Switch OLED strange issue with usb functionality after mod install

[Makc16384]

After modifying my Nintendo Switch OLED (installing the RP2040), I encountered a strange issue. The console works fine in docked mode: charging, fast charging, and video output to the screen all function perfectly. However, external devices connected to the dock’s USB ports (e.g., external hard drives, mice (linux/android), or gamepads) do not work.
At the same time, if I connect an external hard drive directly to the console’s USB port, it is recognized and displayed in DBI, and I can interact with it without any issues.
However, when I connect the Switch to a computer, it is not detected at all. I’ve tried using the original gamepad cable, various other cables, and multiple computers, but no computer even sees it as an unrecognized device.
I also tested with two different docks, and in both cases, external devices connected to the USB ports are not recognized (under Linux/atmosphere). This is strange because everything worked fine right after installing the chip and the problem with usb devices started after a while.

I disassembled the console, checked all the chips and surrounding components, but found nothing unusual. All the connections from the USB input to the chips have continuity when tested.

Does anyone have an idea where I should look next? Has anyone encountered a similar problem? I would greatly appreciate any thoughts or suggestions on what this could be.

 

[Makc16384]

So, I finally figured out what the problem was. Just in case someone encounters the same issue. When I carefully measured all the resistances again, I found that there was very low resistance, literally 7–8 ohms, between contacts B6 and B7, which are D+ and D-. ChatGPT told me that this was abnormal. I started tracing the circuit and discovered that I had desoldered an electromagnetic ESD filter, a tiny component, and the resistance increased to over 1 MOhm. I realized that the ESD filter was shorted. Fortunately, it wasn’t a big issue. I ordered a replacement filter from Aliexpress, but before it arrived, I found a board from an old Lenovo phone and desoldered a 6-pin ESD filter from it. I soldered it in (I soldered the side contacts of the new filter to the ground. The original filter has only four contacts. I believe that’s why the original filter doesn’t protect as well as the six-contact one, which can discharge static electricity to the ground.), and everything works perfectly. Hopefully, this helps someone.

Thanks, everyone, for your attention.

 

[mengzhiquan]

Wow! I'm really envious of your hands-on ability to solve problems. These electronic components are so tiny that they require a microscope to view and solder. I'm all thumbs; I always end up damaging anything I try to solder. The soldering station at home has been sitting idle; it's my dream.

 

[Makc16384]

Wow! I'm really envious of your hands-on ability to solve problems. These electronic components are so tiny that they require a microscope to view and solder. I'm all thumbs; I always end up damaging anything I try to solder. The soldering station at home has been sitting idle; it's my dream.

Bro, you definitely need to get a microscope for soldering work (like on AliExpress for $15) or use your phone's photo zoom. When I chipped my first Switch, I just placed an iPad on an upside-down glass above the board and used maximum zoom. That was enough

 

[dangbawu]

Just wondering, when you say desoldered, was it off before you took that pic? Because it’s still on there. Or has the filter just shorted when you checked. Thank you