Please help: Resoldering switches ducky one 2

[Shot4213]

Hi everyone, first time here and first time modding a keyboard. I desoldered all my switches and resoldered them after doing a stem swap. Now the qaz column and the caps lock shift ~ column no longer fire, control is always pressed, and I’m not sure what to do. Looking online, I think there’s a short but I don’t know what column or diode I even need to look for. If the pcb pictures here help, please explain. Sorry, I feel like I’m in over my head

[yui]

the 1st step would be to look around the key that has the problem, although your problem too me sound compound, as the ducky should have n-key rollover and so one shorted switch should not disable 2 columns. the easiest thing to spot though would be that shorted ctrl key, look around the switch pads for a solder bridge, and maybe if you have a multimeter test if the diode is good (should only conduct on way the multimeter should display an overload one way and a low resistance the other) as if overheated diodes can fail, and from what i have learned the solder ducky uses is rather high temperature, if you used zealPC switches they are rather sensitive to temperature too so maybe if you stayed on too long the plastic holding the contact melted. as far as the keys not working go i would guess that it would be a lifted pad, but as the columns seems to be on the other side you may need to test with a multimeter and a piece of wire to check what connect to what and what fixes what, for example is your windows key still works try to bridge it to A for example and see if it restores A or more.
maybe someone with more experience of the ducky could help you better

[suicidal_orange]

Looking at your pic it appears there are a number of damaged pads - can you confirm the purple ones are ones you had problem soldering?

These will not be shorts but breaks, and if those pins are vias you have quite a lot of poke-testing ahead of you but it's definitely fixable.

Which Control is it that's stuck?

[Shot4213]

It was the left control, but that seems to be working in the sense that they keyboard knows it was pressed. It doesn’t recognize the left windows control or alt, but the rgb lights up indicating a key press. Those are indeed the keys not working that you highlighted in the picture. When I did some short testing they seemed to still be connected to their respective traces, as each switch was able to show a connection when check against the nearest adjacent component. Is it possible that I missed one, and what should I do if it’s a bad pad?

Edit: the control windows alt thing was a software bug. Resetting the keyboard fixed that. The only issue is ~ 1 tab q caps lock a lshift z still not working

[suicidal_orange]

So the purple dots are connected to the blue squares?

[Shot4213]

Yes. The diodes are also still connected to the controller and I think are still good?

[Shot4213]

The green here are all connected together, and each blue pair is also connected. This was tested via a short tester so that’s why I’m stumped.

[suicidal_orange]

8 keys is not enough, there must be a break and there should be more keys connected to the green group.

What happens if you short the would-be green pin on Escape, Control, Windows or Alt key to any of the blues?  The whole 'column' could be connected to the controller through the dodgy pad on the Windows key, that would make sense.

[Shot4213]

Max grouping I could find on the keyboard was 8 switches, two sets of four keys for all of those sets. When I touch a faulty blue to a working green, like one found on the escape and e keys, the corresponding escape or e fires normally. It doesn’t seem like the faulty group is connected to anything on the bottom row. If you want, this is what the bottom row looks like

[suicidal_orange]

How bizarre, I really don't understand professional PCB designers.  If those 8 pins really are the whole group (and if there's no bigger group elsewhere it seems likely) then they must all connect to the controller through one of the damaged pads.

Can you read the writing on the square chip with the red paint(?) on it?  That's the only controller looking chip in your pics, if we're lucky it's a standard chip and we can find a datasheet showing where the I/O pins are.  Then you'll need to poke each of them until you find one that's not connected to a group of switches or the far side of the diodes.  Short that pin to one of your blue connections and it should type the correct letter.  Hopefully it has a nice trace to solder to as the pins on the chip are way too small (unless it happens to be on a corner)

[Shot4213]

I found the chip I think? it’s a holtek ht32f1654, but the font is really blurry and the paint makes it difficult. Am I trying to get a specific voltage pin to the blue pins or ground? Also the connection from the chip to the black diodes (those are diodes right?) still work. I checked by running through the chips pins while connected to diode end opposite the connection to the switch.

[suicidal_orange]

That's a valid answer - datasheet is in the Documents section here and the pinout is on page 24.  The dent in the corner under the red paint matches the pinout so you know what's where.

The green should be connected to one of the PAx, PBx, PCx or PDx pins but it isn't.  Some of them may be used for LEDs and PA11-13 look like the i2c connection which probably connect to the chip for RGB.  One of the others (probably on the side nearest the switches) will type the correct letter when shorted to blue.  The other pins in use will output other keys from the 'row' (the columns don't run top to bottom so who knows where the rows run physically...)

Looks like it's a 3.3v chip and all pins are at least 3.3v tolerant so no chance of frying it either

[Shot4213]

I couldn’t get an exact pin, but it’s one of pc5, pc6, pc4, or pb1. The issue now is how do I connect to something that small? I don’t see any convenient spot to solder to. Is there a way to find out where the trace is damaged, or what else should be my next step?

[suicidal_orange]

Sorry but it's the exact pin you need to find.  Hopefully it's not pulled to ground when the switch is activated...

I'm at work now so can't look

[Shot4213]

It’s pc4, and take your time, I’m just grateful that you’re helping out. This is the pin, and I don’t know where to go from here. I don’t have anything fancy like magnifiers or a really fine tip iron, so any advice would be great.

[suicidal_orange]

You don't have much luck do you!  If it were round the corner in PB2-PC8 you could have scraped off some mask and soldered to the trace, but no.

Which of the dead switches has a damaged pad on the green side, from my first pic it looks like only Q?  If so desolder that switch and hopefully through the hole in the  plate you can see a trace heading towards the controller.  You'll need to scrape that trace and solder a wire to it then stick the wire down (hot glue gun?  Not sure it will fit in the hole...) then run the wire through the switch pin hole.  So you don't heat and desolder the fix I'd suggest soldering it to the pin away from the PCB, and you'll need to connect that pin to another green pin as well to connect the other switches.

Hopefully that train of thought makes sense?

[Shot4213]

Just a picture to confirm before I go in. Are you sure it’s the q key? The pad by the q seems fine, or am I just seeing it wrong? Or do I have to just check all the switches?

[suicidal_orange]

On a proper screen A looks worse, and it's more in line with the controller chip which would be sensible.  That said are you sure about the pin on the controller?  It's the completely wrong side of the chip which is just stupid.  Much like routing a whole column invisibly through a single switch pad, and the designer did that...

You can see better which pads are damaged so try whichever switch that is - you can't break it worse than it already is.

[Shot4213]

Sorry if I’m misunderstanding, but do I just desolder the switch and stick a wire down there? I don’t have a magnifier or anything like that so I don’t know what I’m looking for. Also, yes I’m sure about the cross the chip thing. When I try other groups, they’re randomly distributed across the chip.

[suicidal_orange]

Desolder the switch and remove it then have a look at the other side of the PCB through the hole in the plate - hopefully there's a visible trace heading towards the controller (not just up and down to the other switches) that should be attached to a damaged ring around the switch pin.

[Shot4213]

Would masking the other pins on the controller and soldering directly to it work, or is that too risky?

[suicidal_orange]

It would work if you can do it without shorting the pins on either side.  Am I right in reading it has 0.18mm legs with a 0.22mm gap between them?  That is insanely small.  I guess you could insulate all the pins then just before the insulator dries completely scrape it off the leg you want to solder, then put a thin stiff wire touching the end and drag some solder along the wire onto the chip leg.  Not sure what you can use as an insulator though - nail varnish is recommended when you're done but what happens when you put a hot soldering iron practically on it?

I would be removing switches looking for a trace.

[Shot4213]

I’m trying that but can’t seem to find anything. Honestly, I’m kinda stumped on where I should go from here. The board really doesn’t want to give any hints either, seeing as how none of the traces show where they jump to the pin on the controller. Any advice on how I should go about the soldering fix, or if I should send it to a repair shop asking them to do it? My plan is to use kapton tape to tape off the surrounding pins, but I’m not sure if it’ll work with something this small. And even if it does work, what gauge wire should I connect back to the switches with?

[suicidal_orange]

Maybe we're thinking too sensibly.  As the trace goes to the far side of the chip maybe it comes out the top of the 1 key?  If you've got the four switches out (surely they wouldn't go from the end column...) take a pic, not sure what I hope to see but there has to be something!

The problem with tape is you need to insulate the sides of the legs as well so you would need really tin tape to get between them.  If you have an electronic repair shop locally (and they're open) I would hope they could do it in seconds and it's good to support small businesses.

What wire?  Thin.  You can wire a switch matrix using enameled magnet wire and that's not much thicker than a hair including insulation, but it's fragile and bends easily when tring to solder it.  For soldering to the chip I'd go for single core so there's no chance of a straw strand shorting, for soldering a trace on the front stranded as you could accidentally press on it and lift the trace when fitting the switch.  You'll only have one shot (unless you remove the next key left and it goes straight...)

[Shot4213]

I sent it in to a local ubreakifix asking the, to do the microsoldering job because they have the tools I don’t. Hopefully they sort it out, and I’ll give an update when they get back to me.

[suicidal_orange]

That's a great name for a company

Will be interesting to see how a pro does it, and with what.

[Shot4213]

Honestly, been a while and I just wanted to check back in for anyone unfortunate enough to be in my situation. I fixed it, with a lot of hopes a prayers. The ubreakifix took the board for a week, said they couldn’t fix it, and gave it back. I ended up using what suicidal_orange said and used magnetic wire to directly connect the switch to the pin on the chip, seeing as how I couldn’t find any other solder points. It was ugly, and I did it by using kapton tape on the other legs. I put it there using tweezers, and pretinned the iron and the wire. I ended up pretty much not using any more solder because the joint was so small and hard to get at. I taped down the rest of the excess wire using the nonconducting kapton tape and I think it should be fine. The picture of the 2 tapes side by side is the one that I just finished, and the excessive tape is the permanent version. I just wanted to thank orange for his help, couldn’t have done it without you bro.

[suicidal_orange]

I don't know how sticky kapon tape is or how long it will stay that way, hot glue is the go-to for sticking wires to a PCB but - it works!  I guess if you leave it sealed in a case you wont put any strain on the joint anyway as the wire weighs nothing.

Seriously impressed with the soldering - did you get a needle tip or just use the edge of the standard one?