ) .   

Thanks for your help strict.

[strict]

Nice work! Glad I could help