Below are the Pin Signal Names & Functions
1- AUD_MIC Front Panel Microphone input signal
2- AUD_GND Ground used by Analog Audio Circuits
3- AUD_MIC_BIAS Microphone Power
4- AUD_VCC Filtered +5 V used by Analog Audio Circuits
5- AUD_FPOUT_ R Right Channel Audio signal to Front Panel
6- AUD_RET_ R Right Channel Audio signal to Return from Front Panel
7- HP_ON Reserved for future use to control Headphone Amplifier
8- KEY No Pin
9- AUD_FPOUT_L Left Channel Audio signal to Front Panel
10- AUD_RET_L Left Channel Audio signal Return from Front Panel
Audio1 pin has 2 jumpers that cross in Pin 5-6 and 9-10. If you don't connect the front audio cable on it, you have to short 5-6, 9-10. Otherwise, the I/O panel Auido out won't get sound output.