Re: K9N6SGM-V audio header

Patrick Harvey wrote:
> Can anyone explain the pin layout for the audio? Thanks
>
>

MIC X X GND
MIC_BIAS X X VCC (+5V used to power a separate optional amplifier)
FPOUT_R X X RETURN_R (audio signal returned to drive green jack on back of computer)
HP_ON X
FPOUT_L X X RETURN_L (audio signal returned to drive green jack on back of computer)

To understand the signals a bit, they can be divided into groups.

MIC, MIC_BIAS, GND - used for a front mounted microphone jack

FPOUT_L, FPOUT_R, GND - used for a front mounted headphone jack

The order of the signals is Tip, Ring, Sleeve. Tip is the metal contact
at the end of the 1/8" stereo plug. Sleeve is generally a ground signal.

The audio codec sends FPOUT_L and FPOUT_R. They travel to the front
mounted headphone jack. The jack has some switch contacts inside it.
If no plug is inserted in the front headphone jack, then FPOUT_L is
passed back as RETURN_L. FPOUT_R is passed back as RETURN_R.
And by doing that, when no headphone is plugged into the front
headphone jack, the rear green Lineout jack still has a signal
on it.

If you plug in a headphone to the front headphone jack, the switches
in the jack open. Now, FPOUT_R isn't passed back on RETURN_R. So
the green jack on the back of the computer, falls silent. This
is called "muting", and the rear green jack is muted, whenever
headphone are plugged into the front of the computer.

If no front panel audio wiring is present in the computer, or is
not provided with the computer case, then something is still
required. You need a jumper plug, from FPOUT_R to RETURN_R.
And a second jumper plug from FPOUT_L to RETURN_L. That makes
the green Lineout on the back of the computer work. The jumper
plugs are factory installed, so the rear green Lineout jack
will work when the user first tries it.

There are an additional two signals, which have not been described
yet. The "VCC" signal is a power source, of +5V. On some older computer
cases, there may have been a 2 watt amplifier, and the +5V could
be used to power it. Today, the "VCC" pin is unused, and is generally
left unconnected.

The HP_ON signal, as far as I know, is a signal to tell the optional
amplifier to turn ON. Again, people no longer connect to that, and
that pin is left unconnected.

Page 20 - no explanations here.
http://web.archive.org/web/200404070..._guideline.pdf

Page 20 here, shows the switch contacts, for muting the rear green audio jack.
http://www.formfactors.org/developer...928604-005.pdf

Note that the above information, applies to "pure AC'97" or older
type motherboards. Newer motherboards use HDaudio. The
audio header on those, still has pin labels and options for
connecting an AC'97 computer case - the difference in that
particular case, would be that the RETURN_R and RETURN_L pins
are no longer used or needed - also, no jumpers are needed if
the HDaudio header is not being used. The only wires that
need to be hooked up to the HDaudio header are -

MIC, MIC_BIAS, GND, FPOUT_L, FPOUT_R (one ground is enough for both jacks)

But since the original question was about a "pure AC'97" type
motherboard, the above description is appropriate for that
kind of motherboard.

HTH,
Paul

Thanks for nice posting. I think it will be helpful for others.