Switches not working after soldering - keychron k4

[joseph274]

I've seen how helpful this forum is and hope someone can help me. I desoldered then soldered new switches on my Keychron K4 and my "F" and "." keys don't work now. I'm hoping someone can help guide me on where to solder the jumper cables.

As you can see on the bottom left, I did it for that entire row and it worked for those keys. But when I try to do the same for "F" and "." it doesn't work. Does this mean it's a column and not a row? I've tested it with tweezers above the pink and orange and it doesn't seem to light up like the ones that have the jumper cables.
I've tested all the keys surrounding it as well and it doesn't seem to light up unless it connects to the opposite pin, but the key stays activated. I've colour coded the pins for the keys that are not working and hope someone can assist. This was my first time soldering and desoldering so please don't come for me after seeing the picture

[zegonix]

my best guess is, that you ripped of some pads when you desoldered the (old?) switches.

first step is diagnosis, can't fix something unless you know what the problem is. do you have a multimeter?

first thing to do, measure the resistance (DO NOT TRUST THE BEEP) between pin (blue & magenta) and diode (small red-ish component beside each switch) for 'F' and '.'. then measure the resistance from the other pins (green & orange) to other pins in the same row. if they are not less than 5 Ohms, that is most likely your problem and you want to fix that connection.

[joseph274]

Thanks for the reply! I set my multimeter to 200 under resistance setting, trying the blue and magenta to the diode nearest to it with a reading of 0.05. Then the green and orange to another pin on the same row, with the same reading about 0.05. Does this mean I now need to solder a jumper cable (green/orange) to a pin on the same row?

[zegonix]

what do you mean by

I set my multimeter to 200 under resistance setting

usually multimeters have several modes for current and voltage and ONE for resistance.

you can see the traces (connections) on the circuit board (sometimes there is a little hole in the board, there the traces switch side). follow the traces from the switches in question to the next components and measure the connection (resistance) between the components pads/legs. if a connection is faulty, bridge it with a wire. if all connections are good (below 5 ohms) you will need to do further investigation.

[barkerxavierr]

 Make sure to check the solder connections on the corresponding column pads for those keys. If you're unsure, try soldering a jumper wire from the column pad associated with "F" and "." to ensure they are connected properly. Testing nearby switches can help identify the exact connectivity needed.

[joseph274]

Thanks for sharing some tips!

Just wanted to provide an update, i've been racking my brain over what's been causing the issue, but soldering jumper cables were not working....
Decided to unsolder those two keys specifically and it turns out that the pins were bent so I switched them out and the keys work perfectly now.