My dad has one of those chinese BT headphones with a 3.5mm jack input and a built in mp3 player, one day he told me that one of the speakers wasnt working at all so he asked me if i can weld the wires because he opened the headphones and saw one of the wires detached from the speakers.

I tried my best to weld it back togheter, but my poor soldering iron and its bumpy point made it impossible to do so, i welded it, but it didnt worked. My dad told me to trash it if it doesnt work, but i told him i can weld a 3.5mm jack i found at the university many years ago to the speakers output, i didnt wanted to use the built in 3.5mm jack because i wanted it to work as an mp3 player, and the headphones were designed to cut the mp3 function when you connect the jack, i tried to shortcircuit the boards testpoints to check if there was a way to bypass this, but it didnt worked, so i kept the idea of welding a 3.5mm input to the speakers output.

as you can see, theres the test points, i connected 2 wires previously tied to my earphones to L- and L+, the left speaker output and played a song, as i expected, i listened the song i was playing from my phone, so i just had to weld the jack pins to one of the outputs... ¿why just one? because the 3.5mm output i have is too old and i dont really know if it can handle stereo sound, so im just assuming its only mono.

the easiest thing was identify the jack input´s pinout, i found the input and ground in my first try, so i had like 40% of the job done, until i had to solder the pins, it was a hell because my soldering iron´s point is too bumpy and full of waste, i managed to weld them, and like 10 minutes before they detached again, so i had to be really careful to keep the wires and the jack itself in a place where it cant move, the reason behind the welding being so weak is mainly beacuse the wires im using are thicker than the original ones, they were very thin.

My dad had the idea of enlarge the hole in the housing that was used to connect the right speaker to the motherboard where the left speaker is, so he used the soldering iron make the hole bigger enough for the jack input.

Once he finished, we put the speaker back togheter ensuring that the new jack input fits almost perfectly in the speaker housing, we tested the sound, and thanks to the wires being thicker then the original ones the sound quality was immensely better, and the volume was even higher than before.

This is how it looked in the beginning.

i succesfully repaired it, in a cursed way, now its an mp3 player, a BT earphones, and a kind-of BT... Driver?.