A7N8X Deluxe Mobo SOund - One Channel dead

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

Is the fix to just pop in a real sound card ? I assume I can disable
the mobo sound in the CMOS, somehow.

One channel of the mobo sound output jack on my A7N8X Deluxe has gone
out. The volume control applet shows that all the balance controls
are centered. A reboot doesn't fix anything.

When I slide the balance control to one extreme I hear _nothing_. In
the other direction I get full level audio in one ear.

I've tried a couple pair of headsets and the effect is the same. I
wiggled the jack and don't get any intermittant connection. I have
this output jacked into the HiFi system fill time, so it doesn't get
many insertion cycles. Even if it was the jack I don't think
it can be fixed.

Any suggestions ?


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a d y k e s @ p a n i x . c o m
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2 answers Last reply
More about a7n8x deluxe mobo sound channel dead
  1. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    In article <cp00kn$gbl$1@panix5.panix.com>, adykes@panix.com (Al Dykes) wrote:

    > Is the fix to just pop in a real sound card ? I assume I can disable
    > the mobo sound in the CMOS, somehow.
    >
    > One channel of the mobo sound output jack on my A7N8X Deluxe has gone
    > out. The volume control applet shows that all the balance controls
    > are centered. A reboot doesn't fix anything.
    >
    > When I slide the balance control to one extreme I hear _nothing_. In
    > the other direction I get full level audio in one ear.
    >
    > I've tried a couple pair of headsets and the effect is the same. I
    > wiggled the jack and don't get any intermittant connection. I have
    > this output jacked into the HiFi system fill time, so it doesn't get
    > many insertion cycles. Even if it was the jack I don't think
    > it can be fixed.
    >
    > Any suggestions ?

    All the outputs are capacitively coupled. About all you can do
    from a diagnostic point of view, is monitor the output right at
    the chip pins itself, for debugging purposes. In the reference
    schematic, I don't think there is anything hanging off the Lineout
    left and right signals (no sharing circuit):

    http://www.realtek.com.tw/downloads/downloads1-3.aspx?refdesign=True&compamodel=ALC650

    Best site for download - 2MB
    ftp://202.65.194.18/pc/ac97/alc650/alc650_data5.zip

    Unzip file, then unzip ALC650_DEMO_CIRCUIT_VER_11.zip, to
    find alc650_demo_circuit_ver_11.pdf

    So, things to check.

    1) Something grounding to the bottom of the board ? Some of the
    A7N8X family boards use 9 standoffs, and your cases may have had
    10 standoffs screwed into them. The extra standoff can short to
    some of the audio circuit.

    2) Check the FPAUDIO header. Jumpers sometimes corrode. Remove the
    two jumper plugs and reinstall them in their original location.
    That little bit of scraping, may improve the contact of the
    shorting jumpers.

    3) If using front panel headphone jack, remove wiring assembly from
    FPAUDIO, and put the two jumpers back. See if Lineout returns, in
    which case, the problem is with the front panel wiring.

    4) When all else fails, examine the demo_circuit above. Line-L and
    Line-R are pins 23 and 24. With no audio output signal applied,
    the DC level on the pins should sit at mid-rail (i.e. the output
    is driven by a DAC, and code point 0x0 should be a voltage between
    VDD and VSS, perhaps 2.5V. To work, the quiet voltage cannot get
    too close to the rails, or the signal will be clipped). Compare
    the reading on pin 23 and 24 for similarity, as much as anything.
    You can also flip the meter to AC volts, and take a measurement
    for both channels. Next, take a recording of a stereo 1KHz test
    tone, and play in on Lineout at full volume. Probe with meter
    again, and see if the AC reading on both channels is the same.
    The output is supposed to be 1Vrms or so, and a typical cheap
    multimeter when set on AC, will read the combined total of the
    AC and DC components (and I'm not even going to guess what the
    reading will be). If, again, both channels read the same, higher
    value, then you know the chip isn't blown.

    Note: The pins are extremely tiny, and chips with these tiny
    pins cannot take a lot of probing. I use needle points on my
    multimeter, for circuits like this. If you probe too much, you
    run the risk of scraping solder off one pin and onto a neighbour,
    or bending the IC pins. You really need to work with the board
    outside the case, and use a good magnifier on a stand, to be
    able to probe safely. I don't really consider this step of
    debugging to be that practical (I probably would be throwing
    in the towel at this point, rather than wasting time pulling
    the board etc.)

    5) In demo_circuit, page 4, upper left hand corner, the ref
    design shows the inclusion of room for serial resistors. So,
    that makes the audio path: chip, series 1uf capacitor, series
    resistor (could be a zero ohm shunt), FPAUDIO header jumper
    plugs or front panel audio wiring, then back through the
    circuit board, to the Lineout jack on the back.

    There is an "onboard AC97 audio controller" in the BIOS, and you
    can disable that if you want. Check Google to see if anyone has
    had problems with installing a third party sound card on the
    board. I don't remember any posted problems with that.

    HTH,
    Paul
  2. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    In article <nospam-0512042136260001@192.168.1.177>,
    Paul <nospam@needed.com> wrote:
    >In article <cp00kn$gbl$1@panix5.panix.com>, adykes@panix.com (Al Dykes) wrote:
    >
    >> Is the fix to just pop in a real sound card ? I assume I can disable
    >> the mobo sound in the CMOS, somehow.
    >>
    >> One channel of the mobo sound output jack on my A7N8X Deluxe has gone
    >> out. The volume control applet shows that all the balance controls
    >> are centered. A reboot doesn't fix anything.
    >>
    >> When I slide the balance control to one extreme I hear _nothing_. In
    >> the other direction I get full level audio in one ear.
    >>
    >> I've tried a couple pair of headsets and the effect is the same. I
    >> wiggled the jack and don't get any intermittant connection. I have
    >> this output jacked into the HiFi system fill time, so it doesn't get
    >> many insertion cycles. Even if it was the jack I don't think
    >> it can be fixed.
    >>
    >> Any suggestions ?
    >
    >All the outputs are capacitively coupled. About all you can do
    >from a diagnostic point of view, is monitor the output right at
    >the chip pins itself, for debugging purposes. In the reference
    >schematic, I don't think there is anything hanging off the Lineout
    >left and right signals (no sharing circuit):
    >
    >http://www.realtek.com.tw/downloads/downloads1-3.aspx?refdesign=True&compamodel=ALC650
    >
    >Best site for download - 2MB
    >ftp://202.65.194.18/pc/ac97/alc650/alc650_data5.zip
    >
    >Unzip file, then unzip ALC650_DEMO_CIRCUIT_VER_11.zip, to
    >find alc650_demo_circuit_ver_11.pdf
    >
    >So, things to check.
    >
    >1) Something grounding to the bottom of the board ? Some of the
    > A7N8X family boards use 9 standoffs, and your cases may have had
    > 10 standoffs screwed into them. The extra standoff can short to
    > some of the audio circuit.
    >
    >2) Check the FPAUDIO header. Jumpers sometimes corrode. Remove the
    > two jumper plugs and reinstall them in their original location.
    > That little bit of scraping, may improve the contact of the
    > shorting jumpers.
    >
    >3) If using front panel headphone jack, remove wiring assembly from
    > FPAUDIO, and put the two jumpers back. See if Lineout returns, in
    > which case, the problem is with the front panel wiring.
    >
    >4) When all else fails, examine the demo_circuit above. Line-L and
    > Line-R are pins 23 and 24. With no audio output signal applied,
    > the DC level on the pins should sit at mid-rail (i.e. the output
    > is driven by a DAC, and code point 0x0 should be a voltage between
    > VDD and VSS, perhaps 2.5V. To work, the quiet voltage cannot get
    > too close to the rails, or the signal will be clipped). Compare
    > the reading on pin 23 and 24 for similarity, as much as anything.
    > You can also flip the meter to AC volts, and take a measurement
    > for both channels. Next, take a recording of a stereo 1KHz test
    > tone, and play in on Lineout at full volume. Probe with meter
    > again, and see if the AC reading on both channels is the same.
    > The output is supposed to be 1Vrms or so, and a typical cheap
    > multimeter when set on AC, will read the combined total of the
    > AC and DC components (and I'm not even going to guess what the
    > reading will be). If, again, both channels read the same, higher
    > value, then you know the chip isn't blown.
    >
    > Note: The pins are extremely tiny, and chips with these tiny
    > pins cannot take a lot of probing. I use needle points on my
    > multimeter, for circuits like this. If you probe too much, you
    > run the risk of scraping solder off one pin and onto a neighbour,
    > or bending the IC pins. You really need to work with the board
    > outside the case, and use a good magnifier on a stand, to be
    > able to probe safely. I don't really consider this step of
    > debugging to be that practical (I probably would be throwing
    > in the towel at this point, rather than wasting time pulling
    > the board etc.)
    >
    >5) In demo_circuit, page 4, upper left hand corner, the ref
    > design shows the inclusion of room for serial resistors. So,
    > that makes the audio path: chip, series 1uf capacitor, series
    > resistor (could be a zero ohm shunt), FPAUDIO header jumper
    > plugs or front panel audio wiring, then back through the
    > circuit board, to the Lineout jack on the back.
    >
    >There is an "onboard AC97 audio controller" in the BIOS, and you
    >can disable that if you want. Check Google to see if anyone has
    >had problems with installing a third party sound card on the
    >board. I don't remember any posted problems with that.
    >
    >HTH,
    > Paul


    Thanks for the thoughtful response. I hadn't though
    of chassis grounds.

    --
    a d y k e s @ p a n i x . c o m
    ----
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