official cable is DCU-60
| Pin | Signal | Description |
| 1 | USB +5V in | USB 5V supply - not used in K750 |
| 2 | SP_REF | Reference / GND for handsfree |
| 3 | Mic+/AUXIN_L | Mic + / AUX in (left)/ short with pin 4 for handsfree answer (*) |
| 4 | Mic-/AUXIN_R | Mic - / AUX in - (right) / short with pin 3 |
| 5 | DFMS/SP_L | DFMS / Earphones left |
| 6 | DTMS/SP_R | DTMS / Earphone right |
| 7 | VIDEO/STB | Video / strobe |
| 8 | VPPFLASH | short with pin 9 via R=130 Om for handsfree detection |
| 9 | GND | Ground |
| 10 | CTMS / USB DATA+ | CTMS / USB+ (data) - not used in K750 |
| 11 | CFMS / USB DATA- | CFMS / USB- (data) - not used in K750 |
| 12 | Charge In | Battery charge (+5V) - not used in K750 |
Used Shortcuts:
* CTMS stands for Control To Mobile Station
* CFMS stands for Control From Mobile Station
* DTMS stands for Data To Mobile Station
* DFMS stands for Data From Mobile Station
Notices:
The key in near pin 1.
If you want to make a stereo converter with a SE socket, you should use pins 5 and 6. It may not work well with an amplifier due to low output i.e. just enough power for headphones . (May need pre-amp).
Suggestion:
To make a stereo-amp using the cell phone you must shortcircuit pins 8 and 9. Then connect the outputs (L) (R) (GND) using pins 5 = (left), 6 = (right) and 9 = (GND).
Sony-Erisson Walkman original handset uses pins 2 (GND), 5 (Left) and 6 (Right).
(*) For incoming call answering short pin 3 and 4
Headset for S302 and similiar phones pinout: R pin 7, L pin 8, pin 11 is GND for both channels and probbably for microphone too. Active gain should be between 50 and 200 for LM386.
