Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
hi paul
thanks for your advice i think its defective myself as you say,well the....
spdif.... in the volume control panel.(win xp) is greyed out.
i have reformated a new drive to see if its anything i have put on my pc to
stop it working,well the drive just has win xp on and the asus driver
software the came with the board,and its just the same as when i have my
other drive on,anyway i have phoned the place ware i got it from and thay
want me to bring it in to look at it so do you think i should take the box
and all the bits with me aswell
yours Samantha
"Paul" <nospam@needed.com> wrote in message
news:nospam-2601050514040001@192.168.1.177...
> In article <juzJd.233683$Z7.226293@fe2.news.blueyonder.co.uk>, "Sam"
> <sam1254@hotmail.com> wrote:
>
>> hi
>> can anybody help,got no sound from the spdif output on the board but from
>> the optical.
>> K8N-E DELUXE
>> BIOS,1007.007
>> SANDRASAM
>
> The K8N-E uses the Realtek ALC850.
>
> The Realtek datasheet is in this ZIP file.
>
ftp://210.51.181.211/pc/ac97/alc850/alc850_data3.zip
>
> The Realtek reference schematic is in this ZIP file.
>
ftp://202.65.194.18/pc/ac97/alc850/alc850_a64.zip
>
> Page 4 of ALC_AC97_COLAY_VER_064.pdf from the a64.zip
> file, shows that the SPDIF copper connector and the
> SPDIF optical module (TOTX178 in the diagram), are
> driven from a common signal. If the output of the
> optical module is working, then the copper output should
> work at the same time.
>
> The Realtek datasheet for the chip, shows that the SPDIF
> output driver has a 3.3V signal on it, and it can drive a
> 75 ohm load to ground. This sounds like a very powerful
> driver. The Realtek circuit uses a couple of resistors, to
> attenuate the signal a bit, and match the line impedance.
>
> You should be using 75 ohm coaxial cable, to connect the
> motherboard to the receiver. The coax cable should have
> RCA jacks on the ends, or adapters of some sort, to get
> connected to the coax.
>
> I thought the signal level of SPDIF was pretty low -
>
> Cable: 75ohm +/-5% (l<10m) or 75ohm +/-35% (l>10m)
> * Line driver:
> * Zout: 75ohm +/-20% (100kHz .. 6Mhz)
> * Vout: 0.4Vpp .. 0.6Vpp, <0.05Vdc (75ohm terminated)
> * Line receiver:
> * Zin: 75ohm +/-5%
> * Vin: 0.2Vpp .. 0.6Vpp
>
> I wonder if the Realtek circuit just has too high an
> amplitude ? By my calculation, the Realtek circuit
> will develop a 1Vpp signal at the receiver, which is
> not quite the same as the little blurb I copied above.
>
> I don't know of an easy way to prove there is any signal
> at all on the coax connector. Due to the simplicity of the
> Realtek reference circuit, it is highly unlikely the
> motherboard is defective. I say this, because you have
> got an optical signal from the motherboard, and if it is
> working, there are precious few components between that
> (proven) point in the circuit, and the RCA copper output
> jack. So, maybe your receiver just doesn't like the signal.
> Does the lock indicator make any indication when connected
> to the copper connector ?
>
> If you have a long piece of coax cable handy, try using
> a longer cable. A long cable should attenuate the signal
> somewhat.
>
> Paul
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