saturnlee@yahoo.com wrote:

> I 've just received a free intel 815 motherboard with onboard sound.
> The board is good except there is buzzing sound(sound like a machine
> gun fires the bullets all the time) from the speaker jack(connect to
> speaker). The sound starts at the POST and does not stop at all.
>
> I swap the speaker, the power supply, reinstall all the compontents
> and put the board on phone board. The problem still persists.
>
> I have couples of sound cards, so putting a new card is not a problem.
>
> I'm just curious of what part of the circuit is causing the problem?

Sounds like either clipped 50/100Hz, or else motorboating. A bad
capacitor could cause either, or a bad audio lead could cause it. It
might be worth unplugging the cd to soundcard lead just in case its the
lead or cd. Another sound card is probably the next easiest thing to
try. There is piggybacking decoupling caps, but its just easier not to
bother. Theres also the poss that the output jack has lost its ground
connection, you could try connecting your speaker ground to the metal
case. But a new sound card will cover most likely problems, and is
simple.


NT