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geekhack Community => Keyboards => Topic started by: backspace_syd on Mon, 30 August 2021, 23:00:38

Title: Need help with PCB issue after Desoldering a Keychron k6 (Probably a Short Circu
Post by: backspace_syd on Mon, 30 August 2021, 23:00:38

So I’m desoldering a keychron K6 for a friend of mine (to millmax),

Just for context, I’m not that new to desoldering, I have desoldered about 300 switches at this point but I’ve never encountered any problems thus far, this is the first time I’m experiencing a real issue with the board.

So, as I was desoldering the switches, about halfway through I decided to check if all was good, and everything was working fine. But when I did end up finishing the switches and tested the board, when I tested one pad, it would register all the pads of the entire row at the same time or randomly. I’m guessing its a short somewhere on the PCB, note this is my first time dealing with this kind of issue, is there anything I should be looking out for, or if you could spot a problem through the images I will be sending please do point it out for me as I am unfamiliar with these kinds of issues.

Additionally, the desoldering job isn’t the best but I tested every pad and it still works so I’m pretty sure I didn’t lift a pad. I read a little online saying it might be a broken diode (?) however not sure what the actual problem is.

Any help / suggestions would be very appreciated!

testing the pcb after desoldering video & photos of the PCB

https://imgur.com/a/arnLRG6

Title: Re: Need help with PCB issue after Desoldering a Keychron k6 (Probably a Short Circu
Post by: suicidal_orange on Wed, 01 September 2021, 11:29:27

Non RGB Keychrons are special boards which have the LEDs connected to the switch matrix, don't think I've helped with an RGB, or a K6 but lets.  Keychron are also annoying because they usually use a black PCB so you can't follow the traces, which makes working them out hard.  Can you turn the LEDs off?  If doing so changes what happens that suggests you have a short to the wrong bit of an LED.

If you don't think there are any lifted pads (check front and back for any that aren't shiny or check the desoldered switch legs)  it might be worth soldering in the sockets - this should repair any of the switch holes that are being used as vias (links between the front and the back of the PCB)

About the only thing I can see for sure thanks to the black PCB is that the diodes are connected to the columns so it's not going to be one of them.