Sick sound problems from on-board Soundmax audio (ASUS P4S800D)

Discussion in 'Asus' started by The Berzerker, Sep 23, 2004.

  1. Crazy thing, I go to connect my SPDIF cable to the 5.1 system, and boom...
    the card cuts out, and no audio is heard from anywhere. I eventually solve
    this by randomly leaving the computer alone, and turning it back on later to
    find everything is dandy, and drivers etc can be installed wirthout errors.
    Before finding this simple soultion I tried many things, and even stuck in a
    different hard disk. The audio worked fine on that, so I was confident that
    I hadn't blown anything hardware wise... however... now using my normal HDD
    again, I have EXTREME crackle coming from the speakers. It's definatly not
    the speakers fault, because connecting headphones results in the same thing.
    What on earth is going on?

    I am using the same software, the latest, as I was when it was actually
    working. Interestingly enough, the SPDIF port gives out perfect sound.

    How am I to fix this, please help! Any sound that can be heard is quiet, and
    mainly replaced by crackle etc. Even with no music playing, the speakers are
    often hissing and popping.

    Chris, help help help!
    The Berzerker, Sep 23, 2004
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  2. The Berzerker

    Paul Guest

    I would guess that the sound chip has been damaged by some
    shortcoming of the computer SPDIF interface. It sounds like some
    dangerous potential or current has flowed into the sound chip
    and damaged it. This page is one of my sources of info on SPDIF.

    Some of the circuits on the spdif page are transformer isolated.
    What this does, is avoid grounding problems, or DC problems with
    the receiver at the other end of the line. Here is a sample
    circuit, suitable for converting from a computer sound chip
    output, to drive the cable and SPDIF receiver. No motherboard
    I have looked at yet, has transformer isolation, and is an
    accident waiting to happen.

    +-----| O----+
    | |/ | S/PDIF output
    | | 100nF (RCA or BNC)
    | |\ | || T1
    TTL level signal --+-----| O----+---||----+ +-------+--75R--- center pin
    | |/ | || | | |
    | | )|| | |
    | |\ | 15 )||( 3 220R
    +-----| O----+ turns )||( turns |
    | |/ | )|| | |
    | | | | |
    | |\04 | | +-------+-------- ground
    +-----| 0----+ |
    |/ ---


    I suspect something nasty happened when the SPDIF from your
    computer was connected to the receiver. This is another
    instance where the motherboard doesn't have a sufficiently
    sophisticated interface. (Another example is Firewire, where
    the computer doesn't have proper galvanic isolation, at least
    compared to what chip maker Texas Instruments recommends.)

    When connecting other electrical devices to a computer, a
    conservative approach is to make sure the secondary device
    is powered from the same power strip as the computer. Doing
    so helps to keep the ground potential of all pieces of
    equipment similar. I've drawn sparks and received a shock,
    while bringing the ground of one computer, to the metal
    on a second computer. I've actually measured the potential
    difference between the two computers, and found 50V AC
    between the machines. In that case, there was a problem with
    the safety ground (cut in a distribution bar!).

    If your receiver/decoder/stereo is 50 feet away, and powered
    from another AC circuit, the best advice is to buy an optical
    adapter, and use TOSlink for making the connection. Asus used to
    make adapter brackets to do this, with TOSlink modules on them,
    but I don't know if these are still available any more or not.
    Using an optical link will prevent any kind of electrical calamity
    that seems to have damaged your motherboard.

    I would RMA the motherboard (as the damn thing should have
    been designed better in the first place). Since the computer
    design has no protection against either DC problems or grounding
    problems, I would either convert the computer output via TOSlink
    (adapter bracket or external copper to optical SPDIF box), keeping
    the adapter powered from the same strip as the computer. If your
    receiver doesn't have optical input, then you would need another
    converter box at the receiver, to "armor" its interface. That
    converter should be powered from the same AC power strip as the

    Computer ---SPDIF--Converter--Optical---Converter--SPDIF--Receiver
    | | TOSlink | |
    +---------+--------+ +--------+-------+
    | |
    Wall plug #1 Wall plug #2

    These two devices, at $25 each, can sit at the two ends.
    The optical fiber is potentially the most expensive part, at
    $3 per meter of cable. The cable really shouldn't be that expensive,
    as it is plastic fiber, and not glass like used in long distance
    optical transmission. The TOSLink fiber can be purchased on this
    site as well.

    To repeat, this solution really shouldn't be necessary, but it will
    prevent a similar occurrence in the future, expecially if you leave
    the computer and receiver as they currently sit.

    Paul, Sep 23, 2004
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  3. Hmmmmmm.... found the solution, without the solution.

    Paul kindly explained about the possibilities of the card being damaged...
    but since I had already tested the sound on a different HDD, I was sure it
    couldn't be the case. So, suddenly doubting myself that it even worked when
    I tested it on a different disk, I went to try again. I stick the disk in,
    and by golly, I realise I need a file from the disk I just took out......
    so, connect the original disk back up.... and am amazed when a perfectly
    clean and crisp windows start-up sound plays..... and it's fixed?

    Completely retarded in everyway. I do nothing, and it's fixed. The setup is
    completely as it was before, nothing has changed - yet it works.

    PC's are retards.
    The Berzerker, Sep 23, 2004
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