Re: Can an electrolytic capacitor "sing"?

From: ohaya (ohaya_at_cox.net)
Date: 03/28/05 

Date: Sun, 27 Mar 2005 22:22:56 -0500

Dave VanHorn wrote:
>
> Parallel plates, very close together, with varying applied field, will have
> a varying attractive force between them. I've heard this at 120 Hz in bridge
> rectifier systems where the cap was overlarge and the diode conduction angle
> was rather narrow.

Hi,

I've got the motherboard completely out of the case now, with the power
supply outside also, and separated with some material to deaden the
sound from the power supply.

After running the motherboard for awhile, I think that I've gotten it to
emanate the sound. It's much lower in volume, probably since it's
outside of the case now.

What I've been doing is to block off area by area with a thick pad of
newspaper, to try to isolate where the sound is coming from, and, I know
that this is going to sound very weird, but it sounds like it's coming
from the CPU itself, or something within the footprint of the CPU.

If I place my 'sound barrier on one side of the CPU, immediately
adjacent to the CPU/heatsink, I can hear the sound (it's actually more
like a 'squealing' sound) from the other side of the CPU. In this case,
the sound is probably coming through the channels between the heatsink
fins.

If I place my sound barrier on the direct opposite side of the
CPU/heatsink, I can't hear the sound.

On the motherboard, around the CPU socket (actually kind of underneath
the edge of the CPU socket, I can see a couple of surface mount ICs and
surface mount resistors or caps, but that's all that's there. I've
tried tapping some of those to see if it affects the sound, but no
change.

So now, I guess I have to change my question: Is it possible for a CPU
chip to "sing" or make this "squealing" sound??

Again, I know that this sounds a bit strange, so my apologies.

Jim

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