Investigating and fixing(?) charging problems caused by the ASDA blackweb power bank

Normally I use this power bank only for powering Raspberry Pi Zero and Arduino projects but recently a viewer mentioned that he had problems charging his phone with it. I tested this on mine and found a problem with a bad soldering joint that caused the phone (Samsung A40) to complain and charge very slowly. The bad solder joint might be a one-off but by the looks of it could also be a more common problem. Unfortunately the fix is not a clear-cut thing because you may end up with a power bank that is not able to charge your phone at all.

My previous review of this power bank: https://youtu.be/eHKbtBkfxKM

The Maxim tutorial I mentioned: https://www.maximintegrated.com/en/design/technical-documents/tutorials/5/5801.html ... https://www.youtube.com/watch?v=LSrtbNV9vt4