Hi everyone!
I have a strange problem with my Leeku TX87KIN L3 PCB. I am turning towards the community in hope of some help and assistants. Any suggestions and/or help would be greatly appreciated. Prior to writing this thread I have spent about 2-3 days searching the forum and Google for any answers to my particular problem. Unfortunately without success, hence I am writing this.
Before describing the problem I would like to share some background information about this specific PCB. I bough this new and un-assembled TX-87+TX-Pad directly from kin25. Great guy by the way
Since this would be my 2nd TKL I wanted to try out a different bottom row with a 7u space bar (1.5 x 1 x 1.5 x 7 x 1.5 x 1 x 1.5). After finishing the build the firmware was a bit wonky. My PCs had a hard time recognising the keyboard. It would constantly show up in Device Manager as "Unknown USB Device (Device Descriptor Request Failed)". JigOn was not able to connect to the board and I was not able to flash it using l3cmd.exe. I tested this on several different PCs and after changing several USB ports, PCs and USB cables I managed to flash it using an old laptop with Windows 7 installed on it. I had no luck at all with Windows 10 and 8.1. After a few weeks the board stopped working completely. No key presses were registered and no RGB LEDs were lit. After a lot of searching the GH forum, Reddit and Google I started to suspect that the firmware and/or bootloader was corrupt. So I decided to try to flash it using an USB programmer by connecting it directly to the PCB. I went and bought an USBASP USBISP AVR Programmer (
https://www.google.se/search?q=USBASP+USBISP+AVR+Programmer&oq=USBASP+USBISP+AVR+Programmer&aqs=chrome..69i57j0l5.273j0j7&sourceid=chrome&ie=UTF-8) and successfully managed to re-flash the entire thing with the help of the following URLs:
After this the board was fully functional. Oh the joy! I had no problems with it and tested both JigOn and l3cmd.exe on multiple different PCs at both work and home. Everything was working perfectly.
After using it every day at work for about 1-2 months I still could not get used to the large space bar. I am an ISO user located in Sweden and use the Alt Gr key extensively. Having Alt Gr re-located so far to the right because of the larger space bar was too much for me. So I decided to change the bottom row to a standard one with 6.25u space bar that I am more used to. This would not be my first de-soldering experience with a Korean custom PCB and as always I was extremely careful when pulling out the switches. Before inserting the switches on the bottom row I tested for damaged and/or lifted pads by shorting the switch pads and observing the result in EliteKeyboards Switch Hitter (
https://elitekeyboards.com/switchhitter.php). Everything looked good so I went ahead and installed my new bottom row and soldered the switches. Once again I tested them using the Switch Hitter software from EliteKeyboards to detect chatter. During this test I quickly observed that my left Alt switch was registering key presses without me even touching that particular switch. I figured this was caused by a faulty switch so I de-soldered it. Before installing a new switch I tested the board once again in Switch Hitter and everything looked good. To my big surprise the exact same phenomenon was observed after soldering in (once again) a brand new Zealio switch.... The TX-87 plate supports switch-top removal so I popped up the left Alt switch and removed the stem and spring while the board was still connected to my computer. During that time I observed multiple random key presses in Switch Hitter. I performed the same procedure for the entire bottom row and could still see that left Alt switch registered key presses without me even touching the board. So I figured the firmware and/or bootloader was corrupt again since that was the case previously. Once again I re-flashed the entire thing using my USBASP USBISP AVR Programmer but this time it did not solve the problem...
So here I am completely confused as to what is going on with this board. I doubt this is caused by damaged traces or pads. I also doubt I managed to install a faulty switch twice. Especially when I used brand new switches (not harvested or similar). So I humbly ask for help with this. Thank you in advance.