Mark Twain wrote:
I have a Dell XPS 8500, with Windows 7 Professional, SP1,
with Spywareblaster, Malwarebytes, Avast , Windows Defender
and Windows firewall.

(1) TB HD
Intel (R) Core (TM) i7-33-3770 CPU @ 3.40 GHz
Ram 12.0 GB
System type : 64-bit operating system

I also have

I have a Dell Optiplex 780 Tower, with Windows 7 Professional,
SP1, with Spywareblaster, Malwarebytes, Avast , Windows Defender
and Windows firewall.

Intel (R) Core 2 Duo 2.93 GHz
4GB RAM, 750 GB HD
System type : 64-bit operating system

and (external hard drives)

(8500)
WD BLACK SERIES WD2003FZEX 2TB 7200
RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal
Hard Drive

(780)
Seagate Desktop HDD ST2000DM001 2TB 64MB
Cache SATA 6.0Gb/s 3.5"
Internal Hard Drive


The problem concerns the 8500; I have an intermittent problem,
for some reason when I logged on today there's a humming/buzzing
sound coming from the speakers. This has happened several times
recently. I haven't done a thing other than logging on.

I tried restarting and disconnecting and reconnecting the speaker
connections but it doesn't seem to go away until I power off/on.

So what could this be?

Thoughts/suggestions
Robert

Debug by section.

1) Plug headphones into the LineOut Jack of the
8500, where the speakers are currently connected.
Is the headphone sound clean ?

2) Plug a portable source (Sony Walkman, iPod, or similar)
to the speakers. Is the humming and buzzing still there,
with a driven source (that floats with respect to AC) ?
I even have a transistor radio that will serve for this
purpose (an FM radio with a synthesizer tuner).

It's possible the amplified speakers have a leaking cap in
the power supply section. Since you had a "power event" at your
place, and all your gear operated for a time at the wrong
voltage, just about anything could be wrong with it.

But first you want to separate the 8500 from the speakers,
as in (2) and verify the speakers are the author of their
own misfortune.

When my computer speakers acted up, I ended up running
a finger over the solder points inside it, until I found
a solder point that "made a difference" and the sound
started working properly again. I re-soldered that point
(it was a cold solder joint).

Trouble is though, some computer speakers are *glued*
shut, so this is not as easy as it seems. They can be very
hard to open up. I actually used a saw on mine, and sawed a
slot where I could get prying tools jammed into the
seam and used brute strength to separate the
glue. And the speaker still works :-) It no longer
looks all that nice though. I won't be selling it
on Ebay ("slightly used, some scratches").

Paul