Hardware Switch does not charge left joycon and does not register that its attached

[Kilroytbs]

Hi,

I have a problem with the left Joycon on a Switch V2.
I installed all the parts in a new case and suddenly the Switch no longer registers that the Joycon is plugged in on the side and no longer charges the Joycon. I have already replaced the black rail on the Joycon with a new replacement part. I resettet the connection, unpaired everything and that didn't help either. The Switch still recognizes it on the left side when other Joycons are connected. Either the socket that the flex cable connects to, which leads to the black rail, is broken, or another component on the circuit board is broken. Does anyone have any idea what else could be broken on the circuit board? I have a device to measure everything here, but I'm a complete novice when it comes to this kind of thing. It's mainly a DIY project for me and my son. We want to see if we can still save the Joycon. The Joycon can still establish a wireless connection to the Switch and all the buttons work. The battery gets drained more and more. The 2nd Switch also does not detect the joycon anymore, when its attached. It must be something to do with the components that tell the Switch that it is docked or a component on the Joycon circuit board that is responsible for charging/docking. It would be great if someone could provide a photo for beginners with the areas that need to be checked marked.

Thanks!

 

[thesjaakspoiler]

The joycon detection is done in software where inserting the joycon makes it connect to the USB bus and the Switch detecting that.
Afaik the battery will be charged as soon a the power and gnd lines are connected.
That all happens inside the joycon, as long as it gets power.
So if you have neither, there is likely something wrong with that ribbon/rail part.
Note that the ribbon has to be inserted really perfectly for it to work.
That caught me too once when changing the battery.

If you suspect the ribbon/tail part, easiest thing would be to take the pcb out, disconnect the battery and connect the ribbon.With a fine wire and a multimeter just test for continuity between the rails and the JC point.
https://github.com/dekuNukem/Nintendo_Switch_Reverse_Engineering

Carefull with the ribbon as it is really easy to tear it.

 

[Kilroytbs]

Thanks a lot for your help! I will try this.

"Afaik the battery will be charged as soon a the power and gnd lines are connected."
I already replaced the black connector on the joycon with a new one and the rail connector on the Switch recognizes other joycons without issues. So the problem must be related with the connector on the joycon board. I will check with another joycon, if the cable is insertet properly. But it wasn't even removed, wenn changing the shell of the joycon.

"Carefull with the ribbon as it is really easy to tear it."
I already had the pleasure of soldering a new connector to a joycon board, because in the video by Exxtremerate the guy was just pulling on the cables while removing them without even opening the connector on the board.