Jungle Jim said:
I have (I think) ver 1.02 of subject mobo. It was installed about a
year ago and no problems - solid as a rock. When it was installed, I
connected case leads from the front panel to the speaker out and mic
in on the mobo. I have had no problem connecting speakers and mic to
these front jacks on my case.
But now, because of a new set of furniture, it would be cleaner to
connect these two jacks to the back of the mobo. I did som and can
get NO sound or generate any noise with a mic.
I have looked all over, but cannot find anywhere that says if you
connect external panels to the mobo, then this shorts out the regular
jacks on the back of the moboo. It appeasrs to be what's happening so
can someone tell me if I am right and is there a way to make the
connection to the both and make them functional ?
Ref (page 20, Intel compatible motherboard header):
http://www.formfactors.org/developer/specs/fpio_design_guideline.pdf
Mic In ------------- MIC2 x x AGND --- Ground
Mic Bias ----------- MICPWR x x +5VA
Sound chip Right --- Line out_R x x BLINE_OUT_R --- Return Right
NC x
Sound chip Left --- Line out_L x x BLINE_OUT_L --- Return Left
The sound signal comes from the Line_out_R and Line_out_L signals.
To make a headphone jack on the front of the computer work, these
signals have to be connected to that jack.
If the case wiring is "Intel Compatible", there will be return
wires. You need a wiring path from Line_out_R to BLINE_OUT_R and
a wiring path from Line_out_L to BLINE_OUT_L, in order for
the Lineout connector on the back of the computer to work.
With an Intel compatible headphone jack, in the computer case,
this is easy, as the return wires from the headphone jack do
the job for you.
If you don't have return wires, the job is more difficult. You
will have _two_ wires connected to the Line_out_R, for example.
One wire goes the the headphone jack "right" signal, while
the second wire closes the gap to the BLINE_OUT_R.
I.e. To make both work, no matter what kind of jack is on the
computer case, do this:
Line_out_R connects to "right" on case headphone jack
Line_out_R connects to BLINE_OUT_R
Line_out_L connects to "left" on case headphone jack
Line_out_L connects to BLINE_OUT_L
AGND goes to GND on the headphone jack
Notice how the jumpers can be used for items two and four in the
list of connections, but if you use them, it is hard to get
wires on the Line_out_R and Line_out_L at the same time!
That is why what you want to do is difficult with the provided
materials.
So, while the list above will do the job, the computer
probably doesn't come with the wires needed to make this
easy. Not too many cases have two wires per channel on the
headphone jack - that would make them "Intel Compatible".
As for Microphone, there are two Microphone signals on the
sound chip, and to select the front or back microphone, usually
means a trip to the mixer control panel, to change the
selection. No rewiring should be needed. You can keep the
"mic" jack on the front of the computer case connected to
MIC2, MIC_BIAS, and GND. In some cases, the computer case
will have a GND wire for headphone and a GND wire for microphone,
and again, you may need to be creative, if in fact these connectors
are not already connected together at the computer case.
There can be two GND connections on your computer case, but you may
only need one of them, if in fact the two GND connections from
the computer case front panel, are in fact joined at the front
panel. If they are separate, then a scheme will be needed to
connect them at the computer. Try connecting the GND for the
microphone first, then plug a headphone into the front headphone
jack. If there is no signal on the headphone jack, it means the
two GND pins do need to be connected to the motherboard. One GND
can go to AGND on the FP_AUDIO header, and the other can be plugged
into a GND pin, on say a USB header which has a pin labelled GND.
HTH,
Paul
