continuous beep after power surge tyan

Discussion in 'Tyan' started by jakobmetzger, May 19, 2011.

  1. jakobmetzger

    jakobmetzger Guest

    I am getting a continuous beep after a power surge on a Thunder K8SD
    Pro (S2882-D) . Everything works fine and I have noticed no actual
    changes within the system like ram/cpu issues while running. Is there
    a way to disable this or reset it somehow?
    jakobmetzger, May 19, 2011
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  2. jakobmetzger

    Paul Guest

    By looking at the manual, I notice the Front Panel Connector (J6)
    has two options for audio notification devices.

    Connecting a speaker between pins 12 and 18, creates a tone
    in the speaker. That implies the SuperI/O or similar,
    provides a tone signal suitable for driving, say, s 32 ohm
    load. Normally, the SuperI/O provides a logic level signal,
    and an external switching transistor switches power from the
    +5V rail on and off, to make a tone in a magnetic speaker.
    The transistor functions as an amplifier, providing enough
    drive for a 32 ohm speaker.

    Connecting a piezoelectric buzzer between pins 16 and 18 is
    an alternative. I take it, that the buzzer generates the
    tone, based on receiving DC power, switched on between pins 16 and
    18. So rather than the motherboard generating a tone, the buzzer
    does that on its own. In that case, the driving transistor stays
    ON or OFF, to achieve tone or no-tone condition.

    Now, let's say your enclosure provides a piezoelectric buzzer,
    and it is always on. It's a relatively simple fault, for the
    power to that buzzer to be jammed in the ON position. There might
    be a damaged interface transistor.

    If you were to disconnect the buzzer, and use a small speaker instead,
    and connect the speaker across 12 and 18, that might still be functional.
    (It would be using a different transistor, which might not be damaged.)
    If that speaker drive transistor were to be damaged, it either stays
    ON or OFF, and no tone is there to continuously annoy you. In the ON
    position, the cone would poke out a bit, and OFF, it would be relaxed.
    But it would stay fixed in one position or the other, if it isn't
    being actively modulated.

    If the fault is inside the SuperI/O, and a register bit to enable
    the generation of a tone is set, then using SPKR pins might still
    result in a tone, but that is a more unlikely fault. If the SuperI/O
    was to be damaged, why stop at one bit. Easier for it to just
    blow up completely, if a surge was applied across the device. So
    I don't buy that as a fault. I feel it's more likely to be
    one of the external transistors which got damaged.

    One thing about piezoelectric devices, is they "work in both directions".
    On the one hand, applying electricity, makes sound. And on the other
    hand, compressing or deflecting the piezo material generates electricity.
    In the case of a hand-held barbecue starter, for a propane barbecue,
    a piezoelectric material in there, generates thousands of volts, and
    strikes an actual spark when mechanically excited. In the case of the
    inverter in the back of an LCD monitor, some of those use piezo material,
    and up to 4000 volts can be created by that material leading to the
    cracking of the piezo (if it's over excited). To do damage to your
    motherboard "buzzer" pins, all that has to happen is a "back potential"
    to come back from that device. It could also be, that whatever surge
    you had, somehow induced current into, or followed along the wire pair
    leading to the device. (Like a fault raising the potential on Safety
    Ground, which is the same potential as the chassis of the computer.)

    In any case, you have two I/O options. My interpretation is, you're using
    a piezo buzzer right now (rather than a piezo or magnetic speaker), and
    changing speaker types may be enough to give you peace and quiet. Take
    note of the PANEL pins you're currently using, and switch to a different
    kind of speaker and put it across the alternative pair of pins.

    The fact you have two options, is quite a feature. None of my motherboards
    have that (ability to drive two kinds of beeper).

    Paul, May 19, 2011
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