Re: Front panel audio problem - asusp4p800 + hp compaq tower

Discussion in 'PC Hardware' started by Paul, May 26, 2007.

  1. Paul

    Paul Guest

    wolf7878 wrote:
    > Hi all,
    > My problem is:
    > I changed my chassis to a hp compaq dc7600 tower and now the front
    > panel audio is not working correctly: only the headphones working the
    > mic is not. If anyone can help how to change the wiring to work the
    > mic, I tried several way. I attached an image, on the left side with
    > the case wiring (more precisely it is the connector of the old
    > motherboard from the case), and on the right side is the asus mobo
    > connectors.
    > Thanks in advance.
    > Regards, Wolf
    >
    > http://img152.imageshack.us/img152/6726/frontaudioqa4.jpg
    >


    I would use a multimeter and verify the names on the HP
    side. In particular, I don't like the mention of "sleeve"
    on pin 3.

    The three contacts on a 1/8" stereo miniplug are:

    Tip, Ring, Sleeve.

    With an AC'97 microphone, connector signals are

    Mic-In, Mic-PWR, Ground

    The headphone jack would be

    Left-Out, Right-Out, Ground

    The signals on the Asus pin 1 and pin 3 are
    MIC2 and MICPWR, and they should go to Tip and Ring
    respectively. For some reason, the HP has "sleeve",
    which would be the ground on the connector. So I'd
    want to check and see if they really did that or
    that is a typo.

    Paul
     
    Paul, May 26, 2007
    #1
    1. Advertisements

  2. Paul

    Paul Guest

    wrote:
    > Hi Paul,
    >
    > So here are the wires from the hp side (I checked with a multimeter):
    >
    > 1 - black (thin) -> mic tip
    > 2 - black (thick) -> mic and headphone sleeve
    > 3 - white -> mic ring
    > 4 - nc
    > 5 - red -> headphone ring
    > 6 - green
    > 7 - black (thick) -> mic and headphone sleeve
    > 8 - nc
    > 9 - yellow -> headphone tip
    > 10 - blue (btw. it is marked as nc!)
    >
    > The two black (thick) wires (2 and 7) are grounded together.
    >
    > Any idea?
    >
    > Thank you in advance.
    >
    > Regards, Wolf
    >
    > Paul írta:
    >> I would use a multimeter and verify the names on the HP
    >> side. In particular, I don't like the mention of "sleeve"
    >> on pin 3.
    >>
    >> The three contacts on a 1/8" stereo miniplug are:
    >>
    >> Tip, Ring, Sleeve.
    >>
    >> With an AC'97 microphone, connector signals are
    >>
    >> Mic-In, Mic-PWR, Ground
    >>
    >> The headphone jack would be
    >>
    >> Left-Out, Right-Out, Ground
    >>
    >> The signals on the Asus pin 1 and pin 3 are
    >> MIC2 and MICPWR, and they should go to Tip and Ring
    >> respectively. For some reason, the HP has "sleeve",
    >> which would be the ground on the connector. So I'd
    >> want to check and see if they really did that or
    >> that is a typo.
    >>
    >> Paul

    >


    FP_AUDIO header on the P4P800 (copied from your picture).

    1 2
    MIC2 x x AGND
    MICPWR x x +5VA
    Line_out_R x x BLINE_OUT_R
    NC x
    Line_out_L x x BLINE_OUT_L
    9 10

    Your HP wiring looks like this -

    Tip, Ring, Sleeve
    Microphone MIC2, MICPWR, AGND
    Headphone Line_out_L, Line_out_R, AGND

    black thin MIC2 x x AGND black thick (MIC sleeve)
    white MICPWR x x (NC)
    red Line_out_R x x green
    black thick AGND x nc?
    yellow Line_out_L x x blue NC?

    MIC TIP x x MIC SLEEVE, HEADPHONE SLEEVE
    MIC RING x x (NC)
    HEADPHONE RING x x
    x
    HEADPHONE TIP x x

    Your original complaint was that the microphone was
    not working. Yet, the microphone tip, ring, and sleeve
    seem to be connected to the correct pins. In fact,
    the wiring is consistent with an AC'97 header (the AGND
    on pin 7 isn't, but shouldn't matter).

    The blue and green, are supposed to be returning analog
    signals from the headphone jack. They are intended to
    support a "muting" function on Lineout on the back of the
    computer. In theory, when a headphone plugs in, red (5) to
    green (6) would be open circuit, yellow (9) to blue (10)
    would be open circuit. When the headphones are not
    plugged in, switch contacts are supposed to connect red to
    green, and yellow to blue. The switch contacts make the
    Lineout work, when no headphones are present. And when
    headphones are installed, then no signal is sent to Lineout.
    That is what gives the muting function for AC'97. Cheaper
    cases don't have the switch feature, and may leave (5) to (6)
    shorted, and (9) to (10) shorted on the case side.

    I would check carefully again, what relationship there is
    between pins 1, 2, and 3 of your HP wiring. Using the ohmmeter
    on a high range, there should be no connection between pin 1,
    2, and 3. If you were using an electret microphone, it would
    take power from pin 2. If pin 2 is being loaded, and pulled
    down, that would stop the electret from working. So I'd be curious
    as to what is up, between pins 1, 2, and 3.

    Did the wiring ever work ? Was there ever a working
    microphone with the original HP setup ?

    Paul
     
    Paul, Jun 12, 2007
    #2
    1. Advertisements

  3. Paul

    Paul Guest

    Paul wrote:

    > If you were using an electret microphone, it would
    > take power from pin 2. If pin 2 is being loaded, and pulled
    > down, that would stop the electret from working.
    >


    That should have been pin 3. The electret takes power from pin 3,
    which is MICPWR. MICPWR should be somewhere between 3 to 5 volts
    or so, with a 2K ohm series resistor. Electret microphones vary,
    as to how much voltage they need at a minimum.

    To test that your microphone works with your P4P800, test the
    microphone using the jack on the back of the computer first.
    If your microphone is an electret, the same MICPWR should be
    available to you on the rear microphone connection.

    In the sound control panel, sometimes there is a hidden
    setting, to switch between MIC1 and MIC2. Make sure that you
    have selected the right microphone, when doing your testing.

    Note the "Advanced" button below the Microphone setting. When
    you click that, there should be a selector for MIC1 or MIC2.
    I couldn't find a picture of the Advanced dialog...

    http://forms.analog.com/Form_Pages/soundMax/images/mixer3.GIF

    Paul
     
    Paul, Jun 12, 2007
    #3
  4. Paul

    Paul Guest

    wrote:
    > Hi Paul,
    >
    > Thank you for your kind assistance again.
    > The same headphone-mic pair perfectly working with the rear panel
    > connectors (so I think on the mobo side everything is ok). Beside this
    > when I plug the mic and headphone to the rear or even to the front
    > connectors, the soundmax program automatically detect the devices and
    > offer the configuration of them. If I use the rear panel and I choose
    > this configuration step both device work perfectly. If I use the front
    > panel and I choose this configuration step only the headphone working,
    > at the testing of the mic it says no siglnal on the mic.
    >
    > Regards, Wolf
    >


    Ok, your next test is a simple one.

    Pull the HP wiring harness from the FP_audio header.

    Using your finger, touch the MIC2 (pin 1) pin. If the microphone
    circuit is working, you should pick you some "hum" in your computer
    speakers. (Turn the volume down on the speakers first, then bring it
    up gradually, so you don't blow out an eardrum.)

    The purpose of doing this, is to see if the MIC2 still works or not.

    With the HP wiring harness in place, take a 1/8" to 1/8" male to
    male audio cable. Plug it to the microphone jack on the front of
    the computer. Touch your finger to the tip of the exposed 1/8"
    plug. Is the hum picked up ?

    You could also do testing like this, by connecting a line level
    audio source to the microphone jack. But the hum test is a bit
    safer, as there is no risk to your line level audio device.

    If you can pick up hum, then the next step is verifying the electret
    voltage on the microphone ring contact. Assuming the mic is in fact
    an electret, and not a piezo or a dynamic (magnet plus coil) microphone.

    There is some trivial on microphone powering here. "Sound Blaster way"
    describes what is typical on AC'97.

    http://www.epanorama.net/circuits/microphone_powering.html

    Paul
     
    Paul, Jun 13, 2007
    #4
    1. Advertisements

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Synapse Syndrome

    Re: Help wiring front panel audio please

    Synapse Syndrome, Mar 11, 2007, in forum: DIY Computers
    Replies:
    4
    Views:
    1,220
    Trevor Best
    Mar 13, 2007
  2. db

    Front Panel Audio Connections?

    db, Sep 19, 2003, in forum: PC Hardware
    Replies:
    1
    Views:
    389
  3. Alex
    Replies:
    0
    Views:
    380
  4. Ralph Wade Phillips

    Re: Case front panel audio connectors - Help

    Ralph Wade Phillips, Dec 14, 2003, in forum: PC Hardware
    Replies:
    4
    Views:
    362
    Gary Tait
    Dec 15, 2003
  5. McVagh
    Replies:
    3
    Views:
    272
    pcbldrNinetyEight
    Jan 22, 2008
Loading...

Share This Page