Iris build: key activates entire column

[ergonaut]

Hello everyone,

I'm currently building an Iris keyboard from keeb.io. I finished up soldering everything yesterday evening and flashed the QMK firmware on the Pro Micros, using the default Iris keymap for now. So far, everything works fine, except for the '1' key. Pressing that key apparently yields the keycodes for the entire column it sits in − if I press it, I get '1qaz'. However, the other keys in the same column work normally.

Do any of you have an idea what could be wrong and how I can fix it?


Thanks!

[JianYang]

Diode the wrong way around?

[ergonaut]

Diode the wrong way around?

Thanks, I just checked the diodes. I think they're all in the proper direction.

[suicidal_orange]

Is it in a metal case?  Could be shorting...

[ergonaut]

Is it in a metal case?  Could be shorting...

No, it's not. I don't really have a case for it, the kit only included the PCBs and the plates, which are made from the same material as the PCB I think.

[xack]

hm... to me that also sounds like an diode issue... could you upload a picture of the soldered pcb? that could help

[ergonaut]

hm... to me that also sounds like an diode issue... could you upload a picture of the soldered pcb? that could help

Sure, I can take a picture tomorrow.

[ergonaut]

OK, here's a picture. The key in question is the second from the right in the upper row. The diodes were soldered from the other side, but on the column in question, I have already added some solder from this side just to make sure.



Thanks!

[JianYang]

Yeah, that looks fine. You are going to have to take some measurements with a multi-meter. First would be to test the diode. It should have around ~600mV drop in one direction and seem open circuit in the other. Then you will have to check the row and column connection to both sides of the switch to make sure that they are sane with no shorts.

[ergonaut]

Yeah, that looks fine. You are going to have to take some measurements with a multi-meter. First would be to test the diode. It should have around ~600mV drop in one direction and seem open circuit in the other. Then you will have to check the row and column connection to both sides of the switch to make sure that they are sane with no shorts.

Thanks! I don't own a multi-meter myself, but I think there is one at my workplace, so I'll try that tomorrow.

[ergonaut]

Okay, so I took the keyboard with me to work today. I have never used a multimeter, so I asked my hardware colleague for help. He did some measurements on it and concluded that the diode is not defective or the wrong way round. He suspects that I accidentally soldered two contacts together on the other side, but he wasn't sure himself. Unfortunately, he did the measurements rather quickly and I didn't take notes, so I don't know for sure what he measured. Maybe I'll have to do it again myself.

Regarding his theory: I just learned soldering during this build, so it's absolutely possible that I messed it up somewhere. But I know I did a rather thorough visual examination after soldering it and didn't see anything suspicious. Just taking a look isn't easily done: if I'm not mistaken, I would have to de-solder and take out all the switches, which (given my lack of experience) might introduce other potential failures if done wrong. I wouldn't even know how to do this properly; I guess I'd have to alternate with the soldering iron between both contacts of a switch to warm them at the 'same' time and then quickly pull the switch out?

What would you recommend?

Another option might be to re-program the QMK firmware so that it puts out a '1' whenever '1qaz' is pressed. But I don't know if that's possible, and it's certainly not the most elegant solution.

[Rob27shred]

Okay, so I took the keyboard with me to work today. I have never used a multimeter, so I asked my hardware colleague for help. He did some measurements on it and concluded that the diode is not defective or the wrong way round. He suspects that I accidentally soldered two contacts together on the other side, but he wasn't sure himself. Unfortunately, he did the measurements rather quickly and I didn't take notes, so I don't know for sure what he measured. Maybe I'll have to do it again myself.

Regarding his theory: I just learned soldering during this build, so it's absolutely possible that I messed it up somewhere. But I know I did a rather thorough visual examination after soldering it and didn't see anything suspicious. Just taking a look isn't easily done: if I'm not mistaken, I would have to de-solder and take out all the switches, which (given my lack of experience) might introduce other potential failures if done wrong. I wouldn't even know how to do this properly; I guess I'd have to alternate with the soldering iron between both contacts of a switch to warm them at the 'same' time and then quickly pull the switch out?

What would you recommend?

Another option might be to re-program the QMK firmware so that it puts out a '1' whenever '1qaz' is pressed. But I don't know if that's possible, and it's certainly not the most elegant solution.

I would honestly take another look at the PCB as it really does seem like you have shorted 2 connections in some way. I just went through a similar process fixing a really janky AEK64 PCB & had quite a bit of certain keys actuating the whole column till I got all the proper jumpers figured out. Still not sure if I'll ever use that PCB even though I got it working because of all the janky fixes I had to do on it TBH.

Anyways that's besides the point, what I wanted to get too is that if it is just a solder bridge causing this it will be a very easy fix. All you need to do is run a clean hot iron over the bridge & the excess solder should jump on to the tip. Some flux will help also if you have any at your disposal. Really it's troubleshooting 101, start with the easiest fixes & then work your way up from there.

[ergonaut]

I tried to de-solder the switch in question. I did a very bad job and I think I destroyed the switch in the process. Well, I ordered two spares so it's not a big deal. Anyway, with the switch out of the way, I tried to have a look at the diode solder joints on the other side of the PCB. They looked OK, but maybe one of them overlaps a little with this other thing on the PCB (I don't know what it is). In the picture, I have circled the diode contact in question and the thing that it might now have contact with:



mod edit: couldn't see pic so rehosted it

[JianYang]

I tried to de-solder the switch in question. I did a very bad job and I think I destroyed the switch in the process. Well, I ordered two spares so it's not a big deal. Anyway, with the switch out of the way, I tried to have a look at the diode solder joints on the other side of the PCB. They looked OK, but maybe one of them overlaps a little with this other thing on the PCB (I don't know what it is). In the picture, I have circled the diode contact in question and the thing that it might now have contact with:

Show Image

It seems that that symbol is on the ground plane. In that case, fixing the solder will likely solve your issue.

[suicidal_orange]

First confirm it's connected, check for continuity between the switch pad/hole and the GND pin on the Teensy - if it isn't this isn't the problem.  If it is connected:

It's right at the top of the board so you could solder the switch back in then use a small file to rub away the solder connecting it to the symbol.  There are no other traces on that side of the board so can't break anything.

Alternately you could insulate the hole and pad on that side of the switch (not sure how generous the holes are, you could use a small paper tube or maybe thin superglue?) then carefully insert the switch and move the diode so it connects the tip of the switch pin to the bottom diode pad, bypassing the short.

[ergonaut]

Thanks for your suggestions, and also thanks @suicidal_orange for rehosting the picture.

I won't be able to work on the board until late next week, but I'll report back as soon as I get to it.