Okay, perhaps I'm being a bit picky, but here's the scoop:

I find a lot of switchers are audibly noisy. That is, they emit a 'hiss'
noise from their circuitry. Some units are barely audible, others are
distractingly loud. (yes, I know some people can't hear 'em at all, but
my wife and I certainly can, which is why there are a few toggle
switches inserted on the ac lead of a couple of our 'not often used'
appliances.)

I just bought a new PS-125 to go with my IC-756ProII, and the PSU works
well, but wow it hisses like a leaky bicycle tire! (The DC is pure and
clean, I'm referring to the audible hissing emanating from within the case.)

Is there a common offending component, such as a loose coil form or
winding into which I may drizzle a wee bit of krazy glue? Or did I get
unlucky with one particular unit and everyone else here has a nice quiet
PSU that silently sits there (until of course the internal fan fires up,
but that's quite tolerable.)

So, fixable (as in 'they all do that'), or exchange the darn thing (as
in 'most of them are very quiet') ??


If anyone could share some experience here on this one, I'd be most
grateful.

Thanks!
Bob.

Could it be the internal fan running?

73,
Ed KA9EES


"Bob" wrote in message
.. .
Okay, perhaps I'm being a bit picky, but here's the scoop:

I find a lot of switchers are audibly noisy. That is, they emit a 'hiss'
noise from their circuitry. Some units are barely audible, others are

No, it's not the fan, it's the oscillator I'm hearing, but I don't know
what components are doing the vibrating. The fan fires up occasionally,
but that noise is entirely different.

Thanks for the response.
B.




Edward L. Dowdy wrote:
Could it be the internal fan running?

73,
Ed KA9EES


"Bob" wrote in message
.. .

Okay, perhaps I'm being a bit picky, but here's the scoop:

I find a lot of switchers are audibly noisy. That is, they emit a 'hiss'
noise from their circuitry. Some units are barely audible, others are

No, it's not the fan, it's the oscillator I'm hearing, but I don't know
what components are doing the vibrating. The fan fires up occasionally,
but that noise is entirely different.

I've heard switching PSUs begin to hiss when the electrolytic filter
capacitors start to fail. These caps are in a stressful operating
environment - high ripple currents, and sometimes high temperatures.
They can dry out or leak (this is a particular problem with a whole
batch of Taiwanese-made caps which were manufactured with a defective
electrolyte formula), their ESR increases, and the circuit becomes
audibly noisy. I don't know whether the noise is direct microphonics
from the caps, or from the toroids.

Consider swapping out any suspect 'lytics in the supply with new ones,
preferably ones rated for switching-supply operation at 105 degree C.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

It was hissing right out of the box, it's brand new.
I don't suspect so much that it's defective, I hear a lot of switchers,
it's almost as if there's a couple of popular frequencies, and I happen
to be able to hear one of them. If I knew what section is resonating
(physically vibrating and transducing the sound that is) I could try to
drizzle a bit of super glue on it.

B.




Dave Platt wrote:


I've heard switching PSUs begin to hiss when the electrolytic filter
capacitors start to fail. These caps are in a stressful operating
environment - high ripple currents, and sometimes high temperatures.
They can dry out or leak (this is a particular problem with a whole
batch of Taiwanese-made caps which were manufactured with a defective
electrolyte formula), their ESR increases, and the circuit becomes
audibly noisy. I don't know whether the noise is direct microphonics
from the caps, or from the toroids.

Consider swapping out any suspect 'lytics in the supply with new ones,
preferably ones rated for switching-supply operation at 105 degree C.

On Mon, 07 Jun 2004 08:25:47 -0400, Bob wrote:

If I knew what section is resonating
(physically vibrating and transducing the sound that is) I could try to
drizzle a bit of super glue on it.

B.

You could always poke around inside with an insulated probe to shut
down the oscillating/vibrating component, and go from there.

Bob
k5qwg

On Mon, 07 Jun 2004 08:25:47 -0400, Bob wrote:

If I knew what section is resonating
(physically vibrating and transducing the sound that is) I could try to
drizzle a bit of super glue on it.

B.

You could always poke around inside with an insulated probe to shut
down the oscillating/vibrating component, and go from there.

Bob
k5qwg

It was hissing right out of the box, it's brand new.
I don't suspect so much that it's defective, I hear a lot of switchers,
it's almost as if there's a couple of popular frequencies, and I happen
to be able to hear one of them. If I knew what section is resonating
(physically vibrating and transducing the sound that is) I could try to
drizzle a bit of super glue on it.

B.




Dave Platt wrote:


I've heard switching PSUs begin to hiss when the electrolytic filter
capacitors start to fail. These caps are in a stressful operating
environment - high ripple currents, and sometimes high temperatures.
They can dry out or leak (this is a particular problem with a whole
batch of Taiwanese-made caps which were manufactured with a defective
electrolyte formula), their ESR increases, and the circuit becomes
audibly noisy. I don't know whether the noise is direct microphonics
from the caps, or from the toroids.

Consider swapping out any suspect 'lytics in the supply with new ones,
preferably ones rated for switching-supply operation at 105 degree C.

No, it's not the fan, it's the oscillator I'm hearing, but I don't know
what components are doing the vibrating. The fan fires up occasionally,
but that noise is entirely different.

I've heard switching PSUs begin to hiss when the electrolytic filter
capacitors start to fail. These caps are in a stressful operating
environment - high ripple currents, and sometimes high temperatures.
They can dry out or leak (this is a particular problem with a whole
batch of Taiwanese-made caps which were manufactured with a defective
electrolyte formula), their ESR increases, and the circuit becomes
audibly noisy. I don't know whether the noise is direct microphonics
from the caps, or from the toroids.

Consider swapping out any suspect 'lytics in the supply with new ones,
preferably ones rated for switching-supply operation at 105 degree C.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

No, it's not the fan, it's the oscillator I'm hearing, but I don't know
what components are doing the vibrating. The fan fires up occasionally,
but that noise is entirely different.

Thanks for the response.
B.




Edward L. Dowdy wrote:
Could it be the internal fan running?

73,
Ed KA9EES


"Bob" wrote in message
.. .

Okay, perhaps I'm being a bit picky, but here's the scoop:

I find a lot of switchers are audibly noisy. That is, they emit a 'hiss'
noise from their circuitry. Some units are barely audible, others are