This is about how to adding Bluetooth feature to your old multimedia speaker.
Old phone charger with 5v output.
This AC-DC converter
Connect the phone charger board to 220AC on the speaker board
USB Bluetooth module
Connect the 5v output to Bluetooth USB input (pin 1(+) and pin 4 (-).
Connect the Bluetooth Aux out to speaker Aux input, above is Edifier R202 board.
Manually iron the AC input to phone charger board
Wrap the high voltage circuit for safely!!
Glue the charger board to panel
Glue the Bluetooth beside the charger board