Soundcard noise?

On 4/12/2017 12:08 PM, Mr. Man-wai Chang wrote:
That's why the article I read suggested isolating the ground pin of the
3.5mm plug from the USB ports.

There's about 3 of those 3.5 mm plugs, as it's a 5.1 system. and they
are all right next to a USB 3.0 plug complex. It's a motherboard sound
card afterall.

Yousuf Khan

On 13/04/2017 06:22, Yousuf Khan wrote:

USB 3.0 plug complex. It's a motherboard sound card afterall.

Yousuf Khan

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--
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On 4/11/2017 1:11 PM, Neil wrote:
Off the top of my head, this implies a few things. It's unlikely that
the full output power that would be applied to the speakers is sent to
the headphones, so the static is probably occurring elsewhere in the
amplifier and the cable between your computer and the speakers is not
the likely source of the static. If so, chances are it would cost more
to repair than to replace.

Think it might be some sort of capacitors?

Yousuf Khan

On 4/10/2017 10:11 AM, KenW wrote:
OK, the speaker power is not being turned off when the computer is
off.
With external powered speakers, noise is either coming from the built
in amplifier or being picked up via the speaker wires. Since there is
still power on, the speaker wires act as an antenna, which means
something in the area could be generating the noise.
Trying to find the cause is really trial and error by unplugging
different electronics in the area.
My guess would be the speaker amplifier or it's power supply.
Get a power strip and turn everything on/off with it. I used to have
my desktops power up with ac power applied. Only one thing to turn the
whole mess on/off.

Interesting idea. Radio interference. This is a 5.1 system, so there are
3 wires (2 subwires per wire) going into the back of the computer.
Should I be removing each one to see if the sound goes away?

Yousuf Khan

Yousuf Khan wrote:
On 4/11/2017 1:11 PM, Neil wrote:
Off the top of my head, this implies a few things. It's unlikely that
the full output power that would be applied to the speakers is sent to
the headphones, so the static is probably occurring elsewhere in the
amplifier and the cable between your computer and the speakers is not
the likely source of the static. If so, chances are it would cost more
to repair than to replace.

Think it might be some sort of capacitors?

Yousuf Khan

A cold solder joint can make a noise like that.

In those cases, it's not the capacitor - it's how
the capacitor is fastened to the board.

http://training.ipc.org/demos/pdf/drm-pth-d.pdf

The PCB in the 2W speakers on this computer, all
the solder joints are defective. They're ball-shaped
and don't have the proper meniscus. It looked like
a hand-soldering job, like you'd get in a $5
AM Transistor radio.

When the speakers made a funny, high pitched, white noise
kind of static sound, I ran a finger-nail over each ball,
until I found one that responded to pressure. Re-soldering
that, fixed it. These speakers remain in usage today, because
that's all it took.

*******

Another item that makes noise like that, is a plug-in-jack,
if something is mechanically damaged, and the right amount
of wiping/contact force is not present. If the jack stack
is damaged, you'd replace it. If a wire is snapped in the cord,
replace the connector with a RadioShack generic, and shorten
the cord and use some "fresh" wire for the connection.

*******

We went through a long era of "electrolytic capacitor plague",
and if you could visually inspect the amplifier PCB for
leaking caps, that might indicate the problem. You could do
that before checking the quality of solder joints on the
bottom of it.

https://en.wikipedia.org/wiki/Capacitor_plague

Caps can fail like that, even when the capacitor is not
under bias. I had an Antec PSU that failed after being
stored in the original cardboard box for two years. It
was initially tested, put back in the box, and was leaking
two years later (on inspection).

Paul

On 4/21/2017 6:04 PM, Yousuf Khan wrote:
On 4/11/2017 1:11 PM, Neil wrote:
Off the top of my head, this implies a few things. It's unlikely that
the full output power that would be applied to the speakers is sent to
the headphones, so the static is probably occurring elsewhere in the
amplifier and the cable between your computer and the speakers is not
the likely source of the static. If so, chances are it would cost more
to repair than to replace.

Think it might be some sort of capacitors?

Yousuf Khan

Hard to say without hearing what the static sounds like. As I see it,
though, it doesn't matter if one lacks the knowledge and experience to
fix it themselves, and even if they do whether the effort is justifiable.

--
best regards,

Neil