Around the beginning of summer, I was lucky to get SVEN AP-B550MV wireless headphones. Headphones pleased with sound and autonomy. Thanks to good autonomy, I did not immediately recognize that wireless headphones have become - wired.
One morning the headphones were discharged and refused to turn on. Everything seemed simple. You take the headphones and put them on charge. But neither in an hour, nor after 2 or even not after 4 hours did the headphones never turn on.
Having examined the headphones, first examined the board. The board was intact and had no visible damage. The second in line were voltage measurements. The tension turned out to be all right too. The battery produced 2.9v, both on the board and at the terminals. I connected the charger to the standard port and measured the output voltage from the board. Nothing went to the battery, so I threw the charger directly onto the battery terminals. After 10 seconds of charging from a 5v 0.5A source, I tried to start the headphones. They earned.
Since in repairing any boards, my experience is endlessly nil, I didn’t touch anything (especially the board was still connected via BT and played music well).
The simplest thing that seemed to me was to solder to the battery and draw a conclusion to the additional connector.
The connector was used from a set of adapters in order to fit a DC plug.
The charging cable was soldered directly to USB → DC. Everything worked, the headphones were charging. But there was one "BUT". Charging had no control. Accordingly, when disconnected from charging, the battery could either not fully charge and recharge. And the latter is not very desirable.
In order to control the charge process, I decided to use a small LCD voltmeter.
To protect against overcharging, I used the FDC-2S-2 controller.
The case for this was the Case for 2 AA batteries.
With the help of a soldering iron and a knife, I soldered everything together, and also made a hole in the case.
However, I made a mistake and concluded from the power source, from which the information was not reliable.
Having disassembled everything and having soldered correctly, I got the correct values.Bottom line:
wireless headphones became wireless again and charge without any problems, besides, I can now determine the level of battery charge.
upd: perezalil photo.