1、Structure of 3.5mm front audio jack First of all, we must understand the structure of the front audio jack. According to Intel ’s specifications for the AC97 front audio interface, the front audio panel of the chassis uses two 3.5 mm mini sockets
1. Switch type 2.Without switch type See the figure below:
1.1. Switch type 2/3, 4/5 are two switches, when no plug is inserted, 2/3, 4/5 are connected, when the plug is inserted, 2/3, 4/5 are disconnected . Without a switch, there are no 3 or 4 switch terminals.
2、3.5 mm plug structure 3.5 mm plugs can be generally divided into three cores and two cores, as shown below:
Two-pin plugs are generally used for microphones, and three-pin plugs are generally used for stereo sound headphones (active speakers). Now there are few two-pin plugs, so Mike also uses three-pin plugs. The wiring of the earphone and microphone plug is defined as follows:
The wiring of the microphone and headphone plug is as follows:
There are two ways to connect the three-core microphone plug, as shown below:
There is no microphone bias in this connection, if the wiring with the microphone socket is not accurate. Will not work.
3、Problems with front microphone connection The connection of the front audio port, the headset is generally no problem, the microphone will often have problems, because the wiring method of the front microphone socket of some chassis is not standard. The following diagram lists the difference between standard wiring and non-standard wiring:
The standard wiring has three wires: ground wire, microphone input, and microphone offset. There are two non-standard lines: ground and microphone input, which saves the microphone offset. Non-standard 1 is to short the socket 1, 3, non-standard 2 is 3 feet empty. These two types can be used by connecting MIC_IN to pin 1 of JAUD1. Non-standard 3 is to short 2, 3, this microphone plugged into a standard plug is definitely no sound, unless also use the corresponding non-standard plug microphone.
4、Front audio cable The Intel specification also stipulates the front audio cable: left and right channels, microphone and AUD_VCC / HP_ON must be shielded in pairs, and these lines must also be combined together in an outer shield.