Broken bottom row of keyboard

[Jumpee02]

I recently broke my keyboard RK61 (A cheap 60% layout keyboard). I tried to mod it myself and so I desoldered all the switches. After swapping all the switches, I resoldered all of them again. The 4 switches on the right of the spacebar click non-stop when I press them. The spacebar switch and the remaining switches are all completely not functioning. I tried swapping the switches with my extras but it didn’t work. I don’t see any visible melts whatsoever so I can’t tell what’s the problem. Is there any way I can fix this? Bridging don’t seem to work for them. I tried to bridge spacebar to a key (I’m not sure if it was V or B), it lights up the whole column when I press it but the spacebar still doesn’t work.

Note: I know it is a cheap keyboard and literally everyone told me to just throw it away and buy a new one (I did buy a new one which is glorious tkl) but I really want this fixed because of its sentimental value to me. Please help me

[suicidal_orange]

Welcome to geekhack, sorry it's not under happier circumstances.

This should be an easy fix, more so if it wasn't a pretty matte black PCB.  Looks scarily similar to Keychron boards though and they are ... strange.

You need to be more clear what's happening - "The 4 switches on the right of the spacebar click non-stop when I press them" does this mean they stay clicked when you hold them?  That would be normal.  If they 'tap' you may have a Keychron(ish) where the LEDs are attached to the switches in a way I'm yet to work out, but that usually results in strange LED colours so it might be different.  Also "I tried to bridge spacebar to a key (I’m not sure if it was V or B), it lights up the whole column when I press it but the spacebar still doesn’t work." - what's lighting up, LEDs?  Or are you seeing the whole column above V (or B if that's what you bridged or above spacebar in a switch tester?  Either way it sounds like you're trying to hold a bridge while pressing a switch so you are making it hard for yourself, shorting to the other switch pin (or the diode it should be attached to) bypassing the switch is much easier.

Please post a pic with the shine (seen on the edge of the PCB in the first pic) showing some traces in the affected area, I will then add some dots to hopefully help find a fix

[Jumpee02]

Thank you very much for the reply. About the spacebar, i bridged it to B and whenever i press it, it doesn't work but the LEDS of spacebar, B, H, Y and 6 light up all at once. As for the keys on the right side of the spacebar, whenever I try to press any one of them, that specific key will continuously click (tested on keyboardtester). As for the keys on the left side of the spacebar, they completely don't work.

Here are clearer pictures, I am really sorry for my bad camera quality.

[suicidal_orange]

It's not your fault black PCBs are camera shy!  The LED linkage is worrying so I'll ignore it and hope it fixes itself once the switches work properly.

Looking at the new pics all the diodes are connected to the bottom/right pins and the diodes connect up the columns which hopefully means the top/left pins connect across the row, you're not missing alternate keys so hopefully it is the whole row.  That means if you bridge the left pin of one of the switches on the left of the spacebar to the right pin on a 'dead' switch (or as they have no solder the pad around the pin) it should type the 'dead' key.  Or with dots:



Bridge blue (you probably need to go to the next switch over as space doesn't work but you get the idea) to cyan and it should type Alt (I assume).  I'm not entirely sure what's going on below the orange dot - could just be some loose solder on the surface or could be damage.  I think all the green traces should be connected so if blue->cyan doesn't work try blue->magenta and that should type Alt.  If blue->magenta works but blue->cyan doesn't solder a bridge between red and magenta, then blue->cyan should work.  If it does solder between blue and orange and the switch should work as normal.

The trace going down and left under the orange dot looks to go back to the controller chip so if there is damage there you could have a problem - if that connection is supposed to be grounding the keys on the other side that could explain their ... actually I'm still not sure if these keys are working (continuously pressed when held) or if they are click-unclick-click-unclick-ing.  Try and clean up that area and check for damage, you might need to scrape the trace as I don't think you want to try soldering to the controller pin (a member sent their board off to a professional PCB repair place and they wouldn't even do it!  Somehow he did it himself out of desperation so it's not impossible, but easier to scrape the trace as you can see it)

[Jumpee02]

I will try that. Thank you very much. About the continuous press thing, if I press/tap the key once (not hold), it will continuously register as if I am holding the key. Also, when doing the tweezer test on those malfunctioning keys, I only need to touch 1 hole for the key to register non-stop (I need to touch the 2 holes for the other normal keys to function). I found out that my C broke as well but I tried using a tweezer to touch one of its hole and one of the hole of the next key and it registers C so I shouldn’t worry about it. I’m more worried that I cannot use C to make one of the bottom keys work (by bridging). Sorry if my explanation is quite bad. I really can’t think of any better way to explain it.

My other concern is how the scraping off of trace works. Which specific trace should I scrape and how should I do it?

I tried tweezer testing for spacebar + right alt and it also doesn’t work so I’m not really sure what to do with the spacebar now. Is there any other places I can connect it to?

[suicidal_orange]

No problem, this is weird to talk about and I do it all the time which is why I puts dots on pictures.  Sounds like the switches ground through you (and a very large pair of tweezers!)

You haven't lost enough keys to have damaged the controller chip so I'm sure it's all fixable, the right pin of C is probably disconnected from it's diode as it's one key in the middle and you can go up to the diode for F if necessary to test.  Left pin of right alt to right pin of B should type a stuck space (known thanks to the linked LEDs) and once the bottom row is reconnected it should unstick.  Hopefully there is no damage under orange and you don't need to scrape the trace, a cleaned up pic should confirm.