I attempted to mod a pre-assembled keyboard with different switches and failed

[Genkaz]

I attempted to mod a cheap pre-purchased keyboard by desoldering its hotswappable pegs and taking out the switches and then putting different switches back in. The end result ended up being that some of the switches were not responding and making me suspect that I may have fried something while soldering or desoldering it.

I tested that it was not the switches by re-testing exactly the same place on the PCB with its original switches and it was still not responding in every single possible combination of attempts to my knowledge.

Would anyone have any suggestions as to what I may have done incorrectly in order to ensure that it does not happen again?

I was soldering and desoldering the board at 350 degrees and I also used a really thin needle nose for the solder that allowed me to go into the hole with it in order to melt the solder effectively to suck it up with the desoldering tool, was that the error?

Is 350 degrees way too hot for a keyboard PCB?

Is it something else that I did not consider such as the keyboard being pre-assembled and not really designed for desoldering and is it necessary to purchase a separate empty PCB that is specifically designed for soldering?

Any suggestions or advice would be welcome.

The reason why I tried this is because I purchased a mechanical switch tester and quickly discovered that I liked the feel of a very particular switch that was not present on any premade boards to my awareness.

[JianYang]

Post some pictures. Most likely you pulled some traces off, but it's hard to tell from the description.

[yui]

Given how you describe it i would also guess pulled traces or broken plate through, if you are savvy enough with a multimeter you should try to follow traces from the keys that do not work and check for continuity.
And if there was smd diodes (for NKRO not the rgb kind) those may not have liked the heat too much and failed open circuit, but that is very unlikely.

[suicidal_orange]

I'm just hoping it's not a crazy matrix on a 2 layer PCB and that the OP is competent at soldering.  One broken trace or pulled pad can take out a lot of switches and should be easy to fix, multiple breaks in an unknown matrix with dodgy soldering everywhere would be much more fun to diagnose.  We shall have to wait and see!

[mizzoperator]

You probably broke a trace somewhere or accidentally spat on the board.
It should be easy to fix if you know anything about soldering.

[directheatedtriode]

Your temperature seems fine. I would have personally used a chisel tip so you get more even heat dispersion which means spending less time in contact with the joint.

Were you trying to desolder these joints in a single go? I could see that heating up the pad too much. I go back and forth multiple times between the two joints so the pad never gets too hot.

[Genkaz]

some pictures of the board:
https://i.imgur.com/FtiyHvh.jpg
https://i.imgur.com/3JfK0Vh.jpg
https://i.imgur.com/iLzufTH.jpg
https://i.imgur.com/OUSqK7E.jpg

[suicidal_orange]

You missed a pin on the right of the big white circle in the middle of iLzufTH.  It won't fix everything but it's a start )

Good news: it's not a white PCB where you can't see anything and it's not a burnt mess so your soldering skills are reasonable - most of the switch pins have round solder points though I see some don't.  If the ones that don't are because they just wont work like normal chances are you lifted their circle pads and those are the keys that don't work.  If you can see the trace going from those pins to a diode you can solder a short wire between the switch pin and the side of the diode and that will work in place of the trace.

The bad news - it is a two layer PCB and the matrix isn't obvious.  I'm guessing from all the resistors and vertical traces it has some kind of RGB lighting going on?

If you have a bit of wire and some patience you can touch pins to work out what should be connected where.  For example if the switch with a red dot wasn't working first you would touch the yellow dot to green - if that outputs the letter then the switch is broken.  If not touch yellow to blue - if that works you need to solder a wire between green and blue as that connection is broken.  If that still doesn't work touch yellow to cyan to bypass the diode - if that works the diode needs replacing (doesn't look at all likely as they are all nicely spaced away from the switches and your soldering isn't terrible)  If none of those work the problem is on the yellow pin so you would need to touch nearby switches (pink dots) to the cyan one until you get the right character output.  You can then solder between pink and yellow and the switch should work as normal - if not start again now the yellow pin is working to test the switch and diode.



If you don't have the patience and there aren't many broken switches please post which keys are not working and add some labels to your pictures so we know where to look.  This is definitely fixable

[Genkaz]

These images have the non functional keys highlighted as well as having some extra close up shots of the non activating locations:

IGNORE THE F1 F2 F3 KEYS I ACCIDENTALLY LEFT THAT THERE:

https://i.imgur.com/I7NKBrw.jpg
https://i.imgur.com/4SXwp9C.jpg
https://i.imgur.com/shGSX3U.jpg
https://i.imgur.com/dLtvS8h.jpg
https://i.imgur.com/J11EKdE.jpg
https://i.imgur.com/u5A0TBu.jpg
https://i.imgur.com/rIzqtoD.jpg
https://i.imgur.com/fCL8fjY.jpg

[Genkaz]

I did try the wire rewiring method suggested by orange and it does work really well as long as the key is rewired to a key on the same row. so in theory I could repair the entire bottom row by rewiring all of it to the keys on the right such as the arrow keys, however I am not sure how to do so without running out of space without skipping a few keys.

All of the other rows could be easily repaired by rewiring them in the same manner since space is not an issue.

I am not exactly sure how this repair method affects key ghosting.

[Genkaz]

I just tested a few buttons with this idea and pretty much repaired the f and the b n z switches by using a thin wire to rewire them to the keys on the same row.

I am now facing a mild unrelated issue with the left shift not actuating properly because the switch that I am using seems to be too light for it.

I also tested the ghosting by pressing both switches at the same time which seems to have exactly the same result as pressing two regularly functioning keys.

I also noticed that using the same switches for space shift and enter are too light in general and I need a set of heavier keys for those buttons, I will try purchasing like a pack of 10-20 although it may be problematic because I ended up liking only a single modern switch so far and finding a second modern switch that I like will be tricky.

In either case I am greatly thankful to orange for telling me how to pretty much fix the board with zero downfalls that I can see, seems to be literally no difference whatsoever from what I have noticed so far.

[yui]

in keyboards the switches are most often wired in a matrix, so if your whole bottom row is not working you need to bypass the break in the circuit and for that you may only need one wire not one per switch (if there is only one broken trace) and for the rest as it seems to be a gaming board i would guess that it is a break in only one row, so i would guess that you can fix it with only 2 wires (i may be wrong, i do not have the board on hand to test the theory)

[suicidal_orange]

I did try the wire rewiring method suggested by orange
...
I am not exactly sure how this repair method affects key ghosting.

It doesn't - the board will not know anything changed (because it didn't).  On one side the keys are connected directly and on the other side the diodes are connected and the keys connect to one diode each.  They are called rows and columns because the easiest way to design is having one connection go accross the board and the other down but to save pins some designers use U shaped columns so you have to check both sides to catch these.  Because they're crazy (I assume )) Filco have 'rows' that have four keys connected, miss two, four connected...

Glad to hear your board was designed by a sane person, it makes things much easier.

The bottom row probably need(ed/s?) two wires - one from the damaged pin to the working switch and one to the other dead keys.  Also it's worth mentioning (for anyone who stumbles across this thread if not Genkaz) when dealing with dead mods Aqua Key Test is useful so you can detect they are pressed just like a normal character.


You didn't mention fixing space but did say it's too light so I guess it's all working now?

[Genkaz]

I didn't fix the switches that are too light yet because I am trying to figure out how to make them heavier with the right springs. I made a second thread about making the Tealios switches heavier because I am not positive if I would like any other switches.

all of the letters were fixed, the bottom row is still disabled currently but I am pretty sure that it would be fixable with exactly the same method.

I already tested the space working by temporarily holding a wire up to a different key and pushing it so yeah.

[Genkaz]

I ended up ordering these ones: https://mechanicalkeyboards.com/shop/index.php?l=product_detail&p=3434

[directheatedtriode]

some pictures of the board:
https://i.imgur.com/FtiyHvh.jpg

You have some cold solder joints and some with not enough solder, circled two such examples:

[Genkaz]

I finished the keyboard. a few buttons do not work but are fixable in the future (all of the important ones work). a number of springs were replaced including the space bar to make the buttons heavier.

Thanks everyone for their help and for helping repair this board!