Infrared earphones, transmitter not working "overheating diode"

[mikes1992]

Hey, today I decided to use my wireless earphones only to find they arent working. I took the board out of the case and put my earphones on and noticed I could only hear a minor pop over the static when I switch it on.

The Diode D12 (not sure if that matters) gets extremely hot in a matter of seconds. I traced the diodes circuit back and it connects the +/- directly together through the on/off switch, I'm not sure what it's job is (other then a 1 way circuit?) but if the diode had been fused/shorted which is connecting the +/- directly together would this cause the device not to work and the diode overheat? I just flipped the switch and saw a spark inside the switch (obvious sign of a short...).

The diode says NI or N1... is it possible to get a replacement? could this diode be the problem?

 

[mikes1992]

Here are some terrible pictures taken on my webcam!

http/imageshack.us/f/266/transmit2.png/

and

http/imageshack.us/f/443/transmit.png/

The two circles are the diodes solder
The line across the terminals is to represent the "on" state of the switch

 

[mikes1992]

I'll upload a high res image tomorrow...

 

[mikes1992]

I decided to see what happend with lower voltages and I tested a 5v adapter which I could just hear the music when I put it close to the earphones and then I tested my 9v adapter and could hear it clearly at an average volume with my earphones turn up to full volume.

The diode built up no heat what so ever with both 5 and 9 volts, however at the specified 12v it hits over 80c in a matter of seconds.