I have this Chinese Portable Rechargeable Mp3 player.
It has a two pin plug connector behind that is used to recharge it and some generic rechargeable non removable battery inside it.
It has the following connecting points on the top:
- Speaker out
- Line in
- Sd Card
Whenever I play it with the plug connected to wall outlet, it has mains current flowing through the line out and speaker out. When I insert one end of the 3.5mm pin in the speaker out, I get full 220 volts shock in the other 3.5mm male pin end.
I tried doing this with the other line in port too, even that is releasing 220 volt current. This happens only when it is plugged in for charging and used. It does not happen when unplugged and played.
I am uploading few pics.
The red wire is for the antenna
I want to correct this design flaw. I want to add ground to this device. (am I right with my decision?). where should I solder a third wire on the circuit board for ground?
RM: IT IS ALMOST CERTAIN THAT THE RADIO IS "DESIGNED" TO BE CHARGED FROM A LOW VOLTAGE AC SUPPLY AND NOT FROM MAINS.
While it is not 100% certain what all the circuitry present is it seems that the diode bridge that converts AC input to DC is connected directly to the battery. Even a low voltage power source would damage most batteries if used this way. Connecting AC mains is liable to damage the device, the user and the battery.
Red is (probably) positive.
Green is (probably ) negative.
Purple is AC.